Survival Benefit With Drug-Eluting Stents in Observational Studies

Recently, there has been increased interest in leveraging observational studies for comparative effectiveness research. Without robust and valid risk adjustment, however, findings from these nonrandomized studies may remain biased. Previous studies examining long-term mortality with drug-eluting stents (DESs) have demonstrated discordant results between randomized trials and observational studies. To examine the impact of treatment selection bias on these findings, we used data from a prospective percutaneous coronary intervention (PCI) registry (EVENT [Evaluation of Drug Eluting Stents and Ischemic Events]) to compare clinical outcomes between DESs and bare metal stents (BMSs) using conventional (multivariable regression and propensity matching) and novel (instrumental variable analysis) risk-adjustment techniques.