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Differentiating the Efficacy of 5‐HT 1B/1D Agonists
Author(s) -
Sheftell Fred D.,
Fox Anthony W.,
Weeks Randall E.,
Tepper Stewart J.
Publication year - 2001
Publication title -
headache: the journal of head and face pain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.14
H-Index - 119
eISSN - 1526-4610
pISSN - 0017-8748
DOI - 10.1046/j.1526-4610.2001.111006257.x
Subject(s) - placebo , number needed to treat , medicine , clinical trial , clinical endpoint , confidence interval , relative risk , alternative medicine , pathology
Objective.—To examine, for a set of published clinical trials of serotonin (5‐HT 1B/1D ) agonists as acute treatments for migraine, whether transformation of efficacy data into therapeutic gain (TG) or number needed to treat (NNT) is useful. Background.—Pivotal clinical trials of 5‐HT 1B/1D agonists in migraine use a primary end point of change in pain score from 3 or 2 to 1 or 0. Placebo response rates among such studies are variable. Meta‐analytic comparisons of 5‐HT 1B/1D agonists often employ TG and NNT as efficacy measures. Methods.—Data from US product labeling or published sources were converted into TG (TG = active response rate [%] − placebo response rate [%]) and NNT (NNT = 1/TG). Pivotal clinical trial data were compared before and after transformation. Results.—Therapeutic gain ranged from 17.5% to 51%. The transformation of TG into NNT yielded no clinically significant difference in efficacy estimate for the range of 17.5% to 47% (N = 29 clinical trials). However, NNT and TG had a nonlinear relationship for some secondary end points. When the relationship between the standard primary and secondary end points was compared, the correlation of TG with clinical disability (Pearson coefficient R = 0.93) was stronger than for NNT. Placebo response rates correlated more strongly with NNT ( R = 0.66) than active response rates ( R = 0.42; N = 29 clinical trials), although both TG and NNT were sensitive to placebo response rate. Conclusions.—Transforming efficacy rates into TG or NNT adds no new information to placebo‐controlled trials. The variables, TG and NNT, should not be used to compare members of this class of drugs. Migraine therapies can only be compared using well‐designed head‐to‐head studies and not by meta‐analysis. Broader measures of efficacy should be used to describe and compare 5‐HT 1B/1D efficacy.