Effect of proteinuria on the rapid kidney function decline in chronic kidney disease depends on the underlying disease: A post hoc analysis of the BRIGHTEN study.

AIMS: It is unclear whether the effect of proteinuria on rapid kidney function decline is equivalent among diabetic kidney disease (DKD), non-DKD with diabetes (NDKD + DM), and nephrosclerosis without diabetes (NS-DM), particularly in advanced chronic kidney disease patients.

METHODS: In total, 1038 chronic kidney disease patients who participated in the BRIGHTEN study were included in the present study. A linear mixed effect model was applied to estimate the annual estimated glomerular filtration rate decline in each disease group.

RESULTS: The prevalence of rapid decliners (rapid kidney function decline, defined as an eGFR loss of > 5 mL/min/1.73 m2 /year) in the DKD group (44.6 %) was significantly higher compared with the NDKD + DM (27.9 %) and NS-DM (27.0 %) groups. By contrast, the prevalence of rapid decliners in different urine total protein to creatinine ratio (UPCR) categories (<0.5, 0.5 to < 1.0, 1.0 to < 3.5, and ≥ 3.5 g/g) were equivalent between the DKD and NS-DM groups. Moreover, the prevalence of a UPCR < 1.0 g/g in rapid decliners of the NS-DM group was more than double than in those of the DKD and NDKD + DM groups.

CONCLUSIONS: The risk of rapid kidney function decline in NS-DM patients with low levels of proteinuria may be greater than initially predicted.