Publications by authors named "Annabel X Tan"

8 Publications

  • Page 1 of 1

Association Between Myocardial Strain and Frailty in CHS.

Circ Cardiovasc Imaging 2021 May 17;14(5):e012116. Epub 2021 May 17.

Department of Epidemiology and Population Health, Stanford University, CA (A.X.T., M.C.O.).

Background: Myocardial strain, measured by speckle-tracking echocardiography, is a novel measure of subclinical cardiovascular disease and may reflect myocardial aging. We evaluated the association between myocardial strain and frailty-a clinical syndrome of lack of physiological reserve.

Methods: Frailty was defined in participants of the CHS (Cardiovascular Health Study) as having ≥3 of the following clinical criteria: weakness, slowness, weight loss, exhaustion, and inactivity. Using speckle-tracking echocardiography data, we examined the cross-sectional (n=3206) and longitudinal (n=1431) associations with frailty among participants who had at least 1 measure of myocardial strain, left ventricular longitudinal strain (LVLS), left ventricular early diastolic strain rate and left atrial reservoir strain, and no history of cardiovascular disease or heart failure at the time of echocardiography.

Results: In cross-sectional analyses, lower (worse) LVLS was associated with prevalent frailty; this association was robust to adjustment for left ventricular ejection fraction (adjusted odds ratio, 1.32 [95% CI, 1.07-1.61] per 1-SD lower strain; =0.007) and left ventricular stroke volume (adjusted OR, 1.32 [95% CI, 1.08-1.61] per 1-SD lower strain; =0.007). In longitudinal analyses, adjusted associations of LVLS and left ventricular early diastolic strain with incident frailty were 1.35 ([95% CI, 0.96-1.89] =0.086) and 1.58 ([95% CI, 1.11-2.27] =0.013, respectively). Participants who were frail and had the worst LVLS had a 2.2-fold increased risk of death (hazard ratio, 2.20 [95% CI, 1.81-2.66]; <0.0001).

Conclusions: In community-dwelling older adults without prevalent cardiovascular disease, worse LVLS by speckle-tracking echocardiography, reflective of subclinical myocardial dysfunction, was associated with frailty. Frailty and LVLS have an additive effect on mortality risk.
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May 2021

Association Between Income Inequality and County-Level COVID-19 Cases and Deaths in the US.

JAMA Netw Open 2021 05 3;4(5):e218799. Epub 2021 May 3.

Department of Epidemiology and Population Health, Stanford University, Stanford, California.

Importance: Socioeconomically marginalized communities have been disproportionately affected by the COVID-19 pandemic. Income inequality may be a risk factor for SARS-CoV-2 infection and death from COVID-19.

Objective: To evaluate the association between county-level income inequality and COVID-19 cases and deaths from March 2020 through February 2021 in bimonthly time epochs.

Design, Setting, And Participants: This ecological cohort study used longitudinal data on county-level COVID-19 cases and deaths from March 1, 2020, through February 28, 2021, in 3220 counties from all 50 states, Puerto Rico, and the District of Columbia.

Main Outcomes And Measures: County-level daily COVID-19 case and death data from March 1, 2020, through February 28, 2021, were extracted from the COVID-19 Data Repository by the Center for Systems Science and Engineering at Johns Hopkins University in Baltimore, Maryland.

Exposure: The Gini coefficient, a measure of unequal income distribution (presented as a value between 0 and 1, where 0 represents a perfectly equal geographical region where all income is equally shared and 1 represents a perfectly unequal society where all income is earned by 1 individual), and other county-level data were obtained primarily from the 2014 to 2018 American Community Survey 5-year estimates. Covariates included median proportions of poverty, age, race/ethnicity, crowding given by occupancy per room, urbanicity and rurality, educational level, number of physicians per 100 000 individuals, state, and mask use at the county level.

Results: As of February 28, 2021, on average, each county recorded a median of 8891 cases of COVID-19 per 100 000 individuals (interquartile range, 6935-10 666 cases per 100 000 individuals) and 156 deaths per 100 000 individuals (interquartile range, 94-228 deaths per 100 000 individuals). The median county-level Gini coefficient was 0.44 (interquartile range, 0.42-0.47). There was a positive correlation between Gini coefficients and county-level COVID-19 cases (Spearman ρ = 0.052; P < .001) and deaths (Spearman ρ = 0.134; P < .001) during the study period. This association varied over time; each 0.05-unit increase in Gini coefficient was associated with an adjusted relative risk of COVID-19 deaths: 1.25 (95% CI, 1.17-1.33) in March and April 2020, 1.20 (95% CI, 1.13-1.28) in May and June 2020, 1.46 (95% CI, 1.37-1.55) in July and August 2020, 1.04 (95% CI, 0.98-1.10) in September and October 2020, 0.76 (95% CI, 0.72-0.81) in November and December 2020, and 1.02 (95% CI, 0.96-1.07) in January and February 2021 (P < .001 for interaction). The adjusted association of the Gini coefficient with COVID-19 cases also reached a peak in July and August 2020 (relative risk, 1.28 [95% CI, 1.22-1.33]).

