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Special Focus: Occupational HIV in the emergency room
By Lisa Freeman Grossheim, MD, FACEP, and Katrin Takenaka, MD, FACEP, assistant professors of emergency medicine, Department of Emergency Medicine, University of Texas Medical School at Houston.
Preventing HIV transmission from patients to health care providers has been the subject of extensive research throughout the course of the HIV epidemic. Although it is an uncommon event,1,2 the consequences of occupational HIV transmission can be devastating. The overall risk of seroconversion after a percutaneous needlestick from a known HIV-positive source is widely reported to be 0.3% per exposure, as demonstrated by prospective data from almost 4000 health care workers.3 Mucous membrane exposure to HIV-positive blood has a lower transmission rate of 0.09%. Seroconversion in at least five health care workers has been reported after this form of exposure.4,5
The Centers for Disease Control and Prevention (CDC) defines occupational HIV exposure as a "percutaneous injury (e.g., needlestick, cut from a sharp object) or contact of mucous membranes on nonintact skin (e.g., skin that is chapped, abraded, or affected by dermatitis) with blood, tissue, or other body fluids that are potentially infectious."6 Potentially infectious fluids include cerebrospinal, synovial, pleural, peritoneal, pericardial, and amniotic fluids. Fluids not considered to be infectious unless visibly bloody include feces, nasal secretions, saliva, sputum, sweat, tears, urine, and vomitus.7
The incidence of occupationally transmitted hepatitis B infection has dramatically decreased since the widespread vaccination of health care providers and the general population.8 The CDC estimates that approximately 400 new occupational HBV infections occurred in 1995 among U.S. health care workers, down from 17,000 in 1983.8 The exact incidence of occupational hepatitis C infection transmission is unknown. There were an estimated 19,000 new HCV infections in 2006 in the United States, with 1.5% of the cases having a reported occupational exposure to blood.9 Although the risk of transmission of HIV and hepatitis to health care providers as a result of an occupational exposure is relatively low, the potential consequences of disease transmission are significant.
Percutaneous injury, often inflicted with a hollow-bore needle, is the most common mechanism of occupational HIV transmission.2,10 The handling of sharp instruments ("sharps") represents the greatest risk of HIV transmission to health care workers. Needlesticks are the most commonly reported occupational exposure route, accounting for approximately 80% of exposures.10 Recapping needles is the single most common activity that results in needlestick injuries.3 Needles should never be recapped, manipulated, bent, or broken. Other high-risk activities include improper disposal of used needles and transferring blood/body fluids between different containers.11 Risk of transmission of HIV to health care workers is increased when the device causing the injury was visibly contaminated with blood, when the device had been used for insertion into a deep vein or artery, when the device caused a deep injury, or when the source patient died within two months of the exposure.7,12-14 Latex gloves can be another source of exposure. Glove perforations are more likely when gloves are worn for longer periods, are used during critical care procedures, or are worn during more than one procedure.15
The CDC recommends that the best way to prevent transmission of bloodborne illness is to avoid exposure.7 Standard precautions should be used with all procedures that carry a potential risk of exposure. However, "universal precautions" are not used routinely by many health care providers. As many as 40% of needlestick injuries are preventable.3 Unfortunately, more than 50% of health care workers engage in inadequate infection control practices. Physician universal precaution compliance rates were highest for wearing gloves and disposing of sharps, but lowest for wearing protective clothing and not recapping needles.16
The emergency department management of precutaneous or mucus membrane exposure includes determining the type of exposure, evaluating the source of exposure, the health and immunization history of the exposed health care worker at the time of exposure, and providing appropriate follow-up of the health care worker after exposure. After sustaining an exposure, the health care worker should report the contact as outlined by institutional protocols.
Evaluation of a Potential Exposure
There is no simple way to determine the likelihood that an unknown or untested source is infected with HIV or hepatitis. A step-wise approach considering each variable is a reasonable approach to management of occupational exposures.17
Evaluate the Exposure Incident. The first step is to consider the specific incident that led to concern over potential exposure. Did percutaneous, mucous membrane, or nonintact skin contact potentially infectious material? Percutaneous injuries should be assessed as either less severe (solid needle and superficial) or more severe (large-bore needle, deep puncture, visible blood on device, or needle in patient's artery or vein). Mucocutaneous exposures are deemed either small (few drops) or large (major blood splash) volumes.7,18
There is a risk of disease transmission if the health care worker is exposed to blood, body fluids containing visible blood, cerebrospinal, synovial, pleural, peritoneal, pericardial, and amniotic fluids.19 If the exposure occurred to intact skin only, it is unlikely that a significant exposure occurred.
