Risk factor screening for abnormal glucose tolerance in pregnancy

OBJECTIVES: To assess the prevalence and association of frequently used screening risk factors for gestational diabetes mellitus (GDM) and to compare the validity and cost of universal screening with risk factor screening.

METHOD: A cross-sectional survey of 768 pregnant women at > or = 24 weeks' gestation who were attending the antenatal clinic at the Hospital Universiti Kebangsaan Malaysia (HUKM) was made. Risk factors were determined using a questionnaire. An abnormal oral glucose tolerance test was defined as a 2-h post-prandial blood sugar level of > or = 7.8 mmol/l.

RESULTS: A total of 191 pregnant mothers (24.9%) had GDM. The most commonly identified screening factors were positive family history of diabetes mellitus (31.4%), history of spontaneous abortion (17.8%), vaginal discharge and pruritus vulvae in current pregnancy (16.0%), and maternal age greater than 35 years (14.7%). Five hundred and thirteen mothers (66.8%) had at least one risk factor. All screening risk factors, except past history of diabetes mellitus in previous pregnancy and maternal age, were not significantly associated with abnormal glucose tolerance (GT). Risk factor screening gave a sensitivity of 72.2% and a specificity of 35.0%. Universal screening would cost RM 12.06 while traditional risk factor screening would cost RM 11.15 per identified case and will have missed 53 of the 191 cases.

CONCLUSIONS: Risk factor screening scored poorly in predicting GDM. Cost analysis of universal compared with traditional risk factor screening showed a negligible difference. Thus universal screening appears to be the most reliable method of diagnosing GDM.