The results of this randomized controlled trial of an IMB-based intervention designed to improve HAART adherence among HIV-positive hazardous drinkers demonstrated that the intervention led to significant short-term improvement in viral and immunologic outcomes and improvements in self-reported adherence behavior compared with the education comparison condition. At the 3-month follow-up, participants in the intervention condition demonstrated significantly greater decreases in viral load and increases in CD4 cell count and self-reported adherence behavior compared with participants in the comparison condition. Project PLUS is the first behavioral adherence intervention to demonstrate such improvements in all 3 measures (viral load, CD4 cell count, and percent adherence) and is the first intervention for HIV-positive individuals with alcohol-related problems to demonstrate any significant effects.
The efficacy of the Project PLUS intervention may be attributable to several factors. First, the intervention was designed to incorporate the full IMB model of behavior change, including the provision of information, utilization of MI techniques, and selection of skills-training modules. The combination of MI with CBST seems to confer greater benefit than MI alone.21
Second, the Project PLUS intervention manual includes >15 different skill-building modules, such that the skills training is targeted to specific deficits identified by each participant. Other HAART adherence interventions have used motivational and cognitive-behavioral components25
but failed to find significant effects on viral load or CD4 cell count, perhaps because they did not individually tailor modules, provide ongoing self-monitoring of adherence, and utilize personalized feedback on factors related to nonadherence. The comparison group never achieved at least 90% adherence at follow-up, unlike the intervention group, which may account for the fact that viral loads increased and CD4 cell counts declined in the comparison group.
It is important to note that participants enrolled in the Project PLUS intervention did not have to report difficulties with adherence at baseline, as has been common in other adherence interventions. At baseline, 38% of participants reported that they were already at least 95% adherent. As such, the population enrolled mirrors the broad spectrum of HIV-positive clients with alcohol problems seen in clinical settings. One meta-analytic review of HIV adherence studies found that intervention effects were significantly stronger in trials in which adherence problems were a criterion for eligibility.18
This finding suggests that the impact of the Project PLUS intervention might be even greater were it restricted to those individuals with the most significant adherence problems.
Unlike most published HIV intervention studies,20
our comparison condition was neither a “standard care” condition nor an attention control focused on different behaviors than those in the treatment condition (eg, exercise, diet/nutrition). The comparison condition was time- and content-equivalent to the intervention. Although delivered by health educators rather than by counselors and focused on didactic information and discussion of videotapes rather than on motivation and skills building, the education condition specifically addressed HAART adherence and drinking. For this reason, it is not surprising that the education condition also improved self-reported adherence and drinking behaviors. Although adherence improvement among participants in the education control condition was smaller relative to those in the intervention condition, improvement in self-reported drinking behavior was of similar magnitude, and self-reported improvement in both conditions was sustained through to the 6-month visit. These findings suggest that education alone might be sufficient to change self-reported behavior, but a more individualized and sophisticated intervention is necessary to influence virologic and immunologic outcomes. It is also possible that improvements over time in both conditions reflect a reporting bias, whereas changes in viral load and CD4 cell count reflect true changes in adherence behavior as a result of the intervention.
The intervention, however, did not seem to result in greater changes in drinking behavior compared with the education condition. Because participants were required to have alcohol problems as part of the eligibility criteria, it is possible that perceived demands to report decreased alcohol use were stronger than those for reporting adherence changes. It is also possible that for HIV-positive persons, information alone is enough to reduce alcohol use but that the individualized and tailored motivation and skills-building modules are essential to affect medication adherence. This difference may be attributable to the fact that the information provided for alcohol use focused heavily on the impact that such use has on the health and immune functioning of HIV-positive persons, perhaps making this education more salient than has traditionally been the case when education-based interventions have failed to demonstrate efficacy.
The study failed to maintain significant interaction effects at the 6-month visit, most likely because participants were no longer receiving the intervention content. Other adherence interventions have also failed to find significant effects at 6 months,25,47
and the absence of significant intervention effects for viral load and CD4 cell count at the 6-month follow-up could be attributable to a host of other clinical and biologic factors, including the development of resistance, preexisting resistance, or length of time on HAART. In addition, given the sample size at the 6-month follow-up (n = 116), the study had sufficient power (α = 0.05, 2-tailed; β = 0.20) to detect only a medium effect size or greater (Cohen d
≥ 0.51). Mean scores at the 6-month follow-up are all in the hypothesized direction (ie, the intervention group demonstrating better clinical outcomes, higher levels of adherence, and less drinking compared with the education group). It is possible that the Project PLUS intervention would benefit from “booster visits” to reinforce the intervention components and to help participants sustain the positive effects impact on adherence and virologic and immunologic functioning. Future studies should consider the inclusion of booster sessions to examine their impact on long-term outcomes.
Because of its flexibility in tailoring intervention components to the specific needs of individual patients, the Project PLUS intervention is a perfect model for integration into HIV clinical care settings. Although an “intensive” intervention by some standards, the success of Project PLUS in improving clinical outcomes suggests that it might be a cost-effective investment, especially if delivered to the patients at highest risk for nonadherence. The intervention could be delivered by many different clinic professionals, including nurses, social workers, or case managers. If integrated within an HIV clinic setting, individual CBST modules could be delivered as “booster” sessions during routine care visits or when a client presented with treatment failure because of nonadherence. Many HIV clinics struggle with providing adherence interventions for their substance-using clients, including hazardous drinkers, and Project PLUS provides a model that allows providers to target their intersecting needs and barriers to adherence. It is also possible that although designed for hazardous drinkers, the adherence components of Project PLUS could prove effective even for those without substance use problems. Because all participants were hazardous drinkers, the extent to which the intervention would work effectively with those with fewer drinking problems is unknown, but it is also possible that such persons might require a less lengthy and intensive intervention. More research is needed to develop and replicate the Project PLUS model within HIV care settings and to modify this promising intervention for use with other HIV-positive populations. Adaptations of the Project PLUS intervention, including contracted versions, should be examined for effectiveness.