Persistent Blood in Urine May Be Sign of Kidney Disease Returning, Study Finds
Persistent findings of blood in the urine may predict the likelihood of kidney disease returning in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, a study reports.
And it underscores the role that a simple test — urinalysis — can play in predicting a patient’s risk.
“The findings of this study highlight the value of the urinalysis, an inexpensive, noninvasive, and likely underappreciated biomarker for assessment of disease course in AAV,” the researchers wrote in their study.
Current treatment can induce remission in 70 to 90 percent of patients with ANCA-associated vasculitis (AAV). However, up to half of these patients will eventually see their disease return. Being able to better distinguish those most at risk of relapse could change how their disease is managed and, possibly, the risk of such relapses.
Patients in remission can still show signs of kidney disease, including persistent hematuria (blood cells in urine) and proteinuria (high protein levels in urine). But the real relevance of these symptoms in terms of patient outcomes is still unclear.
Researchers at the University of Pennsylvania reviewed clinical data on 149 patients who participated in the RAVE (NCT00104299) and the WGET (NCT00005007) clinical trials. The Phase 2/3 studies were designed to assess Rituxan (rituximab) and Enbrel (etanercept), respectively, for their ability to induce remission in AAV patients.
All had active kidney involvement and hematuria at baseline. Six months after treatment, 42 percent of these patients had persistent hematuria and 43 percent had persistent proteinuria.
Patients with and without persistent hematuria did not show any difference in relapse rates. But more patients with persistent hematuria experienced renal, or kidney, relapses — 22 percent versus 5 percent, the team found.
This translated in a four-fold higher risk of renal relapse among those with persistent hematuria after six months of treatment in the studies
Researchers also found that the longer a patient had hematuria, the greater was the risk of a return of kidney disease. For each additional month of hematuria, the rate of renal relapse increased by 8 percent.
In contrast, persistent proteinuria was not associated with renal relapse. Showing evidence of both proteinuria and hematuria also did not changed this risk, compared to hematuria alone.
“An increase in the level of hematuria was associated with the risk of short-term renal relapse (within 6 months). Therefore, persistent microscopic hematuria is an important component in the overall relapse risk assessment in patients with AAV,” the researchers wrote.
While the team believes that better biomarkers are still needed, a “greater understanding of existing urinary biomarkers may help refine the use of immunosuppressive therapies, predict relapse, and improve outcomes for patients with AAV,” the study concludes.