The Utility of Modified Wells Score as a Pre-Test Risk Stratification Tool in Suspected Cases of Pulmonary Embolism Undergoing Computed Tomography Pulmonary Angiogram

Abstract

Objectives: To assess the validity of pre-test evaluation of patients with Modified Wells score at our facility to improve diagnostic yield of CT pulmonary angiography for pulmonary embolism. Study Design: Prospective longitudinal study. Place and Duration: Department of Computed Tomography, Armed Forces Institute of Radiology & Imaging, Pak Emirates Military Hospital, Rawalpindi Pakistan, from Feb to Jul 2019. Methodology: After approval from the Ethical Review Board, 60 patients with clinical suspicion of pulmonary embolism were selected. Modified Wells score was calculated for each patient, and a senior consultant reviewed their CT Pulmonary Angiograms. Results: Sixty patients were assessed from February to July 2019. Pulmonary embolism was diagnosed in 21(35%) patients; 22(37%) patients were unremarkable, while alternate diagnosis was provided for 17(28%) patients. Modified Wells score was 66.6% sensitive and 74.3% specific for diagnosis of pulmonary embolism, with a positive predictive value of 58.3% and a negative predictive value of 80.5%. Conclusion: Modified Wells score carries a good negative predictive value for ruling out pulmonary embolism. Hospitals must devise their departmental protocol utilizing risk stratification tools, lab tests and other safer imaging alternatives, where applicable.

Keywords

• Computed tomography
• Diagnostic yield
• Modified Wells score
• Pulmonary angiography
• Pulmonary embolism