Title:
Serum uric acid as a predictor of mortality and future exacerbations of COPD.

Abstract:
Serum uric acid is increased in respiratory disease, especially in the presence of hypoxia and systemic inflammation. We evaluated serum uric acid as a biomarker for prediction of mortality and future acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Serum uric acid was measured in 314 eligible consecutive patients on admission for AECOPD. Patients were evaluated monthly for 1 year. Uric acid levels were higher in patients with more severe airflow limitation and in those experiencing frequent exacerbations. High uric acid levels (≥6.9 mg·dL(-1)) were an independent predictor of 30-day mortality in multivariate Cox regression analysis (HR 1.317, 95% CI 1.011-1.736; p=0.044), but not of 1-year mortality. Patients with high serum uric acid required more prolonged hospitalisation, and more often needed noninvasive ventilation and admission to the intensive care unit within 30 days. In addition, high uric acid levels were associated with increased risk and hospitalisation for AECOPD in 1 year in multivariate Poisson regression analysis (incidence rate ratio 1.184 (95% CI 1.125-1.246) and 1.190 (95% CI 1.105-1.282), respectively; both p<0.001). Serum uric acid is associated with increased 30-day mortality and risk for AECOPD and hospitalisations in 1-year follow-up. This low-cost biomarker may be useful in the identification of high-risk chronic obstructive pulmonary disease patients that could benefit from intensive management.