With the advent of effective combinations of antiretroviral agents in 1996, the crucial importance of patient adherence to medication regimens rapidly became apparent. In response, HIV/AIDS clinical and behavioral researchers launched major research projects aimed at describing the levels and determinants of adherence. In recent years, the percent of prescribed doses taken has been linked consistently to biologic treatment outcomes, including the development of resistance to antiretroviral medications, and to clinical outcomes as well. Unfortunately, it has also become clear that few patients are able to maintain a medication adherence rate of >90%, which is the most likely minimum necessary for successful virologic suppression in the greatest proportion of patients, thus forestalling the development of drug-resistant virus and eventual clinical failure.
Although substantial descriptive data are available now that define the determinants and the consequences of nonadherence in a variety of populations, the same cannot be said regarding adherence interventions. Up to the present, most of the latter have been in the form of case series and demonstration projects that, although of great value, have not provided rigorous and scientific evidence of adherence intervention benefits. To some extent, the paucity of randomized controlled trials of adherence interventions among HIV-infected drug users and other vulnerable populations reflects that fact that the trials have been designed and implemented only recently. Significant methodologic challenges are also limiting needed scientific progress, however. These challenges include the evolving nature of clinical regimens and protocols, the marginal social position occupied by most of the population in need, the lack of a “gold standard” for adherence measurement or intervention effect, and the lack of tight clinical outcome measures of successful adherence.
The rapid development of powerful antiretroviral regimens and the central role of adherence to these regimens, coupled with the emerging global commitment to ensure access to these regimens for the most vulnerable of those suffering from HIV/AIDS, increase the urgency of understanding the best evidence available about interventions to assist patients to adhere to these regimens. We are in the midst of a major expansion of antiretroviral treatment into communities of vulnerable populations, including drug users, around the globe. The need to establish the scientific basis for interventions to improve adherence in these populations is urgent if the medications and best efforts of the world's public health and clinical community are to bear fruit. A critical amount of experience and data is now accumulating, although only a few randomized controlled trials with careful outcome measures have been published or presented in a scientific forum.
In November 2005, a scientific meeting was held at Yale University, bringing together a wide array of biomedical, behavioral, and social scientists engaged in studying interventions to improve adherence among drug users and other vulnerable populations in domestic and international settings. The meeting was supported by the National Institute for Drug Abuse and included representatives from government, academic, and clinical arenas. The meeting's goal was to review current progress, collaborate in developing solutions to common research problems, and propose important new directions in adherence intervention research. The participants in the meeting addressed a range of scientific issues, including the relation between biomedical and behavioral science in adherence research; challenges in the design of rigorous studies of adherence, particularly among drug users and other vulnerable populations; theoretic behavioral models in adherence intervention research; subject recruitment and retention; data management (with a special focus on managing the large data sets generated by measuring medication adherence); intervention dose, duration, fidelity, and durability; and the special role of substance abuse treatment. The meeting also addressed the problems of translating new knowledge from research to practice, including generalizability of findings, implementation in the community and clinic setting, cost-effectiveness and reimbursement for adherence interventions, and implications for health policy.
The articles in this special supplement reflect the presentations and debates conducted at the November meeting in New Haven. They comprise discussions of the theoretic underpinnings of adherence research and of the challenges of collaboration across disciplines (see the articles by Friedland, Fisher et al, and Ware et al), a state-of-the-art review of the outcomes of adherence intervention trials (see the articles by Simoni et al and Gordon), results from 2 adherence intervention clinical trials (see the articles by Mannheimer et al and Smith-Rohrberg et al), explorations of important methodologic aspects of adherence intervention research such as the role of qualitative methods (see the article by Sankar et al), the challenge of developing a theory-driven intervention (see the article by Remien et al), measurement strategies (see the article by Berg and Arnsten), data management issues with electronic monitoring devices (see the article by Fennie et al), an innovative approach to assess intervention effectiveness (see the article by Petersen et al), a promising cost-effectiveness model for adherence interventions (see the article by Freedberg et al), and the earliest reports of exciting work being conducted abroad in the resource-limited parts of the world in which the epidemic continues to expand (see the articles by Maneesriwongul et al, Nachega et al, Mukherjee et al, Wong et al, and Pearson et al). Finally, Margaret Chesney, one of the early leaders in antiretroviral adherence research, comments on where we are today and offers her thoughts for the future.
We have been pleased and excited to have had the opportunity to host the scientific meeting on adherence last year and to assemble the contributed work of the outstanding participants in this supplement. We hope that the contents of this issue provide new knowledge and insight regarding HIV medication adherence, further the research agenda in this critical area, and, ultimately and most importantly, provide substantial benefit for those living with HIV/AIDS.