030227 occupational exposure to hiv in health care settings

The new england journal of medicine Julie Louise Gerberding, M.D., M.P.H.
This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author’s clinical recommendations. While obtaining a peripheral venous blood sample from a patient with the acquired im-
munodeficiency syndrome (AIDS), a 35-year-old phlebotomist is injured by a bloody
18-gauge needle attached to a syringe. The patient has been taking didanosine and
stavudine for more than six months, but her quantitative plasma human immunode-
ficiency virus (HIV) RNA titer and CD4 T-lymphocyte count have not been measured for
many weeks. What is the appropriate postexposure treatment for the phlebotomist?
Health care personnel who have occupational exposure to blood are at risk for HIV in- fection. Prevention of blood exposure, through safer practices, barrier precautions, safer quests to Dr. Gerberding at the Centers forDisease Control and Prevention, Mailstop needle devices, and other innovations, is the best way to prevent infection with HIV and D14, 1600 Clifton Rd., Atlanta, GA 30333, other bloodborne pathogens.1,2 Although these strategies have been successful in reduc- ing the frequency of blood exposure and needle-stick injuries in the past decade, the Copyright 2003 Massachusetts Medical Society. As of December 2001, the Centers for Disease Control and Prevention (CDC) had re- ceived voluntary reports of 57 documented cases of HIV seroconversion temporallyassociated with occupational exposure to HIV among U.S. health care personnel.1,3 Anadditional 138 infections among health care personnel were considered possible casesof occupational HIV transmission. Occupational transmission of HIV has been report-ed in most countries, but the global surveillance data required to estimate the true fre-quency of this problem are not available. Because there is no cure or effective vaccine forAIDS, optimal postexposure care, including the administration of antiretroviral drugsto prevent HIV infection, remains a high priority for protecting health care personnel.
Percutaneous injury, usually inflicted by a hollow-bore needle, is the most common mechanism of occupational HIV transmission. The CDC estimates that more than380,000 needle-stick injuries occur in U.S. hospitals each year; approximately 61 per-cent of these injuries are caused by hollow-bore devices.4 Although the number of nee-dle-stick injuries that occur in nonhospital settings, where 60 percent of the health carelabor force is employed, is not known, it is probably large. The proportion of injuriesinvolving exposure to blood from HIV-infected sources is not known, but each exposureis an urgent health issue for the exposed person. Clinicians in emergency departments,acute care clinics, and many other primary care settings must be equipped to assess thepotential for HIV transmission after occupational exposure to blood and must determinethe need for treatment and testing. Such clinicians must also be able to administer im-mediate postexposure treatment when indicated and refer exposed persons for appro-priate follow-up medical care and counseling.
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health care personnel suggest that the average risk s t r a t e g i e s a n d e v i d e n c e of HIV transmission is approximately 0.3 percent There are two main strategies for managing occu- (95 percent confidence interval, 0.2 to 0.5) after apational exposure to blood. The first approach is to percutaneous exposure to HIV-infected blood andprovide empirical treatment with two or more anti- approximately 0.09 percent (95 percent confidenceretroviral drugs unless additional information (e.g., interval, 0.006 to 0.5) after a mucous-membranethe result of an HIV test in the source patient or a exposure.1 The average risk associated with expo-detailed description of the exposure) suggests that sure of nonintact skin and exposure to HIV-infectedthis treatment is not warranted. The second ap- fluids and tissues other than blood or bloody fluidsproach is to conduct a thorough assessment of the is too low to be estimated in prospective studies. Inexposure (including an HIV test in the source patient a retrospective study, the CDC found that the risk ofif HIV infection has not already been diagnosed) and transmission of HIV to health care workers was in-then initiate antiretroviral treatment only if the ex- creased when the device causing the injury was vis-posure poses a risk of HIV transmission. A single ibly contaminated with blood, when the device hadantiretroviral drug or two or more antiretroviral been used for insertion into a vein or artery, whendrugs in combination may be used. Factors that the device caused a deep injury, or when the sourceshould be considered in the choice of treatment for patient died within two months after the exposure.8an exposed health care worker include the risk of These risk factors may be surrogate markers of theHIV infection associated with the exposure, the ex- viral inoculum (the volume of the exposure and thepected benefit of antiretroviral treatment, the risks viral titer), but this hypothesis has not been proved.