Conclusions And Relevance: This study suggests that income inequality within US counties was associated with more cases and deaths due to COVID-19 in the summer months of 2020. The COVID-19 pandemic has highlighted the vast disparities that exist in health outcomes owing to income inequality in the US. Targeted interventions should be focused on areas of income inequality to both flatten the curve and lessen the burden of inequality.
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May 2021

Brachial Flow-mediated Dilation and Risk of Dementia: The Cardiovascular Health Study.

Alzheimer Dis Assoc Disord 2020 Jul-Sep;34(3):272-274

Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA.

Introduction: Brachial flow-mediated dilation (FMD) is a physiologic measure of endothelial function. We determined the prospective association of brachial FMD with incident dementia among older adults.

Methods: We included 2777 Cardiovascular Health Study participants who underwent brachial FMD measurement. Incident dementia was ascertained by medication use, International Classification of Diseases-9 codes, requirement for a proxy, and death certificates and calibrated to gold-standard assessments performed in a subset of the cohort.

Results: Mean participant age at time of brachial FMD measurement was 77.9 years. We identified 1650 incident dementia cases (median follow-up=10.5 y). After adjusting for age, race, sex, education, clinic site, and baseline arterial diameter, risk of dementia for participants in the highest quartile of percent brachial FMD did not differ from those in lowest quartile (hazard ratio=0.89, 95% confidence interval: 0.77, 1.03).

Conclusions: Brachial FMD, measured late in life, is not associated with an increased risk of incident dementia.
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July 2021

Development and application of a survey instrument to measure collaboration among health care and social services organizations.

Health Serv Res 2019 12 8;54(6):1246-1254. Epub 2019 Oct 8.

Johns Hopkins School of Medicine, Baltimore, Maryland.

Objective: To measure strategies of interorganizational collaboration among health care and social service organizations that serve older adults.

Study Setting: Twenty Hospital Service Areas (HSAs) in the United States.

Study Design: We developed and validated a novel scale to characterize interorganizational collaboration, and then tested its application by assessing whether the scale differentiated between HSAs with high vs low performance on potentially avoidable health care use and spending for Medicare beneficiaries.

Data Collection: Health care and social service organizations (N = 173 total) in each HSA completed a 12-item collaboration scale, three questions about collaboration behaviors, and a detailed survey documenting collaborative network ties.

Principal Findings: We identified two distinguishable subscales of interorganizational collaboration: (a) Aligning Strategy and (b) Coordinating Current Work. Each subscale demonstrated convergent validity with the organization's position in the collaborative network, and with collaboration behaviors. The full scale and Coordinating Current Work subscale did not differentiate high- vs low-performing HSAs, but the Aligning Strategy subscale was significantly higher in high-performing HSAs than in low-performing HSAs (P = .01).

Conclusions: Cross-sector collaboration-and particularly Aligning Strategy-is associated with health care use and spending for older adults. This new survey measure could be used to track the impact of interventions to foster interorganizational collaboration.
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December 2019

Collaboration in Health Care and Social Service Networks for Older Adults: Association With Health Care Utilization Measures.

Med Care 2019 05;57(5):327-333

Department of Health Policy and Management, Yale School of Public Health, New Haven, CT.

Background: Services targeting social determinants of health-such as income support, housing, and nutrition-have been shown to improve health outcomes and reduce health care costs for older adults. Nevertheless, evidence on the properties of effective collaborative networks across health care and social services sectors is limited.

Objectives: The main objectives of this study were to identify features of collaborative networks of health care and social services organizations associated with avoidable health care use and spending for older adults.

Research Design: Through a 2017 survey, we collected data on collaborative ties among health care and social service organizations in 20 US communities with either high or low performance on avoidable health care use and spending for Medicare beneficiaries. Six types of ties were measured: any collaboration, referrals, sharing information, cosponsoring projects, financial contracts, and joint needs assessment. We examined how characteristics of collaborative networks were associated with performance.

