PEDIATRICS Vol. 115 No. 2 February 2005, pp. 280-285 (doi:10.1542/10.1542/peds.2004-0907)
Relationship Between the Clinical Likelihood of Group A Streptococcal Pharyngitis and the Sensitivity of a Rapid Antigen-Detection Test in a Pediatric Practice
From the Division of General Pediatrics and Adolescent Medicine, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin
Objective. The sensitivity of a rapid antigen-detection test (RADT) for group A streptococcal (GAS) pharyngitis is critical to whether the test is cost-effective and to whether a confirmatory throat culture is needed. We evaluated a second-generation RADT to determine if its sensitivity varies across the broad clinical spectrum of patients tested for GAS in pediatric outpatient practice.
Methods. We used laboratory logbooks from a single pediatric clinic to identify 1184 consecutive patient visits at which an RADT was performed. In a blinded chart review, we calculated McIsaac scores to separately estimate the pretest clinical likelihood of GAS pharyngitis for visits at which the RADT result was positive (n = 384) and for visits at which the result proved to be false-negative (n = 65). Positive RADT results were assumed to be true positives, and test sensitivity was estimated by dividing the number of positive results by the sum of positives and false-negatives.
Results. As the clinical likelihood of GAS increased, there were stepwise increases in RADT sensitivity (from 0.67 to 0.88). Sensitivity was low (0.73; 95% confidence interval [CI]: 0.62–0.86) in patients clinically unlikely to have GAS (McIsaac score 
2) and high (0.94; 95% CI: 0.89–0.99) in patients <15 years old who had tonsillar exudate and no cough. False-negative RADT results were associated with lighter growth of GAS than found on specimens obtained from a random sample of clinic patients who had only primary throat cultures ordered.
Conclusions. For pediatric patients who are clinically unlikely to have GAS pharyngitis, as indicated by a McIsaac score 2, the sensitivity of a second-generation RADT may drop below thresholds reported for cost-effectiveness. For children who have tonsillar exudate and no cough, the test may be sensitive enough to meet current pediatric practice guidelines for stand-alone testing.
Key Words: pharyngitis • streptococcal infections • rapid diagnostic tests
Abbreviations: RADT, rapid antigen-detection test • GAS, group A streptococcus • TC, throat culture • CI, confidence interval • AOR, adjusted odds ratio
Accepted Jul 19, 2004.
CiteULike 
Connotea 
Del.icio.us 
Digg 
Facebook 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  R. R. Tanz, M. A. Gerber, W. Kabat, J. Rippe, R. Seshadri, and S. T. Shulman Performance of a Rapid Antigen-Detection Test and Throat Culture in Community Pediatric Offices: Implications for Management of Pharyngitis Pediatrics, February 1, 2009; 123(2): 437 - 444. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. C. Maltezou, V. Tsagris, A. Antoniadou, L. Galani, C. Douros, I. Katsarolis, A. Maragos, V. Raftopoulos, P. Biskini, K. Kanellakopoulou, et al. Evaluation of a rapid antigen detection test in the diagnosis of streptococcal pharyngitis in children and its impact on antibiotic prescription J. Antimicrob. Chemother., December 1, 2008; 62(6): 1407 - 1412. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Rodriguez-Iturbe and J. M. Musser The Current State of Poststreptococcal Glomerulonephritis J. Am. Soc. Nephrol., October 1, 2008; 19(10): 1855 - 1864. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. W. Fox, D. M. Cohen, M. J. Marcon, W. H. Cotton, and B. K. Bonsu Performance of Rapid Streptococcal Antigen Testing Varies by Personnel J. Clin. Microbiol., November 1, 2006; 44(11): 3918 - 3922. [Abstract] [Full Text] [PDF]
|
|
