Disease severity at MPA onset predicts mortality risk, study reports
Two established scales used to determine risk in newly diagnosed patients
People newly diagnosed with microscopic polyangiitis (MPA) — a type of ANCA-associated vasculitis (AAV) — already considered to be more severe by two established measures are a higher risk of death, a study of patient registry data from Japan reports.
The severity of MPA, one of the three main types of AAV, was measured using the Birmingham Vasculitis Activity Score (BVAS) and/or the European Vasculitis Study Group (EUVAS) categorization system. MPA patients with both a high BVAS scores and a severe EUVAS classification faced a 50% higher risk of mortality four years after an AAV diagnosis.
“These findings underscore the importance of early BVAS assessment and appropriate management to optimize clinical outcomes in patients with MPA,” the researchers wrote.
The study, “Risk prediction model for mortality in microscopic polyangiitis: multicentre REVEAL cohort study,” was published in the journal Arthritis Research & Therapy.
Kidney disease is common among people with microscopic polyangiitis
AAV is a group of autoimmune disorders characterized by self-reactive antibodies called ANCAs that abnormally activate neutrophils, a type of white blood cell that usually fights infections. Such activation causes inflammation and damage to small blood vessels, primarily affecting the kidneys, lungs, and skin.
About 80% MPA patients develop kidney disease, while lung involvement is less common than with other AAV types. It also can be distinguished from the other AAV types by the lack of granulomas, or masses of inflammatory immune cells, at inflammation sites.
Although studies have identified factors associated with MPA outcomes, such as age, kidney involvement, and treatment regimens, “the precise predictors of mortality in patients with MPA remain unclear,” the researchers wrote.
Researchers at institutes largely in Osaka set out to develop prediction models for a mortality risk in MPA patients using data from a multicenter Japanese observational study called the Registry of Vasculitis Patients to Establish the REAL World Evidence (REVEAL).
Among the 194 newly diagnosed MPA patients investigated, 60 (30.9%) died during a follow-up that ranged from about 1.5 to nearly seven years. Half of the deaths were due to infections (50%), and 18.3% to MPA-related blood vessel inflammation. Deaths in the remaining 19 cases (31.7%) were classified as due to other causes.
Because infections were the leading cause of death in MPA patients, “the early detection and treatment of [lung] infections may represent a crucial strategy for enhancing patient prognoses,” the team wrote.
At REVEAL enrollment (baseline), those who died during follow-up were significantly older (median of 76.2 vs. 72.3 years), and smoked significantly more often than other MPA patients.
They also had significantly higher blood levels of C-reactive protein, a marker for inflammation, and significantly lower levels of albumin, an indicator of kidney damage at baseline.
Disease severity, as assessed by BVAS, also was significantly higher at baseline in the patients who died. Findings in other measures predicting disease severity and likely outcomes, namely the EUVAS categorization system and the Five-Factor Score, were similar.
Statistical analysis identified significant associations between all these factors and a higher risk of death.
High BVAS score, severe EUVAS class seen as independent risk factors
After adjusting for age, previously linked with mortality risk in MPA, the analysis identified a higher BVAS scores and a more severe EUVAS classification as independent risk factors for a patient’s death. Of note, a severe EUVAS classification reflects kidney failure.
Further analyses showed that a BVAS cutoff score of 19 most accurately predicted death, with a significantly lower survival rate seen with a BVAS score of 20 or more at baseline than with scores under 20. Likewise, significantly higher mortality rates were observed in those with a severe EUVAS designation.
Researchers then developed a risk prediction model for mortality in MPA patients based on combinations of these two risk factors (BVAS score of 20 or more and a severe EUVAS designation). The mortality rate among patients without either of these risk factors was less than 25%, among those one risk factor it was 25%-50%, and risk was put at 50% or higher in those with both factors.
“The combination of these two poor prognostic factors is useful to predict mortality in patients with MPA,” the researchers wrote.
The number of risk factors also significantly influenced survival over two, four, and six years of follow-up, with patients having both risk factors showing a significantly higher mortality rate.
“Our [model], combining the internationally recognized BVAS and EUVAS categorization systems, demonstrated a high potential for general applicability,” the scientists wrote.
Still, larger studies that follow patients over time and include more diverse MPA patient populations “are necessary to assess [the model’s] robustness and applicability,” they added.