Expansion of HIV screening to non-clinical venues is aided by the use of dried blood spots for Western blot confirmation

Abstract

Background: HIV rapid testing programs in New York State (NYS) are required to collect a specimen for confirmation of a preliminary positive result; however, some venues have limited capacity to collect venous blood, and confirmation using oral fluid is restricted by cost and availability.

Objective: To evaluate the feasibility of using dried blood spots (DBS) at non-clinical HIV rapid testing sites for Western blot testing.

Study design: The New York State Department of Health facilitated registration of 48 non-clinical HIV test sites and provided training on DBS procedures. Following a reactive rapid test, DBS were collected by fingerstick onto filter paper cards, dried and mailed to the NYS public health laboratory for Western blot testing.

Results: From October 2010 to December 2012, 280 DBS specimens were submitted for confirmation. Four (1.4%) were unsatisfactory for testing and 276 (98.6%) DBS were tested. Of these, 235 (85.1%) were positive, 37 (13.4%) were negative and 4 (1.4%) were indeterminate. During this period, the laboratory also received 1033 venous blood specimens for rapid test confirmation, and 35 (3.4%) were unsatisfactory. Of the 998 tested by Western blot, 784 (78.6%) were positive, 197 (19.7%) were negative and 17 (1.7%) were indeterminate.

Discussion: Compared to venous blood, the percentage of rapid test referral specimens with a positive Western blot was significantly greater for DBS specimens and the frequency of unsatisfactory specimens did not differ significantly. These results indicate that DBS are a suitable alternative to venous blood for confirmation of HIV rapid tests conducted at non-clinical sites.

Keywords: Confirmation; Dried blood spot; HIV; Rapid testing; Western blot.