A computationally efficient sequential regression imputation algorithm for multilevel data.

Due to the computational burden, especially in high-dimensional settings, sequential imputation may not be practical. In this paper, we adopt computationally advantageous methods by sampling the missing data from their perspective predictive distributions, which leads to significantly improved computation time in the class of variable-by-variable imputation algorithms. We assess the computational performance in a comprehensive simulation study.

Organizational Health Literacy and Health Among New York State Medicaid Members.

Background: The definition of health literacy has recently expanded beyond the idea of individual skills to include the system and environment the individual interacts with to receive care, known as organizational health literacy (OHL). However, neither the prevalence of OHL nor the impact of OHL on individuals' perceptions of their health and healthcare have been examined in New York's Medicaid managed care population.

Objective: This study aimed to estimate the prevalence of organizational health literacy in the New York State (NYS) Medicaid Managed Care (MMC) program.

Organ Donation Willingness Among Asian Americans: Results from a National Study.

Asian Americans are the fastest growing racial group in the USA, but their health disparities are often overlooked. Although their needs for transplantable organs are substantial, they have the lowest rates of organ donation per million compared to other Americans by race. To better understand Asian Americans' disposition toward organ donation, a self-administered survey was developed based on formative data collection and guidance from a Community Advisory Board composed of Asian American stakeholders.

Toxic elements in follicular fluid adversely influence the likelihood of pregnancy and live birth in women undergoing IVF.

Study Question: Are follicular fluid (FF), arsenic (As), mercury (Hg), cadmium (Cd) and lead (Pb) concentrations associated with IVF outcomes among women undergoing IVF?

Summary Answer: There was a non-linear association between higher FF Hg concentration and a lower likelihood of biochemical pregnancy and live birth. Higher FF Pb concentration was also associated with a lower probability of live birth.

What Is Known Already: Previous research suggests that toxic elements may affect fertility among couples conceiving with and without assistance.

Variability of essential and non-essential trace elements in the follicular fluid of women undergoing in vitro fertilization (IVF).

Both essential and non-essential elements have been associated with female reproductive function in epidemiologic investigations, including among IVF populations. To date, most investigators have used blood or urine to assess biomarkers of exposure, with few employing ovarian follicular fluid (FF). FF may offer a more direct "snapshot" of the oocyte microenvironment than blood or urine, however previous studies report follicle-to-follicle variability in FF constituents that may contribute to exposure misclassification.

Seafood consumption is associated with higher follicular fluid arsenic (As) and mercury (Hg) concentrations in women undergoing in vitro fertilization (IVF).

Human exposure to non-essential toxic metals such as cadmium (Cd), mercury (Hg), and lead (Pb), and metalloids such as arsenic (As) commonly occurs through diet. Toxic trace element exposures have been reported in association with fertility and fecundity in epidemiologic studies even at low to moderate levels. While most previous studies employed blood and urine biomarkers of exposure, few have assessed toxic trace elements in ovarian follicular fluid (FF), which surrounds the developing oocyte and hence may better reflect concentrations potentially affecting reproductive outcomes.

Muslim-Non-Muslim Locational Attainment in Philadelphia: A New Fault Line in Residential Inequality?

This study examines Muslim-non-Muslim disparities in locational attainment. We pool data from the 2004, 2006, and 2008 waves of the Public Health Management Corporation's Southeastern Pennsylvania Household Survey. These data contain respondents' religious identities and are geocoded at the census-tract level, allowing us to merge American Community Survey data and examine neighborhood-level outcomes to gauge respondents' locational attainment.

Racial disparity in maternal phthalates exposure; Association with racial disparity in fetal growth and birth outcomes.

Experimental and observational data implicate phthalates as developmental toxicants. However, few data are available to assess the maternal risks of gestational exposure by race and infant sex. To begin to address this data gap, we characterized associations between maternal urinary phthalate metabolites and birth outcomes among African American and white mothers from a southeastern U.

ICU Admission Muscle and Fat Mass, Survival, and Disability at Discharge: A Prospective Cohort Study.

Background: Skeletal muscle dysfunction occurring as a result of ICU admission associates with higher mortality. Although preadmission higher BMI correlates with better outcomes, the impact of baseline muscle and fat mass has not been defined. We therefore investigated the association of skeletal muscle and fat mass at ICU admission with survival and disability at hospital discharge.

Metabolic Syndrome Among Asian Indians in the United States.

Introduction: Metabolic syndrome (MetS), a clustering of cardiometabolic risk factors of type 2 diabetes and cardiovascular disease, disproportionately affects Asian Indians (AIs). We examined prevalence of MetS using 3 ethnicity-specific MetS criteria among immigrant AIs in the United States. We also examined associations between MetS and health promotion behaviors.

Clinical Features of Extrapulmonary Sarcoidosis Without Lung Involvement.

Background: Compared with pulmonary sarcoidosis, sarcoidosis without lung involvement may involve other immunopathologic mechanisms and be associated with other demographic and clinical features.

Methods: This was a retrospective analysis of clinical data collected in real time on 1,686 patients with biopsy-proven sarcoidosis from two large university sarcoidosis outpatient clinics in the United States. We compared differences in demographics characteristics and clinical presentation between pulmonary and nonpulmonary sarcoidosis (NPS).

Occupational exposure to perfluoroalkyl substances and serum levels of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in an aging population from upstate New York: a retrospective cohort study.

Purpose: Perfluoroalkyl substances (PFASs) are environmentally persistent amphiphilic compounds. Exposure to two PFASs, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) is linked to specific occupations and industries. This study examines the contribution of past occupational PFAS exposure to serum PFOS and PFOA levels among 154 older adults in New York State.

