Publications by authors named "Leah M Frerichs"

6 Publications

  • Page 1 of 1

A Guide for Choosing Community Detection Algorithms in Social Network Studies: The Question Alignment Approach.

Am J Prev Med 2020 10;59(4):597-605

Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.

Introduction: Community detection, the process of identifying subgroups of highly connected individuals within a network, is an aspect of social network analysis that is relevant but potentially underutilized in prevention research. Guidance on using community detection methods stresses aligning methods with specific research questions but lacks clear operationalization. The Question Alignment approach was developed to help address this gap and promote the high-quality use of community detection methods.

Methods: A total of 6 community detection methods are discussed: Walktrap, Edge-Betweenness, Infomap, Louvain, Label Propagation, and Spinglass. The Question Alignment approach is described and demonstrated using real-world data collected in 2013. This hypothetical case study was conducted in 2019 and focused on targeting a hand hygiene intervention to high-risk communities to prevent influenza transmission.

Results: Community detection using the Walktrap method best fit the hypothetical case study. The communities derived using the Walktrap method were quite different from communities derived through the other 5 methods in both the number of communities and individuals within communities. There was evidence to support that the Question Alignment approach can help researchers produce more useful community detection results. Compared to other methods of selecting high-risk groups, the Walktrap produced the most communities that met the hypothetical intervention requirements.

Conclusions: As prevention research incorporating social networks increases, researchers can use the Question Alignment approach to produce more theoretically meaningful results and potentially more useful results for practice. Future research should focus on assessing whether the Question Alignment approach translates into improved intervention results.
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October 2020

Demographic Groups Likely Affected by Regulating Sugar-Sweetened Beverage Portion Sizes.

Am J Prev Med 2020 09 21;59(3):e135-e139. Epub 2020 Jun 21.

Department of Health Policy and Management, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina.

Introduction: Sugar-sweetened beverages are a key driver of obesity. Portion-size regulations typically limit the volume of unsealed sugar-sweetened beverage containers to 16 fluid ounces. These regulations could reduce sugar-sweetened beverage consumption, but whom these policies would affect remains unknown. This study evaluates demographic groups likely affected by hypothetical national portion-size regulations modeled on policy language and scopes from New York City and California.

Methods: Data from adults (aged 18-65 years, n=6,594) in the National Health and Nutrition Examination Survey (2013‒2016) were used to classify individuals as likely affected if they consumed a sugar-sweetened beverage larger than 16 fluid ounces from a potentially regulated food source during at least 1 eating occasion. Two classifications of affected food sources were evaluated: (1) excluding convenience stores (New York City scope) and (2) including convenience stores (California scope). In 2020, analyses were conducted using logistic regression to examine associations between affected status and age (<35 and ≥35 years), sex, race/ethnicity (white, non-Hispanic, black, non-Hispanic, andHispanic), education (without college degree and with college degree), and income (≤185% and >185% of the federal poverty line).

Results: Portion-size regulations would affect 8.87% of adults (New York City scope) and 14.71% of adults (California scope). Regulations had a greater potential effect on adults who were aged <35 years, male, and without a college degree (all p<0.05). Differences between demographic groups would be larger in magnitude using California's policy scope.

Conclusions: Portion-size regulations would likely have a greater effect on younger, male, and less-educated adults. Policy effects would likely be larger if these regulations are written to encompass more food sources.
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September 2020

High School Physical Activity and Nutrition Policy: Summarizing Changes Over Time Using Latent Class Analysis.

Am J Prev Med 2019 09;57(3):e69-e76

Department of Health Policy and Management, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Electronic address:

Introduction: High school physical activity and nutrition policies can substantially affect student behavior and outcomes. Although public health officials and legislators have advocated for policy improvements, the extent to which policies have changed at local levels is not well understood. This study identifies latent classes of physical activity and nutrition policy environments and explores changes in prevalence of these classes from 2000 to 2016.

Methods: Data from the School Health Policies and Practices Study, a repeated cross-sectional survey from the Centers for Disease Control and Prevention administered at the school district level in 2000, 2006, 2012, and 2016, were analyzed in 2018. Using latent class analysis, policy environment subgroups were identified, described, and then dichotomized based on satisfaction in meeting recommendations. Associations of latent classes with year and urbanicity were evaluated using logistic regression.

Results: Five latent classes were identified each for physical activity and nutrition policy environments, all with distinct characteristics. Physical activity policies improved from 2000 to 2006 (p<0.001) and then plateaued until 2016, whereas nutrition policies improved consistently from 2000 to 2016 (p<0.001, p=0.011, p<0.001). Though significant disparities between urban and rural school districts were found, these disparities narrowed during the studied years, particularly for physical activity policies.

Conclusions: The estimated proportion of school districts with satisfactory physical activity and nutrition policy environments increased from 2000 to 2016, possibly because of legislative and policy advocacy efforts. However, many areas for improvement remain. Unsatisfactory latent classes that remained prevalent though 2016 may highlight policy domains that should be targeted by future interventions or subject to further research.
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September 2019

Mobilisation of public support for policy actions to prevent obesity.

Lancet 2015 Jun 19;385(9985):2422-31. Epub 2015 Feb 19.

Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.

Public mobilisation is needed to enact obesity-prevention policies and to mitigate reaction against their implementation. However, approaches in public health focus mainly on dialogue between public health professionals and political leaders. Strategies to increase popular demand for obesity-prevention policies include refinement and streamlining of public information, identification of effective obesity frames for each population, strengthening of media advocacy, building of citizen protest and engagement, and development of a receptive political environment with change agents embedded across organisations and sectors. Long-term support and investment in collaboration between diverse stakeholders to create shared value is also important. Each actor in an expanded coalition for obesity prevention can make specific contributions to engaging, mobilising, and coalescing the public. The shift from a top-down to a combined and integrated bottom-up and top-down approach would need an overhaul of current strategies and reprioritisation of resources.
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June 2015

Modeling social transmission dynamics of unhealthy behaviors for evaluating prevention and treatment interventions on childhood obesity.

PLoS One 2013 17;8(12):e82887. Epub 2013 Dec 17.

College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.

Research evidence indicates that obesity has spread through social networks, but lever points for interventions based on overlapping networks are not well studied. The objective of our research was to construct and parameterize a system dynamics model of the social transmission of behaviors through adult and youth influence in order to explore hypotheses and identify plausible lever points for future childhood obesity intervention research. Our objectives were: (1) to assess the sensitivity of childhood overweight and obesity prevalence to peer and adult social transmission rates, and (2) to test the effect of combinations of prevention and treatment interventions on the prevalence of childhood overweight and obesity. To address the first objective, we conducted two-way sensitivity analyses of adult-to-child and child-to-child social transmission in relation to childhood overweight and obesity prevalence. For the second objective, alternative combinations of prevention and treatment interventions were tested by varying model parameters of social transmission and weight loss behavior rates. Our results indicated child overweight and obesity prevalence might be slightly more sensitive to the same relative change in the adult-to-child compared to the child-to-child social transmission rate. In our simulations, alternatives with treatment alone, compared to prevention alone, reduced the prevalence of childhood overweight and obesity more after 10 years (1.2-1.8% and 0.2-1.0% greater reduction when targeted at children and adults respectively). Also, as the impact of adult interventions on children was increased, the rank of six alternatives that included adults became better (i.e., resulting in lower 10 year childhood overweight and obesity prevalence) than alternatives that only involved children. The findings imply that social transmission dynamics should be considered when designing both prevention and treatment intervention approaches. Finally, targeting adults may be more efficient, and research should strengthen and expand adult-focused interventions that have a high residual impact on children.
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October 2014