Publications by authors named "Meghan Quirk"

8 Publications

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A Smartphone App for Families With Preschool-Aged Children in a Public Nutrition Program: Prototype Development and Beta-Testing.

JMIR Mhealth Uhealth 2017 Aug 2;5(8):e102. Epub 2017 Aug 2.

Center for Prevention Research, Tennessee State University, Nashville, TN, United States.

Background: The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) in the United States provides free supplemental food and nutrition education to low-income mothers and children under age 5 years. Childhood obesity prevalence is higher among preschool children in the WIC program compared to other children, and WIC improves dietary quality among low-income children. The Children Eating Well (CHEW) smartphone app was developed in English and Spanish for WIC-participating families with preschool-aged children as a home-based intervention to reinforce WIC nutrition education and help prevent childhood obesity.

Objective: This paper describes the development and beta-testing of the CHEW smartphone app. The objective of beta-testing was to test the CHEW app prototype with target users, focusing on usage, usability, and perceived barriers and benefits of the app.

Methods: The goals of the CHEW app were to make the WIC shopping experience easier, maximize WIC benefit redemption, and improve parent snack feeding practices. The CHEW app prototype consisted of WIC Shopping Tools, including a barcode scanner and calculator tools for the cash value voucher for purchasing fruits and vegetables, and nutrition education focused on healthy snacks and beverages, including a Yummy Snack Gallery and Healthy Snacking Tips. Mothers of 63 black and Hispanic WIC-participating children ages 2 to 4 years tested the CHEW app prototype for 3 months and completed follow-up interviews.

Results: Study participants testing the app for 3 months used the app on average once a week for approximately 4 and a half minutes per session, although substantial variation was observed. Usage of specific features averaged at 1 to 2 times per month for shopping-related activities and 2 to 4 times per month for the snack gallery. Mothers classified as users rated the app's WIC Shopping Tools relatively high on usability and benefits, although variation in scores and qualitative feedback highlighted several barriers that need to be addressed. The Yummy Snack Gallery and Healthy Snacking Tips scored higher on usability than benefits, suggesting that the nutrition education components may have been appealing but too limited in scope and exposure. Qualitative feedback from mothers classified as non-users pointed to several important barriers that could preclude some WIC participants from using the app at all.

Conclusions: The prototype study successfully demonstrated the feasibility of using the CHEW app prototype with mothers of WIC-enrolled black and Hispanic preschool-aged children, with moderate levels of app usage and moderate to high usability and benefits. Future versions with enhanced shopping tools and expanded nutrition content should be implemented in WIC clinics to evaluate adoption and behavioral outcomes. This study adds to the growing body of research focused on the application of technology-based interventions in the WIC program to promote program retention and childhood obesity prevention.
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August 2017

The role of evidence analysts in creating nutrition management guidelines for inherited metabolic disorders.

J Eval Clin Pract 2015 Dec 12;21(6):1235-43. Epub 2015 Aug 12.

Department of Human Genetics, Emory University, School of Medicine, Atlanta, GA, USA.

Rationale, Aims And Objectives: Evidence and consensus-based guidelines for nutrition management of maple syrup urine disease (MSUD) were developed as part of a project to create nutrition guidelines for inherited metabolic disorders identified through newborn screening. The objective of this study was to describe and evaluate the role of evidence analysts in the systematic review phase of guideline development to improve quality of process and output and inform future guideline development projects.

Methods: Recruitment, training and output of evidence analysts were documented throughout the MSUD project. The role of analysts was to critically review and rate the scientific quality of published literature and abstract pertinent information using quality checklists and abstraction worksheets. A secure, web-based application was developed to standardize the process and establish permanent documentation. Analysts completed a post-project survey on perceptions of their role, training and the evidence analysis process.

