A recent study of patients with stage 2 chronic kidney disease (CKD) found that a new drug reduced the progression to end-stage (stage 5) CKD from 37/1,000 placebo-treated cases to 12/1,000 new drug-treated cases over a five-year period.
Which of the following is the number needed to treat in order to obtain a single favorable outcome?

Question

Quizplus · Accepted Answer

The number needed to treat (NNT) provides an estimate of the effectiveness of a treatment or intervention. This can be calculated as the reciprocal of the absolute risk reduction (ARR). In this case, the ARR is 2.5% (37/1,000 or 3.7% in the placebo group - 12/1,000 or 1.2 % in the treatment group = 2.5%). The number needed to treat can then be calculated by dividing 1 by 2.5% (1 / 0.025), or 40. In an ideal world, the number needed to treat would be 1 and would benefit all treated patients. Many clinicians feel that the NNT is more practical and better in estimating an intervention's benefit than the ARR, relative risk reduction, or odds ratio. Educational objective: The number needed to treat is the reciprocal of the absolute risk reduction rate from an intervention. This number is used by some clinicians to present probabilities regarding outcomes to patients. __________ References: The number needed to treat: A clinically useful nomogram in its proper context. (http://www.ncbi.nlm.nih.gov/pubmed/8601116)

A Recent Study of Patients with Stage 2 Chronic Kidney