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The association of adherence to antiretroviral therapy with healthcare utilization and costs for medical care

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Abstract

Background

The association between antiretroviral adherence, healthcare utilization and medical costs has not been well studied.

Objective

To examine the relationship of adherence to antiretroviral medications to healthcare utilization and healthcare costs.

Methods

A retrospective cohort study was conducted using data from 325 previously antiretroviral medication-naive HIV-infected individuals initiating first antiretroviral therapy from 1997 through 2003. The setting was an inner-city safety net hospital and HIV clinic in the US. Adherence was assessed using pharmacy refill data. The average wholesale price was used for prescription costs. Healthcare utilization data and medical costs were obtained from the hospital billing database, and differences according to quartile of adherence were compared using analysis of variance (ANOVA). Multivariate logistic regression was used to assess predictors of higher annual medical costs. Sensitivity analyses were used to examine alternative anti-retroviral pricing schemes. The perspective was that of the healthcare provider, and costs were in year 2005 values.

Results

In 325 patients followed for a mean (± SD) 3.2 (1.9) years, better adherence was associated with lower healthcare utilization but higher total medical costs. Annual non-antiretroviral medical costs were $US7612 in the highest adherence quartile versus $US10 190 in the lowest adherence quartile. However, antiretroviral costs were significantly higher in the highest adherence quartile ($US17 513 vs $US8690), and therefore the total annual medical costs were also significantly higher in the highest versus lowest adherence quartile ($US25 125 vs $US18 880). In multivariate analysis, for every 10% increase in adherence, the odds of having annual medical costs in the highest versus lowest quartile increased by 87% (odds ratio 1.87; 95% CI 1.45, 2.40). In sensitivity analyses, very low antiretroviral prices (as seen in resource-limited settings) inverted this relationship — excellent adherence was cost saving.

Conclusion

Better adherence to antiretroviral medication was associated with decreased healthcare utilization and associated costs; however, because of the high cost of antiretroviral therapy, total medical costs were increased. Combination antiretroviral therapy is known to be cost effective; lower anti-retroviral costs may make it cost saving as well.

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Acknowledgements

This study was presented in part at the 13th Conference on Retroviruses and Opportunistic Infections, Denver, CO, USA, 5–8 February 2006, poster no. 536.

This research was supported in part through the Bristol-Myers Squibb Virology Fellows Research Program, the Centers for Disease Control and Prevention grant U62/CCU806243, Adolescent and Adult Spectrum of Disease and Supplement to HIV/AIDS Surveillance. Dr Gardner is supported through the National Institute of Allergy and Infectious Diseases (NIAID) K01 AI067063. Dr Davidson is supported through a Health Resources and Services Administration (HRSA) grant (1 D12 HP 00054 PI: deGruy) for Academic Administrative Units in Primary Care.

The study design, data collection, data analysis, data interpretation, manuscript preparation and decision for submission were under the sole authority of the authors and decisions were made independently from the funders. The authors have no conflicts of interest that are directly relevant to the content of this study.

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Authors and Affiliations

  1. Denver Public Health, 605 Bannock St, Denver, CO, 80204, USA

    Edward M. Gardner, Moises E. Maravi, Cornelis Rietmeijer, Arthur J. Davidson & William J. Burman

  2. Department of Medicine, Division of Infectious Diseases, University of Colorado at Denver, Aurora, Colorado, USA

    Edward M. Gardner, Cornelis Rietmeijer & William J. Burman

  3. Department of Preventive Medicine and Biometrics, University of Colorado at Denver, Aurora, Colorado, USA

    Cornelis Rietmeijer & Arthur J. Davidson

  4. Department of Family Medicine, University of Colorado at Denver, Aurora, Colorado, USA

    Arthur J. Davidson

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  1. Edward M. Gardner
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  2. Moises E. Maravi
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  3. Cornelis Rietmeijer
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  4. Arthur J. Davidson
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  5. William J. Burman
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Correspondence to Edward M. Gardner.

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Gardner, E.M., Maravi, M.E., Rietmeijer, C. et al. The association of adherence to antiretroviral therapy with healthcare utilization and costs for medical care. Appl Health Econ Health Policy 6, 145–155 (2008). https://doi.org/10.1007/BF03256129

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