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381 results on '"Atem, Folefac"'

6. Regression with a right-censored predictor, using inverse probability weighting methods

Author

Matsouaka, Roland A. and Atem, Folefac D.

Subjects
Statistics - Methodology
Abstract

In a longitudinal study, measures of key variables might be incomplete or partially recorded due to drop-out, loss to follow-up, or early termination of the study occurring before the advent of the event of interest. In this paper, we focus primarily on the implementation of a regression model with a randomly censored predictor. We examine, particularly, the use of inverse probability weighting methods in a generalized linear model (GLM), when the predictor of interest is right-censored, to adjust for censoring. To improve the performance of the complete-case analysis and prevent selection bias, we consider three different weighting schemes: inverse censoring probability weights, Kaplan-Meier weights, and Cox proportional hazards weights. We use Monte Carlo simulation studies to evaluate and compare the empirical properties of different weighting estimation methods. Finally, we apply these methods to the Framingham Heart Study data as an illustrative example to estimate the relationship between age of onset of a clinically diagnosed cardiovascular event and low-density lipoprotein (LDL) among cigarette smokers., Comment: 21 pages

Published
2020

14. Linear regression model with a randomly censored predictor:Estimation procedures

Author

Atem, Folefac and Matsouaka, Roland A.

Subjects
Statistics - Applications
Abstract

We consider linear regression model estimation where the covariate of interest is randomly censored. Under a non-informative censoring mechanism, one may obtain valid estimates by deleting censored observations. However, this comes at a cost of lost information and decreased efficiency, especially under heavy censoring. Other methods for dealing with censored covariates, such as ignoring censoring or replacing censored observations with a fixed number, often lead to severely biased results and are of limited practicality. Parametric methods based on maximum likelihood estimation as well as semiparametric and non-parametric methods have been successfully used in linear regression estimation with censored covariates where censoring is due to a limit of detection. In this paper, we adapt some of these methods to handle randomly censored covariates and compare them under different scenarios to recently-developed semiparametric and nonparametric methods for randomly censored covariates. Specifically, we consider both dependent and independent randomly censored mechanisms as well as the impact of using a non-parametric algorithm on the distribution of the randomly censored covariate. Through extensive simulation studies, we compare the performance of these methods under different scenarios. Finally, we illustrate and compare the methods using the Framingham Health Study data to assess the association between low-density lipoprotein (LDL) in offspring and parental age at onset of a clinically-diagnosed cardiovascular event., Comment: 21 pages; 1 figure

Published
2017

26. Comparison of Early Life Obesity-Related Risk and Protective Factors in Non-Hispanic Black Subgroups

Author

Messiah, Sarah E., Atem, Folefac, Lebron, Cynthia, Ofori, Ashley, Mathew, M. Sunil, Chang, Catherina, and Natale, Ruby A.

Subjects
Obesity -- Risk factors -- Demographic aspects, Children -- Health aspects, African Americans -- Health aspects -- Demographic aspects, Health care industry
Abstract

Objectives Previous obesity prevention studies in preschool-age children have included non-Hispanic Black (NHB) children, but few have investigated between-subgroup differences even though there may be cultural risk and protective practice differences, challenging the generalizability of findings. The purpose of this study was to examine differences in early childhood obesity-related factors in NHB subgroups (Haitian, other Caribbean Islander and African-American [AA]) children. Methods Baseline data from two randomized controlled trials in 52 childcare centers of which 35 had data to test a preschool-based obesity prevention intervention was analyzed. The sub-sample included 370 caregiver-child dyads; 209 self-identified as AA, 120 as Haitian and 41 as Caribbean Islander/West Indian or mixed race. Multilevel regression models generated outcome estimates for group differences in body mass index (BMI) percentile, birthweight, breastfeeding initiation and duration, bottle feeding duration and age when solid foods were introduced. Results Mean BMI percentile was similar for AA, Haitian and Caribbean Islander/West Indian/Multiracial (60.1th percentile, 60.8th percentile, 62.8th percentile, respectively) as was birthweight (6.3, 6.8, and 6.6 lb, respectively). Children of US-born caregivers had significantly lower BMI percentiles (9.13 percentile points) versus foreign-born caregivers. Haitian women were significantly more likely to initiate breastfeeding (64.9%) versus AA (47.6%) and Caribbean Islander/West Indian/Multiracial (62.2%) (p < .01). No significant group differences were found in breastfeeding or bottle feeding duration or age solid foods were introduced. Conclusions Findings here suggest that NHB race classification can identify important subgroup behavioral similarities which in turn may inform culturally sensitive strategies to promote early childhood healthy weight. Foreign-born caregivers may benefit from healthy weight promotion information, and as early as possible in their child's development., Author(s): Sarah E. Messiah [sup.1] [sup.2] , Folefac Atem [sup.1] [sup.2] , Cynthia Lebron [sup.3] , Ashley Ofori [sup.1] [sup.2] , M. Sunil Mathew [sup.1] [sup.2] , Catherina Chang [sup.4] [...]

Published
2020
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46. Family-based pediatric weight management interventions in US primary care settings targeting children ages 6–12 years old: A systematic review guided by the RE-AIM framework.

Author

Yudkin, Joshua S, Koym, Kelsey, Hamad, Yasmin, Malthaner, Lauren Q, Burgess, Rebecca Meredith, Ortiz, Leslie N, Dhurjati, Nalini, Mitha, Sharmin, Calvi, Gabriela, Hill, Kristina, Brownell, Mckenna, Wei, Elena, Swartz, Kyle, Atem, Folefac D, Galeener, Carol A, Messiah, Sarah E, Barlow, Sarah E, and Allicock, Marlyn A

Abstract

Obesity is a pandemic that disproportionately affects children from vulnerable populations in the USA. Current treatment approaches in primary care settings in the USA have been reported to be insufficient at managing pediatric obesity, primarily due to implementation challenges for healthcare systems and barriers for families. While the literature has examined the efficacy of pediatric obesity interventions focused on internal validity, it lacks sufficient reporting and analysis of external validity necessary for successful translation to primary care settings. We conducted a systematic review of the primary-care-setting literature from January 2007 to March 2020 on family-based pediatric weight management interventions in both English and/or Spanish for children ages 6–12 years in the USA using the Reach, Efficacy/Effectiveness, Adoption, Implementation, Maintenance (RE-AIM) framework. A literature search, using PRISMA guidelines, was conducted in January 2022 using the following electronic databases: Medline Ovid, Embase, and Cochrane Library. 22 270 records were screened, and 376 articles were reviewed in full. 184 studies were included. The most commonly reported dimensions of the RE-AIM framework were Reach (65%), Efficacy/Effectiveness (64%), and Adoption (64%), while Implementation (47%) and Maintenance (42%) were less often reported. The prevalence of reporting RE-AIM construct indicators ranged greatly, from 1% to 100%. This systematic review underscores the need for more focus on external validity to guide the development, implementation, and dissemination of future pediatric obesity interventions based in primary care settings. It also suggests conducting additional research on sustainable financing for pediatric obesity interventions. [ABSTRACT FROM AUTHOR]

Published
2024
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