Performance of the OraQuick Rapid Antibody Test for Diagnosis of Human Immunodeficiency Virus Type 1 Infection in Patients with Various Levels of Exposure to Highly Active Antiretroviral Therapy

Point-of-care human immunodeficiency virus (HIV) diagnosis has advantages over conventional testing in time-critical settings (1–3, 5, 6, 8, 11, 12). The OraQuick HIV type 1 (HIV-1) rapid antibody test (OraQuick; OraSure Technologies, Bethlehem, Pa.), is designed as a rapid test that uses oral mucosal transudate (OMT), whole blood, serum, or plasma. It was approved by the U.S. Food and Drug Administration in November 2002 for HIV-1 diagnosis by using finger-stick whole blood. OraQuick detects gp41 immunodominant domain antibody. Early trials of OraQuick on OMT, blood, and serum demonstrated 100% sensitivity and 99.8% specificity (B. Branson, M. Uniyal, C. Fridlund, T. Granade, and P. Kerndt, 9th Conf. Retrovir. Opportunistic Infect., abstr. 599-T, 2002; S. Nookai, C. Sinthuwattannawibool, P. Phanuphak, and R. George, 8th Conf. Retrovir. Opportunistic Infect., abstr. 232, 2001). To evaluate OraQuick with serum and OMT, we studied a cohort of patients whose HIV infection status was known and then expanded the evaluation to characterize the clinical features and antibody response characteristics associated with lower-than-expected OraQuick sensitivity. One hundred volunteers at low risk for HIV infection and 101 HIV-1-infected patients were recruited from an ongoing HIV natural history study. The voluntary, fully informed consent of the subjects used in this research was obtained as required by Air Force Regulation 169-9. OraQuick testing was performed according to the directions on the package insert. OraQuick test results were read by the study technician and an observer unaware of the patient’s HIV status. Serum specimens were subjected to enzyme immunoassay (EIA) (Genetic Systems rLAV; Bio-Rad Laboratories, Redmond, Wash.). Repeatedly reactive specimens were tested by Western blotting (Cambridge Biotech HIV-1 Western blot; Calypte Biomedical Corp., Rockville, Md.). Band reactivity was assigned a value from 0 (no reactivity) to 3 (strongly reactive). Viral load (VL) testing was performed with the Amplicor HIV-1 Monitor test (Roche Molecular Systems, Inc., Branchburg, N.J.) in ultrasensitive mode. Highly active antiretroviral therapy (HAART) was defined as a regimen containing at least three medications, including nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors, in which at least one agent was abacavir, any protease inhibitor, or any nonnucleoside reverse transcriptase inhibitor. After four HIV-infected subjects tested negative with OraQuick (case subjects), 20 subjects were randomly selected from the 97 HIV-1-infected subjects who tested positive with OraQuick (control subjects). Serum had been collected semiannually from all HIV-infected participants in the natural history study and stored at 20°C. The earliest available archived serum was tested with OraQuick. A gp41 peptide EIA (10) was performed on all specimens. Statistical analysis was performed with the Statistical Package for the Social Sciences, version 10.0.7 (SPSS Inc., Chicago, Ill.). Continuous variables were analyzed by an independentsample t test or a Mann-Whitney U test; categorical variables were analyzed by a chi-square test, Fisher’s exact test, or Kruskal-Wallis one-way analysis of variance. Interobserver agreement was examined with Cohen’s kappa test. Nonnumeric VL values reported as 50 were assigned values of 25, and those reported as 750,000 were assigned values of 750,001. Control subjects were selected by using random numbers generated by Microsoft Excel 97. OraQuick was reactive with OMT and sera from 97 of 101 HIV-infected subjects and 0 of 100 subjects who were uninfected (sensitivity and specificity, 96 and 100%, respectively). Concordance between serum and OMT testing and interobserver concordance (kappa  1.0, P  0.001) were 100%. The mean time since HIV diagnosis for the 101 HIV-infected subjects was 7.0 years, 91 (90%) subjects had ever received * Corresponding author. Mailing address: Department of Infectious Diseases, Wilford Hall Medical Center, 59MDW/MMII, 2200 Bergquist Dr., Ste. 1, Lackland AFB, TX 78236. Phone: (210) 292-2225. Fax: (210) 292-3740. E-mail: