Objective: To determine the incidence, clinical manifestations, risk factors and outcome of immune reconstitution inflammatory syndrome (IRIS) in South Africa.
Design: Prospective surveillance cohort and nested case-control study in a large, University hospital-based antiretroviral therapy (ART) clinic.
Methods: A total of 423 ART-naive HIV-infected South African patients were followed for signs and symptoms IRIS during the first 6 months of ART. We also performed a nested case-control study with controls matched to IRIS cases on ART duration.
Results: During the first 6 months of ART, 44 (10.4%) patients experienced IRIS for an overall incidence rate of 25.1 cases per 100 patient-years. Diagnoses included tuberculosis (18/44, 41%), abscess formation and suppurative folliculitis (8/44, 18.2%), varicella zoster (6/44, 13.6%), herpes simplex (4/44, 9.1%), cryptococcal meningitis (3/44, 6.8%), molluscum contagiosum (3/44, 6.8%), and Kaposi's sarcoma (2/44, 4.5%). Median IRIS onset was 48 days (interquartile range, 29-99) from ART initiation. In comparison with controls, IRIS cases had significantly lower CD4 cell counts at baseline (79 versus 142 cells/microl; P = 0.02) and at IRIS diagnosis (183 versus 263 cells/microl; P = 0.05), but similar virological and immunological response to ART. In multivariable analyses, higher baseline CD4 cell count was protective of developing IRIS (HR 0.72 per 50 cells/microl increase). Most IRIS cases were mild, with ART discontinued in three (6.8%) patients, corticosteroids administered to four (9.1%) patients, and hospitalization required in 12 (27.3%) patients. Two deaths were attributable to IRIS.
Conclusions: IRIS may affect 10% of patients initiating ART in Africa, particularly those with advanced immunosuppression, but severe, life-threatening IRIS is uncommon.