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

Abstract

Background: Centor and McIsaac scores are clinical prediction rules for diagnosing group A streptococcus (GAS) infection in patients with pharyngitis. Their recommended thresholds vary between guidelines.

Objectives: To estimate the sensitivity and specificity of the McIsaac and Centor scores to diagnose GAS pharyngitis and evaluate their impact on antibiotic prescribing at each threshold in patients presenting to secondary care.

Data sources: MEDLINE, Embase, and Web of Science were searched from inception to September 2022.

Study eligibility criteria: Studies of patients presenting with acute pharyngitis to emergency or outpatient clinics that estimated the accuracy of McIsaac or Centor scores against throat cultures and/or rapid antigen detection tests (RADT) as reference standards.

Tests: Centor or McIsaac score.

Reference standard: Throat cultures and/or RADT.

Assessment of risk of bias: Quality Assessment of Diagnostic Accuracy Studies.

Methods of data synthesis: The sensitivities and specificities of the McIsaac and Centor scores were pooled at each threshold using bivariate random effects meta-analysis.

Results: Fourteen studies were included (eight McIsaac and six Centor scores). Eight studies had unclear and six had a high risk of bias. 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 RADT to decide antibiotic treatment would reduce antibiotic prescription to patients with non-GAS pharyngitis relative to RADT test for everyone, but also reduce antibiotic prescription to patients with GAS.

Discussion: Centor and McIsaac scores are equally ineffective at triaging patients who need antibiotics presenting with pharyngitis at hospitals. At high thresholds, too many true positive cases are missed, whereas at low thresholds, too many false positives are treated, leading to the over prescription of antibiotics. The former may be compensated by adequate safety netting by clinicians, ensuring that patients can seek help if symptoms worsen.

Keywords: Antibiotic prescription; Centor score; Group A streptococcus; McIsaac score; Meta-analysis; Pharyngitis; Secondary care; Systematic review.