Routine Detection of Acute HIV Infection Through RNA Pooling: Survey of Current Practice in the United States

To the Editor: Acute human immunodeficiency virus (HIV) infection is a highly infectious and infrequently diagnosed stage of HIV infection that holds promising opportunities for clinical and public health intervention. Several state and local public health agencies are now employing quantitative nucleic acid amplification tests (NAATs) to screen pooled specimens for acute HIV infection.1 To describe current nucleic acid amplification testing programs in the United States we collected information from all publicly funded acute HIV detection programs identified through December 1, 2005 (Table 1). We included all publicly funded US programs that used a pooled algorithm, used a qualitative or quantitative NAAT, used screening for acute cases (diagnostic), and supported public-health HIV prevention activities. All government levels (city, county, state, and national) were included in this search. Programs were excluded from the analysis if they performed individual testing (rather than pooled algorithms), employed NAATs for clinical diagnosis rather than screening, were located outside of the United States, or if no preliminary data were available.TABLE 1: Survey of Nucleic-Acid Amplification Testing in Publicly Funded Federal, State, County, and City HIV Testing Programs in the United StatesOur findings suggest that specimen-pooling schemes varied greatly between programs. The development of existing pooled NAAT protocols requires balancing cost against timeliness while taking into account state or regional budgets and factors related to the testing population and the logistical operation of testing programs.5,10 Programs using small pools will have faster turnaround time at the expense of a higher cost. As expected, the yield of NAAT per 1000 specimens tested also varied significantly between different programs. Programs in Los Angeles, San Francisco, Maryland, and Seattle–King County that targeted higher-risk populations (such as gay men and other men who have sex with men and patients from sexually transmitted disease clinics) had a higher diagnostic yield per 1000 specimens tested (6.2–10.5 per 1000) when compared with North Carolina and blood donor programs (0–4 per 1000), whose testing population is similar to the general population. However, by using larger pools when screening populations with lower HIV prevalence, the yield per 100 NAATs was relatively similar among programs (Table 1). The selection of the initial HIV antibody screening test may have a significant influence over the program cost and productivity. The majority of programs described use either a first- or a second-generation enzyme immunoassay (EIA) (window period ranging between 32 and 39 days). In contrast, blood donor programs are using a more advanced EIA with a shortened window period of approximately 22 days (a more expensive, third-generation IgM-sensitive EIA).11 The selection of a less-expensive, first- or second-generation EIA allows for a longer window period (10–17 more days than when third-generation EIA is used), and therefore a potentially higher yield for the detection of patients with negative EIA and positive NAAT, with potential cost-effectiveness implications.12 Throughout the United States, the use of pooled NAATs to detect acute HIV infection is becoming a popular strategy for the screening of large populations. However, the most efficient approach remains to be determined. Further studies of the performance and cost-effectiveness of NAATs in different populations are required before further recommendations can be provided.