Asymptomatic Pyuria as a Prognostic Biomarker in Autosomal Dominant Polycystic Kidney Disease

Abstract

Background: Autosomal dominant polycystic kidney disease (ADPKD) has phenotypic variability only partially explained by established biomarkers that do not readily assess pathologically important factors of inflammation and kidney fibrosis. We evaluated asymptomatic pyuria, a surrogate marker of inflammation, as a biomarker for disease progression. Methods: We performed a retrospective cohort study of adult patients with ADPKD. Patients were divided into asymptomatic pyuria (AP) and no pyuria (NP) groups. We evaluated the effect of pyuria on kidney function and kidney volume. Longitudinal models evaluating kidney function and kidney volume rate of change with respect to incidences of asymptomatic pyuria were created. Results: There were 687 included patients (347 AP, 340 NP). The AP group had more female (65.1% vs 49.4%). Median age at kidney failure was 86 and 80 years in NP and AP groups, respectively (Log-rank, p=0.49) for patients with Mayo Imaging Class (MIC)1A-1B as compared to 59 and 55 years for patients with MIC1C-1D-1E (Log-rank, p=0.02). Compared to NP group, the rate of kidney function (ml/min/1.73m2/year) decline shifted significantly after detection of asymptomatic pyuria in models including all patients (-1.48, p<0.001), MIC 1A-B patients (-1.79 , p<0.001), MIC 1C-1D-1E patients (-1.18, p<0.001), and PKD1 patients (-1.04, p<0.001). Models evaluating kidney volume rate of growth showed no change after incidence of asymptomatic pyuria as compared to NP group. Conclusions: Asymptomatic pyuria is associated with kidney failure and faster kidney function decline irrespective of the ADPKD gene, cystic burden, and cystic growth. These results support asymptomatic pyuria as an enriching prognostic biomarker for the rate of disease progression.-