PURPOSE: To demonstrate the accuracy of pretest probability assessment for pulmonary embolism using Wells score. To evaluate the safety and utility of a clinical diagnostic strategy in the diagnosis of acute pulmonary embolism in patients with various clinical probabilities based on Wells score.
METHODS: Retrospective chart review of patients who underwent CT-angiogram(CTA) to rule out PE in ED,medical-surgical floors and ICU at our institution over 1 year period.Charts reviewed for:Demographics,location of patient at the time of CTA ordered,CTA results,venous doppler of lower extremities results,variables of Wells-score,clinical impression of the attending physician or resident at the time of ordering CTAand outcome in terms of survival and disposition.Patients were divided into three-groups according to pretest clinical probability for pulmonary embolism based on Wells-score.Patients with low clinical probability(LCP)(<2),patients with intermediate clinical probability(ICP)(2-6),patients with high clinical probability(HCP)(>6).
RESULTS: Using wells-score:79%had LCP,18%had ICP,3%had HCP.Only 7%(8out of 108)had positive CTA.Location of ordering CTA:ER(62%),floor(24%),8%Telemetry,6%ICU with the following positive rate of 7.5%,7.7%,0%,&14.3%respectively.Among patients with positive-CTA:0%had-LCP,62.5%had-ICP and 37.5%had-HCP.Among the negative-CTA:85%had-LCP,15%had-ICP and 0%had-HCP.Using HCP and ICP as positve probability and LCP as negative probability for PE, the sensitivity, specificity,negative predictive value and positive predictive value were 100%,85%,100%,&34.8%respectively.
CONCLUSION: The total positivity rate for PE using-CTA was low despite the fact that most of them had low clinical probability(LCP)at the time of ordering the test using wells-score.Most CTA-tests were ordered in ER with the lowest yield among other hospital units.All patients with LCP had negative-CTA,while all those with HCP had positive-CTA.Wells-score had a good sensitivity and negative predicitve value.
CLINICAL IMPLICATIONS: Wells score is a powerful and safe tool to exclude the diagnosis of PE in patients with low clinical probability of acute PE including patients seen in the ED.Intermediate and high probability require further diagnostic testing such as CT-pulmonary angiogram to confirm the dignosis of PE.
DISCLOSURE: Reshma Khetpal, No Financial Disclosure Information; No Product/Research Disclosure Information