Bayesian Peer Calibration with Application to Alcohol Use.

Peers are often able to provide important additional information to supplement self-reported behavioral measures. The study motivating this work collected data on alcohol in a social network formed by college students living in a freshman dormitory. By using two imperfect sources of information (self-reported and peer-reported alcohol consumption), rather than solely self-reports or peer-reports, we are able to gain insight into alcohol consumption on both the population and the individual level, as well as information on the discrepancy of individual peer-reports. We develop a novel Bayesian comparative calibration model for continuous, count, and binary outcomes that uses covariate information to characterize the joint distribution of both self and peer-reports on the network for estimating peer-reporting discrepancies in network surveys, and apply this to the data for fully Bayesian inference. We use this model to understand the effects of covariates on both drinking behavior and peer-reporting discrepancies. Copyright © 2016 John Wiley & Sons, Ltd.

Social and behavioral risk marker clustering associated with biological risk factors for coronary heart disease: NHANES 2001-2004.

BACKGROUND: Social and behavioral risk markers (e.g., physical activity, diet, smoking, and socioeconomic position) cluster; however, little is known whether clustering is associated with coronary heart disease (CHD) risk. Objectives were to determine if sociobehavioral clustering is associated with biological CHD risk factors (total cholesterol, HDL cholesterol, systolic blood pressure, body mass index, waist circumference, and diabetes) and whether associations are independent of individual clustering components. METHODS: Participants included 4,305 males and 4,673 females aged ≥ 20 years from NHANES 2001-2004. Sociobehavioral Risk Marker Index (SRI) included a summary score of physical activity, fruit/vegetable consumption, smoking, and educational attainment. Regression analyses evaluated associations of SRI with aforementioned biological CHD risk factors. Receiver operator curve analyses assessed independent predictive ability of SRI. RESULTS: Healthful clustering (SRI = 0) was associated with improved biological CHD risk factor levels in 5 of 6 risk factors in females and 2 of 6 risk factors in males. Adding SRI to models containing age, race, and individual SRI components did not improve C-statistics. CONCLUSIONS: Findings suggest that healthful sociobehavioral risk marker clustering is associated with favorable CHD risk factor levels, particularly in females. These findings should inform social ecological interventions that consider health impacts of addressing social and behavioral risk factors.

Health Conditions in Younger, Middle, and Older Ages: Are There Differences by Sexual Orientation?

PURPOSE: Sexual minorities engage in more risk behaviors at a younger age than heterosexuals and many are subject to minority stress from a young age, which raises questions about the age at which sexual minorities' experience morbidities. Our objective was to estimate the prevalence of health conditions among young, middle age, and older age groups to examine sexual orientation differences while stratifying by gender. METHODS: We pooled 4 years of data from the California Health Interview Survey to obtain a representative sample of the male and female population in California, allowing us to examine health conditions by sexual orientation in three age strata, age 20-39, age 40-59, and age 60 and older. RESULTS: Compared with same-gender heterosexuals, sexual minority women had a higher likelihood of physical morbidities (disability: adjusted odds ratio [AOR] 2.66 for lesbians and AOR 2.21 for bisexuals; arthritis: AOR 2.12 for lesbians) at a young age, whereas gay men had a higher likelihood of heart disease (AOR 2.78) and cancer (AOR 4.75) at a young age. Across the life span, sexual minorities had higher likelihoods of poor mental health than heterosexuals. CONCLUSION: These findings suggest that at a young age, sexual minorities experience more morbidities than heterosexual individuals. Consideration should be given to early detection, identification, and treatment of these conditions among sexual minorities particularly at younger ages.

Peer associations for substance use and exercise in a college student social network.

