Disseminated M-avium complex infection in the Swiss HIV cohort study: Declining incidence, improved prognosis and discontinuation of maintenance therapy

Background. Introduction of potent antiretroviral combination therapy (ART) has reduced overall morbidity and mortality amongst HIV-infected adults. S ome prophylactic regimes against opportunistic infections can be discontinu ed in patients under successful ART. Questions under study: (1) The influence of the availability of ART on inci dence and mortality of disseminated M avium Complex infection (MAC). (2) Th e safety of discontinuation of maintenance therapy against MAC in patients on ART. Setting: The Swiss HIV-Cohort Study, a prospective multicentre study of HIV -infected adults. Methods: Patients with a nadir CD4 count below 50 cells/mm(3) were consider ed at risk for MAC and contributed to total follow-up time for calculating the incidence. Survival analysis was performed by using Kaplan Meier and Co x proportional hazards methods. Safety of discontinuation of maintenance th erapy was evaluated by review of the medical notes. Results: 398 patients were diagnosed with MAC from 1990 to 1999. 350 had a previous CD4 count below 50 cells/mm(3). A total of 3208 patients had a nad ir CD4 count of less than 50 cells/mm(3), during the study period and contr ibuted to a total follow-up of 6004 person-years. The incidence over the wh ole study period was 5.8 events per 100 person-years. In the time period of available ART the incidence of MAC was significantly reduced (1.4 versus 8 .8 events per 100 person-years, P <0.001). Being diagnosed after 1995 was t he most powerful predictor of better survival (adjusted hazard ratio for de ath: 0.27; p <0.001). None of 24 patients discontinuing maintenance therapy while on ART experienced recurrence of MAC during a total follow-up of 56. 6 person-years (upper 95% confidence limit 5.3 per 100 person-years). Conclusion: Introducing ART has markedly reduced the risk of MAC for HIV-in fected individuals with a history of very low CD4 counts. Survival after di agnosis of MAC has improved after ART became available. In patients respond ing to ART, discontinuation of maintenance therapy against M avium may be s afe.