Adjustment of the GRACE score by 2-hour post-load glucose improves prediction of long-term major adverse cardiac events in acute coronary syndrome in patients without known diabetes

Aims Global Registry of Acute Coronary Events (GRACE) risk score (GRS), a powerful predictor of prognosis after ACE, does not include a glucometabolic measure. We investigate whether 2 hour post-load plasma glucose (2h-PG) could improve GRS based prognostic models in ACE patients without known diabetes mellitus (DM). Methods Retrospective cohort study of 1056 ACE survivors without known DM who had fasting (FPG) and 2h-PG measured pre-discharge. Death and non-fatal myocardial infarction (MI) were recorded as major adverse cardiac events (MACE) during follow up. GRS for discharge to 6 months was calculated. Cox proportional-hazards regression was used to identify predictors of event free survival. The predictive value of 2h-PG alone and combined with GRS was estimated using Likelihood ratio test, Akaike's Information criteria, continuous net reclassification improvement (NRI>0) and integrated discrimination improvement (IDI). Results During 40.8 months follow up 235 MACEs (22.3%) occurred, more frequently in the upper 2h-PG quartiles. 2h-PG, but not FPG, adjusted for GRS independently predicted MACE (HR 1.091; 95 % CI 1.043-1.142; p=0.0002). Likelihood ratio test showed that 2h-PG significantly improved the prognostic models including GRS (χ2=20.56, 1 df, p=0.000). Models containing GRS and 2h-PG yielded lowest corrected Akaike's Information criteria, compared to that with only GRS. 2h-PG, when added to GRS, improved net reclassification significantly (NRIe>0 6.4%, NRIne>0 24%, NRI>0 0.176, p = 0.017 at final follow up). 2h-PG, improved integrated discrimination of models containing GRS (IDI of 0.87%, p=0.008 at final follow up). Conclusion Two-hour PG, but not FPG, is an independent predictor of adverse outcome after ACE even after adjusting for the GRS. Two-hour PG, but not FPG, improves the predictability of prognostic models containing GRS