A randomized pragmatic clinical trial of gestational diabetes screening (ScreenR2GDM): Study design, baseline characteristics, and protocol adherence.

Background: ScreenR2GDM is a pragmatic randomized clinical trial designed to investigate if one of two gestational diabetes (GDM) screening and treatment protocols results in improved outcomes in the context of standard clinical care.

Methods: Pregnant women are randomized to one of two GDM screening strategies: 1-step: 2-h, 75 g, oral glucose tolerance test (OGTT) or 2-step: 1-h, 50 g glucose challenge test (GCT) followed by 3-h, 100 g OGTT if GCT-positive. Providers are prompted within the electronic medical record to order the assigned test but were given the option to order the alternate test. Collected data include maternal and pregnancy characteristics, GDM testing, and outcomes for mother and newborn. We describe the study design and baseline characteristics and evaluate characteristics associated with adhering to the randomized protocol.

Results: Baseline characteristics of the 23,792 randomized pregnancies were comparable between the two groups. Adherence to assigned test differed between the two strategies: 66.1% for 1-step and 91.7% for 2-step (p < .0001). 27% of the women randomized to receive the 1-step completed the 2-step test vs 2% randomized to the 2-step who completed the 1-step (p < .0001). Patient characteristics related to adherence included obesity, age, prior GDM, Medicaid insurance, race and nulliparity. Clinician characteristics related to adherence included provider type, age and gender.

Conclusions: Both patient and provider characteristics were related to adherence to the randomized GDM screening protocol. Analytical techniques that incorporate these findings into the formal evaluation of the two protocols on GDM-associated outcomes will be necessary to account for potential biases introduced by non-adherence.