RESPECT-ED: Rates of Pulmonary Emboli (PE) and Sub-Segmental PE with Modern Computed Tomographic Pulmonary Angiograms in Emergency Departments: A Multi-Center Observational Study Finds Significant Yield Variation, Uncorrelated with Use or Small PE Rates

Abstract

IntroductionOveruse of CT Pulmonary Angiograms (CTPA) for diagnosing pulmonary embolism (PE), particularly in Emergency Departments (ED), is considered problematic. Marked variations in positive CTPA rates are reported, with American 4–10% yields driving most concerns. Higher resolution CTPA may increase sub-segmental PE (SSPE) diagnoses, which may be up to 40% false positive. Excessive use and false positives could increase harm vs. benefit. These issues have not been systematically examined outside America.AimsTo describe current yield variation and CTPA utilisation in Australasian ED, exploring potential factors correlated with variation.MethodsA retrospective multi-centre review of consecutive ED-ordered CTPA using standard radiology reports. ED CTPA report data were inputted onto preformatted data-sheets. The primary outcome was site level yield, analysed both intra-site and against a nominated 15.3% yield. Factors potentially associated with yield were assessed for correlation.ResultsFourteen radiology departments (15 ED) provided 7077 CTPA data (94% ≥64-slice CT); PE were reported in 1028 (yield 14.6% (95%CI 13.8–15.4%; range 9.3–25.3%; site variation p <0.0001) with four sites significantly below and one above the 15.3% target. Admissions, CTPA usage, PE diagnosis rates and size of PE were uncorrelated with yield. Large PE (≥lobar) were 55% (CI: 52.1–58.2%) and SSPE 8.8% (CI: 7.1–10.5%) of positive scans. CTPA usage (0.2–1.5% adult attendances) was correlated (p<0.006) with PE diagnosis but not SSPE: large PE proportions.Discussion/ ConclusionsWe found significant intra-site CTPA yield variation within Australasia. Yield was not clearly correlated with CTPA usage or increased small PE rates. Both SSPE and large PE rates were similar to higher yield historical cohorts. CTPA use was considerably below USA 2.5–3% rates. Higher CTPA utilisation was positively correlated with PE diagnoses, but without evidence of increased proportions of small PE. This suggests that increased diagnoses seem to be of clinically relevant sized PE.

Diagnostic yield of CT pulmonary angiography in the diagnosis of pulmonary embolism: A single center experience

“…Our positive PE rate of 31% on all CT scans and 35% on CTPA scans are higher than the rates reported in other studies including the PIOPED II [20,36,41,42]. The multi-center PIOPED II trail reported the CTPA diagnostic yield of 23%, and their CT scans were performed on older generations of 4-, 8-and 16-slice scanners [41].…”

“…The multi-center PIOPED II trail reported the CTPA diagnostic yield of 23%, and their CT scans were performed on older generations of 4-, 8-and 16-slice scanners [41]. Mountain et al also conducted a multicenter study with inclusion of 14 clinical sites with 94% of CTPA performed on 64-slice CT, indicating the use of recent CT scanners [20]. The overall diagnostic yield of CTPA at all sites was 14.5% (range: 9.3 to 25.3%) with four sites having significantly lower yield which is less than the acceptable rate of 15.3%.…”

“…Sharma and Lucas reported the direct correlation between CTPA and positive rates of PE detection with results justifying the increased use of CTPA [19]. However, Mountain et al in their multi-center study showed significant variations in the diagnostic yield of CTPA with some clinical sites producing lower diagnostic yield of less than 15.3% [20]. Due to these controversial reports and potential risks of radiation dose and use of contrast medium, it is necessary to further determine whether CTPA should be used as a routine diagnostic tool in the detection of PE.…”

Double-Low Dose Protocol of Computed Tomography Pulmonary Angiography (CTPA) in the Diagnosis of Pulmonary Embolism: A Feasible Approach for Reduction of Both Contrast Medium and Radiation Doses

“…9 Increased detection of pulmonary embolism seems to be associated with increased use of CTPA, in particular in the emergency department. [11][12][13][14][15][16][17] Although there are no guidelines available about the minimum acceptable yield of CTPA, it is generally agreed that a diagnostic yield of CTPA less than 10% indicates overuse of CTPA as a diagnostic tool. 18,19 Sharma and Lucas recently reported their single center experience of CTPA in the diagnosis of pulmonary embolism over a period of 8 years.…”

“…Despite the yield variation in this multi-center study, increased use of CTPA is significantly correlated with pulmonary embolism (PE) diagnosis, thus, justifying its clinical value. 17 The increased use of CTPA raises concerns about subjecting patients to excessive radiation exposure and contrast-induced nephropathy (CIN). 7,13,20 CT is a well-recognized modality with high radiation dose, although significant dose reduction has been achieved in recent years with implementation of many dose-reduction strategies.…”