Common problems related to the use of number needed to treat

The basic information about which treatments are compared, the treatment period, the follow-up period, and the direction of the effect should be given when study results are presented in terms of NNTs. Adequate methods should be used for point and interval estimation of NNTs. Unnecessary rounding of NNTs should be avoided. In more complicated situations of confounding or varying follow-up times, the use of more sophisticated methods is required with increasing potential for misinterpretation.