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Operator Influence on Blinded Diagnostic Accuracy of Point-of-Care Antigen Testing for Group A Streptococcal
Carla Penney1, Robert Porter1, Mary O'Brien2
1Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada A1B 3V6.
Insights
Rapid antigen detection tests (RADT) for Group A Streptococcus (GAS) pharyngitis showed similar accuracy when performed by nurses or technologists. This supports RADT use in pediatric emergency departments for faster diagnosis.
Area of Science:
- Pediatric Emergency Medicine
- Clinical Microbiology
- Infectious Diseases
Background:
- Acute pharyngitis caused by Group A Streptococcus (GAS) is common in pediatric emergency departments (ED).
- Conventional throat cultures delay diagnosis by 18-24 hours, hindering point-of-care treatment.
- Rapid antigen detection tests (RADT) offer faster results but may be operator-dependent.
Purpose of the Study:
- To evaluate operator influence on RADT diagnostic accuracy for GAS pharyngitis.
- Compare RADT performance by pediatric ED nurses versus clinical microbiology technologists.
- Utilize conventional culture as the reference standard.
Main Methods:
- Recruitment of children with suspected acute pharyngitis in a pediatric ED.
- Collection of three pharyngeal swabs per patient.
- Performance of RADT in ED by nurses, and RADT/culture in the lab by technologists.
Main Results:
- RADT sensitivity was 81.4% for technologists and 76.3% for nurses (5.1% difference, p=0.791).
- Specificity was similar: 97.7% for technologists and 96.6% for nurses.
- Adequate statistical power was not achieved to confirm significant differences.
Conclusions:
- RADT performance was comparable between technologists and ED nurses.
- No clinically significant loss of sensitivity was observed with RADT use in the ED.
- RADT can be utilized in the ED setting for timely GAS pharyngitis diagnosis.
Abstract:
Background. Acute pharyngitis caused by Group A Streptococcus (GAS) is a common presentation to pediatric emergency departments (ED). Diagnosis with conventional throat culture requires 18-24 hours, which prevents point-of-care treatment decisions. Rapid antigen detection tests (RADT) are faster, but previous reports demonstrate significant operator influence on performance. Objective. To measure operator influence on the diagnostic accuracy of a RADT when performed by pediatric ED nurses and clinical microbiology laboratory technologists, using conventional culture as the reference standard. Methods. Children presenting to a pediatric ED with suspected acute pharyngitis were recruited. Three pharyngeal swabs were collected at once. One swab was used to perform the RADT in the ED, and two were sent to the clinical microbiology laboratory for RADT and conventional culture testing. Results. The RADT when performed by technologists compared to nurses had a 5.1% increased sensitivity (81.4% versus 76.3%) (p = 0.791) (95% CI for difference between technologists and nurses = -11% to +21%) but similar specificity (97.7% versus 96.6%). Conclusion. The performance of the RADT was similar between technologists and ED nurses, although adequate power was not achieved. RADT may be employed in the ED without clinically significant loss of sensitivity.
