Optimal Threshold of Urinary Albumin-to-Creatinine Ratio (UACR) for Predicting Long-Term Cardiovascular and Noncardiovascular Mortality

Background: Traditional cutoff values of urinary albumin-to-creatinine ratio (UACR) for predicting mortality have recently been challenged. In this study, we investigated the optimal threshold of UACR for predicting long-term cardiovascular and noncardiovascular mortality in the general population. Methods: Data for 25,302 adults were extracted from the National Health and Nutrition Examination Survey (2005–2014), with mortality status obtained by data matching with death certificates in the National Death Index until December 31, 2015. Receiver operating characteristic (ROC) curve analysis was performed to assess the predictive value of UACR for cardiovascular and noncardiovascular mortality. A Cox regression model was established to examine the association between UACR and cardiovascular and noncardiovascular mortality. X-tile was used to estimate the optimal cutoff of UACR. Results: The UACR had acceptable predictive value for both cardiovascular (area under the ROC curve [AUC]=0.769, 95% confidence interval [CI]: 0.711–0.828) and noncardiovascular (AUC=0.722, 95% CI: 0.681–0.764) mortality. Excellent linearity was observed between log-transformed UACR and cardiovascular and noncardiovascular mortality. The optimal cutoff values were 16 and 30 mg/g for predicting long-term cardiovascular and noncardiovascular mortality, respectively. The adjusted hazard ratios of cardiovascular and noncardiovascular mortality for the high-risk group were 2.55 (95% CI: 2.03–3.22, P<0.001) and 1.94 (95% CI: 1.72–2.18, P<0.001), respectively. Conclusions: Compared to the traditional cutoff value (30 mg/g), a UACR cutoff of 16 mg/g may be more sensitive for identifying patients at high risk for cardiovascular mortality in the general population.