43 - Evaluation of the Utility of the Wells Score for Predicting Pulmonary...

#43 Evaluation of the Utility of the Wells Score for Predicting Pulmonary Embolus in Patients Admitted to the Spine Surgery Service

Epidemiology-Natural History

Poster Presented by: S.Esmende

Author(s):

J. Wang (1)
M.A. Christino (1)
S. Esmende (1)
N.A. Thakur (2)
P. Evangelista (3)
M.A. Palumbo (1)
S.A. Ritterman (1)
S. Rienert (1)
A.H. Daniels (1)

(1) Warren Alpert Medical School of Brown University, Department of Orthopaedics, Providence, RI, USA
(2) Emory University, Department of Orthopaedics, Atlanta, GA, USA
(3) Warren Alpert Medical School of Brown University, Department of Diagnostic Imaging, Providence, RI, USA

Abstract

Introduction: The decision to perform computed tomography pulmonary angiography (CTPA) to diagnose pulmonary emboli (PE) in spine surgery patients is challenging. Although accurate diagnosis is important, CT scans expose patients to potentially hazardous radiation, are costly, and false positive results may lead to unnecessary anticoagulation. Scoring systems such as the Wells score have been established to assign risk categories for patients suspected of PE to assist in determining need for CTPA. The utility of the Wells Score for predicting PE in spine surgery patients has not been described.

Methods: All patients admitted to the spine service who underwent CTPA from 2001-2011 were identified. CTPAs were determined to be 'positive' or 'negative' for PE based on radiologist interpretation. The Wells score was calculated for each patient by a blinded reviewer and risk categories utilizing the 'traditional' and 'alternative' Wells score were assigned. Billing data from each patient was reviewed. Reason for exam, Wells score, and Wells risk category were compared for patients with and without PE.

Results: In total, 4,179 patients were admitted to the spine service; 66 underwent CTPA for suspected PE. Nineteen of the 66(28.8%) were diagnosed with acute PE(overall PE rate 0.45%). Patients with cervical diagnoses or combined cervical and thoracic injuries were more likely to have a positive CTPA examination compared to patients with isolated thoracolumbar diagnoses (62.5% versus 24.1%;p=0.025). The mean Wells score for patients diagnosed with PE was 5.3; the mean Wells score for patients without PE was 4.9(p=0.793). Neither the ´traditional´ or ´alternative´ interpretation of the Wells score was predictive of PE(p=0.394, p=0.178 respectively). Mean billing cost for the CTPA was $2,158.

Conclusions: This study found no significant correlation between the Wells score and results of CTPA in spine surgery patients. Fewer than 1/3 of CTPA scans were positive for PE. Conservative ordering of CTPA exams is encouraged.