The effect of a rapid kit for detection of streptococcal pharyngitis on the accuracy of the physicians' diagnoses

BACKGROUND: In the last decade, the accuracy of rapid tests for detection of group A streptococcal antigen was evaluated in laboratory and clinical settings, and the tests were suggested as an alternative to the traditional throat culture. METHODS: We evaluated 19 patients with a preliminary diagnosis of nonstreptococcal pharyngitis and 13 patients with a preliminary diagnosis of streptococcal pharyngitis. The physician performed a rapid latex agglutination test (Detect A Strep), took throat culture from all of the patients, reconsidered the preliminary diagnosis, and made a working diagnosis. A clinical score was calculated for each patient during data analysis. The accuracy of the physicians' preliminary diagnoses was compared with the accuracy of the scoring system, with the accuracy of the latex agglutination test, and with the accuracy of the physicians' working diagnoses. RESULTS: The scoring system, the physicians' preliminary diagnoses, the latex agglutination test, and the physicians' working diagnoses correlated significantly with throat culture results (p < or = 0.05). The efficiency of the physicians' preliminary diagnoses was 75% compared with an efficiency of 69% of the clinical scoring system, an efficiency of 66% of the latex agglutination test, and an efficiency of 69% of the physicians' working diagnoses. The physician changed the preliminary diagnosis only for two patients as a result of the latex agglutination test results; ironically, however, the preliminary diagnosis was correct in both of these cases. CONCLUSION: The use of a rapid test for the diagnosis of group A streptococcal antigen under normal working conditions did not improve the accuracy of the physician's diagnosis, so the use of the latex agglutination test in this study was not cost-effective.