Publications by authors named "Keith M Diaz"

83 Publications

Objectively Measured Physical Activity and Sedentary Time Among Adults With and Without Stroke: A National Cohort Study.

Stroke 2021 Nov 27;52(11):e729-e732. Epub 2021 Sep 27.

Center for Behavioral Cardiovascular Health, Columbia University Irving Medical Center, New York, NY (A.T.D., K.M.D.).

[Figure: see text].
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http://dx.doi.org/10.1161/STROKEAHA.121.034194DOI Listing
November 2021

Joint association between accelerometry-measured daily combination of time spent in physical activity, sedentary behaviour and sleep and all-cause mortality: a pooled analysis of six prospective cohorts using compositional analysis.

Br J Sports Med 2021 Nov 18;55(22):1277-1285. Epub 2021 May 18.

School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK.

Objective: To examine the joint associations of daily time spent in different intensities of physical activity, sedentary behaviour and sleep with all-cause mortality.

Methods: Federated pooled analysis of six prospective cohorts with device-measured time spent in different intensities of physical activity, sedentary behaviour and sleep following a standardised compositional Cox regression analysis.

Participants: 130 239 people from general population samples of adults (average age 54 years) from the UK, USA and Sweden.

Main Outcome: All-cause mortality (follow-up 4.3-14.5 years).

Results: Studies using wrist and hip accelerometer provided statistically different results (I=92.2%, Q-test p<0.001). There was no association between duration of sleep and all-cause mortality, HR=0.96 (95% CI 0.67 to 1.12). The proportion of time spent in moderate to vigorous physical activity was significantly associated with lower risk of all-cause mortality (HR=0.63 (95% CI 0.55 to 0.71) wrist; HR=0.93 (95% CI 0.87 to 0.98) hip). A significant association for the ratio of time spent in light physical activity and sedentary time was only found in hip accelerometer-based studies (HR=0.5, 95% CI 0.42 to 0.62). In studies based on hip accelerometer, the association between moderate to vigorous physical activity and mortality was modified by the balance of time spent in light physical activity and sedentary time.

Conclusion: This federated analysis shows a joint dose-response association between the daily balance of time spent in physical activity of different intensities and sedentary behaviour with all-cause mortality, while sleep duration does not appear to be significant. The strongest association is with time spent in moderate to vigorous physical activity, but it is modified by the balance of time spent in light physical activity relative to sedentary behaviour.
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http://dx.doi.org/10.1136/bjsports-2020-102345DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8543228PMC
November 2021

Associations Between Habitual Sedentary Behavior and Endothelial Cell Health.

Transl J Am Coll Sports Med 2020 ;5(12)

Center for Behavioral Cardiovascular Health, Columbia University Irving Medical Center, 622 W. 168 Street, New York, NY, 10032, United States.

Endothelial dysfunction is a mechanism that may explain the link between prolonged sedentary time and cardiovascular disease. However, the relation between habitual sedentary behavior (SED) and endothelial function has yet to be explored.

Purpose-: The purpose of this study was to examine the association of accelerometer-measured SED with markers of endothelial cell health.

Methods-: Healthy adult participants (n=83; 43.4% male; 25.5 ± 5.8 years old) were examined. SED was measured for 7-days by accelerometer. Endothelial function measures included endothelium-dependent vasodilation (EDV); endothelial microparticles (EMPs) [CD62E+ and CD31+/CD42- EMPs]; and endothelial progenitor cells (EPCs) [CD34+/CD133+/KDR+ and CD34+/KDR+EPCs]. Participants were classified as having low or high SED based on a median split.

Results-: Participants in the low and high SED group spent a mean ± SD of 8.6 ± 1.1 and 11.1 ± 1.0 h/day in SED, respectively. No significant differences between the low and high SED groups were detected in mean [95% confidence interval (CI)] EDV (2.51 [2.21-2.81] vs. 2.36 [2.07-2.64], =0.50), EMPs (CD62E+: 6.70 [6.55-6.84] vs. 6.56 [6.42-6.69], =0.20; CD31+/CD42‒: 6.26 [6.10-6.42] vs. 6.18 [6.03-6.33], =0.50), or EPCs (CD34+/KDR+: 11.91 [9.23-14.48]×10 vs. 14.87 [12.41-17.32]×10, =0.13); CD34+/CD133+/KDR+: 1.84 [1.28-2.39]×10 vs. 2.17 [1.64-2.70]×10, =0.43).

Conclusions-: Among healthy adults, habitual SED was not associated with markers of endothelial cell health.
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http://dx.doi.org/10.1249/tjx.0000000000000138DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8087243PMC
January 2020

Long-Term Air Pollution and Blood Pressure in an African American Cohort: the Jackson Heart Study.

Am J Prev Med 2021 03 19;60(3):397-405. Epub 2021 Jan 19.

Department of Mathematics and Statistics, University of West Florida, Pensacola, Florida.

Introduction: African Americans are disproportionately affected by high blood pressure, which may be associated with exposure to air pollutants, such as fine particulate matter and ozone.

Methods: Among African American Jackson Heart Study participants, this study examined associations between 1-year and 3-year mean fine particulate matter and ozone concentrations with prevalent and incident hypertension at Visits 1 (2000-2004, n=5,191) and 2 (2005-2008, n=4,105) using log binomial regression. Investigators examined associations with systolic blood pressure, diastolic blood pressure, pulse pressure, and mean arterial pressure using linear regression and hierarchical linear models, adjusting for sociodemographic, behavioral, and clinical characteristics. Analyses were conducted in 2017-2019.

Results: No associations were observed between fine particulate matter or ozone concentration and prevalent or incident hypertension. In linear models, an IQR increase in 1-year ozone concentration was associated with 0.67 mmHg higher systolic blood pressure (95% CI=0.27, 1.06), 0.42 mmHg higher diastolic blood pressure (95% CI=0.20, 0.63), and 0.50 mmHg higher mean arterial pressure (95% CI=0.26, 0.74). In hierarchical models, fine particulate matter was inversely associated with systolic blood pressure (-0.72, 95% CI= -1.31, -0.13), diastolic blood pressure (-0.69, 95% CI= -1.02, -0.36), and mean arterial pressure (-0.71, 95% CI= -1.08, -0.33). Attenuated associations were observed with 1-year concentrations and at Visit 1.

