The effect of serum uric acid levels on the long-term prognosis of patients with non-ST-elevation myocardial infarction

Background: Cardiovascular diseases (CVD) are the leading cause of death worldwide. Many studies have reported an association between serum uric acid (sUA) and CVD, and its role as a risk marker for mortality.

Objectives: To assess the relationship between sUA levels and the long-term prognosis of patients with non-ST-elevation myocardial infarction (NSTEMI).

Material and methods: The study was conducted at the Clinical Hospital of Białystok (Poland). Based on medical records, 9328 patients were hospitalized between 2011 and 2013, of which 726 had NSTEMI. The exclusion criteria were: any diagnosed neoplasms and estimated glomerular filtration rate (eGFR) <15 mL/min. The average observation time was 2324 days.

Results: A total of 549 patients were qualified for the analysis; men were in the majority (69.03%, n = 379), and the mean age was 68.42 years (standard deviation (SD) = 11.66). The sUA norm was exceeded in 137 of the patients (24.95%). Hyperuricemia is more likely to occur in women (risk ratio (RR) = 1.52, 95% confidence interval (95% CI) = 1.016-2.288, p = 0.042), in patients with chronic kidney disease (CKD) (RR = 3.452, 95% CI = 2.432-4.854, p < 0.001) and in patients with higher body mass index (BMI)s (RR = 1.048, 95% CI = 1.008-1.090, p = 0.018). In the whole study group, during the study, 178 of the patients died (32.41.9%), more often those with hyperuricemia: (60/137 patients (43.8%)) compared to patients with normal sUA values (118/412 values (28.64%)); p < 0.001). There was a significant correlation between an increase in sUA levels and an increase in mortality (p < 0.001). Independent risk factors of death were age (RR = 1.086, 95% CI = 1.065-1.108, p < 0.001), sUA (RR = 1.245, 95% CI = 1.131-1.370, p = 0.041), ejection fraction (EF) (RR = 0.928, 95% CI = 0.910-0.946, p < 0.001) and hemoglobin concentration (RR = 0.685, 95% CI = 0.611-0.768, p < 0.001).

Conclusions: Serum UA concentration is an independent risk factor of long-term mortality in patients who have undergone NSTEMI, and is associated with higher in-hospital death rates. Secondary prevention after NSTEMI should entail management of the patients' sUA levels.