No abstract

Some behavioral change interventions should target lesbians, gays, and bisexuals at all ages, whereas other interventions should specifically target individuals at younger ages.

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.

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 re-introduce 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.

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.

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.

Background An increased frequency of venous thromboembolism (VTE) has been shown among patients with reduced kidney function as measured by a decreased estimated glomerular filtration rate (eGFR). However, current practices with respect to VTE prevention and management in patients with a reduced eGFR in general population settings remain uncertain. Study Design Observational study. Setting & Participants Community investigation of 1,509 metropolitan Worcester (Massachusetts) residents with validated VTE during 1999, 2001, and 2003 with further follow-up for up to 3 years. Predictor VTE patients further classified according to their eGFR on presentation: < 30, 30-59, 60-89, or ≥ 90 ml/min/1.73m2 (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 equation. Results VTE patients with eGFR < 30 ml/min/1.73m2 were at an increased risk for 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) over 3-year follow-up. Patients with reduced eGFR also presented with more co-morbidities 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/1.73m2, respectively; p<0.001). Limitations Reduced 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 reductions in eGFR are associated with an increased risk of long-term recurrent VTE, bleeding, and total mortality in patients with VTE. A greater frequency of serious co-morbidities, difficulties implementing available management strategies, and suboptimal VTE prophylaxis during hospital admissions likely contributed to our findings.

Background and purpose Carotid intima-media thickness (CIMT) is a subclinical marker of cardiovascular disease (CVD). Recent studies suggest that shorter sleep duration is a risk factor for CVD, 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 y; 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, one hour of longer sleep duration was associated with 0.026 mm less CIMT among men (p=0.02, 95% CI -0.047, -0.005), and 0.001 mm less CIMT among women (p=0.91, 95% CI -0.020, 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.