Performance of risk scores for coronary artery disease: a retrospective cohort study of patients with chest pain in urgent primary care

OBJECTIVE: To evaluate the diagnostic performance of the Marburg Heart Score (MHS), INTERCHEST, Gencer rule, Bruins Slot rule and compare these with unaided clinical judgement in patients with chest pain in urgent primary care. DESIGN: Retrospective, cohort study. SETTING: Regional primary care facility responsible for out-of-hours primary care for a quarter-million people in the Netherlands. PARTICIPANTS: Consecutive patients aged ≥18 years who were evaluated for chest pain. MAIN OUTCOME MEASURES: Discriminatory ability (C-statistic), sensitivity, specificity, positive and negative predictive values (PPV/NPV). The reference standard involved a composite endpoint of the occurrence of death, acute coronary syndrome or coronary revascularisation (=major adverse cardiac events; MACE) up to 6 weeks after initial contact. RESULTS: A total of 664 patients were included, of whom 4.8% (n=32) had a MACE event. C-statistics for MHS, INTERCHEST, Gencer and Bruins Slot rule were: 0.77 (95% CI 0.69 to 0.84), 0.85 (95% CI 0.78 to 0.92), 0.72 (95% CI 0.63 to 0.81) and 0.72 (95% CI 0.63 to 0.81), respectively. Optimal diagnostic accuracy was found for MHS ≥2 (sensitivity=81.3%, specificity=67.1%, PPV=11.1%, NPV=98.6%), INTERCHEST ≥2 (sensitivity=87.5%, specificity=78.8%, PPV=17.3%, NPV=99.1%), Gencer ≥2 (sensitivity=84.4%, specificity=37.8%, PPV=6.4%, NPV=98.0%) and Bruins Slot≥2 (sensitivity=90.6%, specificity=40.8%, PPV=7.2%, NPV=98.9%). Physicians referred 157 patients (23.6%) and missed 6 out of 32 MACEs (sensitivity=81.3%, specificity=79.3%, PPV=16.6%, NPV=98.8%). Using INTERCHEST with a referral threshold of ≥2 points, 4 MACEs would have been missed and 162 patients (24.4%) referred. The other risk scores resulted in far higher referral rates. CONCLUSION: While available risk scores have reasonable to good discriminatory properties, they do not outperform unaided clinical judgment for evaluating chest pain in urgent primary care. Only the INTERCHEST score may slightly improve risk stratification.