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<0.001), an implausible finding compared with randomized trial results. Using instrumental variable analysis, DES were associated with no difference in 1-year mortality (risk difference, -0.8%; P=0.76) or bleeding (risk difference, 2.3%; P=0.33) and with significant reduction in target vessel revascularization (risk difference, -8.3%; P<0.0001). CONCLUSIONS: Using an instrumental variable analysis, DES were associated with similar mortality and bleeding and a significant reduction in target vessel revascularization compared with bare metal stents in the extremely elderly. Variation in use rates may be useful as an instrumental variable to facilitate comparative effectiveness in groups underrepresented in randomized trials.
RCT Entities:
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<0.001), an implausible finding compared with randomized trial results. Using instrumental variable analysis, DES were associated with no difference in 1-year mortality (risk difference, -0.8%; P=0.76) or bleeding (risk difference, 2.3%; P=0.33) and with significant reduction in target vessel revascularization (risk difference, -8.3%; P<0.0001). CONCLUSIONS: Using an instrumental variable analysis, DES were associated with similar mortality and bleeding and a significant reduction in target vessel revascularization compared with bare metal stents in the extremely elderly. Variation in use rates may be useful as an instrumental variable to facilitate comparative effectiveness in groups underrepresented in randomized trials.
Authors: Tara I Chang; Maria E Montez-Rath; Thomas T Tsai; Mark A Hlatky; Wolfgang C Winkelmayer Journal: J Am Coll Cardiol Date: 2016-03-29 Impact factor: 24.094
Authors: Lauren Gilstrap; Andrea M Austin; A James O'Malley; Barbara Gladders; Amber E Barnato; Anna Tosteson; Jonathan Skinner Journal: J Gen Intern Med Date: 2021-06-07 Impact factor: 6.473
Authors: Shahzad G Raja; Charles Ilsley; Fabio De Robertis; Rebecca Lane; Tito Kabir; Toufan Bahrami; Andre Simon; Aron Popov; Miles C Dalby; Mark Mason; Richard Grocott-Mason; Robert D Smith; M Bilal Iqbal Journal: PLoS One Date: 2018-02-06 Impact factor: 3.240