Conclusions: Positive associations were observed between ozone and systolic blood pressure, diastolic blood pressure, and mean arterial pressure, and inverse associations between fine particulate matter and systolic blood pressure, diastolic blood pressure, and mean arterial pressure in an African American population with high (56%) prevalence of hypertension. Effect sizes were small and may not be clinically relevant.
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http://dx.doi.org/10.1016/j.amepre.2020.10.023DOI Listing
March 2021

Joint associations of occupational standing and occupational exertion with musculoskeletal symptoms in a US national sample.

Occup Environ Med 2020 Dec 30. Epub 2020 Dec 30.

Center for Behavioral Cardiovascular Health, Columbia University Medical Center, New York, New Yok, USA

Objective: Observational studies have linked occupational standing or walking to musculoskeletal pain. These prior studies, however, are flawed as few accounted for physical exertion; a potential confounder that accompanies many standing-based occupations. The purpose of this study was to examine the individual and joint associations of occupational standing/walking and exertion with musculoskeletal symptoms.

Methods: Data for this analysis come from the 2015 National Health Interview Survey, a US nationally representative survey. Occupational standing/walking and exertion were assessed by self-report on a 5-point Likert scale. The presence of musculoskeletal symptoms (pain, aching and stiffness) for upper extremities (neck, shoulders, elbows, wrists and fingers), lower extremities (hips, knees, ankles and toes) and lower back was also assessed.

Results: Occupational standing/walking was associated with a greater likelihood of upper extremity, lower extremity and lower back musculoskeletal symptoms; however, associations were attenuated and no longer significant with adjustment for exertion. When stratified by levels of occupational exertion, occupational standing/walking was associated with musculoskeletal symptoms only among the group with high exertion (eg, OR=1.69 (95% CI: 1.48 to 1.94) for lower back symptoms comparing high/high for standing or walking/exertion vs low/low). Among groups with low exertion, occupational standing/walking was not associated with musculoskeletal symptoms (eg, OR=1.00 (95% CI: 0.85 to 1.16) for lower back symptoms comparing high/low for standing or walking/exertion vs low/low).

Conclusion: Results from this US representative survey suggest that the association between occupational standing/walking and musculoskeletal symptoms is largely driven by the co-occurrence of occupational exertion and does not provide evidence that standing or walking incurs adverse musculoskeletal symptoms.
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http://dx.doi.org/10.1136/oemed-2020-106911DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8243382PMC
December 2020

Joint associations of accelero-meter measured physical activity and sedentary time with all-cause mortality: a harmonised meta-analysis in more than 44 000 middle-aged and older individuals.

Br J Sports Med 2020 Dec;54(24):1499-1506

Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.

Objectives: To examine the joint associations of accelerometer-measured physical activity and sedentary time with all-cause mortality.

Methods: We conducted a harmonised meta-analysis including nine prospective cohort studies from four countries. 44 370 men and women were followed for 4.0 to 14.5 years during which 3451 participants died (7.8% mortality rate). Associations between different combinations of moderate-to-vigorous intensity physical activity (MVPA) and sedentary time were analysed at study level using Cox proportional hazards regression analysis and summarised using random effects meta-analysis.

Results: Across cohorts, the average time spent sedentary ranged from 8.5 hours/day to 10.5 hours/day and 8 min/day to 35 min/day for MVPA. Compared with the referent group (highest physical activity/lowest sedentary time), the risk of death increased with lower levels of MVPA and greater amounts of sedentary time. Among those in the highest third of MVPA, the risk of death was not statistically different from the referent for those in the middle (16%; 95% CI 0.87% to 1.54%) and highest (40%; 95% CI 0.87% to 2.26%) thirds of sedentary time. Those in the lowest third of MVPA had a greater risk of death in all combinations with sedentary time; 65% (95% CI 1.25% to 2.19%), 65% (95% CI 1.24% to 2.21%) and 263% (95% CI 1.93% to 3.57%), respectively.

Conclusion: Higher sedentary time is associated with higher mortality in less active individuals when measured by accelerometry. About 30-40 min of MVPA per day attenuate the association between sedentary time and risk of death, which is lower than previous estimates from self-reported data.
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http://dx.doi.org/10.1136/bjsports-2020-103270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7719907PMC
December 2020

Possible Reverse Causation and Confounding in Study of the Association of Sedentary Behavior With Cancer Mortality-Reply.

JAMA Oncol 2021 Jan;7(1):139-140

Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston.

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http://dx.doi.org/10.1001/jamaoncol.2020.5877DOI Listing
January 2021

Occupational standing and change in the Ankle-Brachial Index: the Jackson Heart Study.

Occup Environ Med 2020 Nov 3. Epub 2020 Nov 3.

Center for Behavioral Cardiovascular Health, Columbia University Medical Center, New York City, New York, USA

Background: A growing interest in reducing occupational sitting has resulted in public health efforts to encourage intermittent standing in workplaces. However, concerns have been raised that standing for prolonged periods may expose individuals to new health hazards, including lower limb atherosclerosis. These concerns have yet to be corroborated or refuted. The purpose of this study was to investigate the association between occupational standing and adverse changes in the Ankle-Brachial Index (ABI).

Methods: We studied 2121 participants from the Jackson Heart Study, a single-site community-based study of African-Americans residing in Jackson, MS. Occupational standing ('never/seldom', 'sometimes', 'often/always') was self-reported at baseline (2000-2004). ABI was measured at baseline and again at follow-up (2009-2013).

Results: Over a median follow-up of 8 years, 247 participants (11.6%) exhibited a significant decline in ABI (eg, ABI decline >0.15). In multivariable-adjusted models, higher occupational standing was not significantly associated with ABI decline (occupational standing sometimes vs never/seldom: OR 1.05; 95% CI 0.67, 1.66; occupational standing often/always vs never/seldom: OR 1.22; 95% CI 0.77, 1.94). Similarly, higher occupational standing was not associated with low ABI at follow-up reflective of peripheral artery disease (ABI <0.90) or high ABI at follow-up reflective of incompressible vessels (ABI >1.40).

Conclusions: In this community-based study of African-Americans, we found no evidence that occupational standing is deleteriously associated with adverse changes in ABI over a median follow-up of 8.0 years. These findings do not provide evidence implicating occupational standing as a risk factor for lower limb atherosclerosis.
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http://dx.doi.org/10.1136/oemed-2020-106905DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8089112PMC
November 2020

Accelerometer-assessed physical activity and incident diabetes in a population covering the adult life span: the Hispanic Community Health Study/Study of Latinos.

