The screening performance of glucose challenge test for gestational diabetes in twin pregnancies: a systematic review and meta-analysis

Abstract

Background The screening accuracy of the 50 g-glucose challenge test (50 g-GCT) for gestational diabetes (GDM) has been described in singleton pregnancies. Given the physiologic differences and greater increase in insulin resistance in twin compared with singleton pregnancies, the performance of the 50 g-GCT in twin pregnancies may differ. Objectives To perform a systematic review on the screening performance of the 50 g-GCT for gestational diabetes in twin pregnancies. Data sources Ovid Medline, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL). Study eligibility criteria, participants, and interventions We included randomized controlled trials or cohort studies that evaluated the screening accuracy of the 50 g-GCT for GDM in twin pregnancies using the two-step approach. The primary outcome was the positive predictive value of the 50 g-GCT for GDM using the 140 mg/dL (7.8 mmol/L) threshold. Study appraisal and synthesis methods Methodological quality of included studies was assessed using the QUADAS-2 tool. The positive predictive value (PPV) was pooled for studies that used similar test characteristics. Results From 2044 citations, 7 retrospective cohort studies with a total of 55,597 participants were included (6.5% twins and 93.5% singletons). The majority of studies evaluated a 50-g GCT cutoff point of 140 mg/dL. The pooled PPV for a threshold of 140 mg/dL (7.8 mmol/L) for twins was 22.58% (95% CI: 0.1912–0.2647, I2 =34.1%). The 50-g GCT screen positive rate in twin pregnancies was higher than that in singleton pregnancies. None of the studies performed routine OGTT. Conclusions and implications of key findings The PPV of 50 g-GCT for GDM in twin pregnancies when using a threshold of 140 mg/dL (7.8 mmol/L) is approximately 23%. There is currently no data on the sensitivity and specificity of the 50 g-GCT in twins.