Variability in follicular fluid high density lipoprotein particle components measured in ipsilateral follicles.

Purpose: The purpose of this study was to examine the biological variability of follicular fluid (FF) high density lipoprotein (HDL) particle components measured in ipsilateral ovarian follicles.

Methods: We collected FF from two ipsilateral follicles among six women undergoing in vitro fertilization (IVF). We measured concentrations of 19 FF HDL particle components, including HDL cholesterol, free cholesterol, four cholesteryl esters, phospholipids, triglycerides, paraoxonase and arylesterase activities, apolipoproteins A-1 and A-2 (ApoA-1 and ApoA-2), and seven lipophilic micronutrients, by automated analysis and with high-performance liquid chromatography.

Sensitivity to imputation models and assumptions in receiver operating characteristic analysis with incomplete data.

Modern statistical methods using incomplete data have been increasingly applied in a wide variety of substantive problems. Similarly, receiver operating characteristic (ROC) analysis, a method used in evaluating diagnostic tests or biomarkers in medical research, has also been increasingly popular problem in both its development and application. While missing-data methods have been applied in ROC analysis, the impact of model mis-specification and/or assumptions (e.

Lifecourse Socioeconomic Position and Racial Disparities in BMI Trajectories among Black and White Women: Exploring Cohort Effects in the Americans Changing Lives' Study.

Introduction: Few studies have analyzed the cohort effects of lifecourse socioeconomic position (SEP) on racial disparities in body mass index (BMI) trajectories. We assessed the contribution of lifecourse SEP on racial differences in BMI trajectories among two different age cohorts of women.

Methods: Four waves of the Americans' Changing Lives' study (1986-2002) were used to compute BMI trajectories for 2194 Black and White women.

Lifecourse socioeconomic position and 16 year body mass index trajectories: differences by race and sex.

Objective: The aim of this study is to evaluate the association between lifecourse socioeconomic position (SEP) and changes in body mass index (BMI), and assess disparities in these associations across racial/ethnic groups.

Methods: With longitudinal data from 4 waves of the Americans' Changing Lives Study (1986-2002), we employed mixed-effects modeling to estimate BMI trajectories for 1174 Blacks and 2323 White adults. We also estimated associations between these trajectories and lifecourse SEP variables, including father's education, perceived childhood SEP, own education, income, wealth, and financial security.

State of the Multiple Imputation Software.

Owing to its practicality as well as strong inferential properties, multiple imputation has been increasingly popular in the analysis of incomplete data. Methods that are not only computationally elegant but also applicable in wide spectrum of statistical incomplete data problems have also been increasingly implemented in a numerous computing environments. Unfortunately, however, the speed of this development has not been replicated in reaching to "sophisticated" users.

Random-covariances and mixed-effects models for imputing multivariate multilevel continuous data.

Principled techniques for incomplete-data problems are increasingly part of mainstream statistical practice. Among many proposed techniques so far, inference by multiple imputation (MI) has emerged as one of the most popular. While many strategies leading to inference by MI are available in cross-sectional settings, the same richness does not exist in multilevel applications.

Gaussian-based routines to impute categorical variables in health surveys.

The multivariate normal (MVN) distribution is arguably the most popular parametric model used in imputation and is available in most software packages (e.g., SAS PROC MI, R package norm).

Impact of non-normal random effects on inference by multiple imputation: A simulation assessment.

Multivariate extensions of well-known linear mixed-effects models have been increasingly utilized in inference by multiple imputation in the analysis of multilevel incomplete data. The normality assumption for the underlying error terms and random effects plays a crucial role in simulating the posterior predictive distribution from which the multiple imputations are drawn. The plausibility of this normality assumption on the subject-specific random effects is assessed.

Practice variation in parental assessment of pediatric ambulatory care.

Objective: To assess parental experience of pediatric primary care at the level of physician practice and to determine what variation exists among practices.

Methods: This cross-sectional survey assessed 7 pediatric primary care practices in eastern Massachusetts. Parents of children aged < or =12 years who received care between July 1999 and June 2000 were surveyed.

Medicaid managed care and the unmet need for mental health care among children with special health care needs.

Objective: To determine the association between Medicaid managed care pediatric behavioral health programs and unmet need for mental health care among children with special health care needs (CSHCN).

Data Source: The National Survey of CSHCN (2000-2002), using subsets of 4,400 CSHCN with Medicaid and 1,856 CSHCN with Medicaid and emotional problems. Additional state-level sources were used.

Access to care and use of preventive services by Hispanics: state-based variations from 1991 to 2004.

Background: State-level disparities in access to physicians and preventive services between Hispanics and whites may have changed over time.

Objective: To assess state-based changes in Hispanics' access to physicians and preventive services from 1991 to 2004.

Methods: Using data from the Behavioral Risk Factor Surveillance System in the 10 states with the largest Hispanic populations, we examined 4 preventive services for eligible adults (mammography, Papanicolaou testing, colorectal cancer screening, and cholesterol testing) and 2 measures of access to physicians (obtaining routine checkup in prior 2 years and avoiding seeing physician when needed due to cost in prior year).

Multiple imputation inference for multivariate multilevel continuous data with ignorable non-response.

Methods specifically targeting missing values in a wide spectrum of statistical analyses are now part of serious statistical thinking due to many advances in computational statistics and increased awareness among sophisticated consumers of statistics. Despite many advances in both theory and applied methods for missing data, missing-data methods in multilevel applications lack equal development. In this paper, I consider a popular inferential tool via multiple imputation in multilevel applications with missing values.