One-year mortality in elderly adults with non-ST-elevation acute coronary syndrome: effect of diabetic status and admission hyperglycemia

Abstract

Objectives: To determine whether type 2 diabetes mellitus and hyperglycemia on admission should be considered independent predictors of mortality in elderly adults with acute coronary syndrome (ACS).

Design: Prospective cohort study.

Setting: Twenty-three hospitals in Italy.

Participants: Individuals aged 75 and older with non-ST-elevation ACS (NSTEACS) (mean age 82, 47% female) (N = 645).

Measurements: Diabetic status and blood glucose levels were assessed on admission. Hyperglycemia was defined as glucose greater than 140 mg/dL. Multivariable Cox proportional hazard regression was used to assess the potential confounding effect of major covariates on the association between diabetic status, admission glucose, and 1-year mortality.

Results: A history of diabetes mellitus was found in 231 participants (35.8%), whereas 257 (39.8%) had hyperglycemia. Hyperglycemia was found in 171 participants with diabetes mellitus (70%) and 86 (21%) without diabetes mellitus. Participants with diabetes mellitus were significantly (P < .05) more likely to have had prior myocardial infarction and stroke and had lower ejection fraction and blood hemoglobin. Hyperglycemia was associated with lower (P < .05) ejection fraction and estimated glomerular filtration rate (eGFR). Diabetic status and hyperglycemia were associated with greater 1-year mortality according to univariate analysis (54 participants with diabetes mellitus died (23.4%), versus 66 (15.9%) without diabetes mellitus (hazard ratio (HR) = 1.5 95% confidence interval (CI) = 1.0-2.1), and 60 participants with hyperglycemia died (23.3%), versus 60 (15.5%) without hyperglycemia (HR=1.6; 95% CI = 1.1-2.2), but this association was not statistically significant after adjustment for ejection fraction, age, blood hemoglobin, and eGFR.

Conclusion: In elderly adults with NSTEACS, diabetes mellitus and hyperglycemia on admission are associated with higher mortality, mostly because of preexisting cardiovascular and renal damage.

Trial registration: ClinicalTrials.gov NCT00510185.

Keywords: acute coronary syndrome; diabetes mellitus; elderly; hyperglycemia; mortality.