associated with the proposed treatment, and the A low plasma HIV RNA titer may indicate a lowerprobability that the infecting strains will be suscep- inoculum but does not exclude the possibility oftible to the antiretroviral regimen used.1 transmission, especially since this measurementdoes not account for cell-associated HIV. Transmis- r i s k o f h i v t r a n s m i s s i o n
sion from source patients with undetectable HIV A patient whose blood or other potentially infectious RNA has, in fact, been documented.1body fluid is involved in an occupational exposure Suture needles have not been implicated as a should be evaluated to determine the likelihood of source of infection in prospective studies, but oc-HIV infection, in accordance with relevant state reg- cupational HIV infection has been reported amongulations and local policies. The interval between the surgical personnel, and suture needles are one po-onset of viremia and the detection of HIV antibody, tential source of such infection. Exposure of intactwith the use of current enzyme immunoassays for skin to contaminated blood has not been identifiedHIV, is a few days at most.5 Hence, if the result of a as a risk for HIV transmission. The risk associatedreliable HIV test in the source patient is negative, with bite injuries has not been quantified, but boththe risk of transmission is assumed to be zero, un- the biter and the victim should be evaluated for theless the patient has risk factors for infection and the possibility of infection. The victim is usually at lowclinical findings are compatible with acute HIV in- risk unless the biter’s saliva is contaminated withfection (e.g., fever, pharyngitis, rash, lymphadenop- blood, as might happen during an altercation. If theathy, and malaise).
bite results in a puncture wound or bleeding, then The use of a rapid HIV test can reduce the time the biter may have had mucosal exposure to the vic- needed to rule out HIV infection to a few hours or tim’s blood, which poses a risk of infection that is
less. One test that is currently available, the Single low but greater than zero if HIV is present.1
Use Diagnostic System HIV-1 Test (Abbott-Murex
Diagnostics), is highly sensitive, and a negative re- benefits of chemoprophylactic treatment
sult is reliable evidence that infection is not present.6 A convergence of indirect evidence suggests that
A positive test is presumptive evidence of HIV infec- treatment with antiretroviral drugs soon after occu-
tion, but confirmatory tests should be performed, pational exposure to HIV decreases the risk of in-
since false positive results do occur. When properly fection. The pathogenesis of the initial infection
performed by experienced laboratory personnel, provides suggestive evidence that there is a window
rapid testing may not only decrease unnecessary an- of opportunity in which antiretroviral treatment can
tiretroviral treatment and save money but also allay prevent infection or abort it before irreversible sys-
the anxiety of the exposed person.7
temic infection and HIV seroconversion occur.
Pooled data from several prospective studies of Early animal models provided conflicting infor- Downloaded from www.nejm.org by GERARDO MARTINEZ-TOVAR on January 31, 2004.
Copyright 2003 Massachusetts Medical Society. All rights reserved.