Am J Clin Nutr 2020 11;112(5):1318-1327

Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, USA.

Background: The association between accelerometer-assessed physical activity and risk of diabetes remains unclear, especially among US Hispanic/Latino adults who have lower levels of physical activity and a higher diabetes burden compared with other racial/ethnical populations in the country.

Objectives: To examine the association between accelerometer-assessed physical activity and incident diabetes in a US Hispanic/Latino population.

Methods: We included 7280 participants of the Hispanic Community Health Study/Study of Latinos who aged 18-74 y and free of diabetes at baseline. Data on moderate-to-vigorous physical activity (MVPA) were collected using a 7-d accelerometer measurement. Incident diabetes was assessed after a mean ± SD of 6.0 ± 0.8 y using standard procedures including blood tests. RRs and 95% CIs of diabetes associated with MVPA were estimated using survey Poisson regressions. The associations of MVPA with 6-y changes in adiposity measures were also examined.

Results: A total of 871 incident cases of diabetes were identified. MVPA was inversely and nonlinearly associated with risk of diabetes (P-nonlinearity = 0.006), with benefits accruing rapidly at the lower end of MVPA range (<30 min/d) and leveling off thereafter. The association differed by population age (P-interaction = 0.006). Higher MVPA was associated with lower risk of diabetes among individuals older than 50 y (RRQ4 versus Q1 = 0.50; 95% CI: 0.35, 0.73; P-trend < 0.001) but not among younger individuals (RRQ4 versus Q1 = 0.98; 95% CI: 0.66, 1.47; P-trend = 0.92). An inverse association between MVPA and 6-y gain in waist circumference was also limited to the older group (P-interaction with age < 0.001).

Conclusions: Among US Hispanic/Latino adults, baseline accelerometer-derived MVPA was inversely associated with incident diabetes only among individuals aged 50 y and older. Further studies are needed to confirm our findings and to clarify potential mechanisms underlying the possible age differences in the MVPA-diabetes association. This study was registered at clinicaltrials.gov as NCT02060344.
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http://dx.doi.org/10.1093/ajcn/nqaa232DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7657343PMC
November 2020

U.S. Children Meeting Physical Activity, Screen Time, and Sleep Guidelines.

Am J Prev Med 2020 10 27;59(4):513-521. Epub 2020 Aug 27.

Center for Behavioral Cardiovascular Health, Department of Medicine, Columbia University Medical Center, New York, New York.

Introduction: Physical inactivity, high screen time, and short sleep are targets of public health initiatives for children. However, few data exist on how many U.S. children meet guidelines for these behaviors-data vital to inform which needs greater targeting. This study describes national prevalence estimates of U.S. children who meet physical activity, screen time, and sleep guidelines alone or in combination across each childhood year.

Methods: This analysis (completed in 2019) used cross-sectional data from the 2016-2017 National Survey of Children's Health, a nationally representative sample of U.S. children. Child physical activity (days per week with ≥60 minutes), recreational screen time (hours per day of TV viewing and electronic device use), and sleep duration (hours per day) were assessed through parental report. Guidelines recommend ≥60 minutes per day of physical activity, ≤2 hours per day of screen time, and 9-12 hours per day of sleep for individuals aged 6-12 years (8-10 hours for those aged 13-17 years).

Results: Only 8.8% (95% CI=8.2%, 9.5%) of U.S. children meet all the 3 guidelines combined. Majority of children/adolescents attain the sleep guideline (86.0%, 95% CI=85.2%, 86.7%), but a lower proportion meet physical activity (23.0%, 95% CI=22.1%, 23.9%) or screen time (32.9%, 95% CI=31.9%, 33.8%) guidelines. A substantial age effect was identified, with prevalence of meeting each distinct guideline and all the 3 declining with age (p<0.001).

Conclusions: Few U.S. children meet all the 3 movement guidelines, with prevalence rates of children meeting guidelines declining with age. Although many meet sleep guidelines, few meet physical activity or screen time guidelines. Initiatives targeting physical activity and screen time, especially for adolescents, should be pursued.
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http://dx.doi.org/10.1016/j.amepre.2020.05.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7574791PMC
October 2020

Posttraumatic Stress Disorder and Electronically Measured Medication Adherence After Suspected Acute Coronary Syndromes.

Circulation 2020 08 24;142(8):817-819. Epub 2020 Aug 24.

Center for Behavioral Cardiovascular Health, Columbia University Irving Medical Center, New York (I.M.K., T.C., J.E.S., A.S., K.M.D., E.K.R., D.E.).

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http://dx.doi.org/10.1161/CIRCULATIONAHA.120.045714DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7584377PMC
August 2020

Association of Sedentary Behavior With Cancer Mortality in Middle-aged and Older US Adults.

JAMA Oncol 2020 08;6(8):1210-1217

Center for Behavioral Cardiovascular Health, Department of Medicine, Columbia University Medical Center, New York, New York.

Importance: Sedentary behavior is associated with several health outcomes, including diabetes, cardiovascular disease, and all-cause mortality. Less is known about the association between objectively measured sedentary behavior and cancer mortality, as well as the association with physical activity.

Objective: To examine the association between accelerometer-measured sedentary behavior (total volume and accrual in prolonged, uninterrupted bouts) and cancer mortality.

Design, Setting, And Participants: A prospective cohort study conducted in the contiguous US included 8002 black and white adults aged 45 years or older enrolled in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. The present analysis was performed from April 18, 2019, to April 21, 2020.

Exposures: Sedentary time, light-intensity physical activity (LIPA), and moderate- to vigorous-intensity physical activity (MVPA) were measured using a hip-mounted accelerometer worn for 7 consecutive days.

Main Outcomes And Measures: Cancer mortality.

Results: Of the 8002 study participants, 3668 were men (45.8%); mean (SD) age was 69.8 (8.5) years. Over a mean (SD) follow-up of 5.3 (1.5) years, 268 participants (3.3%) died of cancer. In multivariable-adjusted models, including MVPA, greater total sedentary time was associated with a greater risk of cancer mortality (tertile 2 vs tertile 1: hazard ratio [HR], 1.45; 95% CI, 1.00-2.11; tertile 3 vs tertile 1: HR, 1.52; 95% CI, 1.01-2.27). Longer sedentary bout duration was not significantly associated with greater cancer mortality risk: after adjustment for MVPA (tertile 2 vs tertile 1: HR, 1.26; 95% CI, 0.90-1.78; tertile 3 vs tertile 1: HR, 1.36; 95% CI, 0.96-1.93). Replacing 30 minutes of sedentary time with LIPA was significantly associated with an 8% (per 30 minutes: HR, 0.92; 95% CI, 0.86-0.97) lower risk of cancer mortality; MVPA was significantly associated with a 31% (per 30 minutes: HR, 0.69; 95% CI, 0.48-0.97) lower risk of cancer mortality.

