Prolonged treatment interruption after immunologic response to highly active antiretroviral therapy.

Duration of treatment interruption (TI) was investigated in 105 human immunodeficiency virus-infected patients whose antiretroviral therapy was interrupted with the intention to resume therapy on the basis of clinical or laboratory indicators. In a mixed cohort study, 57% of patients had not resumed therapy at the time of writing (median TI duration, 114 weeks); the most recent analysis of this group revealed a mean CD4 cell count of 500 cells/mm3. Patients with lower CD4 cell counts at therapy initiation were more likely to resume therapy than were those with counts of >500 cells/mm3 (<200 cells/mm3 [relative hazard, 4.4]; and 200-350 cells/mm3 [relative hazard, 2.9]). Patients who met current United States Department of Health and Human Services criteria for starting therapy at the time of therapy initiation were 3 times more likely to resume therapy than were those who did not. Our results have implications for this TI strategy: there may be a subset of patients who can safely discontinue therapy for prolonged periods of time.