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ANCA Vasculitis — SCE Rheumatology MCQ

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HardVasculitisANCA VasculitisSCE Rheumatology

A 50-year-old woman with PR3-ANCA-positive granulomatosis with polyangiitis, previously manifesting as upper-airway and pulmonary disease, remains in clinical remission on azathioprine maintenance. Over 3 months, PR3-ANCA measured using the same antigen-specific assay has changed from negative to strongly positive. She has no constitutional, upper-airway, respiratory, neurological or urinary symptoms. Examination is unchanged, and CRP, creatinine, urinalysis and urine albumin:creatinine ratio remain normal. What is the most appropriate response to the serological change?

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Correct answer: E — Continue azathioprine and arrange earlier structured clinical and laboratory reassessment

A rising or recurrent PR3-ANCA increases the probability of a future GPA relapse but does not establish current active vasculitis. Treatment escalation should be driven by structured clinical assessment and objective evidence of disease activity, not serology alone. Azathioprine should therefore be continued, with earlier review including symptom assessment, examination, inflammatory markers, renal function and urinalysis. High-dose prednisolone or rituximab induction would expose her to unnecessary toxicity without evidence of relapse. Switching immediately to rituximab maintenance solely because of the ANCA result is also unjustified. Unchanged routine follow-up is less appropriate because the marked PR3-ANCA rise identifies a period of increased relapse risk warranting closer surveillance.

Reference: Al-Soudi A, Vegting Y, Klarenbeek PL, Hilhorst ML. Do Relapses Follow ANCA Rises? A Systematic Review and Meta-Analysis on the Value of Serial ANCA Level Evaluation. Front Med. 2022. https://pubmed.ncbi.nlm.nih.gov/35860735/