Discontinuing Medications Used To Prevent Pneumocystis carinii Pneumonia in Patients with HIV Infection

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The summary below is from the full report titled "Discontinuation of Chemoprophylaxis against Pneumocystis carinii Pneumonia in Patients with HIV Infection." It is in the 1 February 1999 issue of Annals of Internal Medicine (volume 132, pages 201-205). The authors are B.G. Yangco, J.C. Von Bargen, A.C. Moorman, and S.D. Holmberg, for the HIV Outpatient Study (HOPS) Investigator.

What is the problem and what is known about it so far?

Pneumocystis carinii pneumonia (PCP) is a type of lung infection that can occur in persons infected with the AIDS virus, HIV. Experts recommend that HIV-infected persons who do not have enough of a certain white blood cell (CD4 cells, with counts below 200) take medications that can prevent PCP. The CD4 count provides an indication of how severely the HIV infection has affected a person's immune system. Highly active antiretroviral therapies (HAART) are newer drug regimens that are very effective at treating HIV infection and raising CD4 counts. With HAART, PCP occurs much less frequently than it used to. Many physicians wonder whether it is safe to discontinue PCP-preventive medications if a patient's CD4 counts go above 200 in response to HAART. Stopping PCP-preventive medications is appealing because the pills can cause unwanted side effects and it reduces the number of pills patients with HIV infection need to take.

Why did the researchers do this particular study?

The researchers wanted to see whether patients whose CD4 counts rose above 200 while on HAART could actually stop taking the antibiotics used to prevent PCP without developing PCP.

Who was studied?

From 10 HIV clinics in 8 U.S. cities, 146 patients who stopped taking PCP-preventive medications and 345 patients who continued taking these medications after their CD4 counts rose above 200.

How was the study done?

After the patients in the study and their doctors decided whether to stop or to continue taking PCP-preventive medications, the researchers followed all patients to see who developed PCP.

What did the researchers find?

PCP did not develop in any of the patients, regardless of whether they had stopped or continued PCP-preventive medications. Patients who discontinued those medications appeared to be somewhat healthier with respect to their HIV disease than the patients who continued them.

What were the limitations of the study?

The patients who discontinued PCP-preventive medications had somewhat less severe HIV disease to begin with, and were therefore less likely to get PCP. In addition, the researchers only followed patients for an average of 14 to 18 months after stopping their preventive medications.

What are the implications of the study?

It may be safe to stop the medications used to prevent PCP in some patients with HIV infection whose CD4 counts rise above 200 in response to treatment for the underlying HIV infection.