(48) Outcome Predictability of Serum Uric Acid Among Non-Dialyzed Chronic Kidney Disease Patients – A Hospital Based Prospective Cohort Study

Publication Number: 1093

Background: Hyperuricemia has inimical effects on vascular health and renal histological integrity, but serum uric acid designated as a potential predictor of chronic kidney disease (CKD) progression and mortality remains contentious.

Objectives: This study aims to investigate the prognostic importance of serum uric acid (UA), prevalence, and determinants of hyperuricemia in pre-dialysis chronic kidney disease patients with or without diabetes.

Methods: Study design, Setting, & Population: This study utilized a longitudinal prospective cohort study design. A sample of 360 non-dialysis CKD patients (eGFR 90-15ml/min/1.73m2) (210 male, & 150 female) aged 53.7 ± 13.9 years were enrolled at a special nephro clinic of a tertiary care public teaching hospital.
Follow up: Over a period of more than 12 months.
Materials: Uric acid and serum creatinine and other lab parameters were measured at each patient visit. Serum uric acid 7mg/dL in males and 6mg/dL in females was taken as an indication of hyperuricemia. To increase the robustness of results, serum uric acid was categorized into four quartiles; Q1≤6.1 mg/dL, Q2=6.2-7.4 mg/dL, Q3=7.5-8.7 mg/dL & Q4≥8.8 mg/dL.
Main outcome measures: A composite renal outcome (commencement of dialysis or transplantation, doubling of serum creatinine levels from baseline, or a 50% decline in the eGFR) and death.
Statistical analysis: Survival rates were analyzed using Kaplan-Meier survival curves. Cox regression model was used to assess the relationship between serum uric acid and composite renal outcome.

Results: After a median follow-up of 14±4.24 months. A total of 50(13.9%) of patients died and 135 (37.6%) patients experienced composite end points. The composite end points occurred in 37 in quartile 1, 34 in quartile 2, 38 in quartile 3, and 26 in quartile 4. In cox proportional hazard model, the highest quartile (Q4) had shown increased hazards for mortality (hazard ratio [HR], 1.110; 95% confidence interval [CI], 0.47–2.56; p = 0.812) in reference to the lower quartile (Q1). Patients in quartile 4 had reported significantly higher HR of composite end points in reference to quartile 1 (HR, 0.86; 95% CI, 0.54-1.37). CKD patients with diabetes exhibit poor renal survival rates as compared to non-diabetic CKD patients. The prevalence of hyperuricemia in non-dialysis chronic kidney disease patients was found to be 63.4%. The patients with poor nutritional status, decreased residual renal function and male patients were severely affected with hyperuricemia. Serum sodium, CKD stages, gender, urea, eGFR and HDL had shown significant association with hyperuricemia among chronic kidney disease patients [p= < 0.05].

Conclusions: A very high prevalence (6 out of 10 patients) of hyperuricemia with male predominance was observed in chronic kidney disease patients before they underwent dialysis. Hyperuricemia patients were likely adults, malnourished, and in advanced CKD stages. The higher serum uric acid quartiles were associated with increased hazards for mortality. However, our findings were not able to explain the independent association of serum uric acid quartiles with the renal outcomes. The survival plots were attenuated for serum uric acid quartiles and renal outcomes when stratified with diabetes, abnormal blood urea nitrogen levels, and male gender.