Uric Acid-to-Albumin Ratio as a Complementary Biomarker for In-Hospital Risk Stratification in Patients with Pulmonary Hypertension: A Retrospective Cohort Study

Background: Oxidative stress is pivotal in pulmonary hypertension. The uric acid-to-albumin ratio (UAR) is a readily available composite biomarker reflecting oxidative stress, inflammation and nutritional status. However, its clinical value for short-term risk stratification in PH remains unclear. Objective: This study aimed to evaluate the association of UAR with in-hospital mortality, clinically recorded PH severity grades, and selected cardiac structural and functional indicators in hospitalized patients with PH. Methods: This single-center retrospective cohort study included 8763 PH patients. Patients were stratified by UAR quartiles. Ordinal logistic regression, multivariable logistic regression, and linear regression were used to assess associations of UAR with clinically recorded PH severity grades, in-hospital mortality, left ventricular ejection fraction (LVEF), and right ventricular internal diameter (RVID). Restricted cubic spline analyses, subgroup analyses, receiver operating characteristic curve analyses, and incremental prediction analyses using C-statistics, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) were also performed. Results: In-hospital mortality increased stepwise across UAR quartiles (0.5% vs. 1.0% vs. 1.8% vs. 2.8%, p < 0.001). In the fully adjusted model, each 1-unit increase in UAR was associated with higher odds of a more severe clinically recorded PH grade (OR = 1.11, 95% CI: 1.09–1.13, p < 0.001) and higher odds of in-hospital mortality (OR = 1.09, 95% CI: 1.04–1.14, p < 0.001). Higher UAR was also associated with lower LVEF (β = −0.53, 95% CI: −0.58 to −0.47, p < 0.001) and greater RVID (β = 0.18, 95% CI: 0.15–0.22, p < 0.001). Adding UAR to a model containing routinely available clinical, laboratory, and echocardiographic variables improved the C-statistic from 0.6922 to 0.7230, with significant improvements in NRI and IDI. Conclusions: UAR was independently associated with in-hospital mortality, clinically recorded PH severity, LVEF, and RVID, and provided incremental prognostic information. UAR may serve as a low-cost, routinely available, complementary biomarker for short-term in-hospital risk stratification in patients with PH.