Elsevier

Social Science & Medicine

Volume 72, Issue 8, April 2011, Pages 1383-1392
Social Science & Medicine

Non-adherence to antiretroviral treatment and unplanned treatment interruption among people living with HIV/AIDS in Cameroon: Individual and healthcare supply-related factors

https://doi.org/10.1016/j.socscimed.2011.02.030Get rights and content

Abstract

In low-income countries, health system deficiencies may undermine treatment continuity and adherence to antiretroviral therapy (ART) that are crucial for the success of large-scale public ART programs. In addition to examining the effects of individual characteristics, on non-adherence to ART and treatment interruption behaviors – i.e. treatment interruption for more than 2 consecutive days during the previous 4 weeks, this study aims to extend our knowledge on the role played by healthcare supply-related characteristics in shaping these two treatment outcomes. These effects are examined using multilevel logistic models applied to a sub-sample of 2381 ART-treated patients followed-up in 27 treatment centers in Cameroon (ANRS-EVAL survey, 2006–2007).

Multivariate models show that factors common to both non-adherence and treatment interruption include binge drinking (at the individual-level) and large hospital size (at the healthcare supply-level). Among the individual factors, financial difficulties of paying for HIV-care are the major correlates of treatment interruption [Adjusted Odds Ratio (AOR) 95% confidence interval (CI) = 11.73(7.24–19.00)]. By contrast, individual factors associated with an increased risk of non-adherence include: having a main partner but not living in a couple compared to patients living in a couple [AOR(95%CI) = 1.51(1.14–2.01)]; experience of discrimination in the family environment [AOR(95%CI) = 1.74(1.14–2.65)]; a lack of regular meals [AOR(95%CI) = 1.93(1.44–2.57)], and switching antiretroviral drugs (ARV) regimen [AOR(95%CI) = 1.36(1.08–1.70)]. At healthcare facility-level, the main correlate of ART interruption was antiretroviral stock-outs [AOR(95%CI) = 1.76(1.01–3.32)] whereas the lack of psychosocial support from specialized staff and lack of task-shifting to nurses in medical follow-up were both associated with a higher-risk of non-adherence [respective AOR (95%CI) = 2.81(1.13–6.95) and 1.51(1.00–3.40)].

Results reveal different patterns of factors for non-adherence and treatment interruption behaviors. They also suggest that psychosocial support interventions targeted at the individual patient-level will not be sufficient to achieve favorable treatment outcomes if not combined with interventions focused on strengthening health systems, including appropriate drug supplies and human resources policies, as well as sustainable and equitable financing mechanisms.

Introduction

Although the availability of antiretroviral therapy (ART) has increased rapidly in recent years, the estimated coverage of those in need (42%) is still far from the internationally agreed goal of “universal access” by 2010 (WHO, UNICEF, & UNAIDS, 2009). Nonetheless, to achieve favorable ART outcomes, scaling-up ART programs should go hand in hand with maximizing adherence and treatment continuity, which are key determinants of treatment outcomes and programs’ effectiveness (Harries, Schouten, & Libamba, 2006). Experience of ART roll out has shown that African people living with HIV/AIDS (PLWHA) can reach similar, or even higher levels of adherence compared with those of developed countries, once the financial access barriers to antiretroviral drugs (ARV) are removed (Mills Nachega Bangsberg et al., 2006, Mills Nachega Buchan et al., 2006). Moreover, while treatment interruptions and low adherence are important predictors of drug resistance (Oyugi et al., 2007), observed levels of resistance to first-line ARV regimens in Africa, though already worrying, appear not to currently threaten the public health effectiveness of ART programs (Gupta et al., 2009, Kouanfack et al., 2009).

Previous research on ART adherence in sub-Saharan Africa has mostly focused on either characteristics of treatment regimens (Atkinson & Petrozzino, 2009), or patients’ characteristics (Duggan, Locher, Fink, Okonta, & Chakraborty, 2009), placing emphasis on psychosocial interventions (Ford, Nachega, Engel, & Mills, 2009) and renewing interest in the role of community health workers (CHW) (Koenig et al., 2004, Wouters et al., 2009, Wouters et al., 2008).

