Discontinuing or withholding primary prophylaxis against Mycobacterium avium in patients on successful antiretroviral combination therapy. The Swiss HIV Cohort Study.

OBJECTIVE

To assess the safety of discontinuing or withholding primary prophylaxis against disseminated Mycobacterium avium infection (MAC) in HIV infected patients on successful antiretroviral combination therapy.

SETTING

National prospective multicentre cohort study.

DESIGN

HIV-infected patients were eligible for the analysis if: (i) they had a history of at least two CD4 cell counts < 50 x 10(6)/l; (ii) they had never had MAC; (iii) they had discontinued or never begun primary prophylaxis against MAC; (iv) they received antiretroviral therapy and demonstrated an increase in CD4 cell counts to > or = 100 x 10(6)/l that was sustained for at least 12 weeks. From this time point until last follow-up, incidence of disseminated MAC disease was measured, and 99% confidence intervals were calculated assuming a Poisson distribution of events.

RESULTS

Two-hundred and fifty-three patients (22.5% female; median age, 37 years, 30% injecting drug users) were eligible for analysis. Sixty-six per cent were in Centers for Disease Control and Prevention (CDC) stage C, and 28% were in CDC stage B. Their median nadir CD4 cell count was 10 x 10(6)/l, the median duration of CD4 cell count < 50 x 10(6)/l was 12 months. During a total follow-up of 364.3 patient-years there was no case of disseminated MAC. The one-sided 99% confidence limit for incidence density of MAC was 1.3 per 100 person-years.

CONCLUSION

Discontinuing or withholding primary prophylaxis against MAC is safe in patients who have a sustained increase in their CD4 cell count to > or = 100 x 10(6)/l.