SS LEE
The main routes of HIV transmission, namely, sexual contact and needle-sharing in injection drug users, are closely associated with risk behaviours in the community. The health care setting is not a natural location for HIV transmission in epidemiologic perspective. HIV transmission may however occur through needlestick injuries in hospital or other clinical services. The risk of HIV transmission through such injury is between 0 to 0.46%,1 while that for mucosal membrane is one log lower at 0.09%, and that for non-intact skin (abrasion) is even lower.2,3 Though the risk is infinitesimal, this is undoubtedly an exceedingly emotional issue. The contexts in the discussion of the subject of HIV infection in health care workers are, firstly, size of the potential problem, and secondly, the effectiveness of specific intervention measures.
How many health care workers have been infected as a result of occupational exposure? In the US, as of the end of 2002, less than 200 health care workers (57 documented, and 139 possibly acquired) have contracted HIV after occupational exposure,4 against the background of 384,325 percutaneous injuries sustained. No new documented occupationally acquired HIV cases have been reported after December 2001. At the same time, about 25,000 adult AIDS patients in the country have given a history of employment in the health care setting. There is no international database for estimating the size of the problem in global perspective, though, apparently, this is small. There is however the risk of transmission through contaminated medical injection or procedures, the incidence of which has not been well established.1 In Hong Kong, no occupationally acquired HIV infections have yet been diagnosed nor suspected.
In the event that a needlestick injury has occurred, specific measures are often demanded to reduce the chance of infection. Antiretroviral medicines may theoretically be useful as there is a time lag between exposure and infection. Inhibition of viral replication shortly after exposure may therefore be one means of protecting from subsequent infection. The scientific basis of such practice, now widely known as post-exposure prophylaxis (PEP), has come from animal models with simian immunodeficiency virus exposure.5 PEP initiated 72 hours after exposure in animal models is often ineffective. In human, a retrospective case-control study of health care workers who sustained percutaneous injury in health care setting has demonstrated an 81% (95% confidence interval, 48-94%) reduction in the risk of infection following the use of zidovudine.6 However, treatment with antiretrovirals is not 100% safe, nor is there a standard protocol which has proven to be most effective. Delay to treatment access is the rule rather the exception. In the clinic setting, it's more a test of practicality and a balance between risk and benefit when it comes to decision making.
The objective of addressing HIV/AIDS in health care setting is a matter of promoting a harmonious workplace, rather than a priority prevention strategy. The key principle is to adopt an anticipatory and systematic approach, so as to minimise any potential disruption to the health service implicated. This chapter presents a step-by-step overview of recommended practices, the principles of which have been adopted by the Hong Kong Advisory council on AIDS and its Scientific Committee.7 This chapter covers firstly the issue of HIV prevention in health care setting, followed by recommendations on the management of occupational exposure. The unique situation of an HIV infected health care worker is addressed in the last part of the chapter.
Standard precaution is a core part of infection control practices pertaining to HIV prevention in health care setting. Standard precaution is defined as a "set of precautionary measures including good hand hygiene practices and the use of protective barriers during routine patient care".8 This concept is similar to that embodied in the term "universal precaution" which was normally applied to the handling of selected body fluids in the prevention of bloodborne infections. Standard precaution encompasses measures for the handling of blood, body fluids, secretion and excretions, and the avoidance of contamination of non-intact skin and mucous membrane.
Standard precaution implies that "all patients are treated as if they have a bloodborne virus (BBV), such as HIV or HBV (hepatitis B virus)",9 and are therefore treated no differently from other patients. The concept is different from situations which demand the application of extra infection control precautions, when, for example, an infection is spread by droplets, air or close contacts. In such circumstances, a different concept, that of transmission based precaution, is advocated. Standard precaution covers:
(a) handwashing before and after patient contact;
(b) wearing protective barriers when there's a direct contact or potential contact with blood or body fluids, mucous membrane and non-intact skin of patients (masks and other protection are to be worn as appropriate if splashing is anticipated);
(c) safe handling of sharps, avoiding for example, recapping.
Standard precaution should be practised as part and parcel of a broader set of systems for promoting workplace safety. In this connection, the following list of supporting items, adapted from the Guidance Note published under the HNP (Health, Nutrition and Population) Discussion Paper series of World Bank,9 shall also be in place: (a) reducing the chance of exposure; (b) engineering control; (c) effective staff supervision and education; (d) proper waste management; (e) attention to occupational health and safety issues; and (f) surveillance of incidents and development of outcome indicators on infection control. It would also be desirable to integrate HIV prevention with mechanisms for the prevention of other BBV infections, for example HBV. The principles are identical, while some elements like that of the role of vaccination could be unique for particular virus.
