Lack of sustained improvement in adherence or viral load following a directly observed antiretroviral therapy intervention

Abstract

Background: Methadone clinic-based directly observed antiretroviral therapy (DOT) has been shown to be more efficacious for improving adherence and suppressing human immunodeficiency virus (HIV) load than antiretroviral self-administration. We sought to determine whether the beneficial effects of DOT remain after DOT is discontinued.

Methods: We conducted a post-trial cohort study of 65 HIV-infected opioid-dependent adults who had completed a 24-week randomized controlled trial of methadone clinic-based DOT versus treatment as usual (TAU). For 12 months after DOT discontinuation, we assessed antiretroviral adherence using monthly pill counts and electronic monitors. We also assessed viral load at 3, 6, and 12 months after DOT ended. We examined differences between DOT and TAU in (1) adherence, (2) viral load, and (3) proportion of participants with viral load of <75 copies/mL.

Results: At trial end, adherence was higher among DOT participants than among TAU participants (86% and 54%, respectively; P < .001), and more DOT participants than TAU participants had viral loads of <75 copies/mL (71% and 44%, respectively; P = .03). However, after DOT ended, differences in adherence diminished by 1 month (55% for DOT vs 48% for TAU; P = .33) and extinguished completely by 3 months (49% for DOT vs 50% for TAU; P = .94). Differences in viral load between DOT and TAU disappeared by 3 months after the intervention, and the proportion of DOT participants with undetectable viral load decreased steadily after DOT was stopped until there was no difference (36% for DOT and 34% for TAU; P = .92).

Conclusions: Because the benefits of DOT for adherence and viral load among HIV-infected methadone patients cease after DOT is stopped, methadone-based DOT should be considered a long-term intervention.

Figure 1.

Differences in mean adherence rates between human immunodeficiency virus–infected participants in the directly observed therapy (DOT) group and those in the treatment as usual (TAU) group at each assessment point during both the 24-week intervention and the 12-month postintervention follow-up period. Fewer than 65 observations may be reported due to missing data. *P values for weeks 4, 8, 16, and 24 are based on mixed-effects models that include pill count adherence data from the 24-week intervention period; P values for months 1, 2, 3, 6, and 12 are based on mixed-effects models that include composite adherence data from the 12-month postintervention period.

Figure 2.

Differences in log₁₀ viral load (VL) between human immunodeficiency virus–infected participants in the directly observed therapy (DOT) group and those in the treatment as usual (TAU) group at each assessment point during both the 24-week intervention and the 12-month postintervention follow-up period. Fewer than 65 observations may be reported due to missing data. *P values for weeks 4, 8, 16, and 24 are based on mixed-effects models that include data from the 24-week intervention period; P values for months 3, 6, and 12 are based on mixed-effects models that include data from the 12-month postintervention period.

Figure 3.

Proportion of participants with undetectable viral load (<75 copies/mL) by study arm at each assessment point during both the 24-week intervention and the12-month postintervention follow-up period (DOT, directly observed therapy; TAU, treatment as usual). Fewer than 65 observations may be reported due to missing data. *P values for baseline and weeks 8, 16, and 24 are based on χ² tests evaluating data from the 24-week intervention period; P values for months 3, 6, and 12 are based on χ² tests evaluating data from the 12-month postintervention period.