Background: The diagnostic approach to patients with suspected acute pulmonary embolism (PE) evaluated in an Emergency Department [ED] may affect test utilization, test yield, and patient outcomes.
Methods: This single center cohort study aimed to determine the effects of evidence-based clinical decision support (CDS) on the use of computed tomographic pulmonary angiography (CTPA) (number of patients undergoing CTPA per 1000 ED visits), the yield (percentage of patients with CTPA positive for acute PE), and outcomes of patients with negative diagnostic work-up for PE. The study included consecutive patients with suspected PE before (preintervention period) (from January 1, 2011 to December 31, 2011) and prospectively after (postintervention period) (from January 1, 2012 to December 31, 2012) the introduction of CDS. Investigators assessed patients with negative diagnostic work-up for symptomatic venous thromboembolic events that occurred during 3-months of follow-up.
Findings: The study analyzed 652 patients preintervention and 711 patients postintervention (total 1,363). A greater proportion of patients received CTPA testing in the preintervention period than in the postintervention period (55% vs. 49%; absolute difference [AD], 6.3%; 95% CI, 1.0% to 11.6%; P=0.02). CTPA use increased preintervention (21.5% increase, from 2.60 to 3.16 examinations per 1000 patients; P=0.17) and decreased postintervention (25.4% decrease, from 3.19 to 2.38 examinations per 1000 patients; P=0.09). Of the 362 CTPA examinations performed during the preintervention period, 112 (31%) were positive for PE. Of the 350 CTPA examinations performed during the postintervention period, 116 (33%) were positive for PE. Yield increased from 26.0% to 46.5% (P<0.01) postintervention. Of the patients with a negative diagnostic work-up for PE, the frequency of possible and definite venous thromboembolic events was low (20 of 1,065 patients; 1.9%; 95% confidence interval [CI], 1.1% to 2.7%) during follow-up. Sixteen events (16 of 492 patients; 3.2%; 95% CI, 1.7% to 4.8%) occurred in the preintervention group, whereas 4 events (4 of 573 patients; 0.7%; 95% CI, 0.0% to 1.4%) occurred in the postintervention group (AD, 2.5%; 95% CI, 0.9% to 4.6%; P<0.01).
Interpretation: Implementation of evidence-based CDS in the ED for patients with suspected PE was associated with a decrease in CTPA use, an increase in CTPA yield, and a small but significant decrease in symptomatic venous thromboembolic events in patients that had a negative initial diagnostic work-up for PE.