Prognostic research: design requirements and common mistakes with a focus on obstetrics, gynecology, and reproductive medicine

This article provides a conceptual overview of the methodology and design of predictive studies. Cohort studies are the preferred design for predictive studies. The article discusses the differences between traditional etiological cohort studies and predictive cohort studies. It also provides examples of studies that have been conducted to predict pre-eclampsia, gestational diabetes, postpartum hemorrhage, ovarian hyperstimulation syndrome, and reproductive outcomes in recurrent miscarriage. The importance of adhering to the methodological standards described in the STROBE and TRIPOD guidelines is emphasized, as well as the need to avoid common design and methodology errors, such as measuring predictors after the outcome has occurred or using ROC analysis without building a predictive model. Special attention is given to the use of appropriate statistical methods, as a lack of understanding of these methods can lead to erroneous conclusions. Thus, the implementation of predictive cohort studies and rigorous analytical approaches contributes to improving the quality of clinical training for doctors and strengthening the evidence base for obstetrics, gynecology, and reproductive medicine.