In HIV-positive patients on antiretroviral therapy (ART) who develop opportunistic infections, immune reconstitution inflammatory syndrome (IRIS) most commonly occurs at what CD4 cell count threshold and timing?
- A CD4 < 50–100 cells/µL at baseline, occurring 4–8 weeks after ART initiation ✓
- B CD4 > 350 cells/µL with any OI within 12 months of ART
- C Any CD4 count with OI developing >2 years after ART
- D CD4 < 200 cells/µL with Kaposi sarcoma exclusively
Correct answer: A. CD4 < 50–100 cells/µL at baseline, occurring 4–8 weeks after ART initiation
Explanation
Immune reconstitution inflammatory syndrome (IRIS) is characterised by paradoxical worsening or unmasking of an opportunistic infection after ART initiation. Risk factors are: low baseline CD4 (<50–100 cells/µL), high viral load at ART start, short interval between OI treatment and ART initiation (<2 weeks), and rapid CD4 recovery. IRIS typically occurs 4–8 weeks after ART initiation. Most common triggers: MAC, CMV retinitis, TB, PCP, cryptococcal meningitis. Unmasking IRIS reveals subclinical OI after immune recovery.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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