Assessment of Diagnostic Accuracy of Early OGTT in Prediction of GDM taking 2nd Trimester OGTT as Gold Standard

Abstract

Objectives: To determine the diagnostic accuracy of early OGTT in
prediction of GDM taking 2nd trimester OGTTas gold standard.
Methods: This study cross-sectional study enrolled 420 pregnant women with
single pregnancy between 18 and 40 years of age, who had their first prenatal visit
in PAF hospital at 1st or early 2nd trimester. All the women in their first trimester
were subjected to 75g OGTT and the values of plasma glucose concentration were
recorded at fasting level, after 1-hr and after 2-hrs respectively. All these results
were compared with 2nd trimester OGTT of same patients taking 2nd trimester
OGTTas gold standard.
Results: The mean age±SD of women was 27.77±4.87 years. The mean±SD BSF,
1-hr and 2-hr plasma glucose of women in 1st OGTT were 4.74±0.36 mmol/L,
7.44±0.63 mmol/L and 6.58±0.63 mmol/L respectively. The mean±SD BSF, 1-hr
and 2-hr plasma glucose of women in 2nd OGTT were 4.89±0.32 mmol/L,
7.15±0.92 mmol/L and 6.04±0.97 mmol/L respectively. The prevalence of GDM
in 1st OGTT was found as 6.4% and in 2nd OGTT it was found as 20.5%. The
sensitivity and specificity of 1st OGTT performed between 10 to 17 weeks of
gestation was found as 26.7% and 98.8% respectively. The positive predictive
value and negative predictive value of 1st OGTT performed between 10 to 17
weeks of gestation was found as 85.18% and 83.97% respectively.
Conclusion: The early OGTT performed during 10-17 weeks of gestation has
good specificity, positive predictive value and negative predictive value but poor
sensitivity, taking the late 2nd trimester OGTTas a gold standard.