CD4 cell-monitored treatment interruption in patients with a CD4 cell count > 500 X 10(6) cells/I

Background: Little is known about CD4 cell count changes in patients with high CD4 cell counts who interrupt antiretroviral therapy, especially in those with a nadir of 250-350 × 106 cells/l. Methods: Data derived from 139 patients from seven prospective cohorts who had > 12 months highly active antiretroviral therapy (HAART), CD4 cell count nadir of > 250 × 106 cells/l and at pre-interruption of > 500 × 106 cells/l. Endpoint was time to CD4 cell count < 350 × 106 cells/l or reinitiation of treatment. Results: At interruption, the median CD4 cell countwas 800 × 106 cells/l, median viral load was 1.7 log10 copies/ml. At the time of analysis, 63 (45.3%) had resumed therapy or experienced < 350 × 106 cells/l CD4 cells over a median interruption of 75 weeks. Of these, 33 (52.4%) experienced a decline to < 350 × 106 cells/l and 30 (47.6%) restarted therapy before their CD4 cell count had fallen below this level. In 43 patients with CD4 cell nadir of 251-350 × 106 cells/l, median time to therapy resumption or CD4 cell count < 350 × 106 cells/l was 61 weeks. Higher CD4 cell count nadir, longer duration of viral load suppression on therapy, and higher viral load level at interruption were independently associated with longer time to restart therapy. The risk of clinical events was 5 per 1000 person-years of follow-up. Conclusions: Patients who started therapy with CD4 cell count of 250-350 × 106 cells/l and who later interrupted therapy appear able to remain off therapy with a CD4 cell count > 350 × 106 cells/l for a substantial period of time.