Association of Serum uric acid with Death in the Irish Health System

Background: Hyperuricaemia is common in the general population and emerging evidence suggest strong biological and epidemiological links with several chronic diseases. The aim of this study was to evaluate the relationship of... [ view full abstract ]

Background: Hyperuricaemia is common in the general population and emerging evidence suggest strong biological and epidemiological links with several chronic diseases. The aim of this study was to evaluate the relationship of serum uric acid (SUA) concentrations with mortality in the Irish health system

Methods: We established a retrospective cohort of 128, 014 patients who had a SUA concentration recorded on first entry to the health system between 2005 and 2014. Data were extracted from clinical information systems in the Midwest and Northwest regions and linked with national mortality files. Patients were followed until death, lost to follow-up or December 31^st 2014, which ever occurred first. Serum uric acid was modelled as a continuous variable and in quintile groups (1^st < 233.7, 2^nd 233.7-280, 3^rd 280-326, 4^th 327-386, and 5^th > 386 µmol/L respectively) with mortality. Multivariable models using Cox regression were adjusted for age, sex, location of medical supervision, and 5 clinical indicators of illness.

Results: There were 8,382 deaths overall with an overall crude death rate of 22.9 per 1000 person-years. In multivariable analysis, adjusting for age, sex, location of medical supervision, serum albumin, haemoglobin and estimated glomerular filtration rate (GFR), the adjusted hazard ratio (HR) for each 60 µmol/L increase in SUA with mortality was, 1.04, (95% CI, 1.02-1.06), P< 0.001. However, on further inspection a u-shaped association was observed. The multivariable HR for each increasing quintile of SUA were 1.07 (0.97-1.18), 1.04 (0.94-1.15), 1.00 (referent), 1.07 (0.97-1.18), and 1.17 (1.06-1.28), respectively, with the highest mortality for patients occurring values > 386 µmol/L.

Conclusion: Serum uric acid is independently associated with mortality for patients within the Irish health system. The association is u-shaped with the highest risks for patients with threshold values > 386 µmol/L. Targeting of SUA with ULT may serve to extend patient survival.