Operator Influence on Blinded Diagnostic Accuracy of Point-of-Care Antigen Testing for Group A Streptococcal Pharyngitis

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.

Rapid antigen detection and molecular tests for group A streptococcal infections for acute sore throat: systematic reviews and economic evaluation

“…The assessment of risk of bias and applicability for the 26 included test accuracy studies 20,23,24,[34][35][36][37][38][39][40][41][42][43][44][45][46][48][49][50][51][52][55][56][57][58]69 using the QUADAS-2 tool are summarised in Table 7 and Figure 5. Four of the included studies compared two index tests that are relevant to this review, so there are 30 quality assessment ratings for the index test domains.…”

“…Of the 29 studies (full texts and abstracts) 6,20,23,24, identified by the search, 26 of the studies reported test accuracy data. 20,23,24,[34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]54,57,58,63 Three of the identified studies 6,53,55 reported only other outcomes (such as antibiotic-prescribing rates) and did not report test accuracy.…”

“…39,45 Recent antibiotic use prior to enrolment was considered in eight included studies, and patients without any recent use of antibiotics prior to recruitment were eligible for inclusion in these studies. 24,35,36,42,45,47,48,50…”

“…For instance, the Alere™ TestPack +Plus Strep A (Abbott Laboratories) was the most common antigen detection test, which was evaluated in 13 studies (excluding unpublished studies conducted by the manufacturers). 6,23,[38][39][40][41][42][43][46][47][48]51,58 Conversely, the only molecular test evaluated in a peer-reviewed journal article was the PCR-based cobas Liat Strep A Assay (Roche Diagnostics). 24 As shown in Table 6, there were four studies providing head-to-head comparisons of index tests: BD Veritor System (Becton Dickinson) and QuikRead Go (Orion Diagnostica); 34 Alere i Strep A (Abbott Laboratories) and BD Veritor System (Becton Dickinson); 20 Alere i Strep A (Abbott Laboratories) and Sofia Strep A fluorescent immunoassay (FIA) (Quidel); 23 and Alere i Strep A (Abbott Laboratories) and OSOM Strep A.…”

“…Participants in the included studies were recruited from GP/primary care clinics/family practices, 6,40,41,[43][44][45][46][47] community pharmacies, 53 paediatric clinics, 42,49,54,56 paediatric emergency departments, 23,48,57 hospital outpatient departments 20,51 and emergency departments. 35,50 There were two multicentre studies with mixed populations from primary and secondary care settings: Cohen et al 37 sampled patients from the emergency department (secondary care) and urgent care clinics (primary care); and Wang et al 24 sampled patients from paediatric clinics (secondary care) and family practices (primary care).…”