UNLABELLED: Substance use and exercise have opposite trajectories in young adulthood, and research indicates that peers are influential for both of these health behaviors, but simultaneous investigations of peer associations with substance use and exercise have not been conducted. OBJECTIVE: Use a college residence hall peer network to examine associations between peer behaviors and alcohol use, marijuana use, and exercise behavior. METHOD: 129 undergraduates (51.9% female, 48.1% non-Hispanic White; 84.5% first-year students) in one residence hall completed a Web-based survey of substance use and exercise and identified up to 10 students in the residence hall who were important to them. Two social network analytic methods, community detection cluster analysis and network autocorrelation modeling, were used to identify peer groupings and to examine the associations between peer and participant behaviors, respectively. RESULTS: Participants nominated an average of 4.1 residence hall members, and 53.9% of the ties were reciprocal. 6 clusters were identified that differed significantly on demographics, college activities, substance use, and exercise. Weekly volume of alcohol consumed among nominated peers was significantly associated with that of participants, and all other covariates, including gender and athlete status, were not significant. Peer marijuana use also was associated with participant use after controlling for covariates. Exercise levels of nominated peers were not associated with exercise levels of participants. CONCLUSIONS: College student networks may be good targets for health-related prevention programs. Programs that use close-proximity peers to influence the behavior of others might be more effective with substance use as the target behavior than exercise.

Implementation of permutation testing to determine clustering of social and behavioral risk factors for coronary heart disease, National Health and Nutrition Examination Survey 2001-2004.

PURPOSE: To determine whether social and behavioral risk factors for coronary heart disease, including education, physical activity, fruit/vegetable intake, and smoking, cluster (i.e., co-occur more than expected as the result of chance) in U.S. adults. METHODS: The study included 4305 male and 4673 female subjects aged ≥20 years from the National Health and Nutrition Examination Survey. Risk factors included: ≤high school diploma/general educational development certificate; <150 minutes of moderate/vigorous physical activity per week; <3 or <2 servings of vegetables and fruit, respectively, per day; and smoking cigarettes. Indicator variables were summed into a sociobehavioral risk index (SRI, range 0 [no risk factors] to 4 [all risk factors]). Ratios of observed-to-expected prevalence (under the assumption of independence) of the SRI were assessed. Statistical significance was evaluated by the use of randomly permuted average observed-to-expected SRI ratios and 95% confidence intervals (95% CIs). RESULTS: In male subjects, the ratio of observed-to-expected prevalence of SRI = 0 was 1.70 (permuted ratio = 1.00; 95% CI: 0.92-1.08), and SRI = 4 was 2.10 (permuted ratio = 1.00, 95% CI: 0.86-1.14), demonstrating significant clustering. In females, the ratio of observed-to-expected prevalence of SRI = 0 was 1.67 (permuted ratio = 1.00, 95% CI: 0.92-1.08), and SRI = 4 was 1.86 (permuted ratio = 1.00, 95% CI: 0.85-1.15). CONCLUSIONS: Social and behavioral risk factors for coronary heart disease cluster in this sample of U.S. adults.

Pregnant and moving: understanding residential mobility during pregnancy and in the first year of life using a prospective birth cohort.

To examine residential mobility (i.e., moving) during pregnancy and in the first year of an infant's life using a large, prospective birth cohort in Rhode Island. Participants were recruited from Women and Infants Hospital of Rhode Island between January 5, 2009 and March 19, 2009. Residential histories were collected from mothers in-person immediately post-partum and by phone at 7 months and at 13 months post-partum. Of 1,040 mothers interviewed at birth, 71% (n = 740) completed the 13 month follow-up interview. Forty-one percent of mothers (n = 300) moved at least once between conception and 1 year post-partum, with the number of moves ranging from 0 to 8. Among movers, 69.0% moved once, 21.0% moved twice, and 10.0% moved three or more times. Mothers who moved tended to be younger, have fewer children, were not White, and had lower household incomes than those who did not move. Mothers who moved during pregnancy had 2.05 (95% CI: 1.40-2.98) times the odds of moving post-partum than mothers who had not moved in the antenatal period. There were statistical differences across socio-demographic groups with regard to when, where, and why mothers moved. Forty percent of movers during pregnancy (n = 61) moved for at least one negative reason, while 32.2% of movers during infancy (n = 64) relocated under negative circumstances. A substantial proportion of mothers moved pre- and post-partum, frequently under negative circumstances. Study findings have important implications for obstetric and pediatric providers who seek to understand, retain, and improve the health of their patient populations.

