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424 results on '"Long, D. Leann"'

1. Comparison of methods for mediation analysis with multiple correlated mediators

Author

Appah, Mary, Long, D. Leann, Howard, George, and Smith, Melissa J.

Subjects
Statistics - Applications, Statistics - Methodology
Abstract

Various methods have emerged for conducting mediation analyses with multiple correlated mediators, each with distinct strengths and limitations. However, a comparative evaluation of these methods is lacking, providing the motivation for this paper. This study examines six mediation analysis methods for multiple correlated mediators that provide insights to the contributors for health disparities. We assessed the performance of each method in identifying joint or path-specific mediation effects in the context of binary outcome variables varying mediator types and levels of residual correlation between mediators. Through comprehensive simulations, the performance of six methods in estimating joint and/or path-specific mediation effects was assessed rigorously using a variety of metrics including bias, mean squared error, coverage and width of the 95$\%$ confidence intervals. Subsequently, these methods were applied to the REasons for Geographic And Racial Differences in Stroke (REGARDS) study, where differing conclusions were obtained depending on the mediation method employed. This evaluation provides valuable guidance for researchers grappling with complex multi-mediator scenarios, enabling them to select an optimal mediation method for their research question and dataset.

Published
2024

4. Path-specific causal decomposition analysis with multiple correlated mediator variables

Author

Smith, Melissa J., McClure, Leslie A., and Long, D. Leann

Subjects
Statistics - Methodology
Abstract

A causal decomposition analysis allows researchers to determine whether the difference in a health outcome between two groups can be attributed to a difference in each group's distribution of one or more modifiable mediator variables. With this knowledge, researchers and policymakers can focus on designing interventions that target these mediator variables. Existing methods for causal decomposition analysis either focus on one mediator variable or assume that each mediator variable is conditionally independent given the group label and the mediator-outcome confounders. In this paper, we propose a flexible causal decomposition analysis method that can accommodate multiple correlated and interacting mediator variables, which are frequently seen in studies of health behaviors and studies of environmental pollutants. We extend a Monte Carlo-based causal decomposition analysis method to this setting by using a multivariate mediator model that can accommodate any combination of binary and continuous mediator variables. Furthermore, we state the causal assumptions needed to identify both joint and path-specific decomposition effects through each mediator variable. To illustrate the reduction in bias and confidence interval width of the decomposition effects under our proposed method, we perform a simulation study. We also apply our approach to examine whether differences in smoking status and dietary inflammation score explain any of the Black-White differences in incident diabetes using data from a national cohort study.

Published
2023
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5. Population-average mediation analysis for zero-inflated count outcomes

Author

Sims, Andrew, Long, D. Leann, Tiwari, Hemant K., Cui, Jinhong, Long, Dustin M., Brown, Todd M., Smith, Melissa J., and Levitan, Emily B.

Subjects
Statistics - Methodology
Abstract

Mediation analysis is an increasingly popular statistical method for explaining causal pathways to inform intervention. While methods have increased, there is still a dearth of robust mediation methods for count outcomes with excess zeroes. Current mediation methods addressing this issue are computationally intensive, biased, or challenging to interpret. To overcome these limitations, we propose a new mediation methodology for zero-inflated count outcomes using the marginalized zero-inflated Poisson (MZIP) model and the counterfactual approach to mediation. This novel work gives population-average mediation effects whose variance can be estimated rapidly via delta method. This methodology is extended to cases with exposure-mediator interactions. We apply this novel methodology to explore if diabetes diagnosis can explain BMI differences in healthcare utilization and test model performance via simulations comparing the proposed MZIP method to existing zero-inflated and Poisson methods. We find that our proposed method minimizes bias and computation time compared to alternative approaches while allowing for straight-forward interpretations., Comment: 34 pages, 2 figures, 4 tables, 49 pages of Supplemental material, 2 supplemental figures

Published
2023

6. Childhood Residential Mobility and Mental and Physical Health in Later Life: Findings From the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Author

Yen, Irene H, Bennett, Aleena, Allen, Shauntice, Vable, Anusha, Long, D Leann, Brooks, Marquita, Ream, Robert K, Crowe, Michael, and Howard, Virginia J

Subjects
Epidemiology, Public Health, Health Sciences, Pediatric, Mental Health, Behavioral and Social Science, Stroke, Basic Behavioral and Social Science, Brain Disorders, Aging, 2.3 Psychological, social and economic factors, Aetiology, Good Health and Well Being, Humans, Aged, Race Factors, Social Class, Population Dynamics, African Americans, housing, physical function, childhood residential mobility, physical health, adverse childhood experiences disproportionately affect health, Black people may be especially disadvantaged, Clinical Sciences, Gerontology, Biomedical and clinical sciences, Health sciences, Psychology
Abstract