Conclusions And Relevance: In this cohort study, greater sedentary time, as measured with accelerometry, appeared to be independently associated with cancer mortality risk. Replacing sedentary time with either LIPA or MVPA may be associated with a lower risk of cancer mortality. These findings suggest that the total volume of sedentary behavior is a potential cancer mortality risk factor and support the public health message that adults should sit less and move more to promote longevity.
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http://dx.doi.org/10.1001/jamaoncol.2020.2045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7303924PMC
August 2020

Anxiety Sensitivity and Physical Inactivity in a National Sample of Adults with a History of Myocardial Infarction.

Int J Behav Med 2020 Oct;27(5):520-526

Center for Behavioral Cardiovascular Health, Division of Cardiology, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA.

Background: The psychological factors underlying physical inactivity in vulnerable cardiac adult populations remain understudied. Anxiety sensitivity, a cognitive vulnerability defined as fear of the physical, cognitive, and social consequences of anxiety, may be an important modifiable determinant of physical inactivity. We examined the association of anxiety sensitivity, and each anxiety sensitivity subscale (physical, cognitive, and social concerns), with physical inactivity in adults with a history of myocardial infarction (MI).

Methods: Using cross-sectional data from a nationally representative survey of adults (N = 1417) in the USA who reported a health professional diagnosis of MI, we used weighted logistic regression models to evaluate the association between anxiety sensitivity (overall, and each subscale) and physical inactivity (self-reported exercise 0-1 day/week), with adjustment for age, gender, race, education, number of MIs, and depression.

Results: Overall, 34.3% reported physical inactivity. Anxiety sensitivity was associated with greater odds of physical inactivity (OR = 1.01; 95% CI = 1.00, 1.02; p = .026). Of the subscales, only physical concerns were associated with physical inactivity (OR = 1.02; 95% CI = 1.01, 1.04; p = .008) in the final model. High vs. low fear of shortness of breath was most consistently associated with physical inactivity (OR = 1.49; 95% CI = 1.08, 2.06; p < .021).

Conclusion: Anxiety sensitivity, generally, and fear of the physical sensations of anxiety (i.e., "fear of shortness of breath"), specifically, are important correlates of physical inactivity in adults with a history of MI. Future research should replicate these findings and experimentally test whether cardiac rehabilitation interventions that include an adjunctive component targeting reduction of anxiety sensitivity overall, or specific somatic symptoms, improve physical activity in this population.
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http://dx.doi.org/10.1007/s12529-020-09881-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8127064PMC
October 2020

Physical Activity and Sedentary Behavior Among U.S. Children With and Without Down Syndrome: The National Survey of Children's Health.

Authors:
Keith M Diaz

Am J Intellect Dev Disabil 2020 05;125(3):230-242

Keith M. Diaz, Center for Behavioral Cardiovascular Health, Columbia University Medical Center.

It is unclear whether children with Down syndrome have differing physical activity and sedentary behavior levels compared to typical children. This study addressed this evidence gap in a national sample. Physical activity/sedentary behavior were ascertained by parental report. Findings highlighted that children with Down syndrome were less likely to engage in regular physical activity compared to typical children and had the lowest likelihood of regular physical activity among all subgroups with developmental disabilities/special healthcare needs. Children with Down syndrome were also more likely to watch high volumes of television compared to typical children, although this was nonsignificant upon adjustment for general health. It was concluded that children with Down syndrome are in urgent need for interventions/programs that promote physical activity.
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http://dx.doi.org/10.1352/1944-7558-125.3.230DOI Listing
May 2020

Testing the cross-stressor hypothesis under real-world conditions: exercise as a moderator of the association between momentary anxiety and cardiovascular responses.

J Behav Med 2020 12 22;43(6):989-1001. Epub 2020 Apr 22.

Center for Behavioral Cardiovascular Health, Columbia University Irving Medical Center, New York, NY, USA.

The cross-stressor adaptation hypothesis of exercise training has not been investigated under real-life conditions. Using ecological momentary assessment, we tested whether usual exercise level moderates the relationship of self-reported anxiety to concurrent ambulatory heart rate (HR) and systolic/diastolic blood pressure (SBP/DBP). Participants (N = 832) completed 24-h ambulatory monitoring of HR/BP, using a brachial BP cuff that took readings at 28-min intervals. Anxiety levels were concurrently reported on a visual analog scale (VAS) using a Palm Pilot. Usual exercise behavior was assessed by a self-report questionnaire. Random coefficients linear regression models predicting momentary HR/BP readings from time-matched anxiety scores were estimated, yielding the average within-person effect (slope) of anxiety. The interaction of exercise level (i.e., no weekly exercise, 1-149, and ≥ 150 min/week; a between-person factor) with anxiety was added to the model in order to estimate the average anxiety slope for participants in each exercise category. The relationship of HR/BP to anxiety did not differ significantly among exercise categories, hence not providing evidence for the cross-stressor hypothesis. In an exploratory analysis of the difference in HR/BP between occasions when anxiety was in the top versus bottom person-specific quintiles of responses, the difference in HR (but not SBP or DBP) varied significantly by exercise level (F(2,625) = 4.92, p = 0.008). Though our pre-specified analysis did not support the hypothesis, we provide some post hoc evidence supporting the cross-stressor hypothesis of exercise training for the HR response to anxiety.
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http://dx.doi.org/10.1007/s10865-020-00155-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7578073PMC
December 2020

Sedentary time and peripheral artery disease: The Hispanic Community Health Study/Study of Latinos.

Am Heart J 2020 04 8;222:208-219. Epub 2020 Feb 8.

University of California San Diego, La Jolla, CA, USA.

Background: Experimental evidence suggests that sedentary time (ST) may contribute to cardiovascular disease by eliciting detrimental hemodynamic changes in the lower limbs. However, little is known about objectively measured ST and lower extremity peripheral artery disease (PAD).

