Abstract and Introduction
Abstract
Introduction: The use of single-tablet antiretroviral therapy (ART) regimens and its implications on adherence among HIV-infected women have not been well described.
Methods: Participants were enrolled in the Women's Interagency HIV Study, a longitudinal study of HIV infection in US women. We examined semiannual trends in single-tablet regimen use and ART adherence, defined as self-reported 95% adherence in the past 6 months, during 2006–2013. In a nested cohort study, we assessed the comparative effectiveness of a single-tablet versus a multiple-tablet regimen with respect to adherence, virologic suppression, quality of life, and AIDS-defining events, using propensity score matching to account for demographic, behavioral, and clinical confounders. We also examined these outcomes in a subset of women switching from a multiple- to single-tablet regimen using a case-crossover design.
Results: We included 15,523 person-visits, representing 1727 women (53% black, 29% Hispanic, 25% IDU, median age 47). Use of single-tablet regimens among ART users increased from 7% in 2006% to 27% in 2013; adherence increased from 78% to 85% during the same period (both P < 0.001). Single-tablet regimen use was significantly associated with increased adherence (adjusted risk ratio: 1.05; 95% confidence interval: 1.03 to 1.08) and virologic suppression (risk ratio: 1.06; 95% confidence interval: 1.01 to 1.11), while associations with improved quality of life and fewer AIDS-defining events did not achieve statistical significance. Similar findings were observed among the subset of switchers.
Conclusions: Single-tablet regimen use was associated with increased adherence and virologic suppression. Despite this, 15% of women prescribed ART were still not optimally adherent; additional interventions are needed to maximize therapeutic benefits.
Introduction
Among HIV-infected people who are prescribed potent antiretroviral therapy (ART), treatment adherence is important to maximize its health benefits with respect to virologic suppression and prevention of disease progression. However, it is well known that adherence can be hampered by many factors including dosing requirements, side effects, and behavioral and psychosocial factors that serve as barriers to optimal use, such as substance use and depression. Characteristics associated with race/ethnicity have also been associated with adherence, with African Americans less likely than other groups to report optimal adherence to ART.
A lower daily pill burden has been associated with better adherence and treatment outcomes. One notable innovation among potent ART regimens was the introduction of a once-daily fixed-dose coformulation in 2006 combining tenofovir (TDF), emtricitabine (FTC), and efavirenz (EFV), which reduced the potential pill burden and dosing frequencies required of earlier ART regimens. Two additional once-daily combination pills retaining the TDF/FTC backbone but replacing EFV with 1 or more agents have since become available in the United States: a coformulation containing rilpivirine (RPV) in 2011, and a coformulation containing elvitegravir (EVG) and the boosting agent cobicistat (COBI) in 2012. These new coformulations offer single-tablet regimen alternatives for women planning to become pregnant by replacing EFV, which may have the potential to cause fetal harm.
A few studies have shown single-tablet regimens to either maintain or increase treatment adherence. A multicenter clinical trial of 166 treatment experienced virologically suppressed individuals in the United States found that switching to a single-tablet ART regimen helped patients maintain adherence and increased some aspects of quality of life (QOL). In an observational cohort study of 118 homeless or unstably housed individuals in San Francisco, taking a single-tablet regimen was associated with greater adherence and viral suppression compared with a multiple-tablet regimen. The generalizability of these findings to women has not been fully established because these studies were comprised mostly of men. Numerous studies report lower adherence in women, possibly related to higher toxicity profiles, a higher prevalence of depression, or competing demands such as childcare responsibilities. The extent to which adherence in women may be affected by single-tablet regimen use in the context of these factors is unknown.
Given the limited data on use of these therapies and their influence on adherence in US women, we examined semiannual trends in single-tablet regimen use and adherence among ART-treated HIV-infected women in the Women's Interagency HIV Study (WIHS) between 2006 and 2013. Using a nested cohort study design, we compared the effectiveness of single-tablet versus multiple-tablet regimen use with respect to adherence and related health outcomes, including virologic suppression, disease progression, and QOL using propensity score matching to account for potential confounding by indication in a broad sample of ART-experienced WIHS participants. In a subset of participants who switched from a preexisting regimen to a single-tablet regimen, we conducted a case-crossover study to test for a postswitch increase in adherence and virologic suppression, as an alternate way to account for confounding because each participant's treatment outcomes after switching are compared with her outcomes before switching.