The presence or absence of ANCA antibodies appears to influence which organs are affected by eosinophilic granulomatosis with polyangiitis (EGPA), a rarer subtype of ANCA-associated vasculitis, a recent review of studies suggests.
While EGPA patients carrying these antibodies will more likely develop nervous, renal, and skin manifestations of the disease, those without such antibodies are more likely to experience lung and cardiac problems, the researchers found.
These findings may provide a basis for future surveys and medical follow-ups concerning organ-specific involvement among people with EGPA.
The study, “Antineutrophil cytoplasmic antibodies and organ-specific manifestations in eosinophilic granulomatosis with polyangiitis: A systematic review and meta-analysis,” was published in The Journal of Allergy and Clinical Immunology: In Practice.
The relationship between the presence of ANCAs — a key protein factor in the blood — and which organs are most affected in EGPA patients has mostly been reported through case studies, and these have provided inconsistent findings.
To finally answer the question as to whether ANCA status influences the manifestations of EGPA, researchers at the Taipei Medical University Hospital, in Taiwan, systematically reviewed studies published until March 2020, examining this association.
In the end, 24 studies were selected for further analysis. These included a total of 2,527 people with EGPA, 921 (38%) of whom were positive for ANCA antibodies. This patient group’s average age was approximately 50.
Asthma is a major diagnostic finding in EGPA and the review found that nearly all patients — 94.4% of ANCA-positive patients and 97.7% of those ANCA-negative — had it, showing that ANCA status is not associated with the presence of asthma.
In addition to asthma, a high prevalence of rhinosinusitis, or an inflammation of the nose and sinuses, has been noted. This manifestation, however, was 44% more likely in individuals with ANCA antibodies than in those without.
Several internal organs also appeared to be differentially affected in cases of EGPA, depending on ANCA status, the researchers noted.
In particular, those who were ANCA-positive showed significantly less lung and cardiac involvement than ANCA-negative patients. Conversely, ANCA-positive patients showed more peripheral neuropathy — damage to the nerves outside the central nervous system, comprised of the brain and spinal cord — and kidney symptoms than those who were ANCA-negative.
Despite the lower likelihood of having lung symptoms, patients with ANCA antibodies were not less likely to experience alveolar hemorrhage, a serious condition associated with EGPA and characterized by blood accumulating inside the lungs.
Cardiac complications such as pericarditis — an inflammation of the membrane surrounding the heart — and cardiomyopathy, wherein the heart has trouble adequately pumping blood, are the most common cardiac issues seen in EGPA cases.
In their review, the investigators observed that ANCA-negative patients were more likely to experience cardiomyopathy, but that the prevalence of pericarditis varied little with ANCA status.
Finally, a significant association also was found between ANCA-positive status and purpura, a skin condition involving a rash of purple spots caused by small blood vessels leaking blood into the skin. No other skin symptoms varied with ANCA status in this study.
“Our findings indicate that patients with EGPA comprise groups with different features of disease associated with their ANCA status,” the investigators wrote.
“ANCA-positive patients with EGPA may have a higher prevalence of peripheral neuropathy, renal involvement, and cutaneous purpura, whereas those with ANCA-negative status may have a higher prevalence of pulmonary involvement and cardiac manifestations,” they concluded.
Still, the researchers note that because controversy still exists regarding the effects of ANCA status on EGPA prognosis, more studies are needed to clarify the issue.
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