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PCP Risk and Prophylaxis — SCE Rheumatology MCQ

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ModerateRheumatology EmergenciesPCP Risk and ProphylaxisSCE Rheumatology

A 42-year-old woman with dermatomyositis on immunosuppression develops Pneumocystis jirovecii pneumonia. She is on Prednisolone 30 mg daily and Mycophenolate. What Prednisolone dose threshold is generally considered to increase PCP risk?

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Correct answer: E — Prednisolone ≥20 mg daily for ≥4 weeks (or equivalent immunosuppression) increases PCP risk and prophylaxis should be considered

The generally accepted threshold for considering PCP prophylaxis is Prednisolone ≥20 mg daily for ≥4 weeks particularly when combined with other immunosuppressants. This patient on 30 mg Prednisolone plus Mycophenolate was at significant risk. Co-trimoxazole prophylaxis (480 mg daily or 960 mg three times weekly) should be considered for patients on high-dose glucocorticoids with additional immunosuppression. BSR 2025 AAV guidelines mandate PCP prophylaxis for patients on Cyclophosphamide or Rituximab. For other immunosuppressive combinations the decision should be individualised based on the total immunosuppressive burden.

Reference: BSR 2025 AAV guidelines; BTS 2011 PCP prophylaxis recommendations