Once-daily regimens improve adherence and treatment satisfaction

Michael Carter
Published: 23 July 2004

Once-daily HAART regimens are just as potent as twice-daily regimens and significantly improve patient adherence and satisfaction, according to a Spanish study presented as a poster to the Fifteenth International AIDS Conference in Bangkok last week. The study investigators stress that their study was undertaken before several newer once-daily drugs and formulations were available. They would therefore expect the reduced pill burden associated with these new drugs to make antiretroviral therapy even easier, further improving adherence and possibly efficacy.

Between May and September 2002 investigators from 55 Spanish hospitals recruited a total of 978 patients to a prospective and longitudinal cohort study (the CUVA Study) comparing once-daily and twice-daily HAART regimens. At three visits (baseline, three months and six months) clinical data were collected and individuals’ adherence and satisfaction with their HAART regimens were assessed.

The investigators emphasise that the study was carried out before some formulations of antiretrovirals which are in routine use today became available. These include efavirenz formulated into a single pill for once daily dosing, and once daily 3TC. Further, during the study period, tenofovir was still unavailable for first-line treatment. This meant that the median number of pills used by patients participating in the study was higher than in current practice.

The most frequent prescribed once daily regimen was ddI, 3TC and efavirenz (30.2% of individuals taking once-daily therapy), followed by tenofovir, 3TC and efavirenz (25.7%, a prescribing option which was only available for treatment experienced patients), and ddI, tenofovir and efavirenz (11.1%, again, this option was only available for second-line and later therapy).

A combination consisting of ddI, d4T and efavirenz was the most commonly prescribed twice-daily regimen (25.8%).

Patients were divided into three arms dependent on whether they were naïve to antiretroviral therapy, were changing to a simpler regimen, or were changing regimen because of virological failure. Baseline characteristics were comparable in all three arms between individuals taking once-daily and twice-daily therapy.

Across all three arms of the study, adherence was significantly better amongst patients taking once-daily treatment (p < 0.05). For patients switching therapy either for reasons of simplification or virological failure, taking a once-daily regimen was associated with a higher chance of achieving a viral load below 400 copies/ml. Of the patients in the simplification arm of the study 91.4% taking once-daily treatment had a viral load below 400 copies/ml against 83.4% of those taking twice-daily therapy (p < 0.05). Amongst individuals changing therapy because of virological failure 64.4% of those taking their anti-HIV drugs once a day had a viral load below 400 copies/ml versus only 49.4% of patients on twice-daily treatment (p < 0.05).

Patients taking once-daily treatment expressed a greater degree of overall satisfaction about their HIV therapy than patients taking their drugs twice-daily (p < 0.05).

In multivariate analysis, taking a simpler treatment regimen (p = 0.0016), taking once-daily therapy (p = 0.007), and the number of years with HIV infection (p = 0.0064) were all significantly related to satisfaction with treatment.

The factors associated with achieving a viral load below 400 copies/ml at six months in multivariate analysis were being naïve to antiretroviral therapy (p < 0.0001), and being adherent to treatment (p = 0.0069).

The investigators conclude, that even with the once-daily regimens available in 2002 “once-daily antiretroviral therapy appear as effective as twice-daily [regimens], significantly improving adherence and treatment satisfaction. This should positively affect treatment efficacy given these features are the cornerstone for HAART success in the long-term.”

Moreover, the improvement in adherence and quality of life was, the investigators state, mainly due to the once-daily nature of the regimens assessed, as these “early” once-daily regimens did not have a significantly lower pill burden than the twice-daily regimens they were compared against. The investigators add, “the reduction in pill burden with the new formulations of [once-daily anti-HIV drugs] will make antiretroviral therapy easier, probably improving adherence and even efficacy.”


La Paz, H et al. Adherence, treatment-satisfaction and effectiveness of once-daily versus twice-daily antiretroviral therapy in a large prospective observational cohort (CUVA Study). XV International AIDS Conference, Bangkok, abstract WePeB5780, 2004.

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