INTRODUCTION
Assuming comparable safety and tolerability, patients and healthcare providers strive to choose the most effective treatment for any given condition. For conditions with multiple treatment options, this requires evaluating the relative effectiveness of each. In the absence of head-to-head trials, a common measure of comparative clinical effectiveness is the number needed to treat (NNT).1-3 NNT is a way to provide a clinically useful measure of treatment effect and indirectly compare data across randomized double-blind controlled trials.2,4 Assuming other treatment-related considerations are equal (eg, side effect profile, cost, access), choosing a treatment with the lowest NNT would be a reasonable approach, as this may denote the highest efficacy in attaining a treatment outcome.
In the acne vulgaris literature, NNTs are rarely reported; while there is an example of NNT used as an outcome measure of treatment efficacy,5 NNTs are more frequently calculated in secondary sources such as review articles.6-9 In these publications, NNTs for acne treatments were less than 10 but
The NNT is the reciprocal value of the absolute risk reduction (ARR; Figure 1). More than P values and responder rates, NNT is a clinically intuitive way to determine if one treatment is better than another in a way that is likely to be noticed in routine clinical practice.2 However, the clinical relevance of an NNT is not just based on the number. Acceptable NNTs vary widely by disease and are dictated by many factors, such as severity, epidemiology, and treatability.3
In the acne vulgaris literature, NNTs are rarely reported; while there is an example of NNT used as an outcome measure of treatment efficacy,5 NNTs are more frequently calculated in secondary sources such as review articles.6-9 In these publications, NNTs for acne treatments were less than 10 but
