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Association of Antiretroviral Therapy Adherence and Health Care Costs

Jean B. Nachega, MD, PhD; Rory Leisegang, MBChB; David Bishai, MD, PhD; Hoang Nguyen, MD, MPH; Michael Hislop, MSc; Susan Cleary, PhD; Leon Regensberg, MBChB; and Gary Maartens, MBChB
[+] Article and Author Information

From Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, and Groote Schuur Hospital, Aid for AIDS, and University of Cape Town, Cape Town, South Africa.


Preliminary analyses included in this paper were given as a poster presentation at the 14th Conference on Retroviruses and Opportunistic Infections, 25–28 February 2007, Los Angeles, California, and as an oral presentation at the 4th Southern African AIDS Conference, 1 April 2009, Durban, South Africa.

Acknowledgment: The authors thank Joanna Downer, PhD, for editing and critical reading and David Dowdy, MD, PhD; Bruce Schackman, PhD; and Kenneth Freedberg, MD, MSc, for critical review and valuable advice.

Grant Support: By the Division of AIDS, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, grants R01 AI 5535901 and R01 AI 016137 (Drs. Nachega and Maartens) and Mentored Patient-Oriented Research Career Award K23 AI068582-01 (Dr. Nachega); the European Developing Countries Clinical Trial Partnership Senior Fellowship Award, TA-08-40200-021 (Dr. Nachega); the 2009 John McGoldrick Senior Fellowship Award, Center for Biostatistics in AIDS Research, Harvard School of Public of Health (Dr. Nachega); and the Doris Duke Charitable Foundation Operations Research on AIDS Care and Treatment in Africa Award (Dr. Maartens).

Potential Conflicts of Interest:Grants received: G. Maartens (National Institute of Allergy and Infections Diseases).

Reproducible Research Statement:Study protocol and statistical code: Available from Dr. Nachega (jnachega@hsph.harvard.edu). Data set: Available from Dr. Nachega after formal written agreement by the requesting party to protect patient confidentiality.

Requests for Single Reprints: Jean B. Nachega, MD, PhD, Center for Biostatistics in AIDS Research, Harvard School of Public Health, 651 Huntington Avenue, SPH-2 Building, Room 437C, Boston, MA 02115; e-mail, jnachega@hsph.harvard.edu.

Current Author Addresses: Dr. Nachega: Center for Biostatistics in AIDS Research, Harvard School of Public Health, 651 Huntington Avenue, SPH-2 Building, Room 437C, Boston, MA 02115.

Drs. Leisegang and Maartens: University of Cape Town, K45 Old Main Building, Groote Schuur Hospital, Observatory 7925, Cape Town, South Africa.

Dr. Bishai: Johns Hopkins School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205.

Dr. Nguyen: Tay Ho Clinics, 229 Hoang Hoa Thain Street, Hanoi, Vietnam.

Mr. Hislop and Dr. Regensberg: Aid for AIDS, Medscheme House, The Boulevard, Building F, Searle Street, Woodstock 7925, Cape Town, South Africa.

Dr. Cleary: University of Cape Town, School of Public Health and Family Medicine, Falmouth Building, Faculty of Health Sciences, Observatory 7925, South Africa.

Author Contributions: Conception and design: J.B. Nachega, M. Hislop, S. Cleary, G. Maartens.

Analysis and interpretation of the data: J.B. Nachega, R. Leisegang, D. Bishai, H. Nguyen, M. Hislop.

Drafting of the article: J.B. Nachega, G. Maartens.

Critical revision of the article for important intellectual content: J.B. Nachega, R. Leisegang, D. Bishai, H. Nguyen, M. Hislop, S. Cleary.

Final approval of the article: J.B. Nachega, H. Nguyen, M. Hislop, S. Cleary, L. Regensberg, G. Maartens.

Provision of study materials or patients: R. Leisegang, M. Hislop, L. Regensberg.

Statistical expertise: J.B. Nachega, R. Leisegang, D. Bishai, H. Nguyen.

Administrative, technical, or logistic support: R. Leisegang.

Collection and assembly of data: R. Leisegang, M. Hislop.


