Correspondence
Office-Based Test Systems for HIV Antibody
N Engl J Med 1993; 328:211January 21, 1993
- Article
To the Editor:
The Food and Drug Administration has approved two assays for human immunodeficiency virus (HIV) antibody for use by “properly trained personnel” in physicians' offices, clinics, emergency rooms, and other settings “where enzyme immunoassays are not practical or available.” The indirect immunofluorescence and microfiltration enzyme immunoassays are available for purchase and use in a wide variety of contexts, yet their use raises serious concern about clinical or operational feasibility and about their effect on disease-surveillance programs and preventive intervention.
With respect to clinical usefulness, although the test systems are accompanied by manufacturers' inserts indicating a need for retesting and subsequent confirmatory testing (at other sites) of patients with positive results, quality control remains an issue. The test algorithms do not include measures for periodic quality assurance, and it is possible that less well trained health professionals or others may conduct inferior tests. In view of the implications of the results of HIV-antibody testing, the public may be at risk from such screening. In a population with a low prevalence of HIV like that of the United States (0.4 percent1), assays with a specificity of 99.6 percent and a sensitivity of 99.9 percent (according to the manufacturer) result in 8 positive results per 1000 tests, 4 of which are false positive results. Persons with positive results may not actively seek confirmatory testing at other sites, reacting to what is an incorrect result in 50 percent of cases. In addition, in both assays the end point must be determined visually: in one case with the naked eye (“any blue color” is considered a positive finding) and in the other with a microscope to interpret a fluorescent stain. The final interpretation of the assay depends purely on visual skills and is highly subject to interobserver variability. The College of American Pathologists has promulgated recommendations for the conduct of visual color-discrimination tests for laboratory technologists2. No such evaluation is conducted routinely in physicians' offices, outpatient clinics, or emergency rooms.
Even if operational issues are overcome, these testing systems may undermine national efforts at disease control by compromising effective programs of AIDS surveillance and prevention. Integral to our public health strategy of voluntary testing is a systematic effort to achieve high-quality and effective counseling and health education. This approach couples screening with an appropriate assessment of individual risk and preventive intervention. HIV infection may become more widely reportable in the foreseeable future. The use of office-based HIV assays runs the risk of undermining the integrity of HIV-surveillance programs. Is there a need for rapid assays? HIV infection is a chronic disease, and few circumstances require test results in 10 minutes. Except for instances of occupational exposure to HIV, there is little demand for a rapid assay, and there is a potential for abuse in health care settings in terms of selective provision of care to those presumed on assay to be uninfected; universal precautions should be in place irrespective of the patient's HIV status. Physicians should be cautious about using office-based HIV screening. Further analysis of the implications of this method for public health policy is warranted.
2 ReferencesGeorge H. Gellert, M.D., M.P.H., M.P.A.
Douglas F. Moore, Ph.D.
Penny C. Weismuller, R.N., Dr.P.H.
Rick Greenwood, Ph.D., M.P.H.
Roberta M. Maxwell, Ph.D.
Orange County Health Care Agency, Santa Ana, CA 92701- Citing Articles (2)
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