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Adherence to Anti-HIV Therapy and the Outcome of Treatment
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What is the problem and what is known about it so far?
Treatments containing multiple antiviral drugs have greatly improved outcomes for HIV-infected patients. Regimens that contain powerful drugs called protease inhibitors can be particularly effective. These treatments can be difficult to follow, however, because patients need to take many pills several times a day. “Adherence ” is a term that means how often the patient takes a particular treatment as prescribed. Adherence to anti-HIV treatment is important because missing doses may let the virus multiply and can lead to poor outcomes.
Why did the researchers do this particular study?
To find out more about how adherence to protease inhibitor treatment is related to laboratory test results and outcomes in persons with HIV infection.
Who was studied?
Ninety-nine HIV-infected persons who received care at a Veterans Affairs Medical Center and a university hospital. All patients were prescribed medication regimens that included a protease inhibitor.
How was the study done?
Using special computerized caps that record the date and time whenever someone opens the medication bottle, the researchers measured how often patients took the protease inhibitor as prescribed. Over a follow-up period of 3 to 15 months, the researchers also collected information on patient characteristics; the number of HIV-related infections, hospitalizations, and deaths; and CD4 counts and viral loads (laboratory tests that measure the activity of HIV infection). When anti-HIV medicines are working, they increase the CD4 count and decrease the viral load.
What did the researchers find?
Eighty-one of the 99 patients completed the study. The viral load test indicated that the medicines were not working effectively in 22% of patients who took 95% or more of the protease inhibitor doses, 61% of those who took 80% to 95% of the doses, and 80% in those who took less than 80% of the doses as prescribed. Patients who took 95% or more of the doses as prescribed had fewer days in the hospital, HIV-related infections, and deaths than did patients who took protease inhibitors less often.
What were the limitations of the study?
This study included a small number of patients, and the findings may not apply equally to all HIV-infected patients. The researchers collected information about adherence to only one type of medicine, but the patients were taking many other anti-HIV medicines as well. Although computerized bottle caps are generally a good way to measure adherence, patients can open the bottle and not actually take the pills; they can also open the bottle once and remove several doses to take later.
What are the implications of the study?
Taking 95% or more of protease inhibitor doses as prescribed appears to be related to favorable outcomes for patients with HIV infection. However, improved strategies are needed to help patients take anti-HIV medications as prescribed.
Article and Author Information
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The summary below is from the full report titled “Adherence to Protease Inhibitor Therapy and Outcomes in Patients with HIV Infection.” It is in the 4 July 2000 issue of Annals of Internal Medicine (volume 133, pages 21-30). The authors are D.L. Paterson, S. Swindells, J. Mohr, M. Brester, E.N. Vergis, C. Squier, M.M. Wagener, and N. Singh.
- Copyright ©2004 by the American College of Physicians
