Marginal Structural Cox Models with Case-Cohort Sampling.

A common objective of biomedical cohort studies is assessing the effect of a time-varying treatment or exposure on a survival time. In the presence of time-varying confounders, marginal structural models fit using inverse probability weighting can be employed to obtain a consistent and asymptotically normal estimator of the causal effect of a time-varying treatment. This article considers estimation of parameters in the semiparametric marginal structural Cox model (MSCM) from a case-cohort study.

Comparison of Eight Equations That Predict Percent Body Fat Using Skinfolds in American Youth.

Background: Skinfolds are often used in equations to predict percent body fat (PBF) in youth. Although there are numerous such equations published, there is limited information to help researchers determine which equation to use for their sample.

Methods: Using data from the 1999-2006 National Health and Nutrition Examination Surveys (NHANES), we compared eight published equations for prediction of PBF.

Statin and Aspirin Use Among Hispanic and Latino Adults at High Cardiovascular Risk: Findings From the Hispanic Community Health Study/Study of Latinos.

Background: Despite variations in the prevalence of cardiovascular disease and related risk factors among US Hispanic/Latino adults of diverse backgrounds, there is little information on whether disparities exist in the use of medications for the primary and secondary prevention of cardiovascular disease. We examined the prevalence of statin and aspirin use among diverse US Hispanic/Latino adults at high cardiovascular risk.

Methods And Results: A multicenter population-based study, the Hispanic Community Health Study/Study Of Latinos, included a total of 16 415 participants of Mexican, Puerto Rican, Cuban, Dominican, South American, and Central American backgrounds who were aged 18 to 74 years and enrolled between March 2008 and June 2011.

Association of glucose homeostasis measures with heart rate variability among Hispanic/Latino adults without diabetes: the Hispanic Community Health Study/Study of Latinos (HCHS/SOL).

Background: Reduced heart rate variability (HRV), a measure of cardiac autonomic function, is associated with an increased risk of cardiovascular disease (CVD) and mortality. Glucose homeostasis measures are associated with reduced cardiac autonomic function among those with diabetes, but inconsistent associations have been reported among those without diabetes. This study aimed to examine the association of glucose homeostasis measures with cardiac autonomic function among diverse Hispanic/Latino adults without diabetes.

Comparison of Self-Reported Sleep Duration With Actigraphy: Results From the Hispanic Community Health Study/Study of Latinos Sueño Ancillary Study.

Most studies of sleep and health outcomes rely on self-reported sleep duration, although correlation with objective measures is poor. In this study, we defined sociodemographic and sleep characteristics associated with misreporting and assessed whether accounting for these factors better explains variation in objective sleep duration among 2,086 participants in the Hispanic Community Health Study/Study of Latinos who completed more than 5 nights of wrist actigraphy and reported habitual bed/wake times from 2010 to 2013. Using linear regression, we examined self-report as a predictor of actigraphy-assessed sleep duration.

Recent progresses in outcome-dependent sampling with failure time data.

An outcome-dependent sampling (ODS) design is a retrospective sampling scheme where one observes the primary exposure variables with a probability that depends on the observed value of the outcome variable. When the outcome of interest is failure time, the observed data are often censored. By allowing the selection of the supplemental samples depends on whether the event of interest happens or not and oversampling subjects from the most informative regions, ODS design for the time-to-event data can reduce the cost of the study and improve the efficiency.

Comparison of Echocardiographic Measures in a Hispanic/Latino Population With the 2005 and 2015 American Society of Echocardiography Reference Limits (The Echocardiographic Study of Latinos).

Background: Reference limits for echocardiographic quantification of cardiac chambers in Hispanics are not well studied.

Methods And Results: We examined the reference values of left atrium and left ventricle (LV) structure in a large ethnically diverse Hispanic cohort. Two-dimensional transthoracic echocardiography was performed in 1818 participants of the Echocardiographic Study of Latinos (ECHO-SOL).

Longitudinal study of body mass index in Asian men who immigrate to the US.

Background And Objectives: Cross-sectional studies indicate that adaptation to Western norms, especially at a younger age, might explain the higher average body mass index (BMI) among Asians living in the United States (US) compared to Asians living in Asia. However, migrants differ from non-migrants in sociocultural factors that are difficult to measure and, thus, longitudinal studies on the same individuals prior to and after immigration are needed. The objective of this study was to determine differences in changes in BMI across age by residence (US or Asia) and age at immigration using longitudinal data on BMI prior to and after immigration.

