Poster Presentation International Association of the Diabetes and Pregnancy Study Groups 2022 - Hosted by ADIPS

Hyperglycaemia in Pregnancy: A new paradigm for adverse perinatal outcome risk stratification (#104)

Emma L Jamieson 1 , Erica P Spry 2 3 , Andrew Kirke 1 , Carly Roxburgh 4 , David Atkinson 2 , Julia V Marley 2
  1. The Rural Clinical School of Western Australia, The University of Western Australia, Bunbury, WA, Australia
  2. The Rural Clinical School of Western Australia, The University of Western Australia, Broome, WA, Australia
  3. Kimberley Aboriginal Medical Services, Broome, WA, Australia
  4. The Rural Clinical School of Western Australia, The University of Western Australia, Albany, WA, Australia

Background

Women from rural and remote WA have increased risk for Hyperglycaemia in Pregnancy (HIP), yet poor OGTT completion (50%) and non-adherence to pre-analytical laboratory standards results in significant under-diagnosis (estimated 62%). Measurement of HbA1c and glycated albumin (GA) may improve screening outcomes.

Aims

To determine combined HbA1c and GA cut-points to stratify low- and high-risk for HIP as diagnosed by OGTT (≥24-week gestation) and evaluate accuracy of risk-stratification for detecting adverse birth outcomes.

Methods

Twenty-seven rural and remote WA clinics recruited 694 pregnant women (2015-2018). OGTT were conducted following local pathology guidelines. Paired-sample OGTT time-course comparison of glucose in fluoride/oxalate to fluoride/citrate/EDTA samples informed linear regression correction of OGTT (OGTTc) by delay to analysis (n=12; 363 time-points).

At OGTT, HbA1c (Roche Diagnostics) and GA (AsahiKasei Pharma) were measured and maternal characteristics recorded. Two GP-Obstetricians, blinded to pathology results, defined adverse perinatal outcomes independently as potentially HIP-related.

Outcome measures included: receiver operator characteristics curve derived low-risk (sensitivity ≥95%) and high-risk (specificity ≥90%) cut-points for HbA1c and GA (stratified by BMI: not-obese <30kg/m2; obese ≥30kg/m2), for abnormal OGTTc; OR [95% CI] for composite adverse perinatal outcome (model adjustment: maternal BMI, age, height, ethnicity, and smoking; gestation at OGTT and delivery). To validate thresholds 180 participants were recruited (2020-2022) with OGTT collected into fluoride/citrate/EDTA tubes.

Results

Complete OGTT, HbA1c and GA data was available for 357 participants. Adverse perinatal outcome was common (n =106, 30.7%), however most at-risk women (85.8%) had a normal OGTT (unadjusted OR 1.8 [0.9-3.7], P =0.11 for adverse perinatal outcome). Correction of OGTT by delay to analysis improved identification of risk (unadjusted OR 1.8 [1.1-3.1], P =0.003).

Combined cut-points used to stratify low-risk were HbA1c <4.8% and GA <10.53% (non-obese) or <10.09% (obese); and high-risk were HbA1c ≥5.5% and/or GA ≥12.90% (non-obese) or ≥12.37% (obese). Most women were in the medium risk category (low: 17.6%, medium: 60.5%, high: 21.8%). There was some discordance between abnormal OGTTc and HbA1c-GA risk stratification (low: 14%, medium: 20%, high: 51%). However, the latter was highly predictive of adverse perinatal outcome (47.4% high-risk v 27.6% medium-risk; adjusted OR 2.0 [1.1-3.5] P =0.020) and no abnormal uncorrected-OGTT were missed by low-risk classification. Threshold validation analysis is underway.

Conclusion

As a screening test the OGTT has low sensitivity for identifying women at risk of HIP-related adverse birth outcomes. Combined HbA1c-GA risk-stratification presents an alternative paradigm to detect HIP and reduce the burden of conducting OGTTs.