We assessed 7 different measures of interpersonal care, and 6 of the 7 were independently associated with our measure of adherence. Of these, 4 (general communication, overall satisfaction, willingness to recommend, and physician trust) were generic measures; that is, they were developed for use in general patient populations. One (HIV-specific communication) was a condition-specific scale that focused on physician-patient communication about sexual behaviors and substance abuse. And 1 (adherence dialogue) focused more specifically on how physicians communicate with their patients about antiretroviral medications. The consistency of our findings across these different scales supports the assertion that better physician-patient relationships and physician-patient communication produce better adherence with antiretroviral therapies.
The magnitude of the relationships between these physician-patient relationship quality measures and antiretroviral medication adherence can be appreciated both through the relatively low correlation coefficients seen in bivariate tests (between 0.13 and 0.21), and through the odds ratios in the final models, which ranged from 1.08 to 1.20. Adherence with antiretrovirals is a highly complex behavior, and it has been difficult for researchers to find variables that are strongly and consistently related to adherence. Because of this, it is particularly important that providers understand every potentially modifiable risk factor for poor adherence. Although the relationship between these physician-patient relationship quality variables and adherence is only of moderate strength, for several of the variables the magnitude of the relationship was similar to that of mental health, the variable that in this analysis was most consistently and strongly associated with adherence.
How mutable or modifiable are physician-patient relationships? Studies from several clinical specialties, including general medicine,19,23,26,35–37
oncology, and rehabilitation medicine24
suggest that both trainees and those who have finished training can be taught to behave in ways that are more patient centered. There is also good evidence that the improvements engendered by such training persist over time.38–40
However, no studies of which we are aware have directly examined whether such training improves medication adherence.
patients' beliefs about antiretroviral therapy were also statistically significantly associated with adherence in multivariate regression modeling. Our findings are consistent with those of others who have studied the relationship between patient beliefs and adherence in HIV10,11,41–43
or in other diseases.44
Trying to understand whether patients believe that taking antiretroviral medications will help them, and attempting to educate patients on the benefits and risks of highly active antiretroviral therapy, may improve adherence.
Consistent with previous data,5,14,45,46
we found that better mental health was associated with better adherence. Mental health problems are common in HIV disease,47–51
cause considerable morbidity,51
are highly treatable,52–54
and are often not detected by physicians.55–58
Our findings are another reminder to clinicians to be vigilant for symptoms of depression and other mental disorders in their patients with HIV.
This study had several important methodological strengths. We studied a diverse sample of persons with HIV cared for at 11 different care sites in a metropolitan area, and used multiple validated measures of interpersonal care. Nonetheless there were several relevant study limitations. First, we assessed adherence by report, and may have overestimated adherence rates.45,59
In addition, we used a Likert scale for adherence that cannot be directly translated into percent of prescribed doses taken or therapeutic coverage. However, this is a weakness of any self-report measure of adherence.
Second, it is theoretically possible that self-reports of adherence and patients' assessments of physician-patient relationship quality are both manifestations of a global positive or negative attitude that patients have about their physician and medical care, rather than truly independent measures. Future analyses of the association between physician-patient relationship quality and adherence would benefit from the use of an objective measure of adherence such as MEMS (Medication Event Monitoring System). Third, the generalizability of our findings may be limited by several factors. Because most of our respondents were contacted by mail, we suspect the types of nonresponse bias that are usually seen in mailed surveys,60,61
including fewer responses from nonwhites and those with low incomes, unstable housing, or active substance abuse. For example, only 8.5% of our patients reported injection drug use as their primary HIV risk factor. In addition, we sampled patients from practices of experienced HIV providers in one metropolitan area. However, national data suggest the most patients with HIV in this country are cared for by providers and in sites that have HIV expertise.62
Finally, although no cross-sectional study can unequivocally establish the direction of causal effects, it is unlikely that the direction of the causal relationships between physician-patient relationship quality and adherence was the reverse of that proposed. That is, it is unlikely that patients' reported adherence affects reports of physician-patient relationship quality. Whether improving physician-patient relationship quality can improve adherence can only be definitively addressed by an intervention trial. It is important to note, however, that intervention trials have clearly shown that improving physician-patient communication can result in better health outcomes.63–65
Our findings support the assertion that better adherence may have mediated these effects.
Few clinicians and even fewer researchers are familiar with the methods used to measure the quality of physician-patient relationships and to measure medication adherence. Our regression models describe how an increment of improvement in physician-patient relationship quality is associated with an increment of improvement in self-reported adherence, which we appreciate is not intuitive. However, these measurement and interpretation challenges are inherent in this field of research. The goal of this research was not to rigorously calibrate this relationship, but rather to present an empirical proof of the principal that higher quality physician-patient relationships are associated with better medication adherence. Because our results were both consistent across measures of physician-patient relationship quality and statistically significant, we believe that we have achieved this proof of principal.
This study shows that multiple dimensions of the physician-patient relationship are associated with medication adherence in persons with HIV infection. The observation that physicians can be trained to interact more effectively with their patients suggests that physician-patient relationship quality is a potentially important point of intervention for efforts to improve patients' medication adherence. In addition, our data suggest that it is critical to investigate and incorporate patients' belief systems about antiretroviral therapy into adherence discussions, and to identify and treat mental disorders.