Critical evaluation of a CLIA-waived streptococcal antigen detection test in the emergency department

• Published in: Annals of emergency medicine 2001-04, Vol.37 (4), p.377-381
• Main Authors: Roosevelt, Genie E., Kulkarni, Mona S., Shulman, Stanford T.
• Format: Article
• Language: English
• Subjects: Adolescent; Antigens, Bacterial; Biological and medical sciences; Child; Child, Preschool; Emergency Service, Hospital; Ent. Stomatology; Female; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Pharyngitis - diagnosis; Pharyngitis - microbiology; Reagent Kits, Diagnostic - standards; Sensitivity and Specificity; Statistics, Nonparametric; Streptococcal Infections - diagnosis; Streptococcus pyogenes
• ISSN: 0196-0644; 1097-6760
• DOI: 10.1067/mem.2001.114090

Study Objective: We compare the performance of a Clinical Laboratory Improvement Amendments (CLIA)-waived antigen detection test (ADT) analyzed in the emergency department and a CLIA moderately complex ADT performed in the hospital microbiology laboratory. Methods: Samples from throat swabs were obtained using a double-headed Culturette II (Becton Dickinson Medical Systems, Sparks, MD) from a consecutive sample of 322 patients 3 years or older who presented to the ED of a university-affiliated pediatric referral hospital with the complaint of sore throat during 1998. One swab was transported to the microbiology laboratory and analyzed using a CLIA moderately complex ADT; negative results were confirmed using sheep blood agar culture. The second swab remained in the ED where a nurse conducted a CLIA-waived ADT. The accepted standard for documentation of group A β-hemolytic streptococcal (GABHS) infection was either a positive moderately complex ADT or culture result. The time of specimen collection, as well as the time the ED results and microbiology laboratory results were available to treating physicians, were recorded. Main outcome measures were concordance (κ statistic), sensitivity, and turnaround time (Mann-Whitney U test). Results: Three hundred twenty-two patients (mean age 7.5 years) had both ADTs performed. One hundred one (31%) patients had documented GABHS in the microbiology laboratory; 83 (82%) had a positive ADT result in the microbiology laboratory, and 18 (18%) had a positive culture result after a negative moderately complex ADT result. In 299 patients or 93% (95% confidence interval [CI] 90.8%, 95.8%) of patients, the waived ADT and the moderately complex ADT results were concordant (κ 0.82; 95% CI 0.78, 0.86; P