CDC registry finds that PEP is safe for HCWs
But half drop off regimen due to side effects
Postexposure prophylaxis (PEP) for health care workers who experienced potential occupational exposures to HIV was generally safe, although discomforting side effects caused about one-quarter of the employees to quit the regimen, the Centers for Disease Control and Prevention in Atlanta recently reported.
The CDC collected data from 492 health care workers in an HIV Postexposure Prophylaxis Registry from October 1996 through March 1999 in an effort to determine whether the regimen led to any serious adverse effects. The absence of serious lasting effects among registry participants was good news for health care workers who take the powerful drugs to reduce their odds of HIV seroconversion after exposure.
While scientific evidence suggested that PEP would be effective in preventing HIV infection after occupational exposure, the CDC previously had few data to demonstrate the safety of these potent drugs, says Adelisa Panlilio, MD, MPH, a medical epidemiologist in the HIV Infections Branch of the CDC’s Hospital Infections Program.
"We were going out on a limb and recommending these drugs for healthy, uninfected workers. We were concerned about the thousands of workers who would take these drugs and wanted to find out if they had unexpected events or serious and unexpected adverse consequences," says Panlilio, adding that most of the CDC’s toxicity data had been collected from HIV-infected people.
Data don’t support conclusions about toxicity
The registry results confirmed the CDC’s belief that PEP was a safe preventive measure after an occupational exposure to bloodborne pathogens and that the drugs caused no unexpected serious side effects, says Panlilio. However, the CDC stated that the registry did not contain adequate power to support any definitive conclusions on the rates of occurrence of toxicity or to correlate toxicity with any particular drug.
The registry included data on 492 health care workers; 71% were female, and the overall median age was 37 years. The median time for exposure treatment was 1.75 hours. The majority (63%) of PEP regimens administered consisted of three or more drugs.
The data showed:
• Of the 449 HCWs for whom four to six weeks of follow-up data were available, the median therapy duration for at least one of the PEP drugs was 28 days.
• Overall, 195 workers completed all of the drugs in the PEP regimens as initially prescribed. In contrast, 197 discontinued all PEP drugs and did not complete the regimen. Also, 39 workers discontinued one or more drugs and/or modified drug dosage and/or added a drug but did complete a course of PEP. The remaining 16 workers completed modified regimens, which did not involve discontinuation of any of the drugs in the original regimen.
• Of the 197 workers who discontinued PEP drugs, 95 did so because the source patient tested HIV-negative. Half of the HCWs who discontinued all PEP drugs prematurely cited symptoms or adverse events as the reason.
• Seventy-six percent of the subjects with adequate follow-up data reported some symptoms or adverse events. The most frequently reported side effects were nausea (57%), fatigue/malaise (38%), headache (18%), vomiting (16%), and diarrhea (14%). Laboratory abnormalities were reported by only 8% of subjects. The median time from the start of PEP to the onset of the five most frequently reported side effects was three to four days.
• Serious adverse events were reported to the registry for six HCWs. All but one experienced resolution of symptoms by the six-month follow-up visit.
Effective dose and duration remain unknown
Failing to complete the postexposure regimen can alter its effectiveness, but researchers don’t know exactly what dose or duration is required to prevent HIV transmission, says David K. Henderson, MD, deputy director for clinical care at the Warren G. Magnuson Clinical Center of the National Institutes of Health in Bethesda, MD.
"Both the timing of the first dose and duration of therapy are important variables," he says. In animal studies, all animals treated within 24 hours were protected. Those given drugs for a duration shorter than one month had a higher rate of infection.
Changes in drugs or dosage or the use of other medications can reduce the severity of side effects, says Henderson. "We try hard to manage those symptoms, and I think we’re doing a better job of that than we did 10 years ago," he says.
Though patients who receive PEP may "feel very sick and experience lots of nausea, vomiting, and diarrhea," the registry data should reassure them that the drug regimens are safe over the four- to six-week period that most will take these drugs, said Panlilio.
The registry report mirrors findings from previous studies. Panlilio notes that the registry may contain some bias because many of the HCWs enrolled after three days following their exposures and had probably already begun a PEP regimen. "Maybe many of the health care workers who enrolled in the registry did so because they started having symptoms," she adds. No comparison registry exists to enable comparison with employees who did not receive PEP.
(Editor’s note: The CDC report is available on the Internet at www.cdc.gov/ncidod/hip/default.htm.)
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