Semi-parametric benchmark dose analysis with monotone additive models.

Benchmark dose analysis aims to estimate the level of exposure to a toxin associated with a clinically significant adverse outcome and quantifies uncertainty using the lower limit of a confidence interval for this level. We develop a novel framework for benchmark dose analysis based on monotone additive dose-response models. We first introduce a flexible approach for fitting monotone additive models via penalized B-splines and Laplace-approximate marginal likelihood.

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.

Genetic admixture predictors of fetal alcohol spectrum disorders (FASD) in the South African Cape Coloured population.

Ancestrally admixed populations are underrepresented in genetic studies of complex diseases, which are still dominated by European-descent populations. This is relevant not only from a representation standpoint but also because of admixed populations' unique features, including being enriched for rare variants, for which effect sizes are disproportionately larger than common polymorphisms. Furthermore, results from these populations may be generalizable to other populations.

Meta-analysis on studies with heterogeneous and partially observed covariates.

Individual participant data meta-analysis is a commonly used alternative to the traditional aggregate data meta-analysis. It is popular because it avoids relying on published results and enables direct adjustment for relevant covariates. However, a practical challenge is that the studies being combined often vary in terms of the potential confounders that were measured.

Bayesian outcome selection modeling.

In psychiatric and social epidemiology studies, it is common to measure multiple different outcomes using a comprehensive battery of tests thought to be related to an underlying construct of interest. In the research that motivates our work, researchers wanted to assess the impact of in utero alcohol exposure on child cognition and neuropsychological development, which are evaluated using a range of different psychometric tests. Statistical analysis of the resulting multiple outcomes data can be challenging, because the outcomes measured on the same individual are not independent.

A hierarchical meta-analysis for settings involving multiple outcomes across multiple cohorts.

Evidence from animal models and epidemiological studies has linked prenatal alcohol exposure (PAE) to a broad range of long-term cognitive and behavioural deficits. However, there is a paucity of evidence regarding the nature and levels of PAE associated with increased risk of clinically significant cognitive deficits. To derive robust and efficient estimates of the effects of PAE on cognitive function, we have developed a hierarchical meta-analysis approach to synthesize information regarding the effects of PAE on cognition, integrating data on multiple outcomes from six U.

Comparison of examination techniques of anterior and posterior compartments of the leg for the diagnosis of deep vein thrombosis: A new examination technique.

Objectives: Several examination techniques have been described for the diagnosis of leg deep vein thrombosis. These previously described examination techniques aim to detect muscle pain that occurs secondary to increased pressure in the posterior compartment of the leg. However, to the best of our knowledge no studies investigated the frequency of muscle pain on the anterior compartment in patients with leg deep vein thrombosis the objective of this study is to investigate the prevalence of muscle pain in the anterior compartment.

Propensity score analysis for a semi-continuous exposure variable: a study of gestational alcohol exposure and childhood cognition.

Propensity score methodology has become increasingly popular in recent years as a tool for estimating causal effects in observational studies. Much of the related research has been directed at settings with binary or discrete exposure variables with more recent work involving continuous exposure variables. In environmental epidemiology, a substantial proportion of individuals is often completely unexposed while others may experience heavy exposure leading to an exposure distribution with a point mass at zero and a heavy right tail.

Proximity to Pediatric Cardiac Surgical Care among Adolescents with Congenital Heart Defects in 11 New York Counties.

Background: Many individuals with congenital heart defects (CHDs) discontinue cardiac care in adolescence, putting them at risk of adverse health outcomes. Because geographic barriers may contribute to cessation of care, we sought to characterize geographic access to comprehensive cardiac care among adolescents with CHDs.

Methods: Using a population-based, 11-county surveillance system of CHDs in New York, we characterized proximity to the nearest pediatric cardiac surgical care center among adolescents aged 11 to 19 years with CHDs.

Utility of Capture-Recapture Methodology to Estimate Prevalence of Congenital Heart Defects Among Adolescents in 11 New York State Counties: 2008 to 2010.

Background: Congenital heart defects (CHDs) are the most common birth defects in the United States, and the population of individuals living with CHDs is growing. Though CHD prevalence in infancy has been well characterized, better prevalence estimates among children and adolescents in the United States are still needed.

Methods: We used capture-recapture methods to estimate CHD prevalence among adolescents residing in 11 New York counties.

A Multicomponent Approach to Evaluating a Pre-exposure Prophylaxis (PrEP) Implementation Program in Five Agencies in New York.

Research has shown that pre-exposure prophylaxis (PrEP) is effective for preventing HIV infection. We developed the Targeted PrEP Implementation Program (TPIP), an 18-month project that involved five statewide agencies, to assess the extent to which PrEP could be implemented in "real world" clinical settings. The target population was men who have sex with men at high risk for HIV infection.

Routine HIV testing capacity, practices, and perceptions among school-based health center providers in New York State after enactment of the 2010 amended HIV testing law.

Background: The 2010 New York State (NYS) HIV Testing Law requires that primary care providers routinely offer HIV testing to patients aged 13-64 years, regardless of risk, and link individuals with HIV to medical care. School-based health centers (SBHCs) are in a position to offer HIV screening to a significant proportion of youth. One year after the law went into effect, we conducted a study to assess whether NYS SBHCs implemented these provisions.

Correlates of routine HIV testing practices: a survey of New York State primary care physicians, 2011.

Background: The New York State (NYS) HIV Testing Law of 2010 mandates that medical providers offer HIV testing to patients aged between 13 and 64 years during primary care, to increase the number of people aware of their infection status, and to ensure linkage to medical treatment. To assess physician practices related to this legislation, we conducted a study to identify the frequency and correlates of routine HIV testing behavior among primary care physicians approximately 15 months after the new law went into effect.

Methods: During September 2011 to January 2012, we mailed self-administered surveys to a representative sample of NYS primary care physicians drawn from the AMA Masterfile of Physicians.