OPTICAL IMMUNOASSAY TEST FOR GROUP-A BETA-HEMOLYTIC STREPTOCOCCAL PHARYNGITIS - AN OFFICE-BASED, MULTICENTER INVESTIGATION

Objective.-To compare the accuracy of an optical immunoassay (OIA) for the rapid diagnosis of group A streptococcal pharyngitis with blood a gar plate (BAP) culture. Design.-Blinded comparison with criterion sta ndard. Setting.-A total of 6 private pediatricians' offices, 3 in Conn ecticut and 3 in Chicago, Ill. Patients.-A total of 2113 consecutive p atients with acute pharyngitis, 983 in Connecticut and 1130 in Chicago . Main Outcome Measures.-The sensitivities and specificities of OIA an d BAP culture (both performed and interpreted in the office) were dete rmined using a research laboratory's interpretation of a combination o f BAP culture and Todd-Hewitt broth (THB) culture of transport tube pl edget as criterion standard. Results.-Among patients in Connecticut, t he sensitivities of the OIA and BAP culture were 94% and 89%, respecti vely (P=.004), while the specificities were 96% and 99%, respectively (P=.001), Among patients in Chicago, the sensitivities of the OIA and BAP culture were 79% and 72%, respectively (P<.001), while the specifi cities were 89% and 99%, respectively (P<.001). In each of the 6 pedia tricians' offices, the OIA was more sensitive than the BAP culture. Co mbining the data from Connecticut and Chicago, the overall sensitiviti es of the OIA and BAP culture were 84% and 78%, respectively (P<.001), while the specificities were 93% and 99%, respectively (P<.001). Conc lusions.-The results of this comprehensive office-based investigation suggest that with adequately trained personnel, negative OIA test resu lts may not always need to be routinely confirmed with BAP cultures.