Diabetes after pregnancy prevention trials: Systematic review for core outcome set development

Diabetes prevention intervention studies in women with previous gestational diabetes have increased, but no consensus exists on core outcomes to support comparisons and synthesis of findings. We aimed to systematically catalogue outcomes in diabetes after pregnancy prevention interventions with the goal of developing a core outcome set. Embase, Medline, Cochrane Library, Cochrane Pregnancy and Childbirth Trials Register, and CINAHL were searched from inception to October 2017. Post-partum lifestyle and diabetes screening intervention studies in women with previous gestational diabetes and/or their families were eligible. No limits were placed on intervention type, duration, or location. Two authors independently screened and performed data extraction on outcomes, measurement tools, and relevant study characteristics. We analysed data from 38 studies (29 randomised controlled trials and 9 pre-post intervention evaluations) comprising 12,509 participants. Most publications (80%) occurred between the years 2012 and 2017. Among 172 outcomes, we identified 36 outcome groups and classified them under three domains: health status (body weight, body composition, diabetes risk, cardiometabolic risk, diabetes development, mental health, pregnancy outcomes, and fitness), health behaviours (dietary, physical activity, diabetes screening, behaviour change, and breastfeeding), and intervention processes (implementation). The health status domain contained the most commonly reported outcomes, but measurement tools were very heterogeneous. Despite the recent explosion in diabetes after pregnancy prevention studies, large variation in outcomes and measurement methods exists. Research is needed to define a core outcome set to standardise diabetes after pregnancy prevention interventions. The core outcome set should engage a wide group of stakeholders to identify impactful indicators for future trials.