Poor kidney function, older age linked to higher death risk in AAV
Study highlights importance of initial kidney assessment in predicting outcomes
Written by |
Older age and poorer kidney function at diagnosis are each linked to a higher risk of death among people with ANCA-associated vasculitis (AAV), a real-world study in Turkey found.
These two factors, as well as lung involvement and heart involvement, were found to be independent predictors of death within the first year after an AAV diagnosis, while worse kidney function at diagnosis also predicted progression to kidney failure.
Among 248 patients, nearly three-quarters had kidney involvement, and about one-third of them progressed to kidney failure, data showed.
The study, “Mortality and kidney outcomes in ANCA-associated vasculitis: determinants from a real-world cohort,” was published in the journal Clinical and Experimental Medicine.
‘Risk of mortality remains elevated’ despite treatment advances
AAV is an autoimmune disease marked by inflammation in small blood vessels, which can damage tissues and vital organs, including the kidneys.
“Approximately 8% of patients progress to [kidney failure] within six months, and approximately [14% to 20%] develop it over extended follow-up periods,” the researchers wrote.
Most AAV cases are caused by self-reactive antibodies called ANCAs that usually target myeloperoxidase (MPO) or proteinase 3 (PR3), two proteins found in immune cells called neutrophils.
The disease can be classified into three main types: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Renal-limited vasculitis, in which disease is confined to the kidneys, may be considered a fourth type.
While the implementation of immunosuppressive treatments has prolonged the lives of people with AAV, “the risk of mortality remains elevated,” the researchers wrote, adding that kidney involvement has been shown to be an important predictor of worse AAV outcomes.
However, real-world data integrating kidney outcomes and mortality in people with AAV remain limited.
In this study, researchers retrospectively analyzed data from AAV patients treated at two tertiary referral centers in Turkey between 1999 and 2020. They aimed to identify factors associated with progression to kidney failure, death within the first year, and overall mortality.
Most patients had kidney involvement at diagnosis
The analysis included 248 patients, 143 with GPA, 46 with MPA, 25 with EGPA, and 34 with renal-limited vasculitis. They had a mean age of 51.6 and 53.6% were men. Among the 190 participants (81%) who tested positive for ANCAs, 58% had antibodies against PR3, while the remaining 42% had anti-MPO ANCAs.
At diagnosis, 73% of patients had documented kidney involvement. During a median follow-up period of 60 months (about five years), 58 patients developed kidney failure, representing 24% of all patients and 33% of those with kidney involvement.
Among patients with kidney involvement, those who progressed to kidney failure had significantly higher blood creatinine levels, a marker of poor kidney function, at diagnosis than those who didn’t (median 8 mg/dL vs. 3.2 mg/dL). Those who progressed were also significantly more likely to have excess protein in urine (100% vs. 90%) and blood in urine (96% vs. 77%), two other signs of kidney damage.
They were also significantly more likely to require acute hemodialysis (75% vs. 28%) and plasmapheresis (55% vs. 28%). Hemodialysis filters waste and excess fluid from the blood when the kidneys are not working adequately, while plasmapheresis is a blood-cleaning procedure that can remove ANCAs. ANCA type did not differ significantly between patients who did and did not progress to kidney failure.
Data regarding kidney survival, or the time patients lived without kidney failure requiring hemodialysis or a transplant, were available for 169 patients, including 56 who progressed to kidney failure. Estimated kidney survival was 75.9% at one year and 69.6% at five years.
Patients with kidney involvement showed lower survival rates
A multivariate statistical analysis, which accounts for several different variables, showed that each 1 mg/dL increase in blood levels of creatinine, a marker of reduced kidney function, at diagnosis was significantly associated with a 15% higher risk of progressing to kidney failure. Also, each additional year of age at diagnosis was significantly associated with a 3% higher risk.
When the researchers also accounted for the possibility that patients could die before developing kidney failure, higher creatinine at diagnosis remained a significant predictor of kidney failure, but age did not. In a separate analysis, patients who needed hemodialysis at diagnosis were more than three times more likely to develop kidney failure.
These findings highlight the importance of [initial] clinical and [kidney] assessment for mortality and kidney outcome stratification in AAV.
Overall survival rate was 90.2% at one year and 81.9% at five years. Compared with patients without kidney involvement at diagnosis, those with kidney involvement showed significantly lower survival rates at one year (87% vs. 98.5%) and five years (77.3% vs. 93.9%).
Multivariate statistical analyses showed that age older than 65 years and lower estimated glomerular filtration rate (eGFR) — a measure of how well the kidneys filter waste from the blood — at diagnosis were independently associated with overall mortality.
Regarding mortality during the first year, being older than 65, lower eGFR, lung involvement, and heart involvement were each independently associated with a higher risk.
“These findings highlight the importance of [initial] clinical and [kidney] assessment for mortality and kidney outcome stratification in AAV,” the researchers wrote.
Leave a comment
Fill in the required fields to post. Your email address will not be published.