The study objective was to investigate the effects of childhood residential mobility on older adult physical and mental health. In REasons for Geographic and Racial Differences in Stroke (REGARDS) Study, we used linear regression models to investigate if number of moves during childhood predicted mental and physical health (SF-12 MCS, PCS), adjusting for demographic covariates, childhood socioeconomic status (SES), childhood social support, and adverse childhood experiences (ACEs). We investigated interaction by age, race, childhood SES, and ACEs. People who moved more during childhood had poorer MCS scores, β = -0.10, SE = 0.05, p = 0.03, and poorer PCS scores, β = -0.25, SE = 0.06, p < 0.0001. Effects of moves on PCS were worse for Black people compared to White people (p = 0.06), those with low childhood SES compared to high childhood SES (p = 0.02), and high ACEs compared to low ACEs (p = 0.01). As family instability accompanying residential mobility, family poverty, and adversity disproportionately affect health, Black people may be especially disadvantaged.

Published
2023

11. Spike-and-Slab LASSO Generalized Additive Models and Scalable Algorithms for High-Dimensional Data Analysis

Author

Guo, Boyi, Jaeger, Byron C., Rahman, A. K. M. Fazlur, Long, D. Leann, and Yi, Nengjun

Subjects
Statistics - Methodology, Statistics - Machine Learning
Abstract

There are proposals that extend the classical generalized additive models (GAMs) to accommodate high-dimensional data ($p>>n$) using group sparse regularization. However, the sparse regularization may induce excess shrinkage when estimating smooth functions, damaging predictive performance. Moreover, most of these GAMs consider an "all-in-all-out" approach for functional selection, rendering them difficult to answer if nonlinear effects are necessary. While some Bayesian models can address these shortcomings, using Markov chain Monte Carlo algorithms for model fitting creates a new challenge, scalability. Hence, we propose Bayesian hierarchical generalized additive models as a solution: we consider the smoothing penalty for proper shrinkage of curve interpolation via reparameterization. A novel two-part spike-and-slab LASSO prior for smooth functions is developed to address the sparsity of signals while providing extra flexibility to select the linear or nonlinear components of smooth functions. A scalable and deterministic algorithm, EM-Coordinate Descent, is implemented in an open-source R package BHAM. Simulation studies and metabolomics data analyses demonstrate improved predictive and computational performance against state-of-the-art models. Functional selection performance suggests trade-offs exist regarding the effect hierarchy assumption., Comment: Total of 22 pages, including 2 figures, 7 tables, and 3 pages of references. The supporting information can be found via https://github.com/boyiguo1/Manuscript-BHAM/blob/main/Manuscript/SS_GAM_Supporting_Information.pdf

Published
2021
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15. Age and sex differences in the association between neighborhood socioeconomic environment and incident diabetes: Results from the diabetes location, environmental attributes and disparities (LEAD) network

Author

Uddin, Jalal, Zhu, Sha, Adhikari, Samrachana, Nordberg, Cara M., Howell, Carrie R., Malla, Gargya, Judd, Suzanne E., Cherrington, Andrea L., Rummo, Pasquale E., Lopez, Priscilla, Kanchi, Rania, Siegel, Karen, De Silva, Shanika A., Algur, Yasemin, Lovasi, Gina S., Lee, Nora L., Carson, April P., Hirsch, Annemarie G., Thorpe, Lorna E., and Long, D. Leann

Published
2023
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23. Influence Of Gender Identity on The Modulation of Painful Stimuli for Cisgender and Transgender Individuals

Author

Stocking, Samantha Q., primary, Webb, Caroline K., additional, Gunapati, Shruti R., additional, Goldfeiz, Nathaniel M., additional, Roychowdhury, Ayona, additional, Totsch, Stacie K., additional, Quinn, Tammie L., additional, Long, D. Leann, additional, Aroke, Edwin N., additional, Thomeer, Mieke B., additional, Norian, Lyse A., additional, Goodin, Burel R., additional, and Sorge, Robert E., additional

Published
2024
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24. Associations Between Gender Identity, Depression, And Pain Processing in Cisgender and Transgender Individuals

Author

Webb, Caroline K., primary, Stocking, Samantha Q., additional, Gunapati, Shruti R., additional, Goldfeiz, Nathaniel M., additional, Roychowdhury, Ayona, additional, Totsch, Stacie K., additional, Quinn, Tammie L., additional, Long, D. Leann, additional, Aroke, Edwin N., additional, Thomeer, Mieke B., additional, Norian, Lyse A., additional, Goodin, Burel R., additional, and Sorge, Robert E., additional

Published
2024
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36. Defining diabetes status using medication groups in Medicare data: Trends in prescribing diabetes medications to patients without a diabetes diagnosis over time

Author

Howell, Carrie R., primary, Zhu, Sha, additional, Malla, Gargya, additional, Carson, Gargya, additional, Cummings, Doyle, additional, Uddin, Jalal, additional, Levitan, Emily B., additional, Safford, Monika, additional, Cherrington, Andrea L., additional, and Long, D. Leann, additional

Published
2024
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39. Population‐average mediation analysis for zero‐inflated count outcomes.

