Background: We sought to determine the safety of treatment interruption (TI) and to identify parameters that would define patients with human immunodeficiency virus (HIV) for whom TI is safer.
Methods: AIDS Clinical Trials Group 5170 was a multicenter, 96-week-long, prospective study of HIV-infected patients receiving antiretroviral therapy (ART) who had CD4(+) cell counts >350 cells/mm(3) and who underwent TI.
Results: A total of 167 patients were enrolled. The median nadir in CD4(+) cell count was 436 cells/mm(3). The initial decrease (i.e., during the first 8 weeks) in CD4(+) cell count after ART interruption was 20 cells/mm(3)/week; the subsequent decrease was 2.0 cells/mm(3)/week until week 96. Both the CD4(+) cell count before enrollment and the increase in CD4(+) cell count during ART predicted early decrease; later decrease was predicted by the level of interleukin-7 at enrollment. A Centers for Disease Control and Prevention (CDC) diagnosis of a category B or C event was made for 2 and 2 patients, respectively (all had CD4(+) cell counts >350 cells/mm(3)). At week 96, 17 patients had CD4(+) cell counts < or =250 cells/mm(3), and 46 patients had resumed ART; 5 patients died (unrelated to HIV or acquired immunodeficiency syndrome). In a multivariate analysis, a higher nadir in CD4(+) cell count (>400 cells/mm(3)), a lower HIV load (<50 copies/mL) at the time of TI, and an HIV load < or =22,000 copies/mL before ART predicted a longer time to the primary end point (CDC category B or C event, death, CD4(+) cell count < or =250 cells/mm(3), or resumption of ART).
Conclusion: Disease progression after TI was low in this cohort. A higher nadir in CD4(+) cell count, a lower HIV load before ART, and an HIV load < or =50 copies/mL at the time of TI predicted a longer time to the primary end point.