Performance of the 4-Level Pulmonary Embolism Clinical Probability Score (4PEPS) in the diagnostic management of pulmonary embolism:An external validation study

Background: The recently published 4-level Pulmonary Embolism Clinical Probability Score (4PEPS) integrates different aspects from currently available diagnostic strategies to further reduce imaging testing in patients with clinically suspected pulmonary embolism (PE). Aim: To externally validate the performance of 4PEPS in an independent cohort. Methods: In this post-hoc analysis of the prospective diagnostic management YEARS study, the primary outcome measures were discrimination, calibration, efficiency (proportion of imaging tests potentially avoided), and failure rate (venous thromboembolism (VTE) diagnosis at baseline or follow-up in patients with a negative 4PEPS algorithm). Multiple imputation was used for missing 4PEPS items. Based on 4PEPS, PE was considered ruled out in patients with a very low clinical pre-test probability (CPTP) without D-dimer testing, in patients with a low CPTP and D-dimer &lt;1000 μg/L, and in patients with a moderate CPP and D-dimer below the age-adjusted threshold. Results: Of the 3465 patients, 474 (14 %) were diagnosed with VTE at baseline or during 3-month follow-up. Discriminatory performance of the 4PEPS items was good (area under ROC-curve, 0.82; 95%CI, 0.80–0.84) as was calibration. Based on 4PEPS, PE could be considered ruled out without imaging in 58 % (95%CI 57–60) of patients (efficiency), for an overall failure rate of 1.3 % (95%CI 0.86–1.9). Conclusion: In this retrospective external validation, 4PEPS appeared to safely rule out PE with a high efficiency. Nevertheless, although not exceeding the failure rate margin by ISTH standards, the observed failure rate in our analysis appeared to be higher than in the original 4PEPS derivation and validation study. This highlights the importance of a prospective outcome study.</p

Safety and clinical utility of four clinical decision rules in the diagnostic management of acute pulmonary embolism-the prometheus diagnosis study

Background: Several clinical decision rules (CDRs) are available for the exclusion of acute pulmonary embolism (PE). This prospective multi-center study compared the safety and clinical utility of four CDRs (Wells rule, revised Geneva score, simplified Wells rule and simplified revised Geneva score) in excluding PE in combination with D-dimer testing. Methods: Clinical probability of patients with suspected acute PE was assessed using a computerized based “black box”, which calculated all CDRs and indicated the next diagnostic step. A “PE unlikely” result according to all CDRs in combination with a normal D-dimer result excluded PE, while patients with “PE likely” according to at least one of the CDRs or an abnormal D-dimer result underwent CT-scanning. Patients in whom PE was excluded were followed for three months. Results: 807 consecutive patients were included and PE prevalence was 23%. The number of patients categorized as “PE unlikely” ranged from 62% (simplified Wells rule) to 72% (Wells rule). Combined with a normal D-dimer level, the CDRs excluded PE in 22-24% of patients. The total failure rates of the CDR-D-dimer combinations were similar (1 failure, 0.5- 0.6%, upper 95% CI 2.9- 3.1%). Despite 30% of the patients had discordant CDR outcomes, PE was missed in none of the patients with discordant CDRs and a normal D-dimer result. Conclusions: All four CDRs show similar safety and clinical utility for exclusion of acute PE in combination with a normal D-dimer level. With this prospective validation, the more straightforward simplified scores are ready for use in clinical practice