IRIS uncommon when ART starts in 96,000-person Europe/US study

Immune reconstitution inflammatory syndrome (IRIS) appears to be rare when antiretroviral-naive adults in Europe and the United States start ART, with the possible exception of mycobacterial infections.

Unmasking IRIS remains a serious threat when antiretroviral therapy (ART) starts in low-income countries. Because little is known about IRIS risk in high-income countries, researchers working with the European/US HIV-CAUSAL Collaboration conducted this analysis.

The study involved people at least 18 years old starting their first antiretroviral regimen between 1996 and 2003. Everyone had CD4 count and viral load measurements, and no one had an AIDS illness between these measurements and the start of follow-up. The investigators estimated hazard ratios (HR) for IRIS in people who started ART within the past 3 months versus those who did not start ART.

Of the 96,562 cohort members, 78% were men and 55,144 (57%) started ART. Through a median follow-up of 31 months (interquartile range 13 to 65), numbers of IRIS cases ranged from 113 for progressive multifocal leukoencephalopathy (PML) to 898 for tuberculosis.

Compared with people who did not start ART, those who started ART within the past 3 months had more than a doubled risk of Mycobacterium avium complex (MAC, HR 2.61, 95% confidence interval [CI] 1.05 to 6.49). Chances of TB, another mycobacterial infection, were 21% higher in the recent ART group, but that higher rate did not reach statistical significance (HR 1.21, 95% CI 0.90 to 1.63).

The study produced no evidence that any other IRIS AIDS complication arose more frequently in people who started ART within the past 3 months and those who did not, including cytomegalovirus retinitis, PML, herpes simplex virus infection, Kaposi sarcoma, non-Hodgkin lymphoma, cryptococcosis, and candidiasis.

“With the potential exception of mycobacterial infections,” the researchers conclude, “unmasking IRIS does not appear to be a common complication of cART initiation in high-income countries.”

Source: HIV-CAUSAL Collaboration. Opportunistic infections and AIDS malignancies early after initiating combination antiretroviral therapy in high-income countries. AIDS. 2014; 28: 2461-2473.

For the study abstract

(Downloading the complete article requires a subscription to AIDS or an online payment; the abstract is free.)

Source: IAS

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By Mark Mascolini

Published: Nov. 29, 2014, 5:57 p.m.

Last updated: Nov. 29, 2014, 6:58 p.m.

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