Harm reduction intensity-Its role in HAART adherence amongst drug users in Amsterdam

Opioid substitution treatment seems to improve adherence to highly active antiretroviral therapy (HAART) in drug users (DU). DU in Amsterdam receive methadone within a harm reduction programme. We hypothesized that not only receiving methadone, but joining this complete comprehensive programme would improve HAART adherence.

Included were 102 HIV-positive DU attending the Amsterdam Cohort Study (ACS), reporting HAART use at multiple visits between 1999 and 2009. Non-adherence was defined as taking less than 95% of medication in the past 6 months (self-reported). Harm reduction intensity (HR) was measured by combining injecting drug use, methadone dosage and needle exchange, in different levels of participation, ranging from no/incomplete HR, complete HR to low or no dependence on HR. We studied the association between non-adherence and harm reduction intensities with logistic regression models adjusted for repeated measurements.

Non-adherence was reported in 11.9% of ACS visits. Non-injecting DU with low dependence on HR were less adherent than DU with complete HR (aOR 1.78; CI 95% 1.00-3.16), although there was no overall effect of HR. No difference was demonstrated in adherence between DU with complete HR and incomplete HR. Unsupervised housing (no access to structural support at home) (aOR 2.58; CI 95% 1.40-4.73) and having a steady partner (aOR 0.48; CI 95% 0.24-0.96) were significantly associated with respectively more and less non-adherence.

In Amsterdam, still-injecting DU who are exposed to systematic and integrated care, although not practising complete harm reduction, can be just as adherent to HAART as DU who make use of complete harm reduction and non-injecting DU with no dependence on harm reduction. These findings suggest the importance of a systematic and comprehensive support system including supervised housing and social and medical support to increase HAART adherence rates amongst all HIV-infected DU. When such programmes are introduced in settings where injecting drug use is highly prevalent, access to HAART for drug users in these settings can and should be increased.