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HIV Screening of Pregnant Women and Newborns 6 FORMULATING PRENATAL HIV SCREENING POLICY Although the committee concluded that the overall goal of prenatal HIV screening should be the identification and treatment of all HIV-infected pregnant women, it does not at this time recommend screening for all pregnant women in the United States, particularly given the wide variation across states in HIV seroprevalence rates among childbearing women. Development of screening policy should be founded on sound epidemiological data, such as estimates. of the frequency and distribution of the condition (i.e., HIV infection) in the population for which screening is proposed (Allen, 1988). The committee selected the prevalence of HIV infection (i.e., HIV seroprevalence) among childbearing women as a useful guide to determining when to institute prenatal screening. 1 The evolution of prenatal HIV screening policy ultimately should be responsive to shifts in the prevalence of infection in this population. There has been considerable discussion in many quarters of the threshold seroprevalence level that should trigger screening. The committee chose not to specify an absolute seroprevalence level but rather to identify two general means by which individual states could establish an informed foundation for prenatal screening. Establishing an Epidemiological Basis for Prenatal Screening The first, or "majority-of cases," approach is to first identify those jurisdictions that account for a high proportion of cases of HIV infection among childbearing women and then institute screening. The second, or 1 Most states now routinely conduct anonymous HIV screening of all newborns for surveillance purposes, which provides information on the overall prevalence of infection among childbearing women, as well as on the relative distribution of infection within the state.
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HIV Screening of Pregnant Women and Newborns "threshold prevalence," approach is to specify a threshold prevalence of HIV infection among childbearing women above which screening would be considered appropriate in light of available health care resources, and initiate screening in those areas that exceed this threshold. The majority-of-cases method can be applied from a national perspective. By examining the distribution of infection among childbearing women across states, one could identify those states that account for approximately 80 to 85 percent of the total cases of HIV infection among these women in the United States. ("The committee used the 80 to 85 percent limit as an arbitrary target for identifying states with relatively high seroprevalence rates among childbearing women.) Implementing screening in the states identified by this method would make the service available to the majority of HIV-infected pregnant women in the country. Similarly, this method could also be applied within individual states. In this case, the "catchment" area for screening within a state would be defined as the cumulative counties that accounted for approximately 80 to 85 percent of the total cases of HIV infection among childbearing women (without specifying an absolute seroprevalence level). The committee selected counties as the most useful geographic units because in most states HIV seroprevalence data are easier to analyze by county or aggregate counties than by some smaller geographic unit, such as individual cities. A cutoff lower than 80 to 85 percent could also be used, but its limitation must be acknowledged: namely, that a substantial number of HIV-infected pregnant women who could benefit from screening might be missed as a result. The threshold prevalence approach involves a judgment about what HIV prevalence level among childbearing women must be reached before the yield from screening all pregnant women is considered sufficient to justify the costs of the screening effort. The committee found that data regarding the specific costs and benefits of HIV screening were inadequate to support the choice of one threshold prevalence value for use in all states. Rather, the committee recommends that individual state (or county) public health authorities be the final judge of whether prenatal screening at various HIV seroprevalence levels is an efficient or appropriate use of resources, particularly in the likely event that other public health programs may be competing for the same pool of limited resources. In most cases, state (or county) HIV seroprevalence rates among childbearing women and the availability of adequate resources for mounting a prenatal screening program should be considered together, For example, at a particular HIV seroprevalence level, a state could estimate the number of HIV-infected childbearing women in the state, the proportion of these women expected to be identified through prenatal screening, and the approximate counseling and testing costs associated with
