Nucleic acid testing by public health referral laboratories for public health laboratories using the U.S. HIV diagnostic testing algorithm

Abstract

Background: Many public health laboratories adopting the U.S. HIV laboratory testing algorithm do not have a nucleic acid test (NAT), which is needed when the third- or fourth-generation HIV screening immunoassay is reactive and the antibody-based supplemental test is non-reactive or indeterminate.

Objectives: Among public health laboratories utilizing public health referral laboratories for NAT conducted as part of the algorithm, we evaluated the percentage of screening immunoassays needing NAT, the number of specimens not meeting APTIMA (NAT) specifications, time to APTIMA result, the proportion of acute infections (i.e., reactive APTIMA) among total infections, and screening immunoassay specificity.

Study design: From August 2012 to April 2013, 22 laboratories enrolled to receive free APTIMA (NAT) at New York or Florida public health referral laboratories. Data were analyzed for testing conducted until June 2013.

Results: Submitting laboratories conducted a median of 4778 screening immunoassays; 0-1.3% (median 0.2%) needed NAT. Of 140 specimens received, 9 (6.4%) did not meet NAT specifications. The median time from specimen collection to reporting the 11 reactive NAT results was ten days, including six days from receipt in the submitting laboratory to shipment to the referral laboratory. Acute infections ranged from 0 to 12.5% (median 0%) of total infections. Third- and fourth-generation immunoassays met package insert specificity values.

Conclusions: Public health referral laboratories provide a feasible option for conducting NAT. Reducing the time from specimen collection to submission of specimens for NAT is an important step toward maximizing the public health impact of identifying acute infections.

Keywords: Algorithms; Diagnostic tests; HIV; Nucleic acid amplification test.