#553 Renal tubular damage is an independent risk factor for all-cause and cardiovascular mortality in a community-based population: the Takahata Study

Background and Aims Renal tubulointerstitial damage is a risk for renal failure. However, the association between renal tubulointerstitial damage and all-cause and cardiovascular mortality in the general population remains unclear. In this prospective cohort study, we examined this point using urinary β2-microglobulin/creatinine ratio (UBCR) as a marker of renal tubulointerstitial damage in the general Japanese population. Methods We examined the association between UBCR values at entry and all-cause and cardiovascular mortality during the follow-up period (median 9.2 years) in 3 427 residents (mean age 62.5 years, 45.1% male, mean eGFR 81.6 ml/min/1.73 m², ≥1+ protein 4.4%) of Takahata Town in Japan. Results Study participants were divided into two groups (low < 300 μg/gCre, high ≥300 μg/gCre) based on UBCR at entry. Kaplan-Meier analysis showed a significantly higher incidence of all-cause and cardiovascular mortality in the high UBCR group (Log-rank P < 0.01). A multivariate Cox proportional hazards analysis adjusted for age, sex, eGFR, urinary protein level, comorbidities, smoking status, and other background factors showed a hazard ratio of 1.47 (95% CI 1.09-2.00, P = 0.01) for all-cause mortality and a hazard ratio of 1.82 (95% CI 1.06-3.12, P = 0.03) for cardiovascular death in the high-UBCR group. The addition of high UBCR to conventional risk factors, including eGFR and urinary protein level, significantly improved the net reclassification improvement (NRI) for all-cause and cardiovascular mortality (P < 0.01). Conclusions UBCR, a marker of tubulointerstitial damage, was identified as a risk factor for all-cause and cardiovascular mortality in the general population independent of eGFR and urinary protein levels.