Using restriction to minimize bias in observational studies.
- Using restriction to minimize bias in observational studies.
- Turakhia MP, Heidenreich PA
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In their Commentary, Drs Psaty and Siscovick 1 emphasized the importance of restriction to minimize confounding by indication and bias in the conduct of observational comparative effectiveness research. We agree with this strategy for less complicated therapies, such as β-blockers for hypertension, for which the dose-adjusted efficacy would not likely be affected by clinician-level, facility-level, or other nonpatient factors. However, we caution against the broad use of restriction to evaluate therapies or services for which quality of care delivery would impact effectiveness.
For example, there is controversy as to whether aspirin or warfarin is more effective for stroke prevention in low-risk patients with atrial fibrillation because the benefits of warfarin, which requires regular blood testing to monitor anticoagulation, may be offset by the potential harms of major bleeding. 2, 3 This evidence gap could be evaluated with electronic health record data in hundreds of thousands of …
Using restriction to minimize bias in observational studies. Turakhia MP, Heidenreich PA. JAMA 2010; 304(21):2359-60.