Theory- and Evidence-based Intervention to Improve Adherence to Antiretroviral Therapy Among HIV-infected Patients in the Netherlands: a Pilot Study

The objectives of this study were to describe and pilot-test a theory- and evidence-based intervention to improve adherence of HIV-infected patients with antiretroviral medication. Twenty-six treatment-experienced patients (>6 months on treatment) participated in a within-subject comparison design. Adherence was measured electronically with Medication Event Monitoring System (MEMS) caps for at least 5 months: 2 months before the intervention and 3 months during the intervention. MEMS data were used to measure the outcome of the intervention, but also served as feedback to participants during the intervention. Mean adherence during the month before intervention was compared to mean adherence during the third month of intervention. Data for the process evaluation were gathered through direct observation and semi-structured interviews. Adherence improved significantly during the intervention (Z = -2.1, p < 0.05). Mean adherence (percentage of prescribed doses taken within correct time interval) before the intervention was 81.8% compared to 92.5% during the third month of the intervention. More than 65% of the nonadherent patients (<95% adherence) before the intervention were adherent during the third month of the intervention. Both health care professionals and patients positively evaluated the intervention protocol and the electronic measurement of adherence. The only critique from some patients was the lack of userfriendliness of the MEMS cap and its medication container (size and shape). It can be concluded that the proposed intervention fits in standard care procedures, can be executed by trained HIV nurses, seems to improve adherence to antiretroviral medication, and is positively evaluated by the users. Large-scale and long-term research is warranted.