Short sleep duration is associated with carotid intima-media thickness among men in the Coronary Artery Risk Development in Young Adults (CARDIA) Study.

BACKGROUND AND PURPOSE: Carotid intima-media thickness (CIMT) is a subclinical marker of cardiovascular disease. Recent studies suggest that shorter sleep duration is a risk factor for cardiovascular disease, but there is limited evidence regarding this association using high-quality, objective assessments of sleep. The aim of this study is to determine whether sleep duration is associated with CIMT. METHODS: The study used an observational cohort consisting of 617 black and white middle-aged healthy participants (37-52 years; 58% female) in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Multivariable-adjusted linear regression analyses were performed. Sleep duration was measured using wrist actigraphy monitors. CIMT was calculated using the average of 20 measurements of the mean common carotid, bulb, and internal CIMT, which was assessed using ultrasound images. RESULTS: After adjusting for covariates, 1 hour of longer sleep duration was associated with 0.026 mm less CIMT among men (P=0.02; 95% CI, -0.047 to -0.005) and 0.001 mm less CIMT among women (P=0.91; 95% CI, -0.020 to 0.022). Segment-specific analyses indicated that the carotid bulb was a key driver of the observed association. CONCLUSIONS: Shorter objectively assessed sleep duration was associated with greater CIMT among men but not women.

Adult health behaviors over the life course by sexual orientation.

OBJECTIVES: We estimated differences in health behaviors among adults by sexual orientation. METHODS: We pooled 4 years of data (2001, 2003, 2005, and 2007) from the California Health Interview Survey. We estimated the frequency of smoking, alcohol use, healthy dietary behaviors, physical activity, and health care utilization, and we used logistic regression modeling to determine the odds of each behavior with increasing age and for 2 age groups: younger than 50 years and 50 years old or older. RESULTS: At any adult age, lesbians had greater odds of smoking and binge drinking than did heterosexual women, and gay and bisexual men had greater health care utilization than did heterosexual men. Other risk behaviors differed with age. CONCLUSIONS: Some behavioral change interventions should target lesbians, gays, and bisexuals at all ages, whereas other interventions should specifically target individuals at younger ages.

Inverse associations between perceived racism and coronary artery calcification.

PURPOSE: To evaluate whether racial discrimination is associated with coronary artery calcification (CAC) in African-American participants of the Coronary Artery Risk Development in Young Adults (CARDIA) study. METHODS: The study included American Black men (n = 571) and women (n = 791) aged 33 to 45 years in the CARDIA study. Perceived racial discrimination was assessed based on the Experiences of Discrimination scale (range, 1-35). CAC was evaluated using computed tomography. Primary analyses assessed associations between perceived racial discrimination and presence of CAC using multivariable-adjusted logistic regression analysis, adjusted for age, gender, socioeconomic position (SEP), psychosocial variables, and coronary heart disease (CHD) risk factors. RESULTS: In age- and gender-adjusted logistic regression models, odds of CAC decreased as the perceived racial discrimination score increased (odds ratio [OR], 0.94; 95% confidence interval [CI], 0.90-0.98 per 1-unit increase in Experiences of Discrimination scale). The relationship did not markedly change after further adjustment for SEP, psychosocial variables, or CHD risk factors (OR, 0.93; 95% CI, 0.87-0.99). CONCLUSIONS: Perceived racial discrimination was negatively associated with CAC in this study. Estimation of more forms of racial discrimination as well as replication of analyses in other samples will help to confirm or refute these findings.

Decreased births among black female adolescents following school desegregation.

Although the socioeconomic impact of school desegregation in the U.S. has been well documented, little is known about the health consequences of this policy. The purpose of this study was to quantify the associations between school desegregation and adolescent births among black and white females. We compared the change in prevalence of adolescent births in areas that implemented school desegregation plans in the 1970s with areas that implemented school desegregation plans in other decades, using difference-in-difference methods with 1970 and 1980 Census microdata. School desegregation policy in the U.S. in the 1970s was associated with a significant reduction of 3.2 percentage points in the prevalence of births among black female adolescents between 1970 and 1980. This association was specific to black female adolescents and was not observed among white adolescents.

