Use of pooling and outpatient laboratory specimens in an anonymous seroprevalence survey of HIV infection in British Columbia, Canada.
OBJECTIVE
To conduct an anonymous HIV seroprevalence survey to establish a baseline estimate of HIV seroprevalence in a general population; to evaluate serum pooling and alternative testing strategies as cost-saving measures.


METHODS
Prospective anonymous HIV seroprevalence study using outpatient laboratory specimens.


METHODS
Two large non-hospital-associated outpatient chemistry testing laboratories in the major population centers in British Columbia, Canada. PATIENTS AND SERA: Leftover sera received for chemistry screen testing in outpatient laboratories were provided to the study after chemistry testing was completed. Those from patients aged < 15 and > or = 55 years were excluded.


METHODS
Patient identifiers were erased from samples. Sera were pooled 10:1 and tested by viral lysate enzyme-linked immunosorbent assay (ELISA). Sera from HIV-positive pools were tested individually. All individual HIV-positive specimens were retested for verification of positivity using a recombinant protein ELISA.


METHODS
HIV seroprevalence rates were stratified by sex, age group, and geographic area; and costs of pooling and alternative algorithm strategy were compared with those of conventional methods.


RESULTS
A total of 80,238 sera were collected from 66,658 individuals (53% women, 47% men). Of these, 276 men (88.3 per 10,000) and 24 women (6.8 per 10,000) were HIV-seropositive. The highest rates were in those aged 30-34 years, for both men and women. Using pooling and non-Western blot verification saved US$2.07 per specimen, or 80% of the cost for conventional testing.


CONCLUSIONS
The anonymous outpatient laboratory setting is practicable to obtain a reasonable estimate of HIV seroprevalence rates in a general population. Such studies can be made cost-effective by pooling sera and using alternative confirmatory strategies.
Sherlock
C H
CH
Department of Pathology, University of British Columbia, Vancouver, Canada.
Strathdee
S A
SA
Le
T
T
Sutherland
D
D
O'Shaughnessy
M V
MV
Schechter
M T
MT
D015492:AIDS Serodiagnosis / Q000191:economics; D000293:Adolescent; D000328:Adult; D001955:British Columbia / Q000453:epidemiology; D003365:Costs and Cost Analysis; D005260:Female; D015528:HIV Seroprevalence; D006801:Humans; D007753:Laboratories; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D011446:Prospective Studies