Hyperuricemia and long-term survival in patients with chronic kidney disease undergoing hemodialysis

Uric acid (UA), a breakdown product of purines, has been associated with mortality in different populations. Less is known about associations between hyperuricemia and mortality in chronic kidney disease (CKD) patients, later undergoing hemodialysis (HD), during a long observation period. The aim of this study was to determine the impact of elevated UA levels on long-term (19.5 years) survival of CKD patients.

120 CKD patients (49 female, 71 male) enrolled in our study were observed from their first visit at the patients' nephrology outpatient clinic (NOC). All patients later started HD and were followed until their death or January 1, 2016. UA was measured regularly from venous sampling during NOC visits and HD sessions. Patients with mean UA below 420 µmol/L were defined as normouricemic, patients with mean UA above 420 µmol/L as hyperuricemic. No patients were treated for hyperuricemia. Survival rates were analyzed using Kaplan-Meier survival curves. Cox regression model was used to assess the influence of UA, age, arterial hypertension, diabetes mellitus, total cholesterol, triglycerides, smoking, and body mass index on the survival of our patients.

Mean UA was 383.6 ± 83, range 220 to 710 µmol/L. 86 (71.7%) patients were normouricemic, and 34 (28.3%) hyperuricemic. 43 (50.0%) normouricemic and 28 (82.4%) hyperuricemic patients died. Kaplan-Meier survival analysis showed the risk of death to be higher for hyperuricemic patients (log-rank test; p < 0.0001). With Cox multivariable regression model, the mean UA still remained a predictor of mortality in our patients (p < 0.0001).

The results indicate an association between UA and long-term survival of CKD patients and show that hyperuricemia was directly associated with higher mortality among our patients.
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