Assessing Pretest Clinical Risk of Pulmonary Thromboembolism in the Emergency Department: Proposal of a Simple Modification to the Wells' Score

Background: Clinical scores have been proposed to stratify the risk of pulmonary thromboembolism (PTE), although this approach suffers a low specificity and the unavoidable need for computed tomography pulmonary angiography (CTPA) scans. Objective: Our study aimed to investigate a simple modification to the already validated Wells’ score to improve its diagnostic accuracy in the emergency department (ED). Methods: We retrospectively reviewed all CTPA scans performed in the ED setting to rule out PTE over a 1-year (2017) period. Clinical variables potentially associated with PTE were assessed to improve diagnostic accuracy of the Wells' score, thus introducing a modified Wells’ score (mWells). Results: Four thousand four hundred thirteen CTPAs were identified, of which 504 were for suspected PTE. The prevalence of PTE was 23.9%. Among clinical data, only peripheral capillary oxygen saturation was consistently correlated with PTE at univariate (odds ratio 2.75 [95% confidence interval 1.61–4.73]) and multivariate (odds ratio 3.78 [95% confidence interval 2.13–6.72]) logistic regression analysis. The mWells' score had a higher area under the receiver operating characteristic curve compared with the original Wells’ score: 0.71 (95% confidence interval 0.67–0.75) vs. 0.65 (95% confidence interval 0.61–0.69) (p < .01) and improved diagnostic accuracy. Conclusions: Current clinical stratification tools for PTE are characterized by low specificity, leading to an overuse of CTPA. mWells', rather than Wells', score showed a better predictive performance of PTE detection. Our results suggest that current diagnostic pathway for PTE may be improved by simple adjustments (i.e., mWells’) of clinical prediction scores.