Rapid prediction of adverse outcomes for acute normotensive pulmonary embolism: derivation of the Calgary Acute Pulmonary Embolism score

Kevin Solverson; Christopher Humphreys; Zhiying Liang; Graeme Prosperi-Porta; James E Andruchow; Paul Boiteau; Andre Ferland; Eric Herget; Doug Helmersen; Jason Weatherald

doi:10.1183/23120541.00879-2020

Rapid prediction of adverse outcomes for acute normotensive pulmonary embolism: derivation of the Calgary Acute Pulmonary Embolism score

ERJ Open Res. 2021 Apr 19;7(2):00879-2020. doi: 10.1183/23120541.00879-2020. eCollection 2021 Apr.

Authors

Affiliations

¹ Dept of Critical Care Medicine, University of Calgary, Calgary, AB, Canada.
² Dept of Medicine, University of Calgary, Calgary, AB, Canada.
³ Libin Cardiovascular Institute of Alberta, Calgary, AB, Canada.
⁴ Dept of Emergency Medicine, University of Calgary, Calgary, AB, Canada.
⁵ Dept of Radiology, University of Calgary, Calgary, AB, Canada.
⁶ Section of Respirology, Dept of Medicine, University of Calgary, Calgary, AB, Canada.

Abstract

Background: Acute pulmonary embolism (PE) has a wide spectrum of outcomes, but the best method to risk-stratify normotensive patients for adverse outcomes remains unclear.

Methods: A multicentre retrospective cohort study of acute PE patients admitted from emergency departments in Calgary, Canada, between 2012 and 2017 was used to develop a refined acute PE risk score. The composite primary outcome of in-hospital PE-related death or haemodynamic decompensation. The model was internally validated using bootstrapping and the prognostic value of the derived risk score was compared to the Bova score.

Results: Of 2067 patients with normotensive acute PE, the primary outcome (haemodynamic decompensation or PE-related death) occurred in 32 (1.5%) patients. In simplified Pulmonary Embolism Severity Index high-risk patients (n=1498, 78%), a multivariable model used to predict the primary outcome retained computed tomography (CT) right-left ventricular diameter ratio ≥1.5, systolic blood pressure 90-100 mmHg, central pulmonary artery clot and heart rate ≥100 beats·min^-1 with a C-statistic of 0.89 (95% CI 0.82-0.93). Three risk groups were derived using a weighted score (score, prevalence, primary outcome event rate): group 1 (0-3, 73.8%, 0.34%), group 2 (4-6, 17.6%, 5.8%), group 3 (7-9, 8.7%, 12.8%) with a C-statistic 0.85 (95% CI 0.78-0.91). In comparison the prevalence (primary outcome) by Bova risk stages (n=1179) were stage I 49.8% (0.2%); stage II 31.9% (2.7%); and stage III 18.4% (7.8%) with a C-statistic 0.80 (95% CI 0.74-0.86).

Conclusions: A simple four-variable risk score using clinical data immediately available after CT diagnosis of acute PE predicts in-hospital adverse outcomes. External validation of the Calgary Acute Pulmonary Embolism score is required.