Results: Of 23 recruits, 65% (15) completed evidence analyst training; 73% of those (11) participated in the analysis of 98 literature articles. Analysts reviewed a median of four articles (range 1-16) with median productivity of 1.1 articles per month. All analysts surveyed (n = 9) understood their role and agreed that training was adequate; 100% agreed that analyst involvement was critical in developing guidelines for MSUD.

Conclusion: Evidence analysts played a key role in appraising and abstracting evidence to develop nutrition guidelines for MSUD. With critical improvements to the process, particularly more stringent and systematic evaluation and documentation of analyst performance related to productivity and quality, we will continue to recruit, train and support evidence analysts in evidence-based guideline development projects.
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December 2015

Accuracy of six anthropometric skinfold formulas versus air displacement plethysmography for estimating percent body fat in female adolescents with phenylketonuria.

JIMD Rep 2013 29;10:23-31. Epub 2012 Dec 29.

Graduate Division of Biological and Biomedical Sciences, Nutrition and Health Sciences Program, Emory University School of Arts and Sciences, Decatur, Georgia, USA.

Background: The reliability of studies investigating biological and therapeutic factors that influence body composition in PKU patients depends on accurate anthropometric measurements.

Objective: To determine the precision of six anthropometric skinfold equations versus air displacement plethysmography (ADP) for predicting body fat (BF) percentage in female adolescents with PKU.

Design: Skinfold and ADP measurements were recorded from a cross section of 59 female patients with PKU, ages 10-19 years. Anthropometric measures were used to calculate percent BF using equations published by Peterson et al., Loftin et al. (TAAG), Slaughter et al., Wilmore and Behnke, Durnin and Womersley, and Jackson et al. Bland-Altman agreement analysis and Lin's concordance correlation coefficient (ρ c) were used to determine the precision of each equation compared with percent BF determined by ADP.

Results: Adolescent females with PKU had a mean BF content of 33% measured by ADP, with an inverse association to birth cohort (r = -0.3, P = 0.016). Based on the Bland-Altman method for evaluating agreement, only Peterson's equation did not differ significantly from ADP percent BF results (P = 0.23). Peterson's skinfold equation yielded percent BF estimates with the smallest mean difference from ADP and the smallest standard deviation (0.76 ± 4.8), whereas Slaughter's equation had the largest (-7.7 ± 7.4). Loftin's TAAG equation had the least mean percent error (2.2%), while Slaughter's equation had the highest (19%). Both TAAG and Peterson's equations had the highest concordance correlation coefficients (ρ c = 0.8, ρ c = 0.8), while Slaughter's equation had the lowest (ρ c = 0.3).

Conclusions: Peterson's equation is a precise surrogate for ADP when estimating percent BF in female adolescents with PKU, though Loftin's TAAG equation is also effective. Observed decreases in adiposity correlating with birth cohort could reflect steady improvements in patient nutrition care.
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May 2013

Utility of phenylalanine hydroxylase genotype for tetrahydrobiopterin responsiveness classification in patients with phenylketonuria.

Mol Genet Metab 2012 Sep 20;107(1-2):31-6. Epub 2012 Jul 20.

Division of Biological and Biomedical Sciences, Nutrition and Health Sciences, Emory University, Atlanta, GA, USA.

Background: A need exists to expand the characterization of tetrahydrobiopterin (BH(4)) responsiveness in patients with phenylketonuria (PKU), beyond simply evaluating change in blood phenylalanine concentrations. The clinical interpretation of BH(4) responsiveness should be evaluated within the context of phenylalanine hydroxylase (PAH) genotype.

Aim: This investigation seeks to use a modified version of a previously developed PAH genotype severity tool, the assigned value (AV) sum, to assess the molecular basis of responsiveness in a clinical cohort and to explore the tool's ability to differentiate BH(4) responsive groups.

