In patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), the presence of proteinuria 6 months following induction therapy and low renal function were significantly associated with an increased risk for chronic kidney disease, according to findings from a retrospective study published in Clinical and Experimental Nephrology.
Among individuals with AAV, systemic organ involvement is common, which develops most often in the kidney. Disease presentations can include such urinary abnormalities as proteinuria and hematuria, and the condition can lead to chronic kidney disease and possible end-stage renal disease.
Recognizing that urinalysis has often been used as a clinical parameter for evaluation of renal outcomes in patients with AAV, the researchers sought to establish the prognostic value of proteinuria monitoring in these individuals. They conducted a retrospective analysis of data from patients diagnosed with AAV with renal involvement, which was confirmed via kidney biopsy, between March 2004 and August 2021 at a single tertiary center in Seoul, South Korea.
Urine-to-protein creatinine ratios and urine dipstick tests were reported at baseline and at 6 months after induction treatment with corticosteroids and immunosuppressants. Proteinuria via urine dipstick results were reported as negative, trace, 1+, 2+, 3+, and 4+. Patients with negative or trace results were considered to have no proteinuria, whereas those with results of 1+ or more were defined as having proteinuria. Hematuria was defined as more than 10 red blood cells per high-power field on microscopy.
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In the current study, the primary outcome was decreased renal function, which was associated with stage 4/5 chronic kidney disease and an estimated glomerular filtration rate (eGFR) of less than 30 mL/min/1.73 m2. Remission was defined as a Birmingham Vasculitis Activity Score (BVAS) of 0 or persistent 1 within 1 year of undergoing induction therapy. In these individuals, a daily corticosteroid dose of 7 mg or less was needed.
Renal relapse was defined as a BVAS of 1 or more, with new or worsening hematuria or declining renal function—that is—a 30% rise in creatinine or a 25% decline in eGFR, based on BVAS.
The study included 77 patients with AAV. At diagnosis, the mean participant age was 64.5±9.4 years. Overall, 42 patients were male and 35 were female. The median duration of follow-up was 36 months (range, 18-79 months). Following the exclusion of 8 patients undergoing dialysis at 6 months, 85.5% (59 of 69) of participants attained remission following induction therapy.
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These individuals were divided into 2 groups at 6 months—29 with proteinuria and 40 without proteinuria. Study results showed no significant difference in rates of relapse or death based on occurrence of proteinuria (P =.304 and .401, respectively). Participants with proteinuria exhibited significantly lower kidney function compared with those without proteinuria (P =.003).
Per multivariate analysis, proteinuria and eGFR values at 6 months were significantly associated with stage 4/5 chronic kidney disease (hazard ratio [HR], 4.613; 95% CI, 1.230-17.298; P =.023 and HR, 0.925; 95% CI, 0.875-0.978; P =.006, respectively).
“These findings suggest that monitoring and follow-up of proteinuria could help predict renal function and optimal management for patients with AAV,” the researchers concluded.
Lee Y-J, Ahn S-M, Oh J-S, et al. Prognostic value of proteinuria monitoring in anti-neutrophil cytoplasmic antibody-associated vasculitis. Clin Exp Nephrol. Published online April 24, 2023. doi:10.1007/s10157-023-02352-y