If the control rate (CR) in a clinical trial represents the incidence or the baseline severity of illness in the study population, the size of treatment effects may tend to vary with the size of control rates.
To investigate this hypothesis, we examined 115 meta-analyses covering a wide range of medical applications for evidence of a linear relationship between the CR and three treatment effect (TE) measures : the risk difference (RD) ; the log relative risk (RR), and the log odds ratio (OR).
We used a hierarchical model that estimates the true regression while accounting for the random error in the measurement of and the functional dependence between the observed TE and the CR.
Using a two standard error rule of significance, we found the control rate was about two times more likely to be significantly related to the RD (31 per cent) than to the RR (13 per cent) or the OR (14 per cent).
Correlations between TE and CR were more likely when the meta-analysis included 10 or more trials and if patient follow-up was less than six months and homogeneous.
Use of weighted linear regression (WLR) of the observed TE on the observed CR instead of the hierarchical model underestimated standard errors and overestimated the number of significant results by a factor of two. (...)
Mots-clés Pascal : Métaanalyse, Essai clinique, Prédicteur, Efficacité traitement, Contrôle, Epidémiologie, Analyse statistique
Mots-clés Pascal anglais : Metaanalysis, Clinical trial, Predictor, Treatment efficiency, Check, Epidemiology, Statistical analysis
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 98-0411394
Code Inist : 002B28F. Création : 25/01/1999.