There is however growing evidence that the main challenges faced by ART programs in sub-Saharan Africa are due to structural deficiencies within the health systems, related especially to healthcare supply component, including the lack of appropriate infrastructure and human resources (Samb et al., 2009, Van Damme et al., 2008). Such weaknesses in the African healthcare supply exercise a strong negative influence not only on ART adherence, but also on treatment continuity. Moreover, some studies have found that for the most common ARV first-line regimens in Africa, unplanned treatment interruptions pose a greater risk of virological and clinical failure than do the same number of interspersed missed doses at low-to-moderate adherence (Oyugi et al., 2007, Parienti et al., 2008), and that these interruptions may be related to patients’ negative experience with the healthcare facilities (Marcellin et al., 2008).

The EVAL survey (ANRS 12–116) conducted in 2006–2007 as part of the independent evaluation of the national ART program in Cameroon provided us the opportunity to explore the role played by healthcare supply-related characteristics on ART adherence and on treatment interruption in a low-income country context. The objectives of this study are twofold: first, it aims to examine the effects of the supply-side while assessing non-adherence and treatment interruption, and secondly to identify whether these two outcomes have a set of common factors (individual and healthcare supply-related) or whether each of them presents specific correlates.

Cameroon suffers from a generalized HIV epidemic, with an estimated average HIV prevalence of 5.5% in the adult population (15–49 years of age), which increases to 11.9% in women in the most affected areas (UNAIDS, 2008). Through the national ART program, initiated in 2001, a total of 75,000 PLWHA had access to ART at the end of 2009 in circa 120 treatment centers throughout the country (National AIDS Control Committee, 2009).

A key factor in the rapid increase in access to ART has been the use of the pre-existing decentralized framework of the Cameroonian health system to deliver HIV-care and ART at the district level. Accredited Treatment Centers (ATC) were first set up during 2001–2002 in the central hospitals of the two main cities of Cameroon, Yaoundé and Douala, and in each provincial hospital from the eight other provinces. Diffusion of ART delivery services was then extended from 2005 onwards with the implementation of HIV Management Units (MU) in district hospitals. In accordance with WHO recommendations for scaling-up ART in resource-limited settings, simplified HIV-care guidelines were introduced in decentralized MU to allow ART initiation even when CD4 counts are not available, using only total lymphocytes count and clinical stage (Ministry of Public Health, 2005). Four standard regimens composed of two nucleoside reverse transcriptase (NRTI) and one non-nucleoside reverse transcriptase (i.e. zidovudine or stavudine + lamivudine + nevirapine or efavirenz) were recommended in first-line and four regimens in second line including one protease inhibitor (lopinavir) and two NRTI (i.e. abacavir or lamivudine + didanosine or tenofovir).

Like most of the countries in sub-Saharan Africa, Cameroon applied the user fees policy to health services at the beginning of the 90’s (Chabot, 1988). With respective public and total health expenditures of 20 USD and 94 USD per capita in 2009 (purchasing power parity), health financing is largely supported by the population through out-of-pocket payments, estimated at 80% of total health expenditures (WHO, 2009). A global budget of circa 138 million US$ has been allocated to the HIV infection by the international community during the period 2003–2007 with the Global Fund to Fight AIDS, Tuberculosis and Malaria representing 61% of the total financing. Although the contribution of the Cameroonian government increased from 2.4 million US$ in 2002 to 9.6 million US$ in 2007, its contribution was estimated to represent only 12% of the total expenditures allocated to the disease during 2003–2007 (Nkoa, Eboko, & Moatti, 2010). Biological tests and ART prices have thus been strongly subsidized with the aim of enhancing accessibility however user fees were applied at the time of the survey and remained until May 2007 when free access to ART was adopted. For all others services, such as medical consultation, hospitalization or drugs for opportunistic infections, PLWHA have also to pay various user fees.

