Self-reported adherence supports patient preference for the single tablet regimen (STR) in the current cART era

Gaetana Sterrantino,¹ Lucia Santoro,¹ Dario Bartolozzi1,¹ Michele Trotta,¹ Mauro Zaccarelli^2
1SOD Malattie Infettive, Azienda Ospedaliera Universitaria Careggi, Firenze, ²Istituto Nazionale per le Malattie Infettive "Lazzaro Spallanzani," Roma, Italy

Objective: To analyze self-reported adherence to antiretroviral regimens containing ritonavir-boosted protease inhibitors, nonnucleoside reverse transcriptase inhibitors (NNRTI), raltegravir, and maraviroc.
Methods: Overall, 372 consecutive subjects attending a reference center for HIV treatment in Florence, Italy, were enrolled in the study, from December 2010 to January 2012 (mean age 48 years). A self-report questionnaire was filled in. Patients were defined as "nonadherent" if reporting one of the following criteria: <90% of pills taken in the last month, ≥1 missed dose in the last week, spontaneous treatment interruptions reported, or refill problems in the last 3 months. Gender, age, CD4, HIV-RNA, years of therapy, and type of antiretroviral regimen were analyzed with respect to adherence.
Results: At the time of the questionnaire, 89.8% of patients had <50 copies/mL HIV-RNA and 14.2% were on their first combined antiretroviral therapy. 57% of patients were prescribed a regimen containing ritonavir boosted protease inhibitors (boosted PI), 41.7% NNRTI, 17.2% raltegravir, and 4.8% maraviroc; 49.5% of the subjects were on bis-in-die regimens, while 50.5% were on OD regimens, with 23.1% of these on the single tablet regimen (STR): tenofovir/emtricitabine/efavirenz. The nonadherence proportion was lower in NNRTI than in boosted-PI treatments (19.4% vs 30.2%), and even lower in STR patients (17.4%). In multivariable logistic regression, patients with the NNRTI regimen (OR: 0.56, 95% CI: 0.34–0.94) and the STR (OR: 0.45, 95% CI: 0.22–0.92) reported lower nonadherence. Efavirenz regimens were also associated with lower nonadherence (OR: 0.42, 95% CI: 0.21–0.83), while atazanavir/ritonavir regimens were associated with higher nonadherence. No other relation to specific antiretroviral drugs was found. A higher CD4 count, lower HIV-RNA, and older age were also found to be associated with lower nonadherence, while a longer time on combined antiretroviral therapy was related to higher nonadherence.
Conclusion: STR maintains an advantage in improving adherence with respect to other combined antiretroviral therapies, even though new antiretroviral drugs and drug classes have become available in recent years.

Keywords: HIV, self-reported adherence, single tablet regimen, boosted protease inhibitors, nonnucleoside reverse-transcriptase inhibitors