Application of Nonparametric Procedure for Bioassay Data to the Evaluation of Analgesics in Man

Abstract

Parametric tests for bioassay data were commonly applied to scores of pain intensity and relief for the assessment of potency ratios of analgesic drugs. Scores derived from semiquantitative scales often deviated from normal distribution. In addition, when scores decreased as a consequence of analgesic treatment, the variances may be nonhomogeneous. Both parametric and nonparametric procedures were employed for the evaluation of results of a double-blind multicenter trial of the analgesic effect of indoprofen and ASA [acetylsalicyclic acid] (both drugs at 3 dose levels) and placebo in episiotomy pain. There was good agreement between potency ratios obtained with the 2 assays. Peak PID [pain intensity difference] appeared a less efficient means of estimating potency ratio than other measurements such as SPID [sum of pain intensity differences] and TOTPAR [total pain relief]. The nonparametric test for quantitative bioassay appeared to be a valid statistical procedure for evaluating results of clinical trials, and it did not imply any assumptions as to the type of distribution of the data.