Ann Intern Med. 2010;152(1):18-25. doi:10.7326/0003-4819-152-1-201001050-00006
Text Size: A A A

Background: Antiretroviral therapy (ART) adherence predicts HIV disease progression and survival, but its effect on direct health care costs is unclear.

Objective: To determine the effect of ART adherence on direct health care costs among adults in a resource-limited setting.

Design: Cohort study.

Setting: Aid for AIDS, a private-sector disease management program in South Africa.

Patients: 6833 HIV-infected adults who started ART between 6 August 2000 and 30 April 2006.

Measurements: Monthly direct health care costs authorized by Aid for AIDS were averaged over all months. Pharmacy claim adherence, expressed as a percentage, was categorized into quartiles, from 1 (lowest) to 4 (highest). Effects of covariates on monthly total costs were assessed with a 2-step model with logit for probability of nonzero costs and a generalized linear model (GLM).

Results: Total mean monthly costs were $370 (SD, $644). Mean monthly costs of ART were $32 (SD, $18); hospitalizations, $151 (SD, $436); consultations, $76 (SD, $66); investigations, $37 (SD, $50); and non-ART medications, $53 (SD, $180). Total mean monthly costs ranged from $313 (SD, $598) for quartile 4 to $376 (SD, $657) for quartile 1. Hospitalization costs increased from 29% to 51% of total costs as adherence decreased. In the GLM 2-step model, moving from adherence quartile 1 to quartile 2, 3, or 4 increased the probability of having nonzero total monthly costs by 0.078, 0.15, and 0.21 percentage point, respectively (P < 0.001). For patients with nonzero costs, increasing adherence from quartile 1 to quartile 2, 3, or 4 decreased total monthly costs by $70, $133, and $192, respectively (P < 0.001). Moving from adherence quartiles 1 to 4 had the highest decrease in net overall median monthly health care costs (–$85 [interquartile range, –$116 to –$41]).

Limitations: Indirect health care costs were not included. Experience may not reflect that of public HIV/AIDS programs.

Conclusion: High ART adherence was associated with lower mean monthly direct health care costs, particularly reduced hospitalization costs, in this South African HIV cohort.

Primary Funding Source: National Institute of Allergy and Infectious Diseases, John McGoldrick Senior Fellowship for Biostatistics in AIDS Research, and the Doris Duke Charitable Foundation.

Figures

Grahic Jump Location
Figure 1.
Study flow diagram.

Adherence quartiles range from lowest adherence (first quartile) to highest adherence (fourth quartile). AfA = Aid for AIDS; ART = antiretroviral therapy; NNRTI = nonnucleoside reverse transcriptase inhibitor.

* No copayment, large size, long follow-up, and open enrollment.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Costs, by pharmacy claim adherence quartile.

Lowest adherence is the first quartile, and highest adherence is the fourth quartile. ART = antiretroviral therapy; Med = medication; VL = viral load.

Grahic Jump Location
Grahic Jump Location
Figure 3.
Net overall effect on total costs of moving from the lowest quartile of adherence to quartile 2, 3, or 4.

The calculation accounts for both the upward effect created by any adherence (step 1) and the downward effect of improved adherence (step 2). IQR = interquartile range.

Grahic Jump Location
Grahic Jump Location
Figure 4.
Kaplan–Meier plots of time to first hospitalization, by quartile of adherence.

Log-rank test results: P = 0.78 for quartile 2 vs. 1, P = 0.010 for quartile 3 vs. 1, and P < 0.001 for quartile 4 vs. 1. Lowest adherence is the first quartile, and highest adherence is the fourth quartile.

Grahic Jump Location

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Summary for Patients

Adherence to HIV Treatment and Costs of Care

The summary below is from the full report titled “Association of Antiretroviral Therapy Adherence and Health Care Costs.” It is in the 5 January 2010 issue of Annals of Internal Medicine (volume 152, pages 18-25). The authors are J.B. Nachega, R. Leisegang, D. Bishai, H. Nguyen, M. Hislop, S. Cleary, L. Regensberg, and G. Maartens.

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