In the era of HAART, IRIS has been reported widely and occurred in 36% (12 of 33) and 32% (six of 19) of patients in two studies The majority of reactions occur within 60 days of initiating HAART, with a median of 15 days . IRIS does not appear to be associated with any particular antiretroviral regimen or drug class . Most patients with IRIS have advanced HIV infection. In the recent CAMELIA trial, the risk of IRIS was increased around fourfold if HAART were started in the first 2 weeks compared with delaying HAART until beyond week 8 of TB treatment .

With limited data it is difficult to predict the risk of IRIS, but the following appear to be relevant :

  • low baseline CD4 cell count
  • rapid recovery in CD4 numbers
  • rapid decline in HIV viral load
  • dissemination of TB outside the lung (may be attributable to high burden of bacilli)
  • HAART started within first 2 months of TB treatment