Author

Sims, Andrew, Long, D. Leann, Tiwari, Hemant K., Cui, Jinhong, Long, Dustin M., Brown, Todd M., Smith, Melissa J., and Levitan, Emily B.

Subjects
*DIAGNOSIS of diabetes, *COUNTERFACTUALS (Logic)
Abstract

Mediation analysis is an increasingly popular statistical method for explaining causal pathways to inform intervention. While methods have increased, there is still a dearth of robust mediation methods for count outcomes with excess zeroes. Current mediation methods addressing this issue are computationally intensive, biased, or challenging to interpret. To overcome these limitations, we propose a new mediation methodology for zero‐inflated count outcomes using the marginalized zero‐inflated Poisson (MZIP) model and the counterfactual approach to mediation. This novel work gives population‐average mediation effects whose variance can be estimated rapidly via delta method. This methodology is extended to cases with exposure‐mediator interactions. We apply this novel methodology to explore if diabetes diagnosis can explain BMI differences in healthcare utilization and test model performance via simulations comparing the proposed MZIP method to existing zero‐inflated and Poisson methods. We find that our proposed method minimizes bias and computation time compared to alternative approaches while allowing for straight‐forward interpretations. [ABSTRACT FROM AUTHOR]

Published
2024
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45. OBLIQUE RANDOM SURVIVAL FORESTS

Author

Jaeger, Byron C., Long, D. Leann, Long, Dustin M., Sims, Mario, Szychowski, Jeff M., Min, Yuan-I, Mcclure, Leslie A., Howard, George, and Simon, Noah

Published
2019

48. Life-Space Mobility: Normative Values From a National Cohort of U.S. Older Adults.

Author

Lo, Alexander X, Wadley, Virginia G, Brown, Cynthia J, Long, D Leann, Crowe, Michael, Howard, Virginia J, and Kennedy, Richard E

Subjects
OLDER people, AGE groups, MOBILITY of older people, PHYSICAL mobility, ACTIVITIES of daily living, RACIAL inequality
Abstract

Background Life-space mobility, which measures the distance, frequency, and independence achieved as individuals move through their community, is one of the most important contributors to healthy aging. The University of Alabama at Birmingham Life-Space Assessment (LSA) is the most commonly used measure of life-space mobility in older adults, yet U.S. national norms for LSA have not previously been reported. This study reports such norms based on age and sex among community-dwelling older adults. Methods A cross-sectional analysis using data from the national REasons for Geographic and Racial Disparities in Stroke cohort study. LSA data were available for 10 118 Black and White participants over age 50, which were grouped by age (in 5-year increments) and sex, weighted for the U.S. national population. Correlations were calculated between LSA and measures of functional and cognitive impairment and physical performance. Results The weighted mean LSA ranged from 102.9 for 50–54-year-old males to 69.5 for males aged 85 and older, and from 102.1 for 50–54-year-old females to 60.1 for females aged 85 and older. LSA was strongly correlated with measures of timed walking, activities of daily living, cognition, depressive symptoms, and quality of life (all p <.001). Conclusions We report U.S. national norms for LSA among community-dwelling Black and White older adults. These norms can serve as a reference tool for determining if clinical and research samples have greater or lesser life-space mobility than typical older adults in the United States for their age and sex. [ABSTRACT FROM AUTHOR]

Published
2024
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49. Application of marginalized zero-inflated models when mediators have excess zeroes.

Author

Sims, Andrew, Tiwari, Hemant, Levitan, Emily B., Long, Dustin, Howard, George, Brown, Todd, Smith, Melissa J., Cui, Jinhong, and Long, D. Leann

Abstract

Mediation analysis has become increasingly popular over the last decade as researchers are interested in assessing mechanistic pathways for intervention. Although available methods have increased, there are still limited options for mediation analysis with zero-inflated count variables where the distribution of response has a "cluster" of data at the zero value (i.e. distribution of number of cigarettes smoked per day, where nonsmokers cluster at zero cigarettes). The currently available methods do not obtain unbiased population average effects of mediation effects. In this paper, we propose an extension of the counterfactual approach to mediation with direct and indirect effects to scenarios where the mediator is a count variable with excess zeroes by utilizing the Marginalized Zero-Inflated Poisson Model (MZIP) for the mediator model. We derive direct and indirect effects for continuous, binary, and count outcomes, as well as adapt to allow mediator-exposure interactions. Our proposed work allows straightforward calculation of direct and indirect effects for the overall population mean values of the mediator, for scenarios in which researchers are interested in generalizing direct and indirect effects to the population. We apply this novel methodology to an application observing how alcohol consumption may explain sex differences in cholesterol and assess model performance via a simulation study comparing the proposed MZIP mediator framework to existing methods for marginal mediator effects. [ABSTRACT FROM AUTHOR]

Published
2024
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