Mycobacterium avium complex immune reconstitution inflammatory syndrome: Long term outcomes

Cases of MAC IRIS were retrospectively identified at four HIV clinics (Michigan, Maryland, Rhode Island, and Indiana) from 1996–2004. Patients were included if they were initially diagnosed with AIDS and found to have evidence of focal MAC infection documented by tissue culture or PCR after initiating HAART, and at least 6 months of follow up.

Among the 20 patients included, the mean age was 40 years, mean CD4 cell count was 24/mm³ at pretreatment baseline and 100/mm³ at time of MAC IRIS diagnosis. Sites of disease included lymph nodes (15 patients [8 peripheral, 8 abdominal and 1 peripheral and abdominal]), gastrointestinal tract (7) and liver (3). Sixteen patients (80%) responded to treatment and were disease free after a mean of 17.4 months of therapy for MAC IRIS; IRIS therapy was withdrawn in 6 without relapse. Four patients (non-responder group) had persistent or relapsing disease despite 27 months of ongoing MAC IRIS treatment. At the time of resolution or last follow-up, the mean CD4 cell count and viral load was 143/mm³ and 7,000 c/mL for responders, and 65/mm³ and 17,000 c/mL for non-responders, respectively. Most patients with peripheral adenopathy were responders (7/8; 88%); many with abdominal adenopathy (4/8; 50%) were nonresponders.

The majority of patients with MAC IRIS eventually responded to treatment. Our sample size was not adequate to perform statistical analysis, but there was a tendency towards adequate CD4 response to HAART and peripheral rather than intraabdominal adenopathy among responders.