Urine Injury Biomarkers and Risk of Adverse Outcomes in Recipients of Prevalent Kidney Transplants: The Folic Acid for Vascular Outcome Reduction in Transplantation Trial.

Recipients of kidney transplants (KTR) are at increased risk for cardiovascular events, graft failure, and death. It is unknown whether urine kidney injury biomarkers are associated with poor outcomes among KTRs. We conducted a post hoc analysis of the Folic Acid for Vascular Outcome Reduction in Transplantation (FAVORIT) Trial using a case-cohort study design, selecting participants with adjudicated cardiovascular events, graft failure, or death.

BMI and all-cause mortality among Chinese and Caucasians: the People's Republic of China and the Atherosclerosis Risk in Communities Studies.

Background: Lower ethnic-specific body mass index (BMI) cutpoints have been proposed for Asians and adapted in some countries. However, to our knowledge, no study has directly compared Asians to other ethnic groups to test differences in associations between BMI and all-cause mortality using common methods.

Objectives: We estimated the association between BMI and all-cause mortality in Chinese Asians and Caucasian Americans to determine if lower Asian-specific BMI cutpoints are warranted.

Objectively Measured Sedentary Time and Cardiometabolic Biomarkers in US Hispanic/Latino Adults: The Hispanic Community Health Study/Study of Latinos (HCHS/SOL).

Background: Sedentary behavior is recognized as a distinct construct from lack of moderate-vigorous physical activity and is associated with deleterious health outcomes. Previous studies have primarily relied on self-reported data, whereas data on the relationship between objectively measured sedentary time and cardiometabolic biomarkers are sparse, especially among US Hispanics/Latinos.

Methods And Results: We examined associations of objectively measured sedentary time (via Actical accelerometers for 7 days) and multiple cardiometabolic biomarkers among 12 083 participants, aged 18 to 74 years, from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL).

Improving the efficiency of estimation in the additive hazards model for stratified case-cohort design with multiple diseases.

The case-cohort study design has often been used in studies of a rare disease or for a common disease with some biospecimens needing to be preserved for future studies. A case-cohort study design consists of a random sample, called the subcohort, and all or a portion of the subjects with the disease of interest. One advantage of the case-cohort design is that the same subcohort can be used for studying multiple diseases.

Parameter estimation in Cox models with missing failure indicators and the OPPERA study.

In a prospective cohort study, examining all participants for incidence of the condition of interest may be prohibitively expensive. For example, the "gold standard" for diagnosing temporomandibular disorder (TMD) is a physical examination by a trained clinician. In large studies, examining all participants in this manner is infeasible.

Sex difference in the association between obesity and asthma in U.S. adults: Findings from a national study.

Background: Obesity and asthma are both prevalent in the U.S. The a few studies that have examined the differences in association between obesity and asthma by sex provided mixed results.

High Cholesterol Awareness, Treatment, and Control Among Hispanic/Latinos: Results From the Hispanic Community Health Study/Study of Latinos.

Background: We assessed high cholesterol (HC) awareness, treatment, and control rates among US Hispanic/Latino adults and describe factors associated with HC awareness and management.

Methods And Results: Baseline data (collected 2008-2011) from a multisite probability sample of Hispanic/Latino adults in the Hispanic Community Health Study/Study of Latinos (18 to 74 years old; N=16 207) were analyzed. HC was defined as low-density lipoprotein-cholesterol ≥130 mg/dL and/or total cholesterol ≥240 mg/dL or use of cholesterol-lowering medication.

Joint Analysis of Survival Time and Longitudinal Categorical Outcomes.

In biomedical or public health research, it is common for both survival time and longitudinal categorical outcomes to be collected for a subject, along with the subject's characteristics or risk factors. Investigators are often interested in finding important variables for predicting both survival time and longitudinal outcomes which could be correlated within the same subject. Existing approaches for such joint analyses deal with continuous longitudinal outcomes.

Monocytosis is associated with hemolysis in sickle cell disease.

Background: The clinical relevance of monocytosis in sickle cell disease (SCD) is uncertain. The purpose of this study was to explore the association of monocyte counts with clinical and laboratory variables in SCD.

Design And Methods: This cross-sectional study was performed using a cohort of adult patients with SCD and control subjects without SCD.