Methods: We included 7,609 Hispanic/Latinos (ages 45-74) from the Hispanic Community Health Study/Study of Latinos. PAD was measured using the ankle brachial index (≤0.9). ST was measured using accelerometry. We used multivariable logistic regression to assess associations of quartiles of ST and PAD, and then used the same logistic models with restricted cubic splines to investigate continuous nonlinear associations of ST and PAD. Models were sequentially adjusted for traditional PAD risk factors, leg pain, and moderate- to vigorous-intensity physical activity (MVPA).

Results: Median ST was 12.2 h/d, and 5.4% of individuals had PAD. In fully adjusted restricted cubic splines models accounting for traditional PAD risk factors, leg pain, and MVPA, ST had a significant overall (P = .048) and nonlinear (P = .024) association with PAD. A threshold effect was seen such that time spent above median ST was associated with higher odds of PAD. That is, compared to median ST, 1, 2, and 3 hours above median ST were associated with a PAD odds ratio of 1.16 (95% CI = 1.02-1.31), 1.44 (1.06-1.94), and 1.80 (1.11-2.90), respectively.

Conclusions: Among Hispanic/Latino adults, ST was associated with higher odds of PAD, independent of leg pain, MVPA, and traditional PAD risk factors. Notably, we observed a threshold effect such that these associations were only observed at the highest levels of ST.
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http://dx.doi.org/10.1016/j.ahj.2020.02.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7085461PMC
April 2020

Factors associated with long-term wearable physical activity monitor user engagement.

Transl Behav Med 2021 02;11(1):262-269

Center for Behavioral Cardiovascular Health, Columbia University Medical Center, New York, NY, USA.

Wearable physical activity monitors (PAMs) have potential to positively influence physical activity. However, high rates of disengagement have been reported, which dampens enthusiasm, as these devices are unlikely to impact habitual physical activity if they are not worn for a sustained period of time. The purpose of this study was to identify demographic and device-use characteristics (e.g., data sharing) associated with sustained device engagement. Current PAM users (n = 418; mean age: 35.0 ± 12.5; 78% female) from across the USA were recruited online and completed a baseline web-based survey in 2015-2016 comprising questions about demographics and device use. Participants were followed-up again in 2017, at which time they reported whether or not they still used a PAM. Sustained PAM engagement was defined as those who continued use at follow-up. The median follow-up time was 15.5 (±3.7) months. In fully adjusted models, the following were significantly associated with long-term engagement: age (odds ratio [OR]: 1.03; 95% confidence interval [CI]: 1.01-1.05, p = .014), Hispanic ethnicity (OR: 3.67; 95% CI: 1.20-11.26, p = .023), running as a preferred exercise (OR: 1.82; 95% CI: 1.02-3.24, p = .043), wanting to monitor health variables as a reason for choosing to use a PAM (OR: 1.73; 95% CI: 1.02-2.92, p = .042), and sharing data from the PAM publicly on social media (e.g., Facebook and Twitter; OR: 5.11; 95% CI: 1.64-15.93, p = .005). A number of sociodemographic and use characteristics were associated with sustained device use over a median follow-up of 1.3 years. One modifiable factor that may lead to longer device engagement is encouraging users to share data publicly.
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http://dx.doi.org/10.1093/tbm/ibz153DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7982124PMC
February 2021

Dose-response associations between accelerometry measured physical activity and sedentary time and all cause mortality: systematic review and harmonised meta-analysis.

BMJ 2019 08 21;366:l4570. Epub 2019 Aug 21.

Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.

Objective: To examine the dose-response associations between accelerometer assessed total physical activity, different intensities of physical activity, and sedentary time and all cause mortality.

Design: Systematic review and harmonised meta-analysis.

Data Sources: PubMed, PsycINFO, Embase, Web of Science, Sport Discus from inception to 31 July 2018.

Eligibility Criteria: Prospective cohort studies assessing physical activity and sedentary time by accelerometry and associations with all cause mortality and reported effect estimates as hazard ratios, odds ratios, or relative risks with 95% confidence intervals.

Data Extraction And Analysis: Guidelines for meta-analyses and systematic reviews for observational studies and PRISMA guidelines were followed. Two authors independently screened the titles and abstracts. One author performed a full text review and another extracted the data. Two authors independently assessed the risk of bias. Individual level participant data were harmonised and analysed at study level. Data on physical activity were categorised by quarters at study level, and study specific associations with all cause mortality were analysed using Cox proportional hazards regression analyses. Study specific results were summarised using random effects meta-analysis.

Main Outcome Measure: All cause mortality.

Results: 39 studies were retrieved for full text review; 10 were eligible for inclusion, three were excluded owing to harmonisation challenges (eg, wrist placement of the accelerometer), and one study did not participate. Two additional studies with unpublished mortality data were also included. Thus, individual level data from eight studies (n=36 383; mean age 62.6 years; 72.8% women), with median follow-up of 5.8 years (range 3.0-14.5 years) and 2149 (5.9%) deaths were analysed. Any physical activity, regardless of intensity, was associated with lower risk of mortality, with a non-linear dose-response. Hazards ratios for mortality were 1.00 (referent) in the first quarter (least active), 0.48 (95% confidence interval 0.43 to 0.54) in the second quarter, 0.34 (0.26 to 0.45) in the third quarter, and 0.27 (0.23 to 0.32) in the fourth quarter (most active). Corresponding hazards ratios for light physical activity were 1.00, 0.60 (0.54 to 0.68), 0.44 (0.38 to 0.51), and 0.38 (0.28 to 0.51), and for moderate-to-vigorous physical activity were 1.00, 0.64 (0.55 to 0.74), 0.55 (0.40 to 0.74), and 0.52 (0.43 to 0.61). For sedentary time, hazards ratios were 1.00 (referent; least sedentary), 1.28 (1.09 to 1.51), 1.71 (1.36 to 2.15), and 2.63 (1.94 to 3.56).

Conclusion: Higher levels of total physical activity, at any intensity, and less time spent sedentary, are associated with substantially reduced risk for premature mortality, with evidence of a non-linear dose-response pattern in middle aged and older adults.

Systematic Review Registration: PROSPERO CRD42018091808.
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http://dx.doi.org/10.1136/bmj.l4570DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6699591PMC
August 2019

Inappropriate Left Ventricular Mass and Cardiovascular Disease Events and Mortality in Blacks: The Jackson Heart Study.

J Am Heart Assoc 2019 08 13;8(16):e011897. Epub 2019 Aug 13.

Columbia University Irving Medical Center New York NY.

