[Number needed to treat (NNT), an index for clinical therapeutic efficacy assessment--its significance and application].

Number needed to treat (NNT) is a simple and effective index for clinical therapeutic effect assessment worldwide accepted in recent years. By calculation of absolute risk reduction (ARR) of classified variables, it made the effect estimate reflect objectively the therapeutic effect of an intervention. However, clinical application of this index was introduced rarely in Chinese literature. With the examples from some published clinical reports, the calculation of NNT and its 95% confidence interval were demonstrated in this paper, and its application was illustrated by some relevant terms explanation and Meta-analysis methods introduction.