Accuracy and Discomfort of Different Types of Intranasal Specimen Collection Methods for Molecular Influenza Testing in Emergency Department Patients.
Author(s): Frazee BW, Rodríguez-Hoces de la Guardia A, Alter H, Chen CG, Fuentes EL, Holzer AK, Lolas M, Mitra D, Vohra J, Dekker CL
Publication: Ann Emerg Med, 2018, Vol. 71, Page 509-517.e1
PubMed ID: 29174837 PubMed Review Paper? No
Purpose of Paper
This paper compared the sensitivity and specificity of influenza diagnosis by real-time PCR using midturbinate and nasal specimens to nasopharyngeal specimens.
Conclusion of Paper
Using the nasopharyngeal specimen as the control, influenza was diagnosed in 30.3% of patients, 68% of which tested positive for influenza A and 32% for influenza B. The midturbinate swab had a significantly higher sensitivity than the nasal swab and a better negative likelihood ratio; however, there was no significant difference in specificity or positive likelihood ratios between the two specimen types. Swab discomfort levels were correlated with depth of specimen collection with a median discomfort score of 0 for the nasal swab, 1 for the midturbinate swab, and 3 for the nasopharyngeal swab.
Studies
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Study Purpose
This study compared the sensitivity and specificity of influenza diagnosis by real-time PCR using midturbinate and nasal specimens to using nasopharyngeal specimens. Patient discomfort with both collection methods was also assessed. Specimens were collected in four different emergency departments (2 in the San Francisco Bay Area and 2 in Santiago, Chile) from 484 patients aged ≥2 years presenting with documented fever (temperature >37.8°C) at triage or self-reported fever within the last 72 hours and at least one additional influenza-like symptom, including headache, extreme tiredness, dry cough, sore throat, runny or stuffy nose, or muscle aches. Nasal swabs were collected from the nasal vestibule first, then midturbinate swabs were collected 2 to 3 cm inside the nasal passage, and nasopharyngeal swabs were collected from the posterior nasopharynx. Swabs were placed immediately in viral transport media and sent to a regional laboratory for real-time RT-PCR analysis. Influenza A and B were detected in the specimens from California by the Alameda Department of County Public Health Laboratory using the CDC Human Influenza Virus Real-Time PCR Diagnostic Panel (Influenza A/B Typing Kit) and in specimens from Chile by the Bioscan Medical Molecular Biology Laboratory using the Argene Influenza A/B R-GENE Kit. Patients were asked to rate discomfort during specimen collection for each method using the 6-point Faces Pain Scale–Revised (0 to 10 scale with zero being “no discomfort” and 10 being “worst imaginable”).
Summary of Findings:
Using the nasopharyngeal specimen as the control, influenza was diagnosed in 30.3% of patients, 68% of which tested positive for influenza A and 32% for influenza B. Collection using the midturbinate swab had a significantly higher sensitivity than the nasal swab (98.0% versus 84%) and a better negative likelihood ratio (0.02 versus 0.16); however, there was no significant difference in specificity (99.1% versus 98.5%) or positive likelihood ratios (94 versus 65) between the two specimen types. Swab discomfort levels were correlated with depth of specimen collection with a median discomfort score of 0 for the nasal swab, 1 for the midturbinate swab, and 3 for the nasopharyngeal swab.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Pneumonia/Respiratory Infection
Platform:
Analyte Technology Platform RNA Real-time qRT-PCR Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Acquisition Biospecimen location Nasopharynx
Midturbinate
Nasal vestibule