Associations between Presence of Relevant Information in Referrals to Radiology and Prevalence Rates in Patients with Suspected Pulmonary Embolism

Abstract

The purpose of this study was to assess if the presence of information including the pretest probability (Wells score), other known risk factors, and symptoms given on referrals for computed tomography (CT) pulmonary angiography correlated with prevalence rates for pulmonary embolism (PE). Also, to evaluate for differences between a university and a regional hospital setting regarding patient characteristics, amount of relevant information provided on referrals, and prevalence rates for pulmonary embolism. Retrospective review of all consecutive referrals (emergency room, inpatient, and outpatient) for CT performed on children and adults for suspected PE from two sites: a tertiary (university) hospital (site 1) and a secondary (regional) hospital (site 2) over a 5-year period. The overall prevalence rate was 510/3641 or 14% of all referrals. Significantly higher number of males had a positive CT compared to women (18% versus 12%, P < .001). Although no statistically significant relationship between a greater amount of relevant information on the referral and the probability for positive finding existed, a slight trend was noted (P = .09). In two categories, "hypoxia" and "signs of deep vein thrombosis," the presence of this information conferred a higher probability for pulmonary embolism, P < .001. In the categories, "chest pain," "malaise," and "smoker/chronic obstructive pulmonary disease", the absence of information conferred a higher probability for pulmonary embolism. The amount of relevant clinical information on the request did not correlate with prevalence rates, which may reflect a lack of documentation on the part of emergency physicians who may use a "gestalt" approach. Request forms likely did not capture all relevant patient risks and many factors may interact with each other, both positively and negatively. Pretest probability estimations were rarely performed, despite their inclusion in major society guidelines.