Background Left ventricular hypertrophy (LVH) is associated with an increased risk for cardiovascular disease (CVD) events and all-cause mortality. Many individuals without LVH have a left ventricular mass that exceeds the level predicted by their sex, body size, and cardiac workload, a condition called inappropriate left ventricular mass (iLVM). We investigated the association of iLVM with CVD events and all-cause mortality among blacks. Methods and Results We analyzed data from the Jackson Heart Study, a community-based cohort of blacks. The current analysis included 4424 participants without CVD and with an echocardiogram at baseline. Among this cohort, the prevalence of iLVM was 13.8%. There were 262 CVD events and 419 deaths over a median follow-up of 9.7 years (maximum, 12 years). Compared with participants without iLVM, participants with iLVM had a higher rate of CVD events and all-cause mortality. After multivariable adjustment, including for the presence of LVH, iLVM was associated with an increased risk of CVD events (hazard ratio, 1.87; 95% CI, 1.33-2.62). The multivariable-adjusted hazard ratio for all-cause mortality was 1.29 (95% CI, 0.98-1.70). Among participants without and with LVH, the multivariable-adjusted hazard ratios of iLVM for CVD events were 2.53 (95% CI, 1.68-3.81) and 1.21 (95% CI, 0.74-2.00), respectively (P=0.029); and for all-cause mortality, the hazard ratios were 1.24 (95% CI, 0.81-1.89) and 1.26 (95% CI, 0.86-1.85), respectively (P=0.664). Conclusions iLVM is associated with an increased risk for CVD events among blacks without LVH.
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http://dx.doi.org/10.1161/JAHA.118.011897DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6759894PMC
August 2019

Patterns of Sedentary Behavior in the First Month After Acute Coronary Syndrome.

J Am Heart Assoc 2019 08 31;8(15):e011585. Epub 2019 Jul 31.

Center for Behavioral Cardiovascular Health Columbia University Irving Medical Center New York NY.

Background Sedentary behavior is a key contributor to cardiovascular disease. Few data exist on the sedentary behavior patterns of patients with acute coronary syndrome. Methods and Results We characterized patterns of sedentary time and their correlates in 149 patients with acute coronary syndrome over the first month postdischarge, a critical period when lifestyle behaviors are formed. Sedentary time was measured by accelerometry for 28 days postdischarge. Group-based modeling at the day level was used to characterize sedentary patterns. Participants spent a mean of 9.7±2.0 hours per day sedentary during the 28 days postdischarge, with significant decreases in sedentary time observed in each consecutive week (P<0.01 for all). Three distinct sedentary patterns were identified: high (20.6% of participants), moderate (47.9%), and low (31.5%). The high and moderate sedentary groups spent a mean of 12.6±0.8 and 10.0±0.7 hours per day sedentary, respectively, and had only minimal decreases in their sedentary time (<3 minutes per day) over the 28 days. The low sedentary group spent a mean of 7.3±0.8 hours per day sedentary, with a rapid decrease in sedentary time (14 minutes per day) observed during the first week postdischarge followed by a relatively smaller decrease (≈5 minutes per day) that persisted until day 21 postdischarge. Non-Hispanic ethnicity, left ventricular ejection fraction <40%, lower physical health-related quality of life, and not having a partner were associated with an increased likelihood of being in the high sedentary group. Conclusions Survivors of acute coronary syndrome accrued high volumes of sedentary time during the first month postdischarge, with most showing little change over time. Interventions targeting reductions in sedentary time among survivors of acute coronary syndrome may be warranted, particularly for those with poor physical health and greater disease severity.
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http://dx.doi.org/10.1161/JAHA.118.011585DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6761643PMC
August 2019

Types of Sedentary Behavior and Risk of Cardiovascular Events and Mortality in Blacks: The Jackson Heart Study.

J Am Heart Assoc 2019 07 26;8(13):e010406. Epub 2019 Jun 26.

2 Center for Behavioral Cardiovascular Health Columbia University Medical Center New York NY.

Background Previous cross-sectional studies have shown conflicting results regarding the effects of television viewing and occupational sitting on cardiovascular disease ( CVD ) risk factors. The purpose of this study was to compare the association of both television viewing and occupational sitting with CVD events and all-cause mortality in blacks. Methods and Results Participants included 3592 individuals enrolled in the Jackson Heart Study, a community-based study of blacks residing in Jackson, Mississippi. Television viewing (<2, 2-4, and >4 h/day) and occupational sitting (never/seldom, sometimes, often/always) were self-reported. Over a median follow-up of 8.4 years, there were 129 CVD events and 205 deaths. The highest category of television viewing (>4 h/day) was associated with a greater risk for a composite CVD events/all-cause mortality end point compared with the lowest category (<2 h/day; hazard ratio, 1.49; 95% CI , 1.13-1.97). In contrast, the highest category of occupational sitting (often/always) was not associated with risk for a composite CVD events/all-cause mortality end point compared with the lowest category (never/seldom; hazard ratio, 0.90; 95% CI , 0.69-1.18). Moderate-to-vigorous physical activity moderated the association of television viewing with CVD events/all-cause mortality such that television viewing was not associated with greater risk among those with high moderate-to-vigorous physical activity levels. Conclusions Television viewing was associated with greater risk of CVD events and all-cause mortality, while occupational sitting had no association with these outcomes. These findings suggest that minimizing television viewing may be more effective for reducing CVD and mortality risk in blacks compared with reducing occupational sedentary behavior.
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http://dx.doi.org/10.1161/JAHA.118.010406DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6662345PMC
July 2019

Potential Effects on Mortality of Replacing Sedentary Time With Short Sedentary Bouts or Physical Activity: A National Cohort Study.

Am J Epidemiol 2019 03;188(3):537-544

Exercise Science and Health Promotion Program, College of Health Solutions, Arizona State University, Phoenix, Arizona.

