Diagnostic accuracy of rapid nucleic acid tests for group A streptococcal pharyngitis: systematic review and meta-analysis

Abstract

Background: Acute pharyngitis is one of the most common conditions in outpatient settings and an important source of inappropriate antibiotic prescribing. Rapid antigen detection tests (RADTs) offer diagnosis of group A streptococcus at the point of care but have limited sensitivity. Rapid nucleic acid tests (RNATs) are now available; a systematic review of their accuracy is lacking.

Objectives: To evaluate the accuracy of RNATs in patients with pharyngitis; to explore test-level and study-level factors that could explain variability in accuracy; and to compare the accuracy of RNATs with that of RADTs.

Data sources: MEDLINE, Embase, Web of Science (1990-2020).

Study eligibility criteria: Cross-sectional studies and randomized trials.

Participants: Patients with pharyngitis.

Index test/s and reference standards: RNAT commercial kits compared with throat culture.

Methods: We assessed risk of bias and applicability using QUADAS-2. We performed meta-analysis of sensitivity and specificity using the bivariate random-effects model. Variability was explored by subgroup analyses and meta-regression.

Results: We included 38 studies (46 test evaluations; 17 411 test results). RNATs were most often performed in a laboratory. The overall methodological quality of primary studies was uncertain because of incomplete reporting. RNATs had a summary sensitivity of 97.5% (95% CI 96.2%-98.3%) and a summary specificity of 95.1% (95% CI 93.6%-96.3%). There was low variability in estimates across studies. Variability in sensitivity and specificity was partially explained by test type (p < 0.05 for both). Sensitivity analyses limited to studies with low risk of bias showed robust accuracy estimates. RNATs were more sensitive than RADTs (13 studies; 96.8% versus 82.3%, p 0.004); there was no difference in specificity (p 0.92).

Conclusions: The high diagnostic accuracy of RNATs may allow their use as stand-alone tests to diagnose group A streptococcus pharyngitis. Based on direct comparisons, RNATs have greater sensitivity than RADTs and equal specificity. Further studies should evaluate RNATs in point-of-care settings.

Keywords: Diagnosis; Diagnostic techniques and procedures; Group A streptococcus; Meta-analysis; Molecular probe techniques; Pharyngitis; Sensitivity and specificity; Streptococcus pyogenes; Systematic review.