OBJECTIVE

To determine the impact of once-nightly versus twice-daily dosing and beliefs about highly active antiretroviral therapy (HAART) on adherence to efavirenz-based HAART in antiretroviral-naive patients.

METHODS

A multicenter, open-label, 48-week, randomized controlled trial. Participants were randomized to receive once nightly didanosine plus lamivudine, or twice-daily combivir (zidovudine plus lamivudine) both in combination with efavirenz. Medication Event Monitoring Systems were used to compile drug-dosing histories. Beliefs about HAART (necessity and concerns) were measured at baseline using validated questionnaires. Perceptions of HAART intrusiveness were assessed after 4 weeks.

RESULTS

Eighty-seven patients were randomized (44 once-nightly and 43 twice-daily). Overall adherence was higher among the once-nightly arm (P = 0.0327). Eighty-one percent once-nightly and 62% twice-daily patients persisted with treatment for 48 weeks (P = 0.0559). Regimen execution was similar between both arms. Participants were significantly less likely to persist with HAART if their initial concerns about HAART were high relative to their perceived need for treatment (P = 0.025).

CONCLUSIONS

The difference in adherence observed between once-nightly and twice-daily dosing was driven by a difference in persistence with treatment. Psychological preparation for starting HAART should address patients' perceptions of necessity for HAART and concerns about adverse effects to maximize persistence with treatment.