Methods: BH(4) response was previously clinically classified in 58 patients with PKU, with three response groups emerging: definitive responders, provisional responders, and non-responders. Provisional responders represented a clinically ambiguous group, with an initial decrease in plasma phenylalanine concentrations, but limited ability to improve dietary phenylalanine tolerance. In this retrospective analysis, mutations in the PAH gene were identified in each patient. PAH genotype was characterized through the AV sum approach, in which each mutation is given an AV of 1, 2, 4, or 8; the sum of both mutations' AV corresponds to genotype severity, with a lower number representing a more severe phenotype. An AV sum cutoff of 2 (indicative of the most severe genotypes) was used to dichotomize patients and predict BH(4) responsiveness. Provisional responders were classified with the definitive responders then the non-responders to see with which group they best aligned.

Results: In 17/19 definitive responders, at least one mutation was mild or moderate in severity (AV sum>2). In contrast, 7/9 provisional responders carried two severe or null mutations (AV sum=2), suggesting little molecular basis for responsiveness. Non-responders represent a heterogeneous group with 15/25 patients carrying two severe mutations (AV sum=2), 5/25 patients carrying one moderate or mild mutation in combination with a severe or null mutation (AV sum>2), and the remaining five patients carrying an uncharacterized mutation in combination with a severe mutation. Predictive sensitivity of the AV sum was maximized (89.5% vs. 67.9%) with limited detriment to specificity (79.4% vs. 80.0%), by classifying provisional responders with the non-responders rather than with the definitive responders.

Conclusions: In our clinical cohort, the AV sum tool was able to identify definitive responders with a high degree of sensitivity. As demonstrated by both the provisional responder group and the substantial number of non-responders with AV sums>2, a potential exists for misclassification when BH(4) response is determined by relying solely on change in plasma phenylalanine concentrations. PAH genotype should be incorporated in the clinical evaluation of BH(4) responsiveness.
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September 2012

Using change in plasma phenylalanine concentrations and ability to liberalize diet to classify responsiveness to tetrahydrobiopterin therapy in patients with phenylketonuria.

Mol Genet Metab 2011 Dec 16;104(4):485-91. Epub 2011 Sep 16.

Department of Human Genetics, Emory University School of Medicine, Decatur, GA 30033, USA.

Tetrahydrobiopterin (BH(4)) responsiveness is currently defined as a decrease in plasma phenylalanine concentrations in patients with phenylketonuria (PKU). This definition does not offer insight beyond the initial assessment of patients, which may lead to treatment ambiguity in patients who only experience an initial decrease in plasma phenylalanine concentrations. We present our experience with a novel classification approach using sequentially-applied criteria. Plasma phenylalanine concentrations were measured at baseline and after one month of BH(4) therapy (20 mg/kg/day) in 58 PKU patients (34 M, 24 F; age 17.3±11.0 years). Thirty-two patients (55.2%) were classified as "preliminary responders" at one month, experiencing at least a 15% decrease in plasma phenylalanine concentrations. Preliminary responders' ability to liberalize their dietary restrictions was then systematically assessed. "Definitive responders" were defined as preliminary responders who could increase their dietary phenylalanine tolerance by at least 300 mg/day and lower prescribed medical food needs by at least 25% while maintaining metabolic control (plasma phenylalanine ≤360 μmol/L) and consuming adequate dietary protein. Preliminary responders who could not liberalize their diets according to these criteria were classified as "provisional responders." Nineteen patients (32.8% of patients initiating BH(4) therapy) met the definitive responder criteria, increasing dietary phenylalanine tolerance from 704±518 mg/day to 1922±612 mg/day and reducing medical food to 16.7±19.5% of their baseline prescription. Nine patients (15.5% of patients initiating BH(4) therapy) were classified as provisional responders, all remaining on 100% of their baseline medical food prescription. From this classification approach, a subgroup of provisionally responsive patients emerged who experienced an initial decrease in plasma phenylalanine concentrations but who could not substantially increase their dietary phenylalanine tolerance or decrease medical food needs. Diet liberalization is an essential component of BH(4)-responsiveness classification.
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December 2011

BH(4) therapy impacts the nutrition status and intake in children with phenylketonuria: 2-year follow-up.

