In most studies, adherence refers solely to dose adherence, but successful treatment with ART also includes adhering to scheduling and adhering to dietary instructions that accompany many antiretroviral drugs [32
]. In this study we assessed scheduling and dietary instructions as two additional independent types of adherence and a combined indicator was made to determine the rate of adherence in the study area. Participants' self-reports of adherence in this study indicated a high degree of dose and scheduling adherence, while occasional suboptimal adherence of dietary instructions was quite common.
The rate of dose adherence in the study area was 96% at baseline and 94.3% at M3
; which is higher that reported in Addis Ababa and Arbaminch, Ethiopia [4
]. Consistent findings were also documented in comparable studies in resource limited settings in the sub-Saharan Africa [38
]. The overall rate of self reported adherence in the study area based on the combined indicators of the three adherence errors was 79.3% at base line and 75.7% at M3
. Some studies in resource-rich settings have documented less than 50% of patients taking all their antiretroviral medications on time and according to dietary instructions [31
]. This was much lower than our report confirming that patients in developing countries can achieve good adherence despite limited resources. Orrell et al
also found that low socio economic status was not a predictor of adherence for patients with fully subsidized therapy and concluded that adherence in developing countries has been found to be at least as good as adherence in developed countries [39
This relatively short prospective study underscores the dynamic nature of adherence. Though not significant, within three months, dose adherence decreased by 2%, food adherence by 1% and overall adherence rate reduced by more than 3%. The lack of statistical significance difference may be due to the short duration of follow up. Various studies have indicated the dynamic nature of adherence overtime [31
]. Thus, we believe that the continual monitoring of adherence rate and its determinants in Ethiopian should not be undermined and require further study.
The principal reasons reported for skipping doses were similar to other studies at both visits [4
]. The most important reasons our participants cited were simply forgetting, feeling sick or ill, being busy and running out of medication in more than 75% of the cases. This study shows that patients have a range of reasons for failing to adhere to their antiretroviral regimens. These reasons should be assessed for an individual patient and appropriate adherence-enhancing intervention should be undertaken. In this case, adherence counseling might incorporate strategies to avoid simply forgetting taking pills like the use of memory aids.
Researches' have already shown the dynamic character of HAART-treated patients' adherence behaviors, which are influenced by multiple factors varying over time [31
]. Our study also showed that even short-term non-adherence cannot be reliably predicted on the sole basis of a few patient characteristics that could vary over time. In line with this, depression was one of the predictor variables which were amenable for intervention. Patients who did not have depressive symptoms were two times more likely to be adherent than depressed one. Similar results were also reported in Addis Ababa, Ethiopia [4
]. These findings support a role for HIV/AIDS providers/counselors in screening for depression and providing treatment when appropriate, either directly or through collaboration with mental health professionals. Most importantly the formulation of simple and locally validated screening tool for depression in the Ethiopian context is underscored.
Our results also show that patients who claimed to use memory aids were three times more likely to be adherent than those who did not. This study shows that adherence interventions should include memory aids and other reminders to help patients take their drugs. Social support was a constant predictor of adherence identified in this study. Patients who reported social support were more likely to be adherent than those who did not. This is consistent with many comparable studies both in resource poor and resource rich settings [4
]. Hence, the initial adherence assessment and preparation should include a discussion on the sources of social support for the individual patient and an attempt should be made for possible solutions prior to starting HAART. Further, enlisting support to help patients take their medications correctly, from the family, community health workers, and PLWHA support groups should also be emphasized.
The findings of this study must be interpreted in the light of its limitations. Because it was conducted at a single site, the findings may not be generalizable to other clinical settings. There is no gold standard for measuring adherence and our measurement of adherence is only based on patients' reports of missed doses, scheduling instructions and dietary requirements. This may be subject to social desirability and recall biases and the literature suggests that patients tend to overestimate adherence [23
]. However, many other studies document that well collected self report data clearly correlates with virologic changes and is more practical in most settings [3
]. We were also unable to relate the obtained adherence rate to viral loads and CD4 cell responses due to financial and logistical barriers to frequent laboratory monitoring in this setting. Further, those subjects who have missed their clinical appointment at the follow up visit may have effect on the outcome of interest. Despite the aforementioned limitations, the prospective design allowed us to assess patient characteristics which are assumed to vary overtime and enabled us to detect the dynamic nature of adherence. Moreover, measurement of adherence was not only based on patients' intake of prescribed doses, but other important dimensions of adherence behavior (with respect to food and timing requirements of prescribed regimens) were examined.