Modeling the 4D Study: statins and cardiovascular outcomes in long-term hemodialysis patients with diabetes

Randomized, controlled trials (RCTs) are the gold standard for defining causal inferences but are sometimes not feasible because of cost, ethical, or time considerations. We explored the accuracy and potential use of a "simulated trial" through the modeling of a previously published RCT, Die Deutsche Diabetes Dialyse Studie (4D Study), a landmark study that investigated the cardiovascular benefit of atorvastatin use in 1255 patients with ESRD.

Using a large historical database of interventions and outcomes in dialysis patients, we conducted an observational model of the 4D Study in dialysis patients who had type 2 diabetes and were prescribed a statin (5144 patients) and matched to a non-statin user (5144 control subjects) before multivariate modeling. Inclusion, exclusion, and outcome parameters of the study, as prespecified by the 4D Study, were strictly modeled in this analysis.

In covariate- and propensity-adjusted Cox regression, statin use (versus nonuse) was associated with a decrease in the composite primary outcome of cardiac death, nonfatal myocardial infarction, and stroke. Statin use was also associated with a decrease in cardiovascular mortality and all cardiac events combined. The hazard ratios in this observational model were numerically comparable to the hazard ratios reported in the 4D Study; however, because of the larger number of patients "enrolled," results in this simulated study achieved statistical significance.

Statin use was associated with some cardiovascular benefit in a simulated trial of patients with ESRD; however, the size of benefit was considerably smaller than that seen in the general population. Such simulated trials may represent an exploratory, cost-effective option when RCTs are not immediately feasible.