Dipstick proteinuria and all-cause mortality among the general population

BackgroundDipstick proteinuria, but not albuminuria, is used for general health screening in Japan. How the results of dipstick proteinuria tests correlate with mortality and, however, is not known.MethodsSubjects were participants of the 2008 Tokutei-Kenshin (Specific Health Check and Guidance program) in six districts in Japan. On the basis of the national database of death certificates from 2008 to 2012, we used a personal identifier in two computer registries to identify participants who might have died. The hazard ratio (95% confidence interval, CI) was calculated by Cox-proportional hazard analysis.ResultsAmong a total of 140,761 subjects, we identified 1641 mortalities that occurred by the end of 2012. The crude mortality rates were 1.1% for subjects who were proteinuria (-), 1.5% for those with proteinuria (+/-), 2.0% for those with proteinuria (1+), 3.5% for those with proteinuria (2+), and 3.7% for those with proteinuria (3+). After adjusting for sex, age, body mass index, estimated glomerular filtration rate, comorbid condition, past history, and lifestyle, the hazard ratio (95% CI) for dipstick proteinuria was 1.262 (1.079-1.467) for those with proteinuria (+/-), 1.437 (1.168-1.748) for those with proteinuria (1+), 2.201 (1.688-2.867) for those with proteinuria (2+), and 2.222 (1.418-3.301) for those with proteinuria (3+) compared with the reference of proteinuria (-).ConclusionDipstick proteinuria is an independent predictor of death among Japanese community-based screening participants.