Age, antipsychotics, and the risk of ischemic stroke in the Veterans Health Administration.

BACKGROUND AND PURPOSE: Time-dependent effects of antipsychotics on risk of stroke and potential effect modification by age have not been fully investigated. A case-case-time-control design uses within- and between-case comparisons to evaluate short-term effects at the same time as adjusting for unmeasured time-invariant confounders and exposure-time trends. METHODS: We conducted a case-case-time-control design study using data from the Veterans Health Administration. Veterans with inpatient hospitalizations for ischemic stroke between 2002 and 2007 were included. For every stroke case, the "current" exposure period was defined as 1 to 30 days before hospitalization and the "reference" period as 91 to 120 days before hospitalization. Exposure during the current period was compared with exposure during the reference period within cases. Exposure-time trend-adjusted estimates of the effect of antipsychotic exposure on risk of stroke were obtained by dividing exposure odds for antipsychotic exposure by average exposure odds for other medications over the same time period among the same cases. RESULTS: After adjusting for exposure-time trends, odds of stroke were 1.8 (95% CI, (1.7-1.9) times higher when exposed to antipsychotics than when unexposed. Age-stratified estimates suggest a greater triggering effect of antipsychotics among older patients. CONCLUSIONS: Exposure to antipsychotics may be a proximal trigger for stroke. Elevation in risk is apparent after brief exposure to antipsychotics.

Spatio-Spectral Mixed Effects Model for Functional Magnetic Resonance Imaging Data.

The goal of this paper is to model cognitive control related activation among predefined regions of interest (ROIs) of the human brain while properly adjusting for the underlying spatio-temporal correlations. Standard approaches to fMRI analysis do not simultaneously take into account both the spatial and temporal correlations that are prevalent in fMRI data. This is primarily due to the computational complexity of estimating the spatio-temporal covariance matrix. More specifically, they do not take into account multi-scale spatial correlation (between-ROIs and within-ROI). To address these limitations, we propose a spatio-spectral mixed effects model. Working in the spectral domain simplifies the temporal covariance structure because the Fourier coefficients are approximately uncorrelated across frequencies. Additionally, by incorporating voxel-specific and ROI-specific random effects, the model is able to capture the multi-scale spatial covariance structure: distance-dependent local correlation (within an ROI), and distance-independent global correlation (between-ROIs). Building on existing theory on linear mixed effects models to conduct estimation and inference, we applied our model to fMRI data to study activation in pre-specified ROIs in the prefontal cortex and estimate the correlation structure in the network. Simulation studies demonstrate that ignoring the multi-scale correlation leads to higher false positives.

Venous thromboembolism in patients with reduced estimated GFR: a population-based perspective.

BACKGROUND: An increased frequency of venous thromboembolism (VTE) has been shown in patients with decreased kidney function measured by decreased estimated glomerular filtration rate (eGFR). However, present practices with respect to VTE prevention and management in patients with decreased eGFR in general population settings are uncertain. STUDY DESIGN: Observational study. SETTING & PARTICIPANTS: Community investigation of 1,509 metropolitan Worcester, MA, residents with a validated VTE in 1999, 2001, and 2003 with further follow-up for up to 3 years. PREDICTOR: Patients with VTE classified further according to eGFR on presentation: <30, 30-59, 60-89, or ≥90 mL/min/1.73 m(2) (reference group). OUTCOMES: Recurrent VTE, major bleeding episodes, and all-cause mortality. MEASUREMENTS: Demographic and clinical characteristics, treatment practices, and study outcomes were extracted from patients' hospital and outpatient medical records; eGFR was estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. RESULTS: Patients with VTE with eGFR <30 mL/min/1.73 m(2) were at increased risk of recurrent VTE (HR, 1.83; 95% CI, 1.03-3.25), major bleeding episodes (HR, 2.30; 95% CI, 1.28-4.16), and all-cause mortality (HR, 1.70; 95% CI, 1.12-2.57) during a 3-year follow-up. Patients with decreased eGFR also presented with more comorbid conditions and were less likely to be discharged on any form of anticoagulant therapy (72.6%, 81.0%, 82.1%, and 87.3% for eGFR <30, 30-59, 60-89, and ≥90 mL/min/1.73 m(2), respectively; P < 0.001). LIMITATIONS: Decreased eGFR status is presumed based on creatinine values on clinical presentation. The impact of drug dosage, timing, type of anticoagulant therapy, and medication adherence on study outcomes could not be evaluated. CONCLUSIONS: Severe decreases in eGFR are associated with increased risk of long-term recurrent VTE, bleeding, and total mortality in patients with VTE. A greater frequency of serious comorbid conditions, difficulties implementing available management strategies, and suboptimal VTE prophylaxis during hospital admissions likely contributed to our findings.