Section snippets

Data collection

The EVAL – ANRS 12–116 survey (September 2006–March 2007) was conducted among a random sample of 3151 HIV-positive adult outpatients followed-up in 27 hospitals (8 national ATC in Douala and Yaoundé, 6 provincial ATC and 13 district MU) located in six of the ten provinces of Cameroon. Provinces were selected to better represent the country’s cultural and socio-economic diversity as well as differences in the HIV prevalence. All the treatment centers, which were operational in these provinces at

Results

A total of 3488 HIV-positive patients were randomly selected among eligible patients who consulted in the 27 treatment centers during the survey period. Of these, 3170 agreed to participate and 3151 filled out the questionnaire completely (global response rate: 90.3%). No significant differences were found between participants and non-participants regarding the main socio-economic factors (gender, age, economic activity, transport time to the hospital and access to treatment), except regarding

Discussion

ART adherence have been widely studied in both high- and low-income countries (Mills et al., 2006b), however, this is the first study in a sub-Saharan African country that proposes an analysis distinguishing between two treatment outcomes: non-adherence and treatment interruption behaviors, while exploring the roles jointly played by individual characteristics and structural factors related to healthcare supply. It highlights that the latter set of covariates is specific to each of the above

Acknowledgments

We would like to thank the French National Agency for Research on AIDS and Hepatitis (ANRS) and the French NGO SIDACTION for their financial support to the research project. We also thank the Cameroonian Ministry of Public Health for its technical support, especially Professor Koulla-Shiro, Head of the Operational Research Department and the medical themes of the 27 participating hospitals for their hospitality and strong involvement in the EVAL survey. Thanks are also due to all the patients

References (43)

  • M. Camara et al.

    Procurement policies, governance models and ARV availability in French-speaking African countries: an overview

  • P. Carrieri et al.

    The dynamic of adherence to highly active antiretroviral therapy: results from the French National APROCO cohort

    Journal of Acquired Immuno Deficiency Syndrome

    (2001)
  • J. Cheng et al.

    Real longitudinal data analysis for real people: building a good enough mixed model

    Statistics in Medicine

    (2010)
  • R. Cohen et al.

    Antiretroviral treatment outcomes from a nurse-driven, community-supported HIV/AIDS treatment programme in rural Lesotho: observational cohort assessment at two years

    Journal of International AIDS Society

    (2009)
  • J.M. Duggan et al.

    Adherence to antiretroviral therapy: a survey of factors associated with medication usage

    AIDS Care

    (2009)
  • N. Ford et al.

    Directly observed antiretroviral therapy: a systematic review and meta-analysis of randomised clinical trials

    Lancet

    (2009)
  • H. Goldstein et al.

    Partitioning variation in multilevel models

    Understanding Statistics

    (2002)
  • J. Hox

    Multilevel analysis: Techniques and applications

    (2002)
  • A.C. Justice et al.

    Development and validation of a self-completed HIV symptom index

    Journal of Clinical Epidemiology

    (2001)
  • S.P. Koenig et al.

    Scaling-up HIV treatment programmes in resource-limited settings: the rural Haiti experience

    AIDS

    (2004)
  • C. Kouanfack et al.

    Low levels of antiretroviral-resistant HIV infection in a routine clinic in Cameroon that uses the World Health Organization (WHO) public health approach to monitor antiretroviral treatment and adequacy with the WHO recommendation for second-line treatment

    Clinical Infectious Diseases

    (2009)
  • Cited by (89)

    • Cost-effectiveness of public-health policy options in the presence of pretreatment NNRTI drug resistance in sub-Saharan Africa: a modelling study

      2018, The Lancet HIV
      Citation Excerpt :

      In our model, we capture the fact that some people discontinue ART and become disengaged from care and that this is more likely in people who are poorly adherent or for whom ART is failing, or both. These people are therefore likely to have NNRTI drug resistance.33–35 Nevertheless, model outputs for the proportion of ART initiators with NNRTI pretreatment drug resistance who have previous antiretroviral drug exposure were not substantially higher than for those who have no previous antiretroviral drug exposure, which is in contrast with survey findings of pretreatment drug resistance that show markedly higher levels.

    View all citing articles on Scopus
    View full text