Nasopharyngeal aspirates vs. nasal swabs for the detection of respiratory pathogens: results of a rapid review protocol
Abstract
Background
Nasal pathogen detection sensitivities are often as low as 70% despite advances in molecular diagnostics. It has been suggested that this is linked, in part, to the choice of sampling method.
Methods
A diagnostic test accuracy review for sensitivity, using recently developed Cochrane methods for conducting rapid reviews, and the PRISMA protocol was undertaken, with QUADAS-2 risk of bias assessments and meta-analysis of included studies. Sensitivities were calculated by a consensus standard of positivity by either method as the gold standard. Insufficient and/or inaccurate, cross sectional or anatomical site pooling methodologies were excluded.
Results
Of 13 included studies, 8 had ‘high’ risk of bias, and 5 had ‘high’ applicability concerns. There were no statistical differences in pooled sensitivities between collection methods for 8 different viruses, and neither with use of PCR, Immunofluorescence nor culture. In a single study, Influenza H1N1 favoured nasopharyngeal swabs, with aspirates having 93.3% of the sensitivity of swabs (p>0.001). Similar equivocal sensitivities were noticed in detecting bacteria.
Conclusions
The chain of sampling, from anatomical site to laboratory results, features different potential foci along which sensitivity may be lost. A sufficient body of evidence exists that use of a different sampling method will not yield more respiratory pathogens. The new Cochrane Rapid Reviews guidance helped rapidly answer this relevant and timely clinical question.
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