Journal of the European Society for Gynaecological Endoscopy

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Statistical flaws in design and analysis of fertility treatment studies on cryopreservation raise doubts on the conclusions

P.H.A.J.M. Van Gelder1, M. Nijs2

1 PSCT B.V., Probabilistic Solutions Consult & Training, Nootdorpse Landingslaan 292, 496TB Den Haag, the Nether- lands.
2 The Geertgen Foundation, Fertility Treatment Centre, Elsendorp, the Netherlands.

Correspondence at: Dr. Ir. P.H.A.J.M. van Gelder, PSCT. B.V., Nootdorpse Landingslaan 292, 2496TB Den Haag, the Netherlands.

E-mail: P.H.A.J.M.vanGelder@tudelft.nl; Tel.: 31.15.3618930; Fax : 31.15.2785124

Keywords:

Statistics in infertility studies, subfertility, methodological study requirements, cryopreservation


Published online: Jan 05 2012

Abstract

Decisions about pharmacotherapy are being taken by medical doctors and authorities based on comparative studies on the use of medications. In studies on fertility treatments in particular, the methodological quality is of utmost importance in the application of evidence-based medicine and systematic reviews. Nevertheless, flaws and omissions appear quite regularly in these types of studies. Current study aims to present an overview of some of the typical statistical flaws, illustrated by a number of example studies which have been published in peer reviewed journals. Based on an investigation of eleven studies at random selected on fertility treatments with cryopreservation, it appeared that the methodological quality of these studies often did not fulfil the required statistical criteria. The following statistical flaws were identified: flaws in study design, patient selection, and units of analysis or in the definition of the primary endpoints. Other errors could be found in p-value and power calculations or in critical p-value definitions. Proper interpretation of the results and/or use of these study results in a meta analysis should therefore be conducted with care.