The primary aim of the study was to test an intervention designed to improve adherence among people taking antiretroviral medications. This study was among the first to provide a rigorous test of the use of MI for antiretroviral medication adherence and also among the first to train nurses to deliver the MI intervention for antiretroviral adherence. The results showed that during the follow-up period, participants in the intervention group were taking a greater percentage of their prescribed doses and a significantly greater percentage of doses on time compared to those in the control group. Although no intervention effect was noted for the lab results, viral load tended to be a little lower in the intervention group. Overall, all study participants showed a general improvement in lab values over the course of the study period.
These findings provide evidence to support the usefulness of MI in promoting antiretroviral medication adherence and add to the previous studies in the area. The results of two pilot studies provided preliminary evidence that MI counselling methods could be used to support the adherence efforts of men and women taking antiretroviral medications (DiIorio et al., 2003
; Parsons et al., 2005
). The results of the current study provide additional evidence for a client-centered approach that seeks to increase intrinsic motivation and reduce ambivalence for medication adherence.
Not all studies, however, have shown MI to be more efficacious than usual adherence education in the clinical setting. Samet et al. (2005)
found no difference in self-reported adherence between participants assigned to an MI intervention group and those assigned to the usual care group. Participants (n
= 151) in their study were limited to men and women who had a history of alcohol problems. Although the intervention was similar (four MI encounters versus our five MI sessions and both interventions delivered by a nurse trained in MI), the assessment of adherence was different. We compared the percentage of doses taken using MEMS®
caps, whereas Samet et al. used self-reported measures that were corroborated with data from MEMS®
caps. The researchers also noted that sample size and limited exposure to the intervention for some participants may have been factors in the failure to detect differences between groups.
The MI communication style is used primarily by counsellors and psychologists in their clinical practices. However, in the HIV clinical setting, registered nurses (RN) are most often responsible for adherence education and counselling. Thus, in our study, RNs were trained in MI skills and delivered the intervention. In an early study, Stott et al. (1996)
trained physicians and nurses to deliver brief MI-based counselling sessions to patients with diabetes. The results of this study and the present study provide evidence for the value of incorporating the MI communication style into the clinical practice of nurses, and studies such as these may increase its acceptability among nurses. The median time for MI sessions in the present study ranged from 30–45 minutes, which is longer than a usual clinical appointment with a healthcare provider. However, in many HIV clinics, nurses specialize in providing ART adherence education for patients. In these centers, nurses can use MI as one approach to support adherence. Additional studies can examine the incorporation of the MI approach as a brief ART adherence intervention conducted within the context of the office visit.
The percent of adherence recorded for participants in this study and the pattern of adherence over time were comparable to those reported in other studies. At baseline, participants took, on average, 80% of the prescribed doses of medication and, on average, 58% of the medication on time. One year later, participants took an average of 60% of the doses with about 32% on time. Although direct comparisons are difficult because of varying time periods used to calculate adherence rates, other investigators have reported MEMS®
-based adherence rates that are comparable to the ones found in this study (Liu et al., 2001
). Other investigators have also noted a decline in adherence over time. For example, Remien et al. (2005)
reported adherence rates of 75% and 66% at baseline and 6-month follow-up for their intervention group participants with similar values for the control group. Liu et al. (2001)
also reported a downward change over time in MEMS®
-based adherence rates.
In this study, the pattern of decline was different for the intervention and control groups. For both groups, the percent of adherence declined during the first three months. The decline continued for those in the control group, while it was attenuated for those in the intervention group. That attenuation was noted for both the percent of doses taken and the percent of doses taken on time is an interesting finding and suggests long-term effects of the MI intervention. One goal of MI is to increase intrinsic motivation for behavioral change. People who rely on intrinsic motivation as opposed to extrinsic motivation to support health behaviors are more likely to persevere in the face of difficulties (Ryan & Deci, 2000
). One explanation for the attenuation seen in the present study may be that participants in the intervention group relied upon what they learned in the MI intervention sessions to motivate themselves to take their medications. Further research is necessary to evaluate the long-term outcomes associated with MI.
There are several limitations of this study. First, the sample was composed primarily of low-income African American men. Thus, the results cannot be generalized to those in other groups who are also prescribed ART. Future research should focus on other groups affected by HIV, including women and gay men and other cultural groups, including Hispanic and Asian men and women. Second, all men and women who were initiating or changing ART were eligible to participate provided they met other study criteria. We did not limit participants to those who were reported difficulties taking their medications. We found that many participants maintained a high level of adherence throughout the study, limiting our ability to fully test the usefulness of MI in promoting behavioral change. Finally, we asked participants to use MEMS® caps throughout the one-year study. This proved difficult for some individuals. In future studies, researchers might consider limiting the use of these caps to short periods of time around the follow-up assessment periods. Finally, cost of lab tests limited our ability to fully test the effect of the intervention on viral load and CD4 counts. Although there was some indication that those in the intervention group had more favorable lab values, future research should include systematic assessment of these indices. Finally, the types and doses of medications changed over the course of the study. Overall, these changes were made to reduce medication burden. The extent to which these types of changes influence medication adherence and the need for adherence support should be examined in future research.