Could the number of CT angiograms be reduced in emergency department patients suspected of pulmonary embolism?

doi:10.5847/wjem.j.issn.1920-8642.2012.03.002

Abstract

Abstract:

BACKGROUND: This study was undertaken to identify the prevalence of pulmonary embolism (PE) in the emergency department (ED) of an urban teaching hospital and also to test a Bayesian model in estimating the number of CT pulmonary angiography (CTA) expected to be performed in an emergency department.

METHODS: The data for this study was obtained through a retrospective review of electronic medical records for all ED patients suspected of PE who underwent chest CTA or ventilation perfusion scanning (V/Q) between 2009 and 2010. The data is presented as means and standard deviation for continuous variables and percentages with 95% confidence intervals (95%CI) for proportions. The prevalence of PE was used as pre-test probability in the Bayesian model. Post-test probability was obtained using a Fagan nomogram and likelihood ratios for CTA.

RESULTS: A total of 778 patients (560 females) with mean age of 50 years (range 18-98 years) were enrolled (98.3% underwent chest CTA and 1.7% underwent V/Q scan). A total of 69 patients had PE, rendering an overall prevalence of 8.9% (95%CI, 7.1% to 11.1%) for PE. We calculated that 132 CTA's per year could be avoided in our institution, without compromising safe exclusions of PE (keeping post-test probability of PE below 2%).

CONCLUSIONS: Despite differences in our patient populations and /or study designs, the prevalence of PE in our institution is about average compared to other institutions. Our proposed model for calculating redundant chest CTA is simple and can be used by institutions to identify overuse of CTA.

Key words: Pulmonary embolism, Emergency, CT pulmonary angiography

Zehtabchi Shahriar, Rinnert Stephan, Malhotra Shweta, Subramanian Arun, Timberger Mathew, Patel Brijal, Toro David, Hassan Khaled, Sinert Richard. Could the number of CT angiograms be reduced in emergency department patients suspected of pulmonary embolism?[J]. World Journal of Emergency Medicine, 2012, 3(3): 172-176.

Figures/Tables 7

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Variables	PE +	No PE
Age (yr)	54±16	50±17
Sex (% female)	68% (56%-78%)	73% (70%-75%)
SBP	133±23	138±24
HR	104±22	100±23
SO₂ (%)	97±4	98±4
Mortality (%)	1.5 (0.01-8.6)	2.4 (1.5-3.6)

Study	Date of publication	Journal	Prevalence (%)	95%CI
Kline et al^[14]	2010	Ann Emerg Med	7.2	6.6-7.7
Stein et al^[10]	2010	Am J Roent	13.13	11.36-15.13
Weir et al^[5]	2010	Con Med	7.79	6.85-8.84
Constantino et al^[6]	2008	Am J Roent	9.57	7.42-12.24
Engelka et al^[7]	2006	Radiol	5.95	4.99-7.09
Brown et al^[8]	2005	Acad Emerg Med	5.88	4.68-7.36
KCHC	-	-	8.98	7.17-11.18

Findings	n (%)
Consolidation/opacity	66 (9.3)
Pulmonary nodule, mass, or metastasis	114 (16)
Pleural effusion	62 (8.7)
Pericardial effusion	12 (1.7)
Mediastinal/hilar adenopathy	48 (6.8)
Large numerous axillary lymph nodes	11 (1.6)
Pulmonary cavitary lesions	6 (0.8)
Pneumothorax	1 (0.1)
Hiatal hernia	12 (1.7)
Bronchiectasis	1 (0.1)
Non-pulmonary mass (e.g. neck, breast, liver, etc)	46 (6.5)

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