Background: Measures such as odds ratios and risk ratios are widely used in Cochrane reviews to summarize treatment effects. However, their interpretation is not intuitive. In the Cochrane Handbook for Systematic Reviews of Interventions it is advised to re-express the pooled estimate obtained by meta-analysis into a second, more easily interpretable statistic. The number needed to treat (NNT) is a measure useful in making policy decisions and decisions regarding individual patients.

Objectives: We aim to facilitate the interpretation of the results obtained from meta-analysis, by re-expressing the pooled estimate into NNT. For this purpose, we have developed a piece of software that can be used jointly with RevMan.

Methods: The software shows relative risk, absolute risk reduction, and NNT by studies and overall, with their 95% confidence intervals. It requires very little space on the computer's hard drive and can be used on a variety of computers and over the internet. We developed it with Personal Hypertext Processor (PHP), and using a database management system (DBMS) PostgreSQL, version 7.4.5. This is open source software, with a General Public Licence (GPL). Output from the software can be copied and pasted into RevMan.

Results: Information and details on the program are available from www.cochrane.fcs.uc.edu.ve/nnt.

Conclusions: We expect that the software will encourage Cochrane authors to report and use NNT more frequently.