Future cases as present controls to adjust for exposure trend bias in case-only studies.

Self-matched case-only studies (such as the case-crossover or self-controlled case-series method) control by design for time-invariant confounders (measured or unmeasured), but they do not control for confounders that vary with time. A bidirectional case-crossover design can be used to adjust for exposure-time trends. In pharmacoepidemiology, however, illness often influences future use of medications, making a bidirectional design problematic. Suissa's case-time-control design combines a case-crossover and case-control design, and adjusts for exposure-trend bias in the cases' self-controlled odds ratio by dividing that ratio by the corresponding self-controlled odds ratio in a concurrent matched control group. However, if not well matched, the control group may reintroduce selection bias. We propose a "case-case-time-control" that involves crossover analyses in cases and future-case controls. This person-time sampling strategy improves matching by restricting controls to future cases. We evaluate the proposed study design through simulations and analysis of a theoretically null relationship using Veterans Administration (VA) data. Simulation studies show that the case-case-time-control can adjust for exposure trends while controlling for time-invariant confounders. Use of an inappropriate control group left case-time-control analyses biased by exposure-time trends. When analyzing the relationship between vitamin exposure and stroke, using data on 3192 patients in the VA system, a case-crossover odds ratio of 1.5 (95% confidence interval = 1.3-1.7) was reduced to 1.1 (0.9-1.3) when divided by the concurrent exposure trend odds ratio (1.4) in matched future cases. This applied example demonstrates how our approach can adjust for exposure trends observed across time axes.

Development of a cardiovascular risk score for use in low- and middle-income countries.

Summary measures of cardiovascular risk have long been used in public health, but few include nutritional predictors despite extensive evidence linking diet and heart disease. Study objectives were to develop and validate a novel risk score in a case-control study of myocardial infarction (MI) conducted in Costa Rica during 1994-2004. After restricting the data set to healthy participants (n = 1678), conditional logistic regression analyses modeled associations of lifestyle factors (unhealthy diet, decreased physical activity, smoking, waist:hip ratio, low or high alcohol intake, and low socioeconomic status) with risk for MI. Using the estimated coefficients as weights for each component, a regression model was fit to assess score performance. The score was subsequently validated in participants with a history of chronic disease. Higher risk score values were associated with a significantly increased risk of MI [OR = 2.72 (95% CI = 2.28-3.24)]. The findings were replicated in a model (n = 1392) that included the best covariate measures available in the study [OR = 2.71 (95% CI = 2.26-3.26)]. Performance of the score in different subsets of the study population showed c-statistics ranging from 0.63 to 0.67. The new score presents a quantitative summary of modifiable cardiovascular risk factors in the study population.

The association between blood pressure and years of schooling versus educational credentials: test of the sheepskin effect.

