Hemoglobin A1C as a Prognostic Factor in Patients Admitted to a Tertiary Care Intensive Coronary Care Unit

Introduction: Hemoglobin A1C (HbA1c) is a form of hemoglobin that is bound to glucose and has been used to measure glucose control. Data regarding the prognostic factor of HbA1c level in intensive coronary care unit (ICCU) patients is lacking.

Material and method: All patients admitted to the ICCU at the Shaare Zedek Medical Center between January 1, 2020 and December 31, 2020 who had HbA1c level on admission were included in the study. Patients were divided into 3 groups according to the range of their HbA1c levels: <5.7g% [no diabetes mellitus (DM)], 5.7 -6.4g% (pre-DM), ≥6.5 g% (DM). Survival and in-hospital complications were measured.

Results and discussion: A total of 795 patients were included. Of them a 550 (69%) were male with a mean age of 67(±15) years old. HbA1c level <5.7 g% was found in 331 (42%) patients, 5.7-6.4 g% in 252 (32%) patients and >6.5 g% in 212 (26%) patients. Interestingly, although 37 (4.7%) patients did not have a diagnosis of DM on admission, their HbA1c level was >6.5 g%. In-hospital complication rate was similar between groups. Crude mortality rate at follow-up was almost twice as high among patient with pre-DM and DM as compared with patients with no DM (10.6% vs. 5.4%, respectively, p=0.01). Nevertheless, after multivariable logistic COX regression model for mortality rate using HbA1c < 5.7 gr% as a reference group, we found that pre-DM was associated with the higher mortality rate as compared with DM, although it did not reach statistically significance (HR=1.77; 95% CI: 0.9-3.5, p=0.09 vs. HR=1.3; 95% CI: 0.6-2.8, p=0.4, respectively), Figure 1.

Conclusion: HbA1c level of >5.7 g% is associated with a worse prognosis in patients admitted to ICCU. Moreover, pre-DM patients have probably the highest risk for mortality following admission in the ICCU.