Empirical evidence of bias in infertility research: overestimation of treatment effect in crossover trials using pregnancy as the outcome measure

Fertility and Sterility
K S KhanS D Walter

Abstract

To determine whether crossover trials with simple pooling of data over different study periods leads to a different estimate of treatment effect compared with parallel group trials in infertility research using pregnancy as the outcome measure. An observational study using nine overviews that included trials with both crossover and parallel group designs. These overviews comprised 17 crossover and 17 parallel group trials. In total, there were 5,291 outcomes including 775 pregnancies. The association between study design and treatment effect estimate was analyzed using multiple logistic regression, controlling for differences in the therapeutic interventions and variations in the methodological quality of the trials. Infertile patients in an academic research environment. Infertile patients undergoing treatment efficacy evaluation in controlled trials. Random allocation to a variety of treatments including clomiphene citrate, hCG, IUI, tamoxifen, and bromocriptine. Estimate of bias between study designs, based on the interaction of study design and treatment in the logistic regression model. Crossover trials produced a larger average estimate of treatment effect compared with trials with a parallel group design, overestimating ...Continue Reading

Citations

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