Comparing Prevalence of Pulmonary Embolism in an Urban Tertiary Care Center After Implementation of CHEST/ATS Practice Guidelines on Choosing Wisely Regarding Imaging Tests

Abstract

SESSION TITLE: Venous Thromboembolism SESSION TYPE: Original Investigation Poster PRESENTED ON: Wednesday, November 1, 2017 at 01:30 PM - 02:30 PM PURPOSE: The Choosing Wisely initiative aims to minimize the number of chest computed tomography (CT) scans performed when the pretest probability for pulmonary embolism (PE) is low. As a consequence of this initiative, a screening protocol for PE was initiated in our Emergency Room. This protocol mandated the calculation of PERC, Geneva, or Well’s prior to ordering a diagnostic test to evaluate for PE. We compared the prevalence of PE before and after protocol initiation. We hypothesized that unnecessary testing decreased after protocol implementation. METHODS: We conducted a retrospective cohort study of patients suspected of having a PE between January-June 2010 and October-December 2016. We included all consecutive subjects who had a CT chest with PE protocol or ventilation-perfusion scan. Baseline demographics, pretest probability scoring, and imaging results were collected. A positive CT chest with PE protocol or a high probability V/Q scan was diagnostic for PE. Our primary outcome was the prevalence of PE before and after the protocol was started. Secondary outcomes included the diagnostic yield of PERC, revised Geneva, and Wells criteria as the most appropriate screening tool. Fisher’s exact test was used for categorical variables while student’s t-test was used to compare means. Mann-Whitney U was used to compare nonparametric linear variables. The area under the receiver operator curve (AUROC) was used to determine which test was most accurate. All analyses were two tailed and a p-value <0.05 was considered statistically significant. RESULTS: The post-protocol cohort included 104 subjects (mean age: 64.1+/-15.5; male: 51%). The pre-protocol cohort consisted of 1677 patients [mean age: 50.6+/-16.5 (P=0.13); male: 29.5% (P<0.0001)]. Before implementation of the protocol, 6.4% of subjects were diagnosed with PE compared to 10.6% post-intervention (P=0.105). After protocol initiation, PERC was low probability in only 4.8%, while Geneva was 22.1% and Wells was 51.0%. The AUROC for each screening tool was as follows: PERC: 0.62 (95% CI: 0.48-0.77), Geneva: 0.54 (95% CI: 0.35-0.73), Well’s: 0.83 (95% CI: 0.70-0.97). CONCLUSIONS: The prevalence of PE did not change significantly after implementation of a protocol designed to decrease the use of needless diagnostic imaging for PE. However, PERC was low probability in very few patients which may indicate a shift in practice patterns and that fewer low probably PERC patients were diagnostically imaged. There was a trend towards improved diagnostic yield using Wells criteria. However, limitations include the sample size and the retrospective nature of this study. CLINICAL IMPLICATIONS: Decreasing the use of diagnostic imaging for PE was unsuccessful at our institution. This may suggest that Choosing Wisely may not be applicable on an individual institutional basis or our institution’s inability to strictly implement the protocol. Perhaps shifting to the Wells criteria instead of PERC or Geneva will improve our outcomes. DISCLOSURE: The following authors have nothing to disclose: Bilal ElChaarani, Kimberley Doucette, Tanuj Sharma, Genese Lamare, Chee Chan No Product/Research Disclosure Information