PURPOSE: Attaining a degree may offer greater opportunities for health than years of schooling alone. This study examines whether there is a degree, or "sheepskin," effect on the association between education and blood pressure. METHODS: Multivariable-adjusted ordinal and linear regression models assessed associations of years of schooling and degree attainment with systolic and diastolic blood pressure in a sample of 552 adults ages 38 to 47 years. RESULTS: Years of schooling was inversely associated with systolic blood pressure adjusting for age, gender and race (ß = -0.4, 95% confidence limit: -0.7, -0.1 mmHg systolic blood pressure/year of schooling). Additional adjustment for mother's education, childhood verbal intelligence quotient, childhood health, and childhood socioeconomic status had minimal impact on effect size (ß = -0.3, 95% confidence limit = -0.7, 0.0). However, years of schooling was no longer associated with blood pressure in the fully adjusted model which included additional adjustment for degree attained (ß = 0.0, 95% confidence limit: -0.5, 0.4). In the fully adjusted model (including adjustment for years of schooling), individuals with a graduate degree still had significantly lower systolic blood pressure than HS degree-holders (e.g., ß = -9.2, 95% confidence limit: -15.2, -3.2 for graduate vs high school degree). Findings were similar for diastolic blood pressure. CONCLUSIONS: The association of years of schooling with blood pressure may be largely due to degree attainment rather than simply the knowledge and skills accumulated due to years of schooling alone.

Opinion networks among long-term care specialists.

A challenge in the adoption of long-term care (LTC) policy reform is the number of constituency groups active in LTC and historical antagonism among these groups regarding critical issues such as LTC financing and regulation. As part of a national survey of LTC specialists, the authors asked previously identified specialists to nominate other "experts" with known or demonstrable experience in LTC. As a proxy for potential information exchange, data about nominations were used to construct and describe the networks of LTC specialists representing consumer advocates, provider representatives, public officials, policy experts, and others. Associations between network characteristics and attitudes about LTC policy reform were also examined. Individuals tended to nominate other people within their same constituency group as experts. Academic and research-based policy experts were most likely to be classified as prominent network members. Network structure was associated with attitudes toward LTC financing but not the regulation of nursing homes.

Functional connectivity: shrinkage estimation and randomization test.

We develop new statistical methods for estimating functional connectivity between components of a multivariate time series and for testing differences in functional connectivity across experimental conditions. Here, we characterize functional connectivity by partial coherence, which identifies the frequency band (or bands) that drives the direct linear association between any pair of components of a multivariate time series after removing the linear effects of the other components. Partial coherence can be efficiently estimated using the inverse of the spectral density matrix. However, when the number of components is large and the components of the multivariate time series are highly correlated, the spectral density matrix estimate may be numerically unstable and consequently gives partial coherence estimates that are highly variable. To address the problem of numerical instability, we propose a shrinkage-based estimator which is a weighted average of a smoothed periodogram estimator and a scaled identity matrix with frequency-specific weight computed objectively so that the resulting shrinkage estimator minimizes the mean-squared error criterion. Compared to typical smoothing-based estimators, the shrinkage estimator is more computationally stable and gives a lower mean squared error. In addition, we develop a randomization method for testing differences in functional connectivity networks between experimental conditions. Finally, we report results from numerical experiments and analyze an EEG data set recorded during a visually-guided hand movement task.

Advance care planning decisions of women with cancer: provider recognition and stability of choices.

Our prior research found that 43% of women with cancer relied on more than one person for advance care planning (ACP) and support. We conducted this follow-up study to address the stability of patient choices around ACP and providers' knowledge of patients' named supports. Living participants from the original survey were recontacted and asked to participate in this study. Of the original 215 participants, 113 (66%) participated. The median time between surveys was 23 months. At resurvey, 33 (26%) patients did not name the same person to all three roles. Controlling for age, race, partner status, tumor type, and remission status, naming one person for all three roles was associated with higher concordance at follow-up for primary support (PS) and health care proxy (HCP). Comparing patients' and providers' responses (N = 162), concordance was 71% for emergency contact (EC), 60% for PS, but only 51% for HCP. In this follow-up study, a smaller percentage of women named more than one person to the roles of EC, PS, and HCP compared to the original survey. Of concern, concordance between patient and provider was low, particularly for HCP. This was notable especially when responses changed over the interval time, and when ACP and PS roles were split between multiple people. Understanding the network of people who serve ACP and support roles may be important as we seek to improve the process of ACP and surrogate decision making.