New study points to racial differences in AAV age and kidney severity
Black patients were diagnosed younger than white patients
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Black people with ANCA-associated vasculitis (AAV) were diagnosed at a younger age than white people and tended to show more signs of kidney disease severity, according to a study in the U.S.
“These findings suggest that [variability] in disease presentation within the spectrum of AAV highlights the importance of examining severity at presentation alongside demographic characteristics,” the researchers wrote.
The study, “Racial Differences in Age at Diagnosis and Renal Manifestations of Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis: Insights From a Multi-institutional Electronic Health Record Retrospective Cohort,” was published in Cureus.
Kidney disease can drive AAV outcomes
AAV is a group of diseases typically caused by self-reactive antibodies, called ANCAs, which abnormally activate neutrophils, a type of immune cell. This results in inflammation and damage to small blood vessels. Symptoms vary depending on where blood vessel damage occurs, but AAV commonly causes problems in the kidneys, lungs, and upper airways.
“Severity of [kidney] disease at presentation, including reduced kidney function … and dialysis dependence, is among the strongest predictors of mortality and progression to [kidney failure], even in the modern treatment era,” the researchers wrote.
Previous research suggests that AAV is more commonly reported in white populations, with a lower prevalence in Black populations. However, it is not known “whether differences exist in disease recognition, timing of diagnosis, or severity at presentation across racial groups,” the researchers wrote.
To learn more, a team of researchers retrospectively analyzed data from Epic Cosmos, a database of electronic medical records that aggregates patients’ data from Epic health systems across the U.S.
A total of 789 adults with AAV, 84.8% white and 8.2% Black or African American, were identified and included in the analysis.
Black patients diagnosed at younger age
Black patients were more frequently women (66.2% vs. 56.4%) and significantly younger at diagnosis than white patients, with a mean age of 55 vs. 64 years. Notably, previous studies have suggested that a younger age at diagnosis “does not necessarily reflect milder disease or more favorable outcomes,” the researchers wrote. It may instead “be associated with prolonged exposure to disease activity, immunosuppressive therapy, and treatment-related toxicity, all of which contribute to long-term [illness].”
Data on the type of ANCAs were incomplete in the database. Results of testing for antibodies against the proteinase 3 protein were available for about 20% of patients in both groups. This common type of ANCA was detected in 5.7% of white patients and 7.7% of Black patients.
Testing for the other common type of ANCA, targeting the myeloperoxidase protein, was documented in less than 3% of the participants from either group.
Some markers of kidney involvement were similar in both groups at presentation, but Black patients more frequently had blood in the urine (38.5% vs. 28.1%) and to need dialysis (21.5% vs. 13.3%) — a procedure to filter waste and excess fluid from the blood when the kidneys can no longer perform this role.
These features are linked to worse kidney outcomes, suggesting that Black patients may have more advanced kidney disease when first diagnosed. However, these differences did not reach statistical significance, meaning they could be due to chance.
In addition, 20% of patients in both groups had excess protein in the urine, a marker of kidney damage, but white patients more frequently had abnormal levels of creatinine, another sign of kidney damage (63.1% vs. 53.8%).
Kidney markers differed by race
Regarding other simultaneous conditions, diabetes was reported in 40.4% of white patients and 44.6% of Black patients.
“Differences in age at diagnosis and [kidney] disease severity were observed between Black and White adults with ANCA-associated vasculitis,” the researchers wrote. “These findings highlight that underrepresentation in rare disease [studies] may coexist with markers of substantial disease burden at presentation.”
Still, the researchers noted that limitations in available data, including incomplete information on ANCA testing and AAV types, made it harder to fully understand all drivers of the observed race-specific differences.
Future studies, including those with long-term outcomes and more complete clinical data, are needed to clarify the mechanisms underlying these race-specific differences, they noted. Such studies may help “inform earlier, risk-informed, and equitable approaches to AAV care,” the researchers wrote.
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