Reporting ‘number needed to treat’ in meta-analyses: A cross-sectional study


Associate Professor Cho Naing, School of Postgraduate Studies and Research, International Medical University, Kuala Lumpur 57000, Malaysia. Tel: +603-8656-7228 Fax: +603-8656-7229 Email:


Aim: In translating clinical research into practice, the summarization of data from randomized trials in terms of measures of effect to be readily appreciated by the point-of-care clinicians is important. In this context, the body of literature highlighted the ‘number needed to treat’ as a useful measure. The objectives of our study were to assess how meta-analyses described number needed to treat and corresponding 95% CI, and to explore issues related to reporting number needed to treat in the selected meta-analyses.

Method: For an illustration, we searched for the Cochrane systematic reviews and non-Cochrane systematic reviews. Two-stage selection was done to identify eligible studies. First, we fixed a date and then, we searched meta-analyses in PUBMED available on the date fixed. Secondly, we purposively selected five Cochrane systematic reviews and three non-Cochrane systematic reviews, according to our inclusion criteria. The critical appraisal of meta-analyses identified for the current study was done with the 5-item quality checklist introduced to the current analysis.

Results: A total of 8 systematic reviews, 5 Cochrane systematic reviews and 3 non-Cochrane systematic reviews/meta-analyses, were identified for the present study. Of these 8 meta-analyses, some (50%; 4/8) described number needed to treat in the method session of the study. However, the majority (87.5%; 7/8) reported number needed to treat in the results. For the details, 80% in Cochrane reviews and 66.5% in non-Cochrane reviews reported number needed to treat in the results. Only two studies (25%; 2/8) reported susceptibility to publication bias, provided simplified interpretation or discussed number needed to treat.

Conclusion: Although the Cochrane handbook for systematic reviews of interventions suggests the reviewers to include number needed to treat in reporting effect estimations, there still is a need to improve.