Trace Urine Albumin and Mortality: Kangbuk Samsung Health Study

BACKGROUND/AIMS: The importance of a trace albumin on the urine dipstick test is not well known and is frequently disregarded in clinical practice. The aim of this study is to investigate the role of trace albuminuria in predicting all-cause mortality in Korean adults. METHODS: In this retrospective cohort study, we analyzed 347,938 Korean adults who underwent urine dipstick test from 2002 to 2012 in a health examination program. The participants were divided into three groups according to dipstick negative, trace (±), and overt (≥1+) albuminuria. The trace group was further stratified by urine specific gravity (SG) and classified as either high (≥1.020) or low (≤1.015) SG. Mortality data was obtained from STATICS KOREA, a Korean federal statistical organization. RESULTS: During a median follow-up period of 5.9 years, 1,855 deaths occurred. Mortality was compared to negative group and adjusted for potential risk factors. Mortality did not increase in the trace group (HR, 1.19; 95% CI, 0.97-1.47; P=0.097), but increased in the overt (HR, 1.69; 95% CI, 1.38-2.07; P< 0.001) albuminuria group. When the trace group was subdivided according to urine SG, mortality did not increase in the high SG (HR, 1.09; 95% CI, 0.86-1.37; P=0.488) group, but increased in the low SG (HR, 1.84; 95% CI, 1.19-2.83; P=0.006) and overt (HR, 1.70; 95% CI, 1.39-2.08; P< 0.001) groups. CONCLUSION: Trace albumin with low SG in urine dipstick test was associated with higher all-cause mortality in Korean adults. We should not neglect the significance of trace albumin and SG when interpreting urinalysis results.