@article {516266, title = {Instrumental variable analysis to compare effectiveness of stents in the extremely elderly}, journal = {Circ Cardiovasc Qual Outcomes}, volume = {7}, number = {1}, year = {2014}, month = {2014 Jan}, pages = {118-24}, abstract = {BACKGROUND: Evaluating novel therapies is challenging in the extremely elderly. Instrumental variable methods identify variables associated with treatment allocation to perform adjusted comparisons that may overcome limitations of more traditional approaches. METHODS AND RESULTS: Among all patients aged >=85 years undergoing percutaneous coronary intervention in nonfederal hospitals in Massachusetts between 2003 and 2009 (n=2690), we identified quarterly drug-eluting stent (DES) use rates as an instrumental variable. We estimated risk-adjusted differences in outcomes for DES versus bare metal stents using a 2-stage least squares instrumental variable analysis method. Quarterly DES use ranged from 15\% to 88\%. Unadjusted 1-year mortality rates were 14.5\% for DES versus 23.0\% for bare metal stents (risk difference, -8.5\%; P, keywords = {Acute Coronary Syndrome, Aged, 80 and over, Data Interpretation, Statistical, Drug-Eluting Stents, Female, Hemorrhage, Humans, Incidence, Male, Massachusetts, Metals, Percutaneous Coronary Intervention, Retrospective Studies, Stents, Survival Rate, Treatment Outcome}, issn = {1941-7705}, doi = {10.1161/CIRCOUTCOMES.113.000476}, author = {Yeh, Robert W and Vasaiwala, Samip and Forman, Daniel E and Silbaugh, Treacy S and Zelevinski, Katya and Lovett, Ann and Normand, Sharon-Lise T. and Mauri, Laura} }