189 Predicting gestational diabetes in subsequent pregnancy using a novel risk calculator: implications for testing

Abstract

The current standard is to screen all women for gestational diabetes (GDM) regardless of prior history. We assessed whether variables from an index pregnancy (PG1) in women with a normal 1-hour glucose challenge test (GCT) can be used to guide testing in subsequent pregnancy (PG2), and created a risk calculator for GDM in PG2. We studied a cohort of women who delivered 2 singleton pregnancies at >24 weeks' gestation at a single institution from June 2009-December 2018. All patients had normal GCTs in PG1 (200mg/dL, >2 elevated values on a 3-hour diagnostic test (GTT, Carpenter-Coustan criteria), or a diagnosis of GDM by ICD codes. Univariable and multivariable analyses (MVA) were performed to examine the relationship between GDM in PG2 and demographic, clinical, and laboratory variables from PG1. A risk calculator for GDM in PG2 was created using regression coefficients from the MVA. 3,719 women met inclusion criteria and 146 (3.9%) developed GDM in PG2 (Table 1). In MVA, those with GDM in PG2 were significantly more likely to be older, have higher GCTs in PG1, be of Hispanic ethnicity or Asian race, have delivered large for gestational age neonates in PG1 and have a higher BMI in PG2 (Table 2). A risk calculator for GDM in PG2 was created using race/ethnicity, PG2 age and BMI and PG1 GCT result and birthweight category. Using a risk cutoff of 20%, 3.7% of patients are identified as being "at risk" of GDM in PG2, with a positive predictive value (PPV) of 29% and a negative PV of 97%. Among patients with a normal GCT in PG1, the likelihood of a diagnosis of GDM in PG2 is only 3.9%. A calculator is presented for estimating individual risk using readily available data. Use of this calculator may permit supplanting the current practice of universal GDM screening in subsequent pregnancies with a targeted approach, limiting screening to fewer than 4% of women with normal GCTs in the index pregnancy.View Large Image Figure ViewerDownload Hi-res image Download (PPT)