Joint effects of uric acid and lymphocyte count on adverse outcomes in elderly patients with rheumatic heart disease undergoing valve replacement surgery

Abstract

Objectives: Increased uric acid and decreased lymphocyte count are common in elderly patients or those with heart failure, which were prognostic markers. We aimed to investigate the joint effect of uric acid and lymphocyte count for risk stratification in elderly patients with rheumatic heart disease undergoing valve replacement surgery.

Methods: Uric acid to lymphocyte ratio was calculated as serum uric acid (mg/dL)/lymphocyte count (×10⁹/L). Univariate and multivariate analyses were performed to investigate the association of uric acid to lymphocyte ratio, with adverse events in 949 elderly patients with rheumatic heart disease undergoing valve replacement surgery. For clinical use, the uric acid to lymphocyte ratio was classified into 3 groups by the tertile, and a cutoff was also selected according to the receiver operator characteristic curve.

Results: Uric acid to lymphocyte ratio produced relatively higher predictive value (area under the curve, 0.703; 95% confidence interval [CI], 0.630-0.776; P < .001) than uric acid or lymphocyte count for in-hospital mortality, and the optimal cutoff was 3.7 (sensitivity, 82.1%; specificity, 52.4%). Uric acid to lymphocyte ratio was an independent predictor for in-hospital (adjusted odds ratio, 1.17; 95% CI, 1.07-1.29; P = .001) and 1-year mortality (adjusted hazard ratio, 1.13; 95% CI, 1.03-1.25; P = .010). The in-hospital mortality increased from the lowest to the highest uric acid to lymphocyte ratio tertile (P < .001) and significantly higher in patients with uric acid to lymphocyte ratio greater than 3.7 (P < .001). The cumulative 1-year postoperative mortality risk was significantly higher in patients with uric acid to lymphocyte ratio greater than 3.7 (P < .001) or upper uric acid to lymphocyte ratio tertile (P < .001).

Conclusions: Uric acid to lymphocyte ratio, combining the effect of uric acid and lymphocyte count, produced more prognostic value in elderly patients with rheumatic heart disease undergoing valve replacement surgery, which could be considered as a preoperative risk-stratified method.

Keywords: lymphocyte; outcomes; rheumatic heart disease; uric acid; valve replacement surgery.