CDC revises follow-up for HIV-exposed workers
Two-hour window is dropped
The Centers for Disease Control and Prevention has revised HIV postexposure prophylaxis (PEP) guidelines for health care workers, streamlining the complex process and adding a new emphasis on when PEP should not be administered.
"We tried to simplify the approach and make it clear when PEP is not indicated," says Linda Chiarello, MS, epidemiologist in the CDC hospital infections program and one of the principal authors of the new guidelines. "I think the previous recommendations were interpreted as anyone who had a blood exposure had to start PEP. The decision-making process wasn't always there."
In addition, since the provisional PEP recommendations were released in 1996, several new antiretroviral drugs have been approved by the Food and Drug Administration and more information is available about the use and safety of antiretroviral agents in exposed health care workers, the CDC noted. The guidelines include an algorithm to ease the complex decision process, reminding throughout when PEP should not be administered, when it should be considered, and when it should be recommended. (See charts, pp. 103-104.) Situations when PEP is not warranted, for example, include when the exposure does not involve blood or involves blood on intact skin, or if the source-patient is HIV-negative.
In general, the decision to recommend prophylaxis must take into account the nature of the exposure and the amount of blood or body fluid involved. Still, erring on the side of caution is understandable, Chiarello concedes.
PEP not justified for 'negligible risk'
"It's one thing to be sitting here and making recommendations, and another to be in the field guiding exposed health care workers," she says. "But there are certainly some circumstances where it is very appropriate to say, `this is just not the type of exposure that requires PEP.'"
Potential side effects are one of the prime reasons not to begin PEP unless warranted, with the CDC reminding that such a decision must balance the risk of infection against the potential toxicity of the agents used.
"Because PEP is potentially toxic, its use is not justified for exposures that pose a negligible risk for transmission," the guidelines state.
Also, there is insufficient evidence to recommend a highly active regimen for all HIV exposures, the CDC emphasizes. Instead, two PEP regimens are described: a "basic" two-drug regimen for most HIV exposures; and an "expanded" three-drug regimen for exposures that pose an increased risk for transmission or if resistance to one or more antiretroviral agents is known or suspected. The basic regimen is four weeks of zidovudine (600 mg per day in two or three divided doses) and lamivudine (150 mg twice daily). The expanded regimen is the basic regimen plus either indinavir (800 mg every eight hours) or nelfinavir (750 mg three times a day).
"We really have tried to streamline this, and have indicated that the three drugs are really intended for a higher-risk exposure where there is an increased opportunity for transmission," Chiarello says. "In part, that's because that is when the protease inhibitors work - after an infection has been established. So the majority of HIV exposures probably would warrant only two drugs."
CDC defers to clinical judgment
Acknowledging that there is not complete medical consensus on the recommended regimens, she notes that the guidelines allow clinicians to use their professional judgment in considering alternative drugs or regimens. The guidelines include an appendix that describes the many drugs currently available for postexposure prophylaxis.
"There are clinicians who believe if you are going to offer PEP that you just use everything that you've got and hit hard," she says. "With their experience, they are entitled to approach PEP in that way."
In an additional revision regarding timely administration of PEP, the CDC has dropped the former language recommending that PEP be administered within one to two hours of exposure, and recommends instead that it be initiated "as soon as possible after the exposure (i.e., within a few hours rather than days)." Although animal studies suggest that PEP probably is not effective when started later than 24 to 36 hours postexposure, the interval after which there is no benefit from PEP for humans is undefined. If there is a question about which antiretroviral drugs to use, or whether to use two or three drugs, it is probably better to start the basic regimen immediately than to delay PEP administration, the guidelines state.
"We removed the one-to-two-hour period [because] people really got locked into that," Chiarello says. "It was intended to be a kind of benchmark or message to quickly implement the regimen, but it was not intended to be so restrictive that if somebody didn't get treated within two hours they didn't get PEP. We try to communicate that this is an urgent medical concern - you don't ignore these exposures. And that PEP, if it is indicated, should be started as soon as possible."
Overall, the new CDC guidelines - particularly the flowchart - make the process easier to follow, says Jeannie Sanborn, RN, infection control practitioner at Heywood Hospital in Gardner, MA.
"They have streamlined it," she says. "They have made it easier to diagnose whether it is a small risk, a severe risk, whether or not you need to include a protease inhibitor, or if it is considered a low risk and two drugs would be OK. Or whether you need any drugs at all."
The guidelines generally support the system already in place at the hospital, which includes a three-drug PEP kit available in the emergency room, says Sanborn, who recently had to deal with a serious exposure incident involving an HIV-positive source patient. (See related story, below right.)
"This would not change anything," she says. "In fact, it pleases me that the recommendation is still the same because we do have those [recommended] drugs. We are a small community hospital. To keep all the drugs available is very costly, and they could outdate before I would ever have to use them."
Is PEP spurring increased reporting?
Another "side effect" of the PEP guidelines may be increased reporting of needlesticks, injuries that health care workers have historically underreported due to fear of disciplinary action or the perception that HIV was untreatable.
"Now that there is an effective treatment, there really is no reason not to report," says Robyn Gershon, MHS, DrPH, assistant research scientist who is studying needle safety and occupational blood exposures at Johns Hopkins University in Baltimore.
Though she still is awaiting survey results that should provide additional data, preliminary indications are that needlestick reporting has increased by 30% to 40% at Johns Hopkins and a nearby medical center since the first PEP guidelines were issued in 1996, Gershon says. The increase appears to be particularly strong among physicians, who have traditionally had low reporting rates, she adds. In addition, the PEP drugs are expensive and health care workers would have to find them on their own within a short time if they wanted treatment without reporting.
"You are so much better off getting [PEP] in-house, where you get it from the ER or from employee health," she says. "Even if they tried to get it on their own they won't get it faster or cheaper."
On the other hand, the CDC has not reported such a trend, and Chiarello notes that it may be difficult to ascribe an increase in reporting to a single intervention.
"We see a lot of health care workers being put on PEP, so it certainly is becoming an accepted practice," she says.
Increased reporting may become more apparent in the wake of the revised guidelines, which emphasize that health care workers should be educated to report occupational exposures immediately after they occur because PEP is most likely to be effective if implemented as soon as possible.
"Information about primary HIV infection indicates that systemic infection does not occur immediately, leaving a brief `window of opportunity' during which post-exposure antiretroviral intervention may modify viral replication," the guidelines state.
Reference
1. Centers for Disease Control and Prevention. Public Health Service guidelines for the management of health-care worker exposures to HIV and recommendations for postexposure prophylaxis. MMWR 1998; 47(No. RR-7):1-33.
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