Determine the Status of the Source. The next step is to determine the HIV and hepatitis status of the source patient, if possible. The person whose blood or body fluid is the source of an occupational exposure should be evaluated for HIV, HBV, and HCV infection. Information available in the medical record at the time of exposure (e.g., laboratory test results or previous medical history) or questioning of the source might confirm HIV or hepatitis infection. If the source person is known to have HIV infection, obtain as much information as possible regarding the person's stage of infection (e.g., asymptomatic, symptomatic, or AIDS), CD4+ T-cell count, viral load, and current and previous antiretroviral therapy, as this is needed to assist in choosing an appropriate post-exposure prophylaxis (PEP) regimen. An exposure to a high-risk source patient may warrant an expanded PEP regimen. High-risk sources are patients with symptomatic HIV infection, AIDS, acute seroconversion, or high viral load. Low-risk sources are patients with asymptomatic HIV infection or viral load of less than 1,500 copies/mL.19,20
Testing to determine the HBV, HCV, and HIV infection status of an exposure source should be performed as soon as possible. If the HBV, HCV, and/or HIV infection status of the source is unknown, the source person should be informed of the incident, and his or her consent should be obtained for HIV and hepatitis testing. If the patient refuses or cannot give consent for testing, that patient should be considered to be infected.3 Some states allow testing the source patient without informed consent. Confidentiality should be protected while still ensuring that the appropriate information is provided to all exposed persons.6,20 Any individual diagnosed with HBV, HCV, or HIV should be referred for appropriate counseling and treatment.
The use of rapid HIV ELISA testing can result in decreased use of PEP and spare the health care provider both undue anxiety and the potential adverse effects of antiretroviral PEP.7 An FDA-approved rapid HIV-antibody test kit, if available, should be used to test the source. Confirmation of a reactive result with additional testing is not necessary to make initial decisions regarding post-exposure management, but should be done to complete the testing process and before informing the source person of a positive result on preliminary testing. A negative result on rapid testing is adequate for a decision to withhold or discontinue therapy if initiated.6 If the source person is HIV seronegative and has no clinical evidence of AIDS or symptoms of HIV infection, no further testing of the person for HIV infection is indicated. The likelihood of the source person being in the "window period" of HIV infection in the absence of symptoms of acute retroviral syndrome is extremely small.6 No case of transmission involving an exposure source during the window period has been reported in the United States.2
Unknown sources pose a more complicated problem. An example of an unknown source is a needle in a sharps container or a suture needle left on a tray. Testing of needles or other sharp instruments implicated in an exposure, regardless of whether the source is known or unknown, is not recommended. The reliability and interpretation of findings in such circumstances are unknown.6 If the exposure source is unknown or cannot be tested, information about where and under what circumstances the exposure occurred should be considered for the likelihood for transmission of HBV, HCV, or HIV. Expert consultation should be considered in this situation.
HIV Postexposure Prophylaxis
Because the majority of occupational HIV exposures do not result in transmission of HIV, the benefits of prescribing PEP should outweigh the risks of potential toxicity. The use of PEP is not justified for exposures that do not pose a credible risk for transmission of HIV. PEP should be provided following exposure of nonintact skin (through percutaneous sharps injury or skin abrasion) or mucous membranes (through splashes to the eyes, nose, or oral cavity) to a potentially infected body fluid from a source that is HIV-positive or has unknown HIV status.17 Because of the complexity of selection of HIV PEP regimens, consultation with an infectious disease specialist is strongly recommended in complicated cases.7
Although preventing exposures to blood and body fluids is the primary way to prevent occupationally acquired HIV infection, when an exposure occurs, appropriate post-exposure management is necessary.7 PEP is thought to prevent the establishment of HIV infection by blocking the replication of the viral inoculum.12 Initial guidelines for PEP were developed from an early study that demonstrated that health care personnel who were treated with zidovudine after needlestick exposures were less likely to seroconvert to HIV.21 Subsequently, the effectiveness of combination therapy for PEP was suggested from studies that showed multidrug therapy was superior to monotherapy in the treatment of HIV infection and in the prevention of perinatal transmission.7 Prospective, randomized studies to evaluate the efficacy of PEP in preventing HIV are unlikely to ever be conducted because the body of data that are generally supportive of its use create difficulty in withholding PEP for ethical reasons.17 Failure of PEP may result from repeated exposures to HIV, delayed initiation or short duration of PEP, drug-resistant viral strains, a large inoculum, or host factors.7,12
The preferred PEP regimen depends on the type of exposure as well as the HIV status of the source patient.6,7 There are no prospective data on the relative efficacy of two- and three-drug HIV PEP regimens. In most cases, when the source is unlikely to have HIV infection that is resistant to antiretroviral therapy, two-drug therapies are likely to be sufficient to prevent HIV transmission. The advantages of using two drugs as opposed to three include ease of administration, lower costs, and fewer side effects. In most cases, the addition of the third drug is considered to supply only a small increase in efficacy but adds significantly to the risk of side effects and reduced compliance.17
Current public health guidelines recommend a four-week regimen of two drugs for most HIV exposures that have occurred by percutaneous or mucous membrane routes.7
The emotional impact of a known or suspected HIV exposure is usually significant, especially in the first hours to days after the episode.24,25 Objective information about exposure risk and the pros and cons of post-exposure prophylaxis must be explained to an individual who is often emotionally upset.26,27 Health care workers who are too confused or upset to make a decision about PEP can sometimes be helped by suggesting that treatment be started immediately, with the option to stop it later. Health care workers who sustain exposure to HIV should be counseled to avoid potential transmission to others during the follow-up period, especially during the first 6-12 weeks after exposure, when seroconversion is most likely to occur.7 Sexual abstinence or condom use should be encouraged in high-risk exposures, as well as avoiding breast feeding.