Exploring Mediators of Physical Activity in Young Adult Cancer Survivors: Evidence from a Randomized Trial of a Facebook-Based Physical Activity Intervention.

Purpose: This study examined the effects of a physical activity (PA) intervention for young adult cancer survivors on changes in self-efficacy, social support, and self-monitoring and determined whether changes in these social cognitive theory constructs mediated the relationship between the intervention and changes in PA.

Methods: A 12-week randomized trial compared a Facebook-based intervention (FITNET) aimed at increasing moderate-to-vigorous intensity PA to a Facebook-based self-help comparison group. Young adult cancer survivors (N=86, aged 21-39) were randomly assigned to one of the two groups.

US adults recommended for weight reduction by 1998 and 2013 obesity guidelines, NHANES 2007-2012.

Objective: To determine the number and proportion of American adults recommended for weight loss treatment under the 1998 and 2013 guidelines on the management of overweight and obesity in adults and to compare characteristics of individuals recommended for treatment.

Methods: A total of 6,692 adult, non-pregnant participants in the National Health and Nutrition Examination Survey 2007-2012 with complete data on demographics, anthropometrics, and biomedical measures were analyzed.

Results: Compared to the 1998 guidelines, the 2013 guidelines increased the number of adults recommended for weight loss treatment by 20.

Periodontitis and Sleep Disordered Breathing in the Hispanic Community Health Study/Study of Latinos.

Study Objectives: To investigate the association between sleep disordered breathing (SDB) and severe chronic periodontitis.

Design: Cross-sectional data analysis from the Hispanic Community Health Study/Study of Latinos.

Setting: Community-based setting with probability sampling from four urban US communities.

Longitudinal study of acculturation and BMI change among Asian American men.

Background: Cross-sectional studies examining the association between Western acculturation and BMI in Asians have been inconsistent, and studies on BMI change are lacking.

Objective: This study examined the associations between indicators of acculturation (generational status, length of US residence, and age at immigration) and overweight (BMI ≥25kg/m(2)) as well as 5-year BMI changes in 7,073 Chinese, Japanese, Korean, Filipino, and Vietnamese men who lived in the US and were 44-71years old at baseline of the California Men's Health Study (2002-2003).

Methods: Indicators of acculturation were reported at baseline.

Modelling recurrent events: a tutorial for analysis in epidemiology.

In many biomedical studies, the event of interest can occur more than once in a participant. These events are termed recurrent events. However, the majority of analyses focus only on time to the first event, ignoring the subsequent events.

Depression, anxiety, antidepressant use, and cardiovascular disease among Hispanic men and women of different national backgrounds: results from the Hispanic Community Health Study/Study of Latinos.

Purpose: To describe prevalence and relationships to cardiovascular morbidity of depression, anxiety, and medication use among Hispanic/Latinos of different ethnic backgrounds.

Methods: Cross-sectional analysis of 15,864 men and women aged 18 to 74 years in the population-based Hispanic Community Health Study/Study of Latinos. Depressive and anxiety symptoms were assessed with shortened Center for Epidemiological Studies Depression Scale and Spielberger Trait Anxiety Scale.

Physical activity in young adults: a signal detection analysis of Health Information National Trends Survey (HINTS) 2007 data.

Many young adults are insufficiently active to achieve the health benefits of regular physical activity. Using signal detection analysis of data from the 2007 Health Information National Trends Survey, the authors examined distinct subgroups of 18-39 year-old adults who vary in their likelihood of not meeting physical activity recommendations. We randomly split the sample and conducted signal detection analysis on the exploratory half to identify subgroups and interactions among sociodemographic and health communication variables that predicted engaging in less than 150 minutes per week of moderate-intensity physical activity (low physical activity).

Risk of Cigarette Smoking Initiation During Adolescence Among US-Born and Non-US-Born Hispanics/Latinos: The Hispanic Community Health Study/Study of Latinos.

Objectives: We assessed risk of cigarette smoking initiation among Hispanics/Latinos during adolescence by migration status and gender.

Methods: The Hispanic Community Health Study/Study of Latinos (HCHS/SOL) surveyed persons aged 18 to 74 years in 2008 to 2011. Our cohort analysis (n = 2801 US-born, 13 200 non-US-born) reconstructed participants' adolescence from 10 to 18 years of age.