Association of urinary injury biomarkers with mortality and cardiovascular events

Kidney damage is a common sequela of several chronic pathologic conditions. Whether biomarkers of kidney damage are prognostic for more severe outcomes is unknown. We measured three urinary biomarkers (kidney injury molecule-1 [KIM-1], IL-18, and albumin) in 3010 individuals enrolled in the Health, Aging and Body Composition (Health ABC) study and used Cox proportional hazards models to investigate the associations of urinary KIM-1/creatinine (cr), IL-18/cr, and albumin/cr (ACR) with all-cause mortality and cardiovascular disease (CVD). Multivariable models adjusted for demographics, traditional CVD risk factors, and eGFR. Mean age of participants was 74 years, 49% of participants were men, and 41% of participants were black. During the median 12.4 years of follow-up, 1450 deaths and 797 CVD outcomes occurred. Compared with the lowest quartile, successive quartiles had the following adjusted hazard ratios (HRs; 95% confidence intervals [95% CIs]) for mortality: KIM-1/cr: (1.21; 1.03 to 1.41), (1.13; 0.96 to 1.34), and (1.28; 1.08 to 1.52); IL-18/cr: (1.02; 0.88 to 1.19), (1.16; 0.99 to 1.35), and (1.06; 0.90 to 1.25); ACR: (1.08; 0.91 to 1.27), (1.24; 1.06 to 1.46), and (1.63; 1.39 to 1.91). In similar analyses, only ACR quartiles associated with CVD: (1.19; 0.95 to 1.48), (1.35; 1.08 to 1.67), and (1.54; 1.24 to 1.91). Urinary KIM-1 had a modest association with all-cause mortality but did not associate with CVD, and urinary IL-18 did not associate with either outcome. In contrast, albuminuria strongly associated with all-cause mortality and CVD. Future studies should evaluate reasons for these differences in the prognostic importance of individual kidney injury markers.