The risk of HIV transmission through occupational injuries is small. This should not however be translated to according a lower priority for quality post-exposure management. The Scientific Committee on AIDS, in conjunction with the Department of Health Scientific Working Group on Viral Hepatitis Prevention, have proposed a set of guiding principles on the effective management following exposure (summarised in Box 10.1). These principles are founded on the need for a systematic approach to the issues. The management of an incident of occupational exposure involves proper risk assessment, counselling tailored to the need of the injured, HIV testing according to standard protocol, and the prescription of antiretroviral if the risk is substantial. An algorithm 10(A) at the end of this chapter is proposed for easy reference.
No two occupational injuries in health care setting are identical. Two sets of factors should be considered in assessing the risk of an exposure, which deal with (a) patient status, and (b) nature of exposure. Exposure to a patient who has progressed to AIDS carries a higher risk of HIV transmission than that for an asymptomatic patient. The amount of virus in the body, and therefore, the blood/body fluid, constitutes one major factor of HIV transmission. As for the nature of exposure, exposure through percutaneous injury predisposes one to a higher risk than through mucous membrane or non-intact skin (for example, abrasion). A high volume of blood, deep injury and the use of a hollow needle (versus solid needle) are other factors associated with a higher chance of viral transmission. Urine, vomit, saliva and faeces are low risk body fluids, the exposure to which does not require PEP unless they are visibly blood-stained. Other factors can be considered in an assessment. The wearing of gloves can effectively reduce the extent of exposure; the exposure to blood in the environment that has begun to dry up would also mean a lower risk of infection.
Risk assessment is rarely a simple procedure. In this connection, the US CDC has developed a matrix to help stratify risk levels and guide management decision:10
(a) Infection status of source - Class 1 (asymptomatic or known low viral load of <1500 copies/mL); Class 2 (symptomatic, AIDS or known high viral load).
(b) Exposure type for percutaneous injuries - less severe (solid needle or superficial injury); more severe (large bore hollow needle, deep puncture, visible blood on device, or needle used in patient's artery or vein).
(c) Exposure type for mucous membrane or non-intact skin exposure - small volume (e.g. a few drops); and large volume (a major blood splash).
Post-expsosure counselling is an important component of the management procedures following occupational injuries involving a source patient that is HIV positive. Counselling is provided in the same setting and in conjunction with risk assessment, and lead naturally to a decision on blood testing and post-exposure prophylaxis. The main purpose of the counselling is to enable the injured health care worker to make an informed decision on the management procedure to be adopted. Subjects to be covered include, inter alia:
(a) exploration of underlying risk of infection unrelated to the injury, for example, sex and injection drug use
(b) assessment of current HIV status, especially if one has previously been tested for HIV
(c) symptomatology of seroconversion illness, which may occur with acute HIV infection, usually at 2-6 weeks following exposure
(d) precautionary measure, for example, safer sex, withhold blood/organ donation, avoidance of pregnancy
(e) toxicity and drug interactions of antiretroviral drugs in PEP
A baseline HIV antibody test is needed for most of the injured persons. The result serves as a reference for interpreting subsequent blood results, especially when there is seroconverison after the exposure. A negative result excludes pre-existing HIV infection if window period is unlikely. Baseline tests for other bloodborne infections, for example, HBV and HCV serology, would be indicated as appropriate. Testing of the source person may theoretically assist in the formulation of strategy, but is a complicated aspect of the management protocol. The ethical dimensions of obligation to inform, need-to-know, confidentiality are seldom a simple issue to be resolved. As a rule of thumb, testing of the source person, if performed, should be undertaken after clear explanation and with consent of the one tested. Confidentiality should be upheld.
For diagnostic purpose, HIV test is a two-step procedure comprising a screening test and a confirmatory assay. It may be perceived as too time-consuming when urgent result (of, source person, injured person or both) is often desirable. One might have to act upon the result of the screening test alone, the implications of which need to be thoroughly and carefully conveyed. The alternative would be that of a rapid test, which has received more attention in the recent years. A rapid test, especially one performed on whole blood, offers one means of obtaining an urgent result. The specificity of such test may be higher than that of a standard screening ELISA, but is not a replacement of a full two-step test for clinical diagnosis and management.
The US CDC recommended the use of either a basic regimen for lower risk type exposure, and expanded regimen for high risk exposure.10 The level of risk is determined during the counselling of the injured health care workers, using criteria discussed in the previous section. No treatment is normally warranted when the risk is minimal or non-existent. Treatment, if indicated, should be initiated as soon as possible, and preferably within 24 to 36 hours. In the case of a delay in consultation and where the risk is substantial, initiation of PEP up to 2 weeks following injury may be considered.11 The normal duration of treatment is 4 weeks.
