Adherence to antiretroviral therapy is improved by antidepressant treatment in depressed HIV-positive patients, according to the results of a retrospective cohort study published in the 1st April edition of the Journal of Acquired Immune Deficiency Syndromes. The study also found that adherence was highest in patients who were also adherent to their antidepressant medication, leading the authors to call for greater attention to the diagnosis and treatment of depressive illness by healthcare workers.
Psychiatric disorders, including depression, are common in HIV-infected individuals. Overall, the lifetime prevalence of at least one psychiatric disorder is estimated to be 38% to 75%, compared with 33% for the general population. For depression, HIV-positive people have an estimated prevalence rate of 22% to 45%, compared with 15% for the general population.
Untreated depression has been associated with reduced adherence to antiretroviral medication. This can lead to the failure of antiretroviral therapy and the development of drug resistance, which can worsen prognosis and limit future treatment options.
To assess the effect of antidepressant treatment on adherence in depressed patients, investigators from Denver, Colorado analysed the medical records and pharmacy files of 1713 HIV-positive patients seen at an urban clinic between January 1997 and December 2001.
“A high prevalence rate of depression was observed among HIV-infected individuals, for whom antiretroviral therapy adherence improved after prescription of antidepressant therapy,” write the authors, “and reached even higher levels among individuals who were adherent to antidepressant therapy.”
Nine hundred and seventy-six (57%) of the patients were identified as being depressed and were included in the study. Of these, 450 (46%) were being treated with antidepressant drugs and 507 (52%) were receiving antiretroviral therapy, with 375 patients being on both antiretroviral and antidepressant medication.
The investigators estimated adherence to antiretroviral therapy by measuring the frequency of refills at the clinic pharmacy. Of those receiving antiretroviral therapy, the mean adherence rate was 72%, with 210 (26%) having optimal adherence rates of more than 95%.
Adherence was higher in patients who were taking antidepressant medication compared to those who were not (65 vs. 35%, p = 0.012).
In addition, the investigators found that patients who were adherent to their antidepressants were more adherent to their antiretroviral medication (69 vs. 31%, p = 0.001). For antidepressants, ‘adherence’ was defined as a rate equal to or greater than the median value.
Adherence to antiretrovirals improved in the six months following the prescription of antidepressant therapy (p < 0.001). This effect was observed in those who were adherent and those who were not adherent to their antidepressant medication. Adherence also increased across a similar timescale in patients who were not prescribed antidepressant medication (p < 0.001). However, the improvement in adherence to antiretrovirals was greater in the patients who were prescribed antidepressants, regardless of their level of adherence level (p < 0.005).
In a multivariate analysis, non-adherence to antiretroviral therapy was found to be associated with non-adherence to antidepressant drugs (p = 0.002) and alcohol use (p = 0.01), but not to age, gender, ethnicity, drug use or frequency of medical visits.
“Our analysis supports the importance of routine assessment of depression, prompt initiation of antidepressant therapy where indicated, and monitoring of antidepressant therapy adherence status,” state the investigators. “Mental health evaluation should be an integral health care component of all HIV-infected patients receiving medical care.”
The researchers did not have access to information on the patients’ depressive symptoms, so cannot conclude that improvement of sympoms was the cause of improved adherence. “Alternative hypotheses may explain the improved antiretroviral therapy adherence over time, such as increased interaction over time with providers (medical and psychiatric) who routinely encourage patients to adhere to all regimens,” they write.
“Those individuals adherent to antidepressant therapy were also more adherent to antiretroviral therapy. Although suggestive of a positive effect of antidepressant therapy toward improved antiretroviral therapy adherence, this might reflect an individual’s intrinsic adherence behaviour to any regimen.”
However, they acknowledge the limitations of their study’s retrospective design. “To corroborate these important findings, prospective studies are needed to assess the accuracy of diagnosis of depression, the correlation between adherence to antidepressant therapy and clinical improvement of depression, and the effect of the improved clinical depression on antiretroviral therapy adherence.”