The new england journal of medicine mation about the probability of effective postexpo- discontinuation of treatment than are two-drug reg-sure prophylaxis, but more recent and more appro- imens.26priate models have consistently demonstrated the A variety of adverse effects have been associated benefit of treatment.9-13 Several factors appear to af- with postexposure prophylaxis (Table 1). Seriousfect the probability of transmission in animal mod- events are rare, but they do occur and can be life-els of postexposure treatment: the viral inoculum, threatening. Nephrolithiasis, impaired ocular mus-the interval between viral inoculation and the initi- cle movement, hepatitis, hyperglycemia, and pancy-ation of treatment, the duration of treatment, and topenia have been reported.1,26-31 From March 1997the choice of antiretroviral drugs.10,11,13 through September 2000, the Food and Drug Ad- In the CDC’s retrospective case–control study of ministration received reports of 22 persons with health care personnel, postexposure treatment with one or more serious adverse events related to thezidovudine was associated with an 81 percent reduc- use of nevirapine as prophylaxis against HIV infec-tion (95 percent confidence interval, 43 to 94) in the tion.30,31 There were 12 cases of hepatotoxicity (1 ofrisk of HIV infection.5 However, there are no data which led to liver transplantation), 14 cases of skinfrom randomized, controlled trials to assess the ef- reactions (including 1 documented and 2 possibleficacy and effectiveness of postexposure prophylaxis cases of the Stevens–Johnson syndrome), and 1 caseamong health care personnel. Given the low risk of of rhabdomyolysis. On the basis of these reports,transmission, several thousand persons would nevirapine is not generally recommended for pro-have to be enrolled for such a trial to have enough phylaxis. Because teratogenic effects have been ob-power to show an effect. Data from clinical trials of served in primate studies, efavirenz is not recom-prophylaxis against perinatal HIV transmission mended during pregnancy. Reports of fatal lacticconsistently demonstrate that antiretroviral treat- acidosis in pregnant women treated with a combi-ment can prevent HIV infection after exposure, even nation of stavudine and didanosine have promptedamong neonates who are not treated until after warnings about the use of these drugs during preg-birth.14-19 The relevance of this clinical situation to nancy. Indinavir is not recommended for use at theoccupational exposure is not known.
end of pregnancy because of the risk of hyperbili- Although these data are encouraging, it is clear rubinemia in newborns.1,32 that, whatever benefit is afforded by postexposure
treatment, the protection is not absolute. Twenty- antiretroviral-drug resistance
one cases of HIV infection have been reported in Resistance to antiretroviral drugs is a growing prob-
health care personnel in the United States and else- lem for all patients, including those whose blood is
where, despite postexposure antiretroviral treat- implicated in an occupational exposure. A study of
ment, which included two or more antiretroviral occupational exposure conducted at seven U.S. sites
drugs in some cases.1,20-25 A variety of factors may in 1998 and 1999 showed that 16 of 41 source per-
have contributed to the treatment failure, including sons whose HIV viral genome was sequenced (39
an intrinsic lack of efficacy of prophylactic antiretro- percent) had mutations associated with resistance
viral treatment and resistance to antiretroviral drugs. to reverse-transcriptase inhibitors, and 4 (10 per-
cent) had mutations associated with resistance to r i s k s a s s o c i a t e d w i t h c h e m o p r o p h y l a c t i c
protease inhibitors. Resistance to antiretroviral t r e a t m e n t
drugs is most likely in patients with clinical progres- All antiretroviral agents are associated with adverse sion of disease, increasing quantitative plasma HIVevents, especially gastrointestinal symptoms. Data RNA titers, a decline in the CD4 T-lymphocytefrom the National Surveillance System for Health count, or a combination of these findings.34 Unfor-Care Workers and the HIV Postexposure Prophylaxis tunately, clinical data alone are not reliable in detect-Registry indicate that nearly 50 percent of health ing resistance, and data from genotyping or phe-care personnel report adverse events while taking notyping assays are rarely available in time to guideantiretroviral drugs prophylactically, and about one decisions about empirical postexposure treatment.
third stop taking the drugs as a result.1,26 Most of For this reason, two or more antiretroviral drugs arethese symptoms are not serious and can be man- usually used for prophylaxis after occupational ex-aged. Prophylactic regimens that include three drugs posure.1are more likely to result in adverse events and early Downloaded from www.nejm.org by GERARDO MARTINEZ-TOVAR on January 31, 2004.
Copyright 2003 Massachusetts Medical Society. All rights reserved.
Table 1. Basic and Expanded Regimens of Postexposure Prophylaxis against Human Immunodeficiency Virus Infection.*
Primary Adverse Effects
muscle pain, weakness; lamiv-udine: abdominal pain, nau-sea, diarrhea, rash, pancreatitis nia, anorexia, pancreatitis, elevated liver-function values, anemia, neutropenia Didanosine, available as a chewable or dis- persable buffered tablet (Videx) or as a delayed-release capsule (Videx EC), plus daily if a buffered tablet is used), or 250 mg daily if a de-layed-release capsule is used; 40 mg of stavudine twice daily Expanded (basic regimen plus one of the
following)
syndrome), insomnia, somno-lence, dizziness, trouble con-centrating, abnormal dreaming dominal pain, fatigue, head-ache, insomnia, hypersensitivi-ty reactions * The information is adapted from the recommendations issued in 2001 by the Public Health Service.1† A combined formulation is also available (Combivir); the recommended dose is one tablet twice a day.
