Nonoccupational Postexposure Prophylaxis

July 2006

Chapter Contents

Background

Subjective

Objective

Assessment

Plan

Patient Education

References

Table 1. Antiretroviral Regimens for Nonoccupational Postexposure Prophylaxis of HIV Infection

Figure 1. Algorithm for Evaluation and Treatment of Possible Nonoccupational HIV Exposures

Background

Although avoiding exposure to HIV is the only reliable way of preventing HIV infection, postexposure prophylaxis (PEP) can decrease the risk of infection after exposure to HIV. Antiretroviral (ARV) therapy is an important prophylactic intervention in appropriate persons with nonoccupational exposures (eg, sexual contact; sharing of injection drug needles or other equipment), as well as those with occupational exposures (eg, needlesticks). The U.S. Department of Health and Human Services has established guidelines for nonoccupational PEP (nPEP) based on data from animal models, perinatal clinical trials, and observational studies.

Overall, the data suggest that nPEP is more likely to be effective when the exposure is a single episode and nPEP is initiated in a timely manner. It is not appropriate for cases of multiple sexual exposures or injection drug use (IDU) exposures over time or for exposures that occurred more than 72 hours before starting nPEP treatment ( Figure 1 ).

The model for nPEP is derived in part from protocols for occupational PEP (eg, in terms of risk stratification, pretreatment testing, timing of treatment, treatment regimens, and duration of treatment). However, the recommendations for PEP and nPEP are distinct from each other and should not be confused. The nPEP guidelines exclude exposures to workers in health care, public safety, sanitation, and laboratory settings. Guidelines for the management of these occupational exposures to HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) are available at: http://www.aidsinfo.nih.gov.

S: Subjective

The patient reports potential exposure to HIV through a sexual encounter or the sharing of needles or other equipment for intravenous drug use.

Take a thorough history of the specific sexual or drug-use activities and the time the exposure occurred, the HIV status of the source person (if known), and HIV risk factors of the source person (if HIV status is not known). In cases of sexual assault, evidence collection and specific paperwork may be required as well.

O: Objective

Examine for trauma and for signs or symptoms of sexually transmitted diseases (STDs), which may increase the risk of HIV transmission. In injection drug users, examine for abscesses and signs or symptoms of infection. For women who may be pregnant, perform a pregnancy test.

A: Assessment

Assess potential exposures to HIV, other STDs and bloodborne pathogens. The risk of HIV infection depends on the HIV status of the source and on the characteristics of the exposure. The estimated risk of HIV exposure will determine whether nPEP should be offered. Figure 1 presents an algorithm for risk evaluation and treatment decisions.

P: Plan

Laboratory Testing

Provide pretest counseling and perform a baseline HIV antibody test. Evaluate and test for other infections transmitted through sexual or IDU exposures, including chlamydia, gonorrhea, syphilis, herpes simplex virus infection, hepatitis B (HBV surface antigen, surface antibody, core antibody), and hepatitis C (HCV antibody). Obtain complete blood count (CBC), liver function tests (LFTs), and chemistry panel at baseline before treatment with ARV medications.

Treatment

Follow the algorithm in Figure 1 to determine whether the patient should be offered nPEP medications. If the patient is a candidate for treatment, counsel him or her about the potential risks and benefits of nPEP. If the patient elects to start therapy, see Table 1 for potential regimens. Select a regimen that is likely to be effective but tolerable; consider the potential adverse effects of ARV agents. Note that certain ARV agents, including nevirapine, should not be used for PEP. Avoid efavirenz in pregnant women.

If the HIV status of the source person is unknown and the exposure is considered to be of relatively low risk, consider 2-drug nPEP (eg, zidovudine + lamivudine) to minimize toxicity. If the source person is known or suspected to have infection with HIV that is resistant to ARV medications, seek expert consultation in selecting an appropriate nPEP regimen.

Once the decision is made to institute nPEP, do the following:

• Begin ARV prophylaxis as soon as possible after the exposure, but always within 72 hours. Treatment should be continued for 28 days.
• Provide counseling about the efficacy of nPEP, including the importance of protection against future HIV exposures, timely initiation of nPEP medications, and adherence to these medications for 28 days. Continued counseling about HIV risk reduction may be appropriate. In cases of sexual assault, refer the patient to a rape counselor.

Follow-Up

Patients should be evaluated at 1 week for review of all test results and further risk reduction counseling. For patients taking nPEP, this follow-up should include adherence assessment and evaluation of any adverse effects. A 2-week blood screening (CBC, LFTs, and chemistry panel) should be done for patients on the 28-day nPEP regimen to monitor for nPEP toxicity. Follow-up testing for HIV antibody in patients with a negative baseline HIV antibody test should be done at 6 weeks, 3 months, and 6 months after the exposure. Some patients may also need health education counseling and emotional support during their follow-up visits. If patients develop acute HIV infection or are discovered to be HIV seropositive at follow-up testing, refer to an HIV specialist for evaluation and care (see chapter Primary HIV Infection ).

Prophylaxis against HBV and HCV

Prophylaxis against HBV is recommended for patients with potential exposure to HBV who have not been vaccinated against HBV. Give HBV immune globulin (HBIG) as a 0.06 mL/kg intramuscular injection and initiate the vaccination series. For patients who received the vaccine series but did not develop protective antibody (HBV sAb+), give HBIG at the time of the postexposure workup and repeat in 1 month. For patients with immunity to HBV (HBV sAb+), no treatment is indicated.

For HCV, no recommended prophylactic treatments are available. After potential exposure, check a baseline HCV antibody test. If the source is known to have HCV infection, consider alanine aminotransferase (ALT) and HCV viral load testing at 4-6 weeks. HCV antibody testing should be repeated at 4-6 months. If HCV seroconversion occurs (indicated by ALT elevation, detectable HCV viral load, or confirmed positive HCV antibody test), refer the patient to a hepatologist because early treatment of acute HCV may be indicated.

Patient Education

• Patients should contact a medical provider or go to an emergency room as soon as possible after a potential HIV exposure has occurred. PEP may be effective if it is started within 72 hours of exposure, but the sooner medications are initiated, the better the chance for preventing HIV transmission.
• PEP medications should be taken as directed for the full 28 days. Adherence to PEP medications is essential for successful treatment.
• If patients are experiencing uncomfortable adverse effects, they should contact their providers. Providers may prescribe medications to alleviate the adverse effects or select other PEP medications.
• The most effective way to prevent HIV infection is to prevent exposure to HIV by practicing safer sex and safer IDU techniques. Using condoms and not sharing needles are successful preventive measures. It is crucial to the success of PEP treatment that patients not engage in risky sexual or needle-use behaviors. If patients have questions about access to condoms or clean needles, they should contact their health care providers for assistance.

References

• U.S. Department of Health and Human Services. Antiretroviral Postexposure Prophylaxis After Sexual, Injection-Drug Use, or Other Nonoccupational Exposure to HIV in the United States . MMWR Recomm Rep. 2005 Jan 21;54(RR02);1-20. Available online at aidsinfo.nih.gov/Guidelines/GuidelineDetail.aspx?GuidelineID=11. Accessed May 19, 2006.
• U.S. Department of Health and Human Services. Updated U.S. Public Health Service Guidelines for the Management of Occupational Exposures to HBV, HCV, and HIV and Recommendations for Postexposure Prophylaxis . MMWR Recomm Rep. 2001 Jun 29;50(RR11). Available online at aidsinfo.nih.gov/Guidelines/GuidelineDetail.aspx?GuidelineID=10. Accessed May 19, 2006.