Number-needed-to-treat analysis of the prevention of myocardial infarction and death by antidyslipidemic therapy.
Level 1 - systematic review of randomized trials
Meta-analysis of clinical trials
What was done
A meta-analysis of 33 studies was conducted to evaluate the clinical and angiographic effects of antidyslipidemic therapy for cardiovascular morbidity and mortality across primary, secondary, and tertiary prevention. Efficacy was quantified using the number needed to treat (NNT).
What was found
In primary prevention (6 trials, excluding the British clofibrate trial; 4.8 years mean treatment with 15% total cholesterol reduction), the NNT was 53 to prevent nonfatal myocardial infarction and 190 to prevent all-cause death. In secondary and tertiary prevention (23 trials; 4.9 years mean treatment with 18% total cholesterol reduction), the NNT was 37 to prevent all-cause death. In trials using quantitative angiography (2.5 years mean treatment with 28% LDL cholesterol reduction), the NNT was 7 to prevent progression and 10 to induce regression of coronary atherosclerosis. Similar benefits were observed with HMG-CoA reductase inhibitors, while niacin and dietary therapy did not achieve statistical significance across all endpoints. Benefits extended to patients over age 65, with less clearly defined benefits for women.
Why it matters
This paper frames the absolute clinical impact of lipid-lowering therapy using NNT, demonstrating substantial mortality reduction in secondary prevention comparable to interventions like aspirin or beta-blockers.
Limits
The total number of participants across all 33 studies was not reported in the abstract. Evidence was less clearly defined for women, non-statin therapies (diet, niacin) were potentially limited by beta error, and the primary prevention estimate required excluding one major trial (British clofibrate study).
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