Little is known concerning the type of activity that should be substituted for sedentary time and its potentially most hazardous form (prolonged sedentary bouts) to impart health benefit. We used isotemporal substitution techniques to examine whether 1) replacing total sedentary time with light-intensity or moderate to vigorous physical activity (LIPA or MVPA) or 2) replacing prolonged sedentary bouts with shorter sedentary bouts is associated with reductions in all-cause mortality risk. Participants (n = 7,999) from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a national cohort of US adults aged ≥45 years, were studied. Sedentary time was measured by accelerometry between 2009 and 2013. There was a beneficial association with mortality risk for replacing total sedentary time with both LIPA (per 30 minutes, hazard ratio (HR) = 0.83; 95% confidence interval (CI): 0.80, 0.87) and MVPA (per 30 minutes, HR = 0.65; 95% CI: 0.50, 0.85). Similarly, there was a beneficial association for replacing prolonged sedentary-bout time with LIPA and MVPA but not for replacement with shorter sedentary bouts (per 30 minutes, HR = 1.00; 95% CI: 0.96, 1.03). These findings suggest short sedentary bouts still carry mortality risk and are not a healthful alternative to prolonged sedentary bouts. Instead, physical activity of any intensity is needed to mitigate the mortality risks incurred by sedentary time.
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http://dx.doi.org/10.1093/aje/kwy271DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395167PMC
March 2019

Factors associated with objectively measured exercise participation after hospitalization for acute coronary syndrome.

Int J Cardiol 2019 Jan 28;275:1-5. Epub 2018 Sep 28.

Center for Behavioral Cardiovascular Health, Columbia University Medical Center, 622 West 168 Street, PH 9, New York, NY 10032, USA.

Background: Guidelines recommend exercise for secondary prevention of acute coronary syndrome (ACS), however adherence to guidelines is low. A paucity of data examining factors associated with objectively-measured exercise post-discharge in ACS survivors exists. The purpose of this study was to identify factors associated with exercise during the 5 weeks after ACS discharge.

Methods: A sample of 151 ACS patients treated at a university hospital were enrolled into an observational cohort study and wore an accelerometer for 35 days post-discharge. Days on which participants accumulated ≥30 min of moderate-to-vigorous physical activity in bouts ≥10 min were considered exercise days. Participants were categorized as non-exercisers (0 exercise days) or exercisers (≥1 exercise day). A multi-variable logistic regression model was used to examine the association between exercise and socio-demographics, depression, SF-12 physical and mental health scores, disease severity, length of hospitalization, and percutaneous coronary intervention.

Results: 39.7% of participants were non-exercisers. Factors associated with non-exercise were age (OR: 1.11; 95% CI: 1.06-1.17, p < 0.001), female sex (OR: 2.76; 95% CI: 1.10-6.95, p = 0.031), and lower SF-12 physical health score (OR: 0.94; 95% CI: 0.90-0.98, p = 0.005).

Conclusion: In ACS patients in whom exercise participation was objectively measured for 5 weeks post-discharge, demographic and poor physical health factors were associated with non-exercise. These findings identify populations (e.g. older adults, women) at especially high risk for being physically inactive in whom more intense intervention may be warranted.
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http://dx.doi.org/10.1016/j.ijcard.2018.09.080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6289665PMC
January 2019

Quantile Coarsening Analysis of High-Volume Wearable Activity Data in a Longitudinal Observational Study.

Sensors (Basel) 2018 Sep 12;18(9). Epub 2018 Sep 12.

Center for Behavioral Cardiovascular Health, Department of Medicine, Columbia University Medical Center, New York, NY 10032, USA.

Owing to advances in sensor technologies on wearable devices, it is feasible to measure physical activity of an individual continuously over a long period. These devices afford opportunities to understand individual behaviors, which may then provide a basis for tailored behavior interventions. The large volume of data however poses challenges in data management and analysis. We propose a novel quantile coarsening analysis (QCA) of daily physical activity data, with a goal to reduce the volume of data while preserving key information. We applied QCA to a longitudinal study of 79 healthy participants whose step counts were monitored for up to 1 year by a Fitbit device, performed cluster analysis of daily activity, and identified individual activity signature or pattern in terms of the clusters identified. Using 21,393 time series of daily physical activity, we identified eight clusters. Employment and partner status were each associated with 5 of the 8 clusters. Using less than 2% of the original data, QCA provides accurate approximation of the mean physical activity, forms meaningful activity patterns associated with individual characteristics, and is a versatile tool for dimension reduction of densely sampled data.
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http://dx.doi.org/10.3390/s18093056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164779PMC
September 2018

Objectively Measured Sedentary Behavior, Physical Activity, and Cardiometabolic Risk in Hispanic Youth: Hispanic Community Health Study/Study of Latino Youth.

J Clin Endocrinol Metab 2018 09;103(9):3289-3298

Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York.

Context: Time spent in moderate-to-vigorous physical activity (MVPA), but not in sedentary behavior (SB), is related to cardiometabolic risk among non-Hispanic white youth.

Objective: Examine associations of SB and MVPA with cardiometabolic risk factors among Hispanic/Latino youth.

Design: Cross-sectional analysis.

Setting: Four US communities.

Participants: Hispanic/Latino youth (N = 1,426) ages 8 to 16 years.

Measurements: Associations of MVPA and SB, measured using 7-day accelerometer data (independent variables), with markers of glucose and lipid metabolism, inflammation, and endothelial function (dependent variables), were assessed in multivariable linear regression models while adjusting for sociodemographic characteristics and accelerometer wear time. Additional models controlled for obesity measures.

Results: SB comprised a mean (SD) of 75% (13%) of accelerometer wear time; mean (SD) time of MVPA was 35 min/d (22 min/d). Deleterious levels of high-density lipoprotein-cholesterol (HDL-C), triglycerides, insulin resistance, C-reactive protein, and plasminogen activator inhibitor-1 were associated with lower levels of MVPA and higher levels of SB (all P < 0.05). Associations of MVPA with log-transformed triglyceride concentrations (β per 15-min/d increment, -0.039; SE, 0.018; P = 0.037) and SB with HDL-C (β per 30-min/d increment, -0.63; SE, 0.26; P = 0.018), but not those with other markers, remained significant after adjusting for MVPA or SB and further adjustment for body mass index and waist circumference. Higher SB tertiles were associated with lower soluble receptor for advanced glycation end products in fully adjusted models (P for trend = 0.037).

Conclusions: Physiological precursors of diabetes and cardiovascular disease were associated with MVPA and SB among US Hispanic/Latino youth, a group that bears a disproportionate burden of metabolic disorders.
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http://dx.doi.org/10.1210/jc.2018-00356DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6126884PMC
September 2018

Putative mechanisms Underlying Myocardial infarction onset and Emotions (PUME): a randomised controlled study protocol.

BMJ Open 2018 05 31;8(5):e020525. Epub 2018 May 31.

Department of Medicine, Columbia University Medical Center, New York, New York, USA.