‡ Abacavir is available as a combined formulation with zidovudine and lamivudine (Trizivir).
tified.35,36 Neither the window of opportunity dur- ing which postexposure antiretroviral treatment is It is unclear why 99.7 percent of occupational inju- beneficial nor the optimal duration of treatment forries involving percutaneous exposure to HIV do not the prevention of infection is known.
transmit infection, and an assessment of the risk of The most effective and safest antiretroviral regi- transmission therefore remains imprecise. Poten- men for exposed persons also remains uncertain.
tially relevant factors, such as the role of the host’s A combination of three or more antiretroviral agentsimmunologic response and characteristics of the is usually advised for the treatment of HIV infection,viral strain that affect infectivity, have not been iden- but there is no clinical evidence that such combina- Downloaded from www.nejm.org by GERARDO MARTINEZ-TOVAR on January 31, 2004.
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The new england journal of medicine tions are more effective in preventing infection after cosal routes (Table 1).1 If the source person isoccupational exposure than is treatment with a sin- determined to be HIV-negative, treatment should begle drug. In fact, of the five health care workers who discontinued. Antiretroviral treatment is not indi-are known to have acquired HIV infection despite cated for contact between intact skin and blood orprophylactic treatment with more than one antiret- other body fluids contaminated by HIV.
roviral drug, three received three or more drugs.33 The Public Health Service guidelines specify that Finally, the efficacy and safety of prophylactic when the injury involves an increased risk of infec- treatment in pregnant and breast-feeding women tion (e.g., an injury caused by a large-bore needle,are not fully established, and there are few data on associated with a deep puncture, or caused by a de-the effect of treatment on fertility, spermatogenesis, vice visibly contaminated with blood or a device in ateratogenesis, and oncogenesis in otherwise healthy patient’s artery or vein), the regimen should be ex-people.
panded to include a third drug (Table 2). Indinaviror nelfinavir is recommended as a good option whena third drug is indicated. Efavirenz, a nonnucleoside analogue, and abacavir are also considered poten- Current Public Health Service guidelines (available tially useful drugs when an expanded regimen is in-at http://www.cdc.gov/mmwr/preview/mmwrhtml/ dicated. Routine use of three drugs is not recom-rr5011a1.htm) recommend that a basic four-week mended for all exposed persons, because adding aregimen of two drugs (zidovudine and lamivudine, third drug increases the probability that adverselamivudine and stavudine, or stavudine and didan- events will occur and that the four-week course ofosine) be started as soon as possible after most cas- treatment will not be completed.1,26es of HIV exposure through percutaneous or mu- HIV testing of exposed persons is recommend- Table 2. Recommendations for Prophylaxis against Human Immunodeficiency Virus (HIV) Infection after Percutaneous Injury, According to
the Infection Status of the Source Person.*
Risk Posed by
Exposure†
Infection Status of Source Person‡
Basic 2-drug prophylax- Expanded (3-drug) Generally, prophylaxis not war- Generally, prophylaxis not tings where exposure to HIV-infected persons is likely Generally, prophylaxis not war- Generally, prophylaxis not tings where exposure to HIV-infected persons is likely * The information is adapted from the recommendations issued in 2001 by the Public Health Service.1† Injuries caused by solid needles and superficial injuries pose a lower risk of infection, and those involving a large-bore hollow needle, a deep puncture, a device visibly contaminated with blood, or a needle used in a patient’s artery or vein pose a higher risk of infection.
‡ A class 1 positive status is defined by asymptomatic HIV infection or a low viral load (e.g., <1500 RNA copies per milliliter); a class 2 positive status is defined by symptomatic HIV infection, the acquired immunodeficiency syndrome, acute seroconversion, or a high viral load. If drug resistance is a concern, an expert should be consulted. Initiation of prophylaxis should not be delayed pending such consultation. Resources should be available to provide immediate evaluation and follow-up care for all exposed persons.