A basic regimen is a two-drug PEP comprising zidovudine and lamivudine, or other options with two nucleoside reverse transcriptase inhibitors (Box 10.2). An expanded regimen is a three-drug PEP no different in principle from standard highly active antiretroviral therapy (HAART) prescribed to chronic HIV infection. While risk level is the major criteria for choosing between basic and expanded regimens, this may be complicated by the perception of people involved, and the difficulty in performing assessment when information is incomplete. An alternative approach is to go for a three-drug regimen whenever PEP is indicated, as advised in the United Kingdom.11 In choosing between the regimens, the followings are considered:
(a) toxicity profile of individual drug and regimen, and potential interaction between the drugs and other medicines that the injured might be taking concurrently
(b) other medical condition that the injured might have
(c) possible resistance pattern in the community
(d) pregnancy
Irrespective of whether PEP has been prescribed, follow-up counselling and evaluation is indicated, alongside repeat blood testing. For those on PEP, incompletion of the full course is common. The injury could be an exceptionally stressful event requiring considerable expert support. In evaluating the situation and the provision of counselling, the following shall be covered:
(a) advice on completion of full course of treatment
(b) side effects that may have arisen from the PEP, and their management
(c) seroconversion illness which may have occurred
(d) need for precautionary measures in health care setting
(e) other preventive advice including safer sex.
Repeat HIV antibody test shall be performed at 3 and 6 months following injury. Other investigations, for example, complete blood picture, renal and liver function tests, sugar level, amylase, creatinine kinase may be performed, the selection of which depends on the profile of antiretroviral drugs that are prescribed.
There have so far been three reports of HIV transmission from an infected health care worker to patients(s) - a Florida dentist, French orthopaedic surgeon and Spanish gynaecologist.12-14 The risk is small, and is attributable to "exposure-prone procedure", a concept that has changed over years. "Exposure-prone procedure" should not be performed by HIV infected health care workers. In principle this encompasses procedures involving a potential risk of HIV transmission from a health care worker to a patient. The UK Department of Health has described this as in Box 10.3.15
On the other hand, procedures undertaken while the worker's hand/fingers are clearly visible and are outside a patient's body, or when internal procedures do not involve injury, are not exposure prone. Specifically these cover: taking blood (venepuncture); setting up and maintaining intravenous lines or central lines; minor surface suturing; the incision of external abscesses; routine vaginal or rectal examinations; and simple endoscopic procedures.
The following perspectives refer when addressing HIV infection in a health care worker: preventive measures in health care setting; duties and obligations of health care workers, public health responses. These have been adapted from the guidelines established by the Hong Kong Advisory Council on AIDS in 1994. The principles have remained the same when the document was reviewed in 2003.16
The infection control practice described in the early part of the chapter is applicable irrespective of the HIV status of health care workers. This is in keeping with the principle of universal precaution, or standard precautions. Sound infection control practice with appropriate quality assurance should be implemented at all levels, taking into consideration factors unique to individual setting.
Confidentiality is a key issue. Health care workers are not required to disclose their HIV status to their employers or clients. There are, however, occasions where the HIV status has to be made known on a need-to-know basis, and this will normally be with the consent of the infected worker. For example, doctors or specialists involved in evaluating an infected health care worker may need to know his HIV status. In exceptional circumstances, breach of confidentiality may be warranted, for instance when an HIV infected health care worker refuses to observe the restrictions and patients have been put at risk.
Health care workers should receive counselling and HIV antibody testing if they have reason to suspect that they have been infected. An HIV infected health care worker should seek appropriate counselling and to act upon it when given. It is unethical if one fails to do so as patients are put at risk. The attending doctor of an HIV-infected health care worker should seek the advice of the expert panel formed by the Director of Health on the areas of management and possible need for job modification. The doctor who has counselled an HIV infected colleague on job modification and who is aware that the advice is not being followed and patients are put at risk, has a duty to inform the Medical/Dental Council for appropriate action.
The status and rights of an HIV infected health care worker as an employee should be safeguarded. Currently there is no justification for restricting practice of health care workers on the basis of the HIV status alone. Restriction or modification, if any, should be determined on a case-by-case basis. If work restriction is required, employers should make arrangement for alternative work, with provision for retraining and redeployment.
The Department of Health has formed an Expert Panel to advise the attending physician of the infected health care worker on whether job modification, limitation or restriction is required. A case-by-case evaluation would be undertaken considering multiple factors that can influence risk and work performance. The concept of "exposure prone procedure" would be used in assessing the need for job restriction. The attending doctor of the HIV infected health care worker should consult the Panel through the Consultant of the Special Preventive Programme, Centre for Health Protection (phone number: 27804390).
HIV infection and AIDS are not notifiable diseases by law in Hong Kong, and reporting is on a voluntary basis. Elsewhere patient notification has been conducted following reports of exposure prone procedure involving HIV infected health care workers. In the UK, this has ceased to be an automatic process. The need for such exercise is determined on a case-by-case basis, a principle that has also been adopted in Hong Kong.
Finally, the issue of HIV transmission in health care setting has caused much public concern despite the minimal risk incurred. Focusing on health care setting in fact deflects the society from proper attention to the major transmission routes through sex and drug abuse. The health care profession has the duty of constantly reassuring the public, and to educate their clients on how HIV can and cannot be contracted. More importantly, the public looks on the health care profession as an example of how HIV/AIDS should be dealt with. By adhering to the guidelines for prevention of HIV infection in the health care setting, public fear can be allayed.
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