Proteinuria Is a Determinant of Quality of Life in Diabetic Nephropathy: Modeling Lagged Effects with Path Analysis

Abstract

Background: Diabetic nephropathy with overt proteinuria often progresses relentlessly to end-stage renal disease (ESRD). Material and Methods: To answer the question whether it is impaired glomerular filtration rate (GFR) or its precursor proteinuria which is more related with multiple domains of health-related quality of life (HRQOL), we measured GFR and proteinuria in 44 patients with type 2 diabetes and overt nephropathy and repeated the measurements after 4 months. 38 patients with ESRD due to diabetic nephropathy served as a control group. We used path analysis to examine the association of baseline proteinuria and GFR with baseline and subsequent HRQOL scales. Results: Compared to patients with ESRD, patients with non-dialysis CKD had Kidney Disease Burden (KDB) that was, on a scale from 0 to 100, 19.8 better (95% CI 6.9–32.8) (p = 0.003). Mental component score (MCS) did not differ and physical component score (PCS) was worse in non-dialysis CKD patients by 8.5 (p < 0.001). Proteinuria at baseline was a predictor of PCS, MCS and KDB score at 4 months, suggesting a lagged effect of proteinuria on HRQOL after controlling for the autoregressive effects. GFR was not shown to have a significant impact on HRQOL. One log unit increase in proteinuria was associated with 3.8 (p = 0.011) fall in PCS, 3.3 (p = 0.043) fall in MCS and 10.6 (p = 0.006) fall in KDB. Conclusion: In patients with advanced diabetic nephropathy, we found that proteinuria has a lagged and profound effect on multiple domains of HRQOL.