§ If the source person has risk factors for HIV infection, prophylaxis is optional and should be based on an individualized decision made jointly by the exposed person and the treating clinician. If prophylaxis is administered and the source person is subsequently determined to be HIV-negative, prophylaxis should be discontinued. Downloaded from www.nejm.org by GERARDO MARTINEZ-TOVAR on January 31, 2004.
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ed as soon as possible after exposure (to establishthat the infection was not already present) and pe- Table 3. Resources for Clinicians Managing Occupational Exposure to Blood.*
riodically during the first six months after the expo- Resource
Contact Information
sure (to detect occupational transmission). Testingafter six months is not usually indicated, but if the exposure posed an especially high risk or if the ex- posed worker needs further reassurance, additional testing may be helpful. An enzyme immunoassay for HIV antibody is the appropriate test for detecting new infections. The routine use of tests to detect plasma HIV RNA is not recommended. Since these Emergency Medicine Center, UCLA School of Medicine‡ tests are optimized to measure very low levels of HIVRNA, they have a relatively high rate of false positive results and a low positive predictive value when used to detect occupational infection — factors that can lead to unnecessary anxiety, unnecessary use of an- Laboratory monitoring, including a complete blood count and tests of renal and hepatic function, is recommended at base line and at two weeks. Theuse of additional tests depends on the specific reg- imen used (Table 1) and the medical condition of the source patient. The guidelines also recommendthat persons who have acquired hepatitis C virus infection from the exposure be followed for 12 * The information is adapted from the recommendations issued in 2001 by the months, because anecdotal evidence indicates that Public Health Service.1 AIDS denotes the acquired immunodeficiency syn- they may be at risk for delayed HIV seroconversion.1 All exposed persons, regardless of the postexposure † The hot line is supported by the Ryan White CARE Act, the HIV/AIDS Bureau, the Health Resources and Services Administration, and the Centers for Dis- treatment regimen, are advised to return for imme- diate evaluation if symptoms or signs that might be ‡ The Web site is supported by the Agency for Healthcare Research and Quality attributable to acute HIV infection appear.
Postexposure care must also address the risks of infection with hepatitis B virus and hepatitis C virus.
The Public Health Service recommendations formanagement of occupational exposure to blood in- tion or a high viral load when last tested, or if otherclude strategies that target these viruses.1 factors suggested an increased risk of HIV trans-mission, I would discuss with the health care work-er the rationale for my recommendation that a third drug, such as a protease inhibitor (e.g., indinavir), be added to the regimen. If I worked in a community In a case such as that described in the vignette, I where the incidence of primary resistance to zido-would prescribe an antiviral regimen that included vudine and lamivudine was known to be high, Iat least two drugs. I would choose drugs that were would also encourage the use of a third drug. If in-not part of the source patient’s current treatment formation from recent tests of resistance to antiret-regimen, even though there is no evidence that this roviral drugs was available or became available dur-strategy reduces the risk of infection. Since the ing treatment, I might adjust the regimen to includesource patient was being treated with a stable regi- at least two drugs to which the virus was susceptible.
men of didanosine plus stavudine, treatment of the To do so, I would rely on the strategies that form theexposed health care worker with zidovudine plus la- basis for selecting empirical “salvage therapy” inmivudine would be reasonable. If the puncture was persons with HIV infection, even though there is nodeep, the needle was visibly bloody before the injury, evidence that this approach is effective.34,38 Theor the source patient had very advanced HIV infec- U.S. National Clinicians’ Post- Exposure Prophylax- Downloaded from www.nejm.org by GERARDO MARTINEZ-TOVAR on January 31, 2004.
Copyright 2003 Massachusetts Medical Society. All rights reserved.
The new england journal of medicine is Hotline (PEPline, 888-448-4911) is a useful re- of drugs. Table 3 lists additional resources for cli-source for discussing treatment options and obtain- nicians who are treating patients with occupationaling advice about the management of adverse effects exposure to blood.
r e f e r e n c e s
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