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July 19, 2000

Assessing Prevention Interventions by "Number Needed to Treat"

Author Affiliations

Stephen J.LurieMD, PhD, Contributing EditorIndividualAuthor

JAMA. 2000;284(3):303-305. doi:10.1001/jama.284.3.303

To the Editor: We agree with the comments of Dr Kumana and colleagues1 on the advantages of using absolute risk reduction rather than RRR to evaluate treatment effectiveness, but would like to emphasize that care is needed in interpreting the effectiveness of statins using the absolute risk approach.

In primary prevention, the absolute risk reduction from treatment of coronary heart disease (CHD) by statins is known to be largely determined by the initial risk of CHD in the populations studied and the duration of follow-up.2 The presence of other risk factors such as smoking or hypertension imposes an additional risk, implying a greater reduction in risk by statins in those with a risk factor than in those without. The smaller expected NNTs in those exposed to risk factors compared with the unexposed were consistently observed for all 4 risk factors in Table 2, thus confirming the anticipated interaction between treatment of statins and the major CHD risk factors.