No need for rescue medication (NNR) as an easily interpretable efficacy outcome measure in analgesic trials: validation in an individual-patient meta-analysis of dental pain placebo-controlled trials of naproxen.

In analgesic trials, pain relief is often assessed using a pain-relief score. We aimed to assess, through a meta-analysis, whether absence of need for rescue medication (NNR) is a reliable outcome measure in the evaluation of acute pain relief. Individual-patient meta-analysis of placebo-controlled trials of single-dose naproxen sodium 220 or 440 mg in dental pain. Efficacy estimates were based on NNR and compared with the more commonly used 50% maximum total pain relief score (50% TOTPAR). The trials included were the full set of trials sponsored by one manufacturer. Need for rescue medication and 50% TOTPAR gave comparable estimates of efficacy of naproxen sodium (220 and 440 mg) relative to placebo in dental pain at both 8 and 12 h after dosing. No need for rescue medication is a reliable outcome measure for use in acute pain trials. As it is more readily understandable than 50% TOTPAR, it should be the preferred primary outcome measure in acute pain trials.