J Inherit Metab Dis 2010 Dec 13;33(6):689-95. Epub 2010 Oct 13.

Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30030, USA.

The impact of tetrahydrobiopterin (BH(4)) treatment on phenylalanine tolerance, medical-food consumption, and nutrition status in patients with phenylketonuria (PKU) was investigated. Six children (5-12 years) with well-controlled PKU, responding to a BH(4) dose of 20 mg/kg per day, were assessed for 24 months. Mean dietary phenylalanine tolerance increased from 421 ± 128 to 1470 ± 455 mg/day. Height Z scores significantly improved from 0.25 ± 0.99 at baseline to 0.53 ± 1.16 at 24 months (p for trend < 0.001). Patients tolerated more phenylalanine and more intact protein and required less medical food (protein supplement). Improved linear growth and nutrition status was seen over the course of the 24-month follow-up. Due to the variation in phenylalanine tolerance, dietary recommendations should be tailored to the patient's individual requirements.
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December 2010

Predictive equations underestimate resting energy expenditure in female adolescents with phenylketonuria.

J Am Diet Assoc 2010 Jun;110(6):922-5

Graduate Division of Biological and Biomedical Sciences, Nutrition and Health Sciences, Emory University, Decatur, GA 30033, USA.

Resting energy expenditure (REE) is often used to estimate total energy needs. The Schofield equation based on weight and height has been reported to underestimate REE in female children with phenylketonuria (PKU). The objective of this observational, cross-sectional study was to evaluate the agreement of measured REE with predicted REE for female adolescents with PKU. A total of 36 females (aged 11.5 to 18.7 years) with PKU attending Emory University's Metabolic Camp (June 2002 to June 2008) underwent indirect calorimetry. Measured REE was compared to six predictive equations using paired Student's t tests, regression-based analysis, and assessment of clinical accuracy. The differences between measured and predicted REE were modeled against clinical parameters to determine whether a relationship existed. All six selected equations significantly under predicted measured REE (P<0.005). The Schofield equation based on weight had the greatest level of agreement, with the lowest mean prediction bias (144 kcal) and highest concordance correlation coefficient (0.626). However, the Schofield equation based on weight lacked clinical accuracy, predicting measured REE within +/-10% in only 14 of 36 participants. Clinical parameters were not associated with bias for any of the equations. Predictive equations underestimated measured REE in this group of female adolescents with PKU. Currently, there is no accurate and precise alternative for indirect calorimetry in this population.
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June 2010

UV radiation effects on plant growth and forage quality in a shortgrass steppe ecosystems.

Photochem Photobiol 2004 May;79(5):404-10

Forest, Range, and Watershed Stewardship Department, Colorado State University, Fort Collins, CO 80523, USA.

Levels of UV were manipulated in a native shortgrass steppe using open-sided structures with tops that either passed or blocked wavelengths shorter than approximately 370 nm. Precipitation was controlled to create a drought or a very wet year. Subplots were either nondefoliated or defoliated to simulate grazing by livestock, which is the primary land use. Plant community productivity and forage quality were assessed in response to the two climate change variables (UV, precipitation) and grazing stress. Productivity and seasonal standing biomass of the dominant grass species were negatively affected by passing versus blocking UV, but only in the dry year. Another species was negatively affected by passing UV in the wet year, indicating the potential for future shifts in species composition. Forage quality for ruminants increased when UV was passed compared with blocked, as determined by in vitro digestible dry matter, depending on species and precipitation. Nitrogen concentrations and soluble and fiber components of vegetation also displayed some UV effects, but they were generally small and depended on species, season or amount of precipitation (or all). Grazing treatment had large positive effects on current-year productivity only in the wet year and some small positive effects on quality in both wet and dry years. Interactions between UV and grazing treatment were not observed.
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May 2004