Introduction: The experience of negative emotions (eg, anger, anxiety and sadness) is associated with an increased short-term risk of incident cardiovascular disease (CVD) events, independent of traditional CVD risk factors. Impairment in endothelial function is one possible biological mechanism which may explain the association between negative emotions and incident CVD events. This laboratory-based, single-blind, randomised controlled experimental study aims to investigate the impact of induced negative emotions including anger, anxiety and sadness on endothelial function.

Methods And Analysis: In a between-subjects design, 280 healthy participants are randomised to one of four experimental negative emotion inductions: anger, anxiety, sadness or a neutral condition. Endothelium-dependent vasodilation, circulating levels of endothelial cell-derived microparticles and bone marrow-derived endothelial progenitor cells, and indices of nitric oxide inhibition are assessed before and 3, 40, 70 and 100 min after negative emotion induction. Finally, in a subsample of 84 participants, the potential moderating effects of cardiorespiratory fitness and habitual physical activity on the adverse effects of an acute negative emotion on endothelial function are investigated.

Ethics And Dissemination: This study is conducted in compliance with the Helsinki Declaration and the Columbia University Medical Center Institutional Review Board. The results of the study will be disseminated at several research conferences and as published articles in peer reviewed journals. The study will be implemented and reported in line with the SPIRIT statement.

Trial Registration Number: NCT01909895; Pre-results.
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http://dx.doi.org/10.1136/bmjopen-2017-020525DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5988091PMC
May 2018

A First Step Towards Behavioral Coaching for Managing Stress: A Case Study on Optimal Policy Estimation with Multi-stage Threshold Q-learning.

AMIA Annu Symp Proc 2017 16;2017:930-939. Epub 2018 Apr 16.

Department of Biostatistics, Columbia University, New York, NY, USA.

Psychological stress is a major contributor to the adoption of unhealthy behaviors, which in turn accounts for 41% of global cardiovascular disease burden. While the proliferation of mobile health apps has offered promise to stress management, these apps do not provide micro-level feedback with regard to how to adjust one's behaviors to achieve a desired health outcome. In this paper, we formulate the task of multi-stage stress management as a sequential decision-making problem and explore the application of reinforcement learning to provide micro-level feedback for stress reduction. Specifically, we incorporate a multi-stage threshold selection into Q-learning to derive an interpretable form of a recommendation policy for behavioral coaching. We apply this method on an observational dataset that contains Fitbit ActiGraph measurements and self-reported stress levels. The estimated policy is then used to understand how exercise patterns may affect users' psychological stress levels and to perform coaching more effectively.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5977571PMC
March 2019

The Influence of Daily Stress on Sedentary Behavior: Group and Person (N of 1) Level Results of a 1-Year Observational Study.

Psychosom Med 2018 09;80(7):620-627

From the Center for Behavioral Cardiovascular Health (Diaz, Thanataveerat, Parsons, Duran, Ensari, Krupka, Schwartz, Davidson), Columbia University Medical Center, New York; Department of Biostatistics (Thanataveerat, Cheung), Mailman School of Public Health, Columbia University, New York; School of Nursing (Yoon), Columbia University, New York; School of Social Work (Alcántara), Columbia University, New York; Teachers College (Duran), Columbia University, New York; Department of Psychiatry and Behavioral Science (Schwartz), Stony Brook University, Stony Brook, NY; Department of Internal Medicine (Burg), Yale University School of Medicine, New Haven, Connecticut; and New York Presbyterian Hospital (Davidson), New York.

Objective: The purpose of this study, which used mobile technologies to continuously collect data for 1 year, was to examine the association of psychological stress with objectively measured sedentary behavior in adults at both the group (e.g., nomothetic approach) and individual (e.g., idiographic approach) level.

Methods: Data were collected in an observational study of healthy adults (n = 79) residing in the New York City metro area who were studied for 365 days from 2014 to 2015. Sedentary behavior was objectively measured via accelerometry. A smartphone-based electronic diary was used to assess level of stress ("Overall, how stressful was your day?" 0-10 scale) and sources of stress.

Results: The end-of-day stress rating was not associated with total sedentary time (B = -1.34, p = .767) at the group level. When specific sources of stress were evaluated at the group level, argument-related stress was associated with increased sedentariness, whereas running late- and work-related stress were associated with decreased sedentariness. There was a substantial degree of interindividual variability in the relationship of stress with sedentary behavior. Both the level and sources of stress were associated with increased sedentariness for some, decreased sedentariness for others, and had no effect for many (within-person variance p < .001).

Conclusions: These findings suggest that the influence of stress on sedentary behavior varies by source of stress and from person to person. A precision medicine approach may be warranted to target reductions in sedentary time, although further studies are needed to confirm the observed findings in light of study limitations including a small sample size and enrollment of participants from a single, urban metropolitan area.
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http://dx.doi.org/10.1097/PSY.0000000000000610DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6113063PMC
September 2018

Using Behavioral Analytics to Increase Exercise: A Randomized N-of-1 Study.

Am J Prev Med 2018 04 21;54(4):559-567. Epub 2018 Feb 21.

Center for Behavioral Cardiovascular Health, Columbia University Medical Center, New York, New York.

Introduction: This intervention study used mobile technologies to investigate whether those randomized to receive a personalized "activity fingerprint" (i.e., a one-time tailored message about personal predictors of exercise developed from 6 months of observational data) increased their physical activity levels relative to those not receiving the fingerprint.

Study Design: A 12-month randomized intervention study.

Setting/participants: From 2014 to 2015, 79 intermittent exercisers had their daily physical activity assessed by accelerometry (Fitbit Flex) and daily stress experience, a potential predictor of exercise behavior, was assessed by smartphone.

Intervention: Data collected during the first 6 months of observation were used to develop a person-specific "activity fingerprint" (i.e., N-of-1) that was subsequently sent via email on a single occasion to randomized participants.

Main Outcome Measures: Pre-post changes in the percentage of days exercised were analyzed within and between control and intervention groups.

Results: The control group significantly decreased their proportion of days exercised (10.5% decrease, p<0.0001) following randomization. By contrast, the intervention group showed a nonsignificant decrease in the proportion of days exercised (4.0% decrease, p=0.14). Relative to the decrease observed in the control group, receipt of the activity fingerprint significantly increased the likelihood of exercising in the intervention group (6.5%, p=0.04).

Conclusions: This N-of-1 intervention study demonstrates that a one-time brief message conveying personalized exercise predictors had a beneficial effect on exercise behavior among urban adults.
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http://dx.doi.org/10.1016/j.amepre.2017.12.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5860951PMC
April 2018
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