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Monitoring the Wall Mechanics During Stent Deployment in a Vessel
Published on: May 8, 2012
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Instrumental variable analysis to compare effectiveness of stents in the extremely elderly
Robert W Yeh1, Samip Vasaiwala, Daniel E Forman
1Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston, MA.
Circulation. Cardiovascular Quality and Outcomes
|November 21, 2013
Summary
Instrumental variable analysis revealed drug-eluting stents (DES) showed similar mortality and bleeding compared to bare metal stents in elderly patients. However, DES significantly reduced target vessel revascularization in this population.
Area of Science:
- Cardiovascular Medicine
- Health Services Research
- Biostatistics
Background:
- Evaluating new treatments in the very elderly presents unique challenges.
- Instrumental variable (IV) methods offer a way to adjust for treatment allocation biases.
- This approach can overcome limitations of traditional comparative effectiveness studies.
Purpose of the Study:
- To assess the comparative effectiveness of drug-eluting stents (DES) versus bare metal stents (BMS) in patients aged 85 years and older.
- To utilize instrumental variable analysis to adjust for confounding factors in this vulnerable population.
Main Methods:
- A retrospective analysis of 2690 patients aged ≥85 undergoing percutaneous coronary intervention in Massachusetts (2003-2009).
- Quarterly drug-eluting stent (DES) use rates were employed as an instrumental variable.
- Two-stage least squares (2SLS) instrumental variable analysis was used to estimate risk-adjusted outcome differences.
Main Results:
- Unadjusted analysis showed implausibly lower mortality for DES (14.5%) vs. BMS (23.0%).
- Instrumental variable analysis indicated no significant difference in 1-year mortality (RD: -0.8%, P=0.76) or bleeding (RD: 2.3%, P=0.33) between DES and BMS.
- DES use was associated with a significant reduction in target vessel revascularization (RD: -8.3%, P<0.0001) compared to BMS.
Conclusions:
- Instrumental variable analysis suggests DES are associated with similar mortality and bleeding risk compared to BMS in the extremely elderly population.
- DES significantly reduced target vessel revascularization in patients aged 85 and older.
- Variations in stent use rates can serve as a valuable instrumental variable for comparative effectiveness research in underrepresented groups.
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