Clinical performance and effect on treatment rates of latex agglutination testing for streptococcal pharyngitis in an emergency department

Of 556 children with symptoms of streptococcal pharyngitis in a pediatric hospital emergency department, 38.8% had positive results on either a rapid latex agglutination test or throat culture for Group A Streptococcus. Twenty-six percent of patients with negative latex agglutination test results had growth on culture of a paired specimen. Under the best assumption rapid test sensitivity was 44.9%. The treatment rate (84%) for cases detected by the rapid test was markedly higher than the rate (44%) for cases detected only by culture (P < 0.001), presumably because the rapid test result is available sooner. We conclude that: (1) the rapid test had a lower sensitivity in routine use in our pediatric emergency department population than in previous reports from research settings; and (2) using the rapid test in addition to culture can significantly increase treatment rates.