Systematic review and meta-analysis of the accuracy of McIsaac and Centor score in patients presenting to secondary care with Pharyngitis

Background Centor and modified Centor (McIsaac) scores are clinical prediction rules used to diagnose group A streptococcus infection in patients with pharyngitis. They aim to identify the patients most likely to benefit from antibiotic treatment and reduce unnecessary antibiotic prescribing. Objectives To systematically review the literature on the diagnostic accuracy of McIsaac and Centor, and produce pooled estimates of accuracy at each score threshold, in patients presenting with acute pharyngitis to secondary care. Data sources MEDLINE, Embase and Web of science were searched from inception to June 2021. Eligibility criteria Studies that included patients who presented with acute pharyngitis to hospital emergency departments and outpatient clinics, reported McIsaac or Centor scores, and used throat cultures and/or rapid antigen detection tests as the reference standard. Review methods The review protocol was registered on PROSPERO (CRD42021267413). Study selection was performed by two reviewers independently and risk of bias was assessed using the QUADAS-2 tool. Sensitivities and specificities of McIsaac and Centor scores were pooled at each threshold using bivariate random effects meta-analysis. Results The McIsaac score had higher estimated sensitivity and lower specificity relative to Centor scores at equivalent thresholds, but with wide and overlapping confidence regions. Using either score as a triage to rapid antigen detection tests (RADT) to decide antibiotic treatment would reduce antibiotic prescription to non-GAS pharyngitis patients relative to RADT test for everyone, but also reduce antibiotic prescription to GAS patients. Conclusion Our findings suggest that high thresholds of either score excludes a proportion of true positive patients from potentially beneficial treatment. The use of a low threshold before a RADT test would reduce antibiotic prescription relative to prescribing based on score only but the economics and clinical effectiveness of this combination strategy needs assessment. We recommend continued use of existing antibiotic prescribing guidelines and patient safety netting.