Seminars in arthritis and rheumatism
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Semin. Arthritis Rheum. · Feb 2021
ReviewStatins and lower mortality in rheumatic diseases: An effect of immortal time bias?
Randomized controlled trials of the effectiveness of statins on rheumatic disease outcomes have shown limited or no benefit. On the other hand, observational studies have reported remarkable effectiveness of statins at reducing mortality in patients with rheumatic diseases. We evaluated these observational studies for the presence of immortal time bias, which tends to exaggerate the effectiveness of drugs by creating a survival advantage for exposed patients. ⋯ Bias in observational studies may explain the discrepancy in findings with randomized controlled trials on the effectiveness of statins in patients with rheumatic diseases. Future observational studies will need to rely on incident and prevalent new-user designs that emulate randomized trials and avoid immortal time bias.