Results: High-performing networks were distinguished from low-performing networks by 2 features: (1) health care organizations occupied positions of significantly greater centrality (P<0.01), and (2) subnetworks of cosponsorship ties were more cohesive, as measured by centralization (P=0.05) and density (P=0.06). Across all networks, Area Agencies on Aging were more centrally positioned than any other type of organization (P<0.05).

Conclusions: Cross-sector engagement by health care organizations, particularly development of deeper types of collaborative ties such as cosponsorship, may reduce preventable health care use and spending. Efforts to foster effective partnerships could leverage the Area Agencies on Aging, which are already positioned as network brokers.
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May 2019

District-level health management and health system performance.

PLoS One 2019 1;14(2):e0210624. Epub 2019 Feb 1.

Vassar College, Poughkeepsie, New York, United States of America.

Strengthening district-level management may be an important lever for improving key public health outcomes in low-income settings; however, previous studies have not established the statistical associations between better management and primary healthcare system performance in such settings. To explore this gap, we conducted a cross-sectional study of 36 rural districts and 226 health centers in Ethiopia, a country which has made ambitious investment in expanding access to primary care over the last decade. We employed quantitative measure of management capacity at both the district health office and health center levels and used multiple regression models, accounting for clustering of health centers within districts, to estimate the statistical association between management capacity and a key performance indicator (KPI) summary score based on antenatal care coverage, contraception use, skilled birth attendance, infant immunization, and availability of essential medications. In districts with above median district management capacity, health center management capacity was strongly associated (p < 0.05) with KPI performance. In districts with below median management capacity, health center management capacity was not associated with KPI performance. Having more staff at the district health office was also associated with better KPI performance (p < 0.05) but only in districts with above median management capacity. The results suggest that district-level management may provide an opportunity for improving health system performance in low-income country settings.
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October 2019

Links between social environment and health care utilization and costs.

J Gerontol Soc Work 2018 Feb-Mar;61(2):203-220. Epub 2018 Feb 22.

b Yale Global Health Leadership Institute , Yale University , New Haven , CT.

The social environment influences health outcomes for older adults and could be an important target for interventions to reduce costly medical care. We sought to understand which elements of the social environment distinguish communities that achieve lower health care utilization and costs from communities that experience higher health care utilization and costs for older adults with complex needs. We used a sequential explanatory mixed methods approach. We classified community performance based on three outcomes: rate of hospitalizations for ambulatory care sensitive conditions, all-cause risk-standardized hospital readmission rates, and Medicare spending per beneficiary. We conducted in-depth interviews with key informants (N = 245) from organizations providing health or social services. Higher performing communities were distinguished by several aspects of social environment, and these features were lacking in lower performing communities: 1) strong informal support networks; 2) partnerships between faith-based organizations and health care and social service organizations; and 3) grassroots organizing and advocacy efforts. Higher performing communities share similar social environmental features that complement the work of health care and social service organizations. Many of the supportive features and programs identified in the higher performing communities were developed locally and with limited governmental funding, providing opportunities for improvement.
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May 2019

Patterns of Collaboration among Health Care and Social Services Providers in Communities with Lower Health Care Utilization and Costs.

Health Serv Res 2018 08 19;53 Suppl 1:2892-2909. Epub 2017 Sep 19.

Vassar College, Poughkeepsie, NY.

Objective: To understand how health care providers and social services providers coordinate their work in communities that achieve relatively low health care utilization and costs for older adults.

Study Setting: Sixteen Hospital Service Areas (HSAs) in the United States.

Study Design: We conducted a qualitative study of HSAs with performance in the top or bottom quartiles nationally across three key outcomes: ambulatory care sensitive hospitalizations, all-cause risk-standardized readmission rates, and average reimbursements per Medicare beneficiary. We selected 10 higher performing HSAs and six lower performing HSAs for inclusion in the study.

Data Collection: To understand patterns of collaboration in each community, we conducted site visits and in-depth interviews with a total of 245 representatives of health care organizations, social service agencies, and local government bodies.

Principal Findings: Organizations in higher performing communities regularly worked together to identify challenges faced by older adults in their areas and responded through collective action-in some cases, through relatively unstructured coalitions, and in other cases, through more hierarchical configurations. Further, hospitals in higher performing communities routinely matched patients with needed social services.

Conclusions: The collaborative approaches used by higher performing communities, if spread, may be able to improve outcomes elsewhere.
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August 2018