Reports on HIV/AIDS: 1990

JUNE 8, 1990, MMWR, Vol. 39, No. 22, pp.380-383
Non-blood-bank hospital laboratories reported the largest percentages of EIA
results in both 1988 and 1989 (2868 [29.8%] of 9617 results in 1988 and 2372 [29.0%]
of 8190 results in 1989). However, the percentages of EIA results reported on MPEP
samples decreased from 1988 to 1989 for both non-blood-bank hospital and hospital
blood bank laboratories (from 1488 [15.5%] in 1988 to 1247 [15.2%] in 1989 for
hospital blood bank laboratories). The percentages of EIA results reported increased
in independent (from 18.4% to 18.6%), nonhospital blood bank (from 17.7% to 17.9%),
health department (from 12.5% to 13.0%), and other types of laboratories (from 6.0%
to 6.3%). Health department and other types of laboratories had the largest distribution increases (4.0% and 5.0%, respectively).
Western Blot
In 1988, the analytic sensitivity for Western blot (WB) tests5 performed for MPEP
was 99.3% (1345 reactive test results out of 1355 positive samples); analytic specific
ity was 91.6% (306 nonreactive test results out of 334 negative samples) (Table 2).
Overall analytic performance of WB in 1988 was 97.8% (1651 correct results out of
1689 tests). Analytic sensitivity, analytic specificity, and overall analytic performance
were similar for WBs performed with licensed and unlicensed test kits.
Four types of laboratories accounted for 115 (82.1%) of the 140 laboratories
performing WB tests in 1988: health department (41 [29.3%]), independent (27
[19.3%]), non-blood-bank hospital (27 [19.3%]), and nonhospital blood bank (20
[14.3%]). For WBs performed in 1988, laboratory type-specific analytic sensitivity
among the major laboratory types ranged from 98.7% to 100.0%; analytic specificity,
from 85.0% to 98.7%; and overall analytic performance, from 96.2% to 99.1%.
In 1989, analytic specificity for WB tests was 97.8% (364 nonreactive test results out
of 372 negative samples)-a 6.8% increase over specificity in 1988 (Table 2). In 1989,
159 (21.1%) MPEP laboratories performed WBs, an increase of 13.6% over the number
in 1988. Four types of laboratories continued to report most WB results on MPEP
samples and accounted for 129 (81.1%) of the laboratories performing WBs: health
department (47 [29.6%]), independent (33 [20.8%)], non-blood-bank hospital (31
[19.5%]), and nonhospital blood bank (18 [11.3%]).
The percentages of WB results reported from the two largest categories of WB
laboratories (health department and independent) increased from 1988 to 1989 (from
453 [26.8%] of 1689 results in 1988 to 246 [27.3%] of 900 results in 1989 for health
department and from 349 [20.7%] in 1988 to 204 [22.7%] in 1989 for independent). In
nonhospital blood bank and other types of laboratories, the percentages of WB
results reported decreased (from 16.9% to 14.7% for nonhospital blood bank and from
17.5% to 16.6% for other laboratories).
For WBs performed in 1989, laboratory type-specific analytic sensitivity among the
major laboratory types ranged from 97.1% to 100.0%; analytic specificity, from 96.0%
to 100.0%; and overall analytic performance, from 97.1% to 99.2%.
Reported by: Div of Laboratory Systems, Public Health Practice Program Office, CDC.
'WBs were performed with both the licensed test kit available in the United States and with
laboratories' own WB test reagents using viral antigen purchased from commercial sources.

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