Risk factor screening to identify women requiring oral glucose tolerance testing to diagnose gestational diabetes: A systematic review and meta-analysis and analysis of two pregnancy cohorts

Abstract

Background: Easily identifiable risk factors including: obesity and ethnicity at high risk of diabetes are commonly used to indicate which women should be offered the oral glucose tolerance test (OGTT) to diagnose gestational diabetes (GDM). Evidence regarding these risk factors is limited however. We conducted a systematic review (SR) and meta-analysis and individual participant data (IPD) analysis to evaluate the performance of risk factors in identifying women with GDM.

Methods: We searched MEDLINE, Medline in Process, Embase, Maternity and Infant Care and the Cochrane Central Register of Controlled Trials (CENTRAL) up to August 2016 and conducted additional reference checking. We included observational, cohort, case-control and cross-sectional studies reporting the performance characteristics of risk factors used to identify women at high risk of GDM. We had access to IPD from the Born in Bradford and Atlantic Diabetes in Pregnancy cohorts, all pregnant women in the two cohorts with data on risk factors and OGTT results were included.

Results: Twenty nine published studies with 211,698 women for the SR and a further 14,103 women from two birth cohorts (Born in Bradford and the Atlantic Diabetes in Pregnancy study) for the IPD analysis were included. Six studies assessed the screening performance of guidelines; six examined combinations of risk factors; eight evaluated the number of risk factors and nine examined prediction models or scores. Meta-analysis using data from published studies suggests that irrespective of the method used, risk factors do not identify women with GDM well. Using IPD and combining risk factors to produce the highest sensitivities, results in low specificities (and so higher false positives). Strategies that use the risk factors of age (>25 or >30) and BMI (>25 or 30) perform as well as other strategies with additional risk factors included.

Conclusions: Risk factor screening methods are poor predictors of which pregnant women will be diagnosed with GDM. A simple approach of offering an OGTT to women 25 years or older and/or with a BMI of 25kg/m2 or more is as good as more complex risk prediction models. Research to identify more accurate (bio)markers is needed. Systematic Review Registration: PROSPERO CRD42013004608.

Fig 1. Flow chart of the systematic review search process.

Fig 2. Screening performance (sensitivity and percentage offered an oral glucose tolerance test (OGTT)) by study and by risk factor method (guideline recommendations, number (No) of risk factors, ‘other method and risk model/score).

The colour of the points indicates the study. The shape of the points (circles, triangle, square, cross) indicates method used No. RF = number of risk factors (i.e. presence of one risk factor, two risk factors and so on). Studies may report more than one performance estimate, this is reflected in the number of coloured shapes for each study.

Fig 3. Screening performance of guidelines using a risk factor screening strategy.

Vertical and horizontal lines show the 95% confidence intervals for sensitivity and positive rate respectively. The colour of the points indicates the study. The shape of the points (circles, triangle, square, cross) indicates method used. RF = Risk factor, No = number. ACOG = American College of Obstetricians and Gynecologists. ADA = American Diabetes Association. ADIPS = Australasian Diabetes In Pregnancy Society. NICE = National Institute for Health and Care Excellence. Studies may report more than one performance estimate, this is reflected in the number of coloured shapes for each study.

Fig 4. Screening performance of risk prediction or scoring models.

The colour of the points indicates the study. Vertical and horizontal lines show the 95% confidence intervals for sensitivity and positive rate respectively. Studies may report more than one performance estimate, this is reflected in the number of coloured shapes for each study

Fig 5. Screening performance of risk factor combinations for identifying GDM using IPD.

The colour of the points indicates the number (No) of risk factors included. Circles indicate results for Atlantic DIP and triangles represent results for BiB.

Fig 6. Sensitivity and positive rate when using a risk prediction model to predict GDM using IPD