Recommendations for Prevention of HIV Transmission in Health-Care Settings [MMWR Vol. 36. No. 2S]

August 21, 1987 - Supplement

When this occurs, the Western blot test should be repeated on the same serum
sample, and, if still indeterminant, the testing sequence should be repeated on a
sample collected 3-6 months later. Use of other supplemental tests may aid in
interpreting of results on samples that are persistently indeterminant by Western blot.
Testing of Patients
Previous CDC recommendations have emphasized the value of HIV serologic
testing of patients for: 1) management of parenteral or mucous-membrane exposures
of health-care workers, 2) patient diagnosis and management, and 3) counseling and
serologic testing to prevent and control HIV transmission in the community. In
addition, more recent recommendations have stated that hospitals, in conjunction
with state and local health departments, should periodically determine the prevalence
of HIV infection among patients from age groups at highest risk of infection (32).
Adherence to universal blood and body-fluid precautions recommended for the
care of all patients will minimize the risk of transmission of HIV and other blood-borne
pathogens from patients to health-care workers. The utility of routine HIV serologic
testing of patients as an adjunct to universal precautions is unknown. Results of such
testing may not be available in emergency or outpatient settings. In addition, some
recently infected patients will not have detectable antibody to HIV (Table 1).
Personnel in some hospitals have advocated serologic testing of patients in
settings in which exposure of health-care workers to large amounts of patients' blood
may be anticipated. Specific patients for whom serologic testing has been advocated
include those undergoing major operative procedures and those undergoing treatment in critical-care units, especially if they have conditions involving uncontrolled
bleeding. Decisions regarding the need to establish testing programs for patients
should be made by physicians or individual institutions. In addition, when deemed
appropriate, testing of individual patients may be performed on agreement between
the patient and the physician providing care.
In addition to the universal precautions recommended for all patients, certain
additional precautions for the care of HIV-infected patients undergoing major surgical
operations have been proposed by personnel in some hospitals. For example,
surgical procedures on an HIV-infected patient might be altered so that hand-to-hand
passing of sharp instruments would be eliminated; stapling instruments rather than
TABLE 2. Predictive value of positive HIV-antibody tests in hypothetical populations
with different prevalences of infection

Prevalence
of infection

Predictive value
of positive test'

Repeatedly reactive 0.2% 28.41%
enzyme immunoassay (EIA)' 2.0% 80.16%
20.0% 98.02%
Repeatedly reactive EIA 0.2% 99.75%
followed by positive 2.0% 99.97%
Western blot (WB)I 20.0% 99.99%
*Proportion of persons with positive test results who are actually infected with HIV.
'Assumes EIA sensitivity of 99.0% and specificity of 99.5%.
'Assumes WB sensitivity of 99.0% and specificity of 99.9%.

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