The clinical efficacy of antiretroviral therapy (ART) in suppressing the HIV virus and improving survival rates for those living with HIV has been well-documented (1-3). However, successful antiretroviral therapy is dependent on sustaining high levels of adherence (correct dosage, taken on time, and in the correct way--either with or without food). The minimum level of adherence required for antiretroviral drugs to work effectively is 95% (4). Although more potent antiretroviral regimens can allow for effective viral suppression at moderate levels of adherence, no or partial adherence can lead to the development of drug-resistant strains of the virus (5-7). Adherence to ART is influenced by factors associated with the patient, the disease, the therapy, and the relationship of the patient with healthcare provider (8-10). Patient-related factors include socioeconomic status (SES) (8,10).
A review of studies since 2005 on SES and adherence to ART primarily in high-income countries, did not provide conclusive support for a clear association between SES and adherence (8). However, it is not clear what effect socioeconomic factors have on adherence to ART in low- and middle-income countries. A possible association between SES and adherence to ART among HIV patients may have an impact on the success of their treatment (8,10).
MATERIALS AND METHODS
We performed a systematic search of the literature to identify reviews and original studies that reported data on the impact of SES on adherence to ART. The relevant studies were identified by the use of electronic databases, such as MEDLINE, EMBASE, SCI Web or Science, NLM Gateway, and Google Scholar. The last search was conducted in November 2011. In addition, relevant articles from the list of references of the initially-retrieved papers were identified. Studies conducted only in low- and middle-income countries were included, according to World Bank classifications (11). Five different search strategies using the following key words were employed: (i) Socioeconomic status AND (HIV OR AIDS) AND (compliance OR adherence), (ii) (Compliance OR adherence) AND (HIV OR AIDS) AND determinants, (iii) (AIDS OR HIV) AND (compliance OR adherence) AND education AND/OR income AND/OR occupation, (iv) (AIDS OR HIV) AND (compliance OR adherence) AND determinants, and (v) (AIDS OR HIV) AND (compliance OR adherence).
Defining socioeconomic status (SES) is difficult because a single, consistent unit of measurement was not used in the studies reviewed. Further, a debate exists in the public-health arena on the appropriate components of socioeconomic status and methods of measurement (12). Krieger et al. (13) have argued that it is important to distinguish two different components of socioeconomic position (actual resources and prestige or rank-related characteristics), and they preferred the use of the term 'socioeconomic position' instead of 'socioeconomic status'. In addition, they argued that it is important to collect data at the individual, household and neighbourhood level (12,13). Additional points emphasized included that data on individuals supported from 'annual family income' should be collected, measurements should incorporate the recognition that socioeconomic position can change over a lifetime, and measures of socioeconomic position may perform differentially based on racial/ethnic group and gender background (12,13). Most of the reviewed articles did not attend to these complexities, rather used one to three measures of SES, most often simplistic measures of income, education, and occupation or employment status. The reviewed articles were analyzed with the understanding that the complexities present in SES highlighted by Krieger et al. (13) should ideally be incorporated in future studies designed to tease out the relationship between SES and adherence to ART in low- and middle-income populations. …