Pulmonary/original researchEffectiveness and Acceptability of a Computerized Decision Support System Using Modified Wells Criteria for Evaluation of Suspected Pulmonary Embolism
Introduction
During the last decade, computed tomography (CT) angiography has become the imaging test of choice for the diagnosis of pulmonary embolism.1, 2 Its easy availability and high sensitivity have led to a dramatic increase in its use for this purpose.3, 4 Pulmonary embolism positivity rates for CT angiography vary from 20% in controlled multicenter trials to less than 10% in observational studies, suggesting that overuse may be occurring in some settings.3, 4 Not only do CT angiography tests expose patients to the direct risks of radiation and contrast nephropathy5, 6, 7 but also their inefficient use may add unnecessary costs, increase management challenges caused by incidental findings, and obstruct patient flow. To improve the use of CT angiography for the diagnosis of pulmonary embolism and to safely rule out pulmonary embolism, evidence-based prediction scores have been derived and validated.8, 9, 10, 11, 12, 13, 14 Despite ample evidence of the utility of these clinical decision support systems, however, they are not routinely applied in clinical practice.3
Computerized physician order entry, a validated tool to promote medication safety, may serve as a platform for a computerized decision support system.15, 16 It is not known whether evidence-based computerized decision support systems for the diagnosis of pulmonary embolism help improve use of CT angiography and whether this process is acceptable to emergency physicians.
We sought to measure the association of introduction of an electronic evidence-based computerized decision support system for the evaluation of pulmonary embolism in an emergency department (ED) with change in CT angiography positivity rates for pulmonary embolism, as well as to determine the computerized decision support system's acceptability to emergency physicians.
Section snippets
Study Design
This study was designed as an intervention study to measure the change associated with the introduction of a computerized decision support system. Comparison data from the preintervention study period were retrospectively obtained.
To show a meaningful difference of 10% of the positivity rates between the both groups, we calculated an estimated sample size of 200 patients undergoing CT angiography for each group (α of 0.05 and power of 80%). The length of the preintervention period therefore was
Results
During the 4-month intervention period from March through June 2008, the computerized decision support system was triggered for 495 ED visits, of which 89 were excluded because the CT angiography tests were ordered for evaluation of trauma (n=51), aortic dissection (n=13), malignancy (n=6), and other reasons (n=11). Records were insufficient or missing for 8 visits. Two patients were excluded by the ordering physician because of pregnancy.
A total of 404 cases during which pulmonary embolism was
Limitations
Although the observed rate of CT angiography positivity for pulmonary embolism increased 4.4% (95% CI –1.4% to 10.1%) from the postintervention period, the 95% CIs for both proportions overlapped, indicating that the study may have been underpowered. Lack of acceptance, however, limited further continuation of the computerized decision support system and over time likely would have led to its failure. An additional limitation is that the study methodology precluded collection of additional
Discussion
In this study, the introduction of a computerized decision support system to guide pulmonary embolism evaluation was associated with a small increase in the proportion of cases with a positive CT angiography result for pulmonary embolism. This difference increased nearly 2-fold when cases in which emergency physicians did not adhere to the computerized decision support system recommendations were excluded, suggesting that poor emergency physician adherence limited the effect of the computerized
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Supervising editor: Allan B. Wolfson, MD
Author contributions: FSD, IDW, JTW, LS, and JMF conceived the study, designed the trial, and obtained research funding. FSD, LB, and PDVB designed the computer order entry system. FSD, SC, RL, and JMF supervised the conduct of the trial and data collection. FSD, SC, and JMF undertook recruitment of participating centers and patients and managed the data, including quality control. FSD, SC, and AA collected and entered data. FSD, YW, and JMF provided statistical advice on study design and analyzed the data. FSD and JMF drafted the article, and all authors contributed substantially to its revision. FSD takes responsibility for the paper as a whole.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist.
Please see page 614 for the Editor's Capsule Summary of this article.
Publication date: Available online November 2, 2010.
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