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HIV Screening of Pregnant Women and Newborns case identification (i.e., the costs per case identified; see Table A-1, Appendix A). In addition to the costs of counseling and testing, a state could examine some of the other costs that might be associated with a screening program—medical monitoring and treatment of individuals identified through the screening program, health care provider and counselor education and training, public education campaigns, laboratory performance evaluation and quality control, and epidemiological surveillance and data collection activities. (Appendix C includes several tables that may serve as a guide to examining the costs associated with a prenatal HIV screening program. These tables provide examples and offer crude estimates of overall screening program costs but are by no means comprehensive or definitive.) Given the underlying premise that HIV-infected women identified through prenatal screening will benefit clinically from such identification, the committee expects that most, if not all, jurisdictions with HIV seroprevalence among childbearing women of 1 infected woman per 100 will find it appropriate to implement prenatal screening Furthermore, it is expected that many jurisdictions with seroprevalence between 1 per 100 and 1 per 1,000 will consider prenatal HIV screening to be an appropriate expenditure of health resources. As noted earlier, in jurisdictions where seroprevalence may not currently warrant prenatal screening, existing HIV testing recommendations for individuals with identifiable risks for HIV infection should be observed. The threshold seroprevalence level at which jurisdictions generally institute prenatal HIV screening is likely to decline as the benefits from early identification of HIV infection become clearer. Pilot Studies of New Screening Programs In general, all new screening programs at the outset contain unique or innovative components for which preexisting data are lacking. Therefore, before wide-scale screening is undertaken, pilot phases or projects (i.e., small-scale experiments) ideally should be conducted (Lappé et al., 1972; National Research Council, 1975; President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research, 1983). Previous experience with mass screening has commonly uncovered, in retrospect, unanticipated effects or negative outcomes of the program— problems that might have been minimized had pilot projects been conducted in advance.2 Pilot studies permit an assessment of the resources needed to support screening and can identify critical program elements 2 See the discussion "Principles and Pitfalls of Mass Screening" in the conference summary in Appendix A.
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HIV Screening of Pregnant Women and Newborns (e.g., laboratory capacity, counseling and follow-up services, provider training) that require further development or expansion. They can also reveal unexpected or adverse outcomes associated with screening. In situations where exigent need precludes the conduct of such pilot projects, new screening programs must still include an ongoing evaluation component to assess whether program objectives are being met and to identify untoward or unanticipated consequences of screening. (See the discussion of program evaluation in Chapter 7.) Implementation of Prenatal HIV Screening Policy Several options are available to states as they move to implement prenatal HIV screening policy. Policy could be established in the form of legislation, regulation, or standards of medical practice. The committee finds that formulating HIV screening policy through legislative or regulatory routes does not permit the flexibility and latitude required to respond to new developments in diagnostic technology and medical therapy, as well as to increased understanding of the pathogenesis and natural history of HIV infection in women and children. Moreover, when screening policy is legislated, the ability to modify policy in response to screening program experience is limited. Therefore, the committee recommends that prenatal HIV screening policy be implemented as a standard of medical practice, which constitutes a more malleable alternative to legislation or regulation and implies a threat of liability for health care provider noncompliance. In choosing to execute prenatal HIV screening policy through changes in medical practice guidelines,3 state public health authorities should include a broad representation of expertise and interests in the guidelines development process—for example, representatives from state medical professional societies (particularly obstetrical and pediatric societies), health facility and hospital administrators, relevant health care practitioners, experts in health law and medical ethics, consumer representatives, and patient advocates. In collaboration with state obstetrical and pediatric medical professional societies, states should also be prepared to implement and disseminate the new practice guidelines. This can be accomplished, for example, through letters from the state health department to individual practitioners or through technical bulletins from state professional medical societies. As part of this dissemination effort, states 3 For further details regarding medical practice guidelines development, see Field and Lohr (1990). In addition, the discussion "HIV Screening Policy Implementation" in the conference summary in Appendix A includes a description of New Jersey's experience in developing and implementing prenatal HIV screening policy as a standard of medical practice.
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HIV Screening of Pregnant Women and Newborns should conduct a broad-based public information and education campaign to alert women—and men—of reproductive age to the new screening policy. Components of such a campaign might include general information about HIV infection, its modes of transmission, and behavioral risk reduction, and specific details about the proposed prenatal HIV screening program (e.g., the rationale for and importance of the program, plans for its implementation, and its expected impact).
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