A systematic review 1 including 16 studies with a total of 8 354 subjects was abstracted in DARE. Overall, the use of nifedipine was associated with a significant increase in mortality (risk ratio 1.16, 95% CI 1.01 to 1.33). A dose-response relationship also appeared to exist for daily doses of 30 to 50, 60 and 80 mg, the risk ratios for total mortality were 1.06 (95% CI 0.89 to 1.27), 1.18 (95% CI 0.93 to 1.50) and 2.83 (95% CI 1.35 to 5.93), respectively.
A systematic review 2 including 60 RCTs with a total of 3 096 patients and 5 571 treatment exposures, 2 635 nifedipine, 2 655 other active drugs and 281 placebo) was abstracted in DARE. Overall unadjusted ORs of major cardiovascular events for nifedipine versus other active drugs were not significant (OR 1.40, 95% CI 0.56 to 3.49). The OR for immediate-release nifedipine was significantly higher than that for sustained or extended release nifedipine for increased angina (OR 4.19, 95% CI 1.14 to 12.49 vs. OR 0.30, 95% CI 0.06 to 1.43). The authors concluded that adverse effects of nifedipine on cardiovascular events in patients with stable angina are due primarily to more frequent episodes of increased angina in patients on monotherapy with immediate release formulation.
Comment: The quality of evidence is downgraded by sparse data and indirectness (mortality associated with the use of nifedipine in patients with hypertension has not been analysed), but upgraded by a clear dose-response gradient.
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