Adherence to Protease Inhibitor Therapy and Outcomes in Patients with HIV Infection

  1. David L. Paterson, MB, BS, FRACP;
  2. Susan Swindells, MD;
  3. Jeffrey Mohr, MSW;
  4. Michelle Brester, RN;
  5. Emanuel N. Vergis, MD;
  6. Cheryl Squier, RN;
  7. Marilyn M. Wagener, MPH; and
  8. Nina Singh, MD
  1. From Veterans Affairs Medical Center and University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; and University of Nebraska Medical Center, Omaha, Nebraska.

    Abstract

    Background: Combination antiretroviral therapy with protease inhibitors has transformed HIV infection from a terminal condition into one that is manageable. However, the complexity of regimens makes adherence to therapy difficult.

    Objective: To assess the effects of different levels of adherence to therapy on virologic, immunologic, and clinical outcome; to determine modifiable conditions associated with suboptimal adherence; and to determine how well clinicians predict patient adherence.

    Design: Prospective, observational study.

    Setting: HIV clinics in a Veterans Affairs medical center and a university medical center.

    Patients: 99 HIV-infected patients who were prescribed a protease inhibitor and who neither used a medication organizer nor received their medications in an observed setting (such as a jail or nursing home).

    Measurements: Adherence was measured by using a microelectronic monitoring system. The adherence rate was calculated as the number of doses taken divided by the number prescribed. Patients were followed for a median of 6 months (range, 3 to 15 months).

    Results: During the study period, 45 397 doses of protease inhibitor were monitored in 81 evaluable patients. Adherence was significantly associated with successful virologic outcome (P < 0.001) and increase in CD4 lymphocyte count (P = 0.006). Virologic failure was documented in 22% of patients with adherence of 95% or greater, 61% of those with 80% to 94.9% adherence, and 80% of those with less than 80% adherence. Patients with adherence of 95% or greater had fewer days in the hospital (2.6 days per 1000 days of follow-up) than those with less than 95% adherence (12.9 days per 1000 days of follow-up; P = 0.001). No opportunistic infections or deaths occurred in patients with 95% or greater adherence. Active psychiatric illness was an independent risk factor for adherence less than 95% (P = 0.04). Physicians predicted adherence incorrectly for 41% of patients, and clinic nurses predicted it incorrectly for 30% of patients.

    Conclusions: Adherence to protease inhibitor therapy of 95% or greater optimized virologic outcome for patients with HIV infection. Diagnosis and treatment of psychiatric illness should be further investigated as a means to improve adherence to therapy.

    Article and Author Information

    • Presented in part at the 38th Interscience Conference on Antimicrobial Agents and Chemotherapy, San Diego, California, 24–27 September 1998, and the 6th Conference on Retroviruses and Opportunistic Infections, Chicago, Illinois, 31 January–4 February 1999.

    • Requests for Single Reprints: Nina Singh, MD, Veterans Affairs Medical Center, Infectious Disease Section, University Drive C, Pittsburgh, PA 15240.

    • Requests To Purchase Bulk Reprints (minimum, 100 copies): the Reprints Coordinator; phone, 215-351-2657; e-mail, reprints{at}mail.acponline.org.

    • Current Author Addresses: Dr. Paterson: European Medical Division, University of Pittsburgh Medical Center, 10th Floor, Forbes Tower, 200 Lothrop Street, Pittsburgh, PA 15213.

    • Dr. Swindells, Mr. Mohr, and Ms. Brester: University of Nebraska Medical Center, 985400 Nebraska Medical Center, Omaha, NE 68198-5400.

    • Drs. Vergis and Singh, Ms. Squier, and Ms. Wagener: Veterans Affairs Medical Center, University Drive C, Pittsburgh, PA 15240.

    • Author Contributions: Conception and design: D.L. Paterson, S. Swindells, J. Mohr, M. Brester, E.N. Vergis, C. Squier, N. Singh.

    • Analysis and interpretation of the data: D.L. Paterson, S. Swindells, M.M. Wagener, N. Singh.

    • Drafting of the article: D.L. Paterson, N. Singh.

    • Critical revision of the article for important intellectual content: D.L. Paterson, S. Swindells, C. Squier, M.M. Wagener, N. Singh.

    • Final approval of the article: D.L. Paterson, S. Swindells, E.N. Vergis, C. Squier, M.M. Wagener, N. Singh.

    • Provision of study materials or patients: D.L. Paterson, S. Swindells, J. Mohr, M. Brester, E.N. Vergis, C. Squier, N. Singh.

    • Statistical expertise: M.M. Wagener.

    • Obtaining of funding: D.L. Paterson, S. Swindells.

    • Administrative, technical, or logistic support: S. Swindells, J. Mohr, E.N. Vergis, C. Squier, N. Singh.

    • Collection and assembly of data: D.L. Paterson, S. Swindells, J. Mohr, M. Brester, E.N. Vergis, C. Squier, M.M. Wagener, N. Singh.

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    1. Ann Intern Med July 4, 2000 vol. 133 no. 1 21-30
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