Predictors of participant retention in infertility treatment trials

Using data from three infertility trials we identified race, ethnicity, body mass index, insurance coverage, history of smoking, and history of alcohol use as significant predictors of retention.


Hongying Kuang, M.D., Ph.D., Susan Jin, M.P.H., Tracey Thomas, M.P.H., Lawrence Engmann, M.D., Karl R. Hansen, M.D., Ph.D., Christos Coutifaris, M.D., Ph.D., Peter Casson, M.D., Gregory Christman, M.D., Ruben Alvero, M.D., Nanette Santoro, M.D., Esther Eisenberg, M.D., M.P.H., Michael P. Diamond, M.D., Richard S. Legro, M.D., Heping Zhang, Ph.D.for the Reproductive Medicine Network

Volume 104, Issue 5, Pages 1236-1243



To identify variables associated with retention (or dropout) in infertility clinical trials. Retention of subjects in randomized controlled clinical trials (RCTs) has received considerable attention, but there have been few consistent findings.


Secondary analysis of data from RCTs.


Randomized controlled clinical trials conducted by academic medical centers in the United States.


Women with polycystic ovary syndrome (PCOS) or couples with unexplained infertility, aged 18–39 years.


This study is not an intervention study, but the patients in the original RCTs were treated with any or combination of metformin, clomiphene citrate (CC), letrozole, and gonadotropins.

Main Outcome Measure(s):

Successful retention versus dropout during the RCTs.


Race, ethnicity, body mass index (BMI), insurance coverage, history of smoking, and history of alcohol use were significantly associated with retention whether they were considered in bivariate analyses or a multivariable logistic model. Specifically, white race, higher income, having graduate degrees, normal weight, better insurance coverage, nonsmokers, and those who reported current use of alcohol at the start of the trial, had higher retention rates.


We identified several additive and persistent predictors of retention that can be used to guide the conduct of RCTs and improve the retention rate. Given the limitation of our association analysis, methodologically sound and theoretically grounded research are warranted so that high quality data can be collected to improve our understanding on the causes of dropout.

Clinical Trial Registration Number:

NCT00068861 (PPCOS-I), NCT00719186 (PPCOS-II), and NCT01044862 (AMIGOS).

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