Causal inference in survival analysis has been centered on treatment effect assessment with adjustment of covariates. The direct adjustment method is usually employed to find the survival function of a treatment. A Cox model that stratifies the cumulative hazard by treatment is an ideal choice for performing direct adjustment because the treatment effects are allowed to vary over time. A SAS ma...

BACKGROUND Morbidity and mortality rates are high among patients with end-stage renal disease (ESRD), and recent evidence suggests that this may be linked to inflammation. Current research has also demonstrated the crucial involvement of interleukin-18 (IL-18) in inflammation. In agreement, the activity of IL-18 has been markedly up-regulated in ESRD patients. However, it has not been establish...

BACKGROUND Antipsychotic use is associated with serious adverse events in the elderly, and consequently can lead to further healthcare utilization such as nursing home admission. OBJECTIVE To evaluate the risk of nursing home admission associated with typical versus atypical antipsychotic use among the US community-dwelling elderly population. METHODS A retrospective cohort design was condu...

BACKGROUND It has been suggested that birth by caesarean section (CS) may affect psychological development through changes in microbiota or stress response. We assessed the impact of mode of delivery, specifically CS, on the development of attention-deficit/hyperactivity disorder (ADHD), using a large, population-based cohort. METHODS The study cohort consisted of all singleton live births in...

It is common for large population-based surveys to select a sample from a population using a complex design. A simulation study was conducted to compare the estimates from the stratified proportional hazards model with the weighted estimates of the Binder method, when a stratified random sample of the population is used. The SAS PHREG procedure performs regression analysis of survival data base...