Worse disease burden found for EGPA patients with MPO-ANCAs
Self-reactive antibodies tied to poorer physical life quality in Korean study
A greater disease burden and poorer physical quality of life were found for people with eosinophilic granulomatosis with polyangiitis (EGPA) who test positive for self-reactive anti-neutrophil cytoplasmic antibodies (ANCAs) against the myeloperoxidase (MPO) protein compared with EGPA patients who don’t have such autoantibodies.
Those are the findings of a new study from Korea involving more than 50 people with EGPA — the rarest type of ANCA-associated vasculitis (AAV) — that used updated criteria recently validated for research into this form of the disease.
The research team classified the patients using the 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR) criteria. The team found a worse disease burden among the group with anti-MPO ANCAs, as well as a lower physical quality of life.
The results also showed higher levels of inflammation markers and a greater frequency of generalized symptoms among individuals with MPO-ANCA positivity. In contrast, disease-specific symptoms occurred at similar rates, the data showed.
“By applying the updated 2022 ACR/EULAR classification criteria to a real-world [group of patients], our study offers new perspectives on the clinical burden of MPO-ANCA-positive EGPA and underscores the need for enhanced surveillance of this subgroup of patients,” the researchers wrote. The team noted that the individuals with MPO-ANCAs had “elevated markers of systemic [bodywide] inflammation.”
The study, “Impact of Early MPO-ANCA Positivity on Unique Clinical Features in Korean Patients with EGPA: A Single-Centre Cohort Study,” was published in the journal Medicina.
Like other types of AAV, EGPA is marked by inflammation of small blood vessels. But in this rare type, inflammation is linked to late-onset asthma and clusters of eosinophils, a type of immune cell. EGPA patients have a wide array of disease symptoms, most commonly affecting the respiratory system.
About 40% of EGPA patients are positive for ANCAs, the self-targeting antibodies that cause most AAV cases, with MPO-ANCAs being the most common ones.
Investigating the disease burden experienced by EGPA patients
Previous studies suggested that EGPA patients positive for ANCAs may manifest the disease in different ways. However, it was unclear if this applies under the latest 2022 ACR/EULAR classification criteria: These measures do not consider the presence of MPO-ANCA, but associate negative points to testing positive for these ANCAs, or ANCAs against the proteinase 3 protein, the other common type of AAV-driving ANCAs.
“The omission of MPO-ANCA from the classification criteria raises important questions regarding its diagnostic relevance and potential utility in predicting outcomes in clinical practice,” the researchers wrote.
To learn more, the team retrospectively reviewed the medical records of 57 adults with EGPA based on the 2022 ACR/EULAR classification criteria and who tested negative for PR3-ANCAs.
All of the patients — 38 women and 19 men — were followed at a single Korean hospital. Their median age was 53. A total of 25 (43.9%) tested positive for MPO-ANCAs, while 32 patients tested negative (56.1%).
The review found that people positive for MPO-ANCAs had more severe EGPA than those without such antibodies, as reflected by significantly higher values on the validated Five-Factor Scores. The MPO-ANCA group also had significantly lower scores on the Short Form 36 Physical Component Summary, indicating poorer physical quality of life.
Lab tests showed that MPO-ANCA-positive patients had higher erythrocyte sedimentation rates, a common marker of body-wide inflammation.
Nonspecific EGPA symptoms nearly 6 times more likely with MPO-ANCAs
Those with MPO-ANCAs were also significantly more likely, by nearly six times, to experience nonspecific symptoms — such as fever, malaise, and muscle and joint pain — compared with MPO-ANCA-negative patients (54% vs. 9.4%).
Interestingly, there were no significant group differences in terms of the frequency of symptoms related to blood vessel inflammation or high eosinophil levels, the researchers noted. This indicates that MPO-ANCA status does not alter the main disease features of EGPA.
These findings suggest that MPO-ANCA positivity in EGPA may be more closely linked to overall disease severity and quality of life than to the distinctions between [blood vessel] and eosinophilic manifestations or prognosis.
During a median follow-up of 59.6 months, or nearly five years, MPO-ANCA-positive and -negative patients had similar outcomes. Specifically, there were no significant differences in overall survival, relapse-free survival, kidney failure, stroke, or heart attack rates between the groups.
The team wrote that “further studies are warranted to better delineate the clinical and biological implications of MPO-ANCA status in EGPA.”
But overall, the researchers wrote that “these findings suggest that MPO-ANCA positivity in EGPA may be more closely linked to overall disease severity and quality of life than to the distinctions between [blood vessel] and eosinophilic manifestations or prognosis.”
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