Background Acute pulmonary embolism (PE) is a common presentation. Currently NICE recommends 2-level Well scoring, which may over-investigate patients leading to unnecessary anti-coagulation and contrast-related risks and significant financial costs. We investigated whether further risk stratification using a combination of 3-level Wells scoring, PERC rules and age-adjusted D-dimers could minimise costs and enhance patient safety.
Methods Retrospective analysis of patients who underwent CTPA and had complete data between September 2014 and August 2015 was carried out. Wells scores, PERC scores and age-adjusted D-dimers were calculated and compared against CTPA findings.
Results Out of 1174 patients who underwent CTPA, 1158 had complete data set. Application of PERC rules to low-risk patients (Wells score 0–1; n = 311, 27%) would have avoided 64 CTPAs, but missed 3 PEs, with a 95% sensitivity (95% CI: 0.85–0.97), 24% specificity (95% CI: 0.19–0.30), and avoided 56 D-dimers.
For intermediate-risk patients (Wells score 2−7), age-adjusted D-dimers would have avoided 265 CTPAs but missed 32 PEs, with an 81% sensitivity (95% CI: 0.74–0.86), 50% specificity (95% CI: 0.45–0.55). High-risk patients should proceed directly to CTPA.
The combination of 3-level Wells scoring, PERC rules, and age-adjusted D-dimers would have avoided 450 CTPAs (39%) but missed 39 PEs (8%), with an estimated financial saving of at least £255,150 (local CTPA tariff £567). Non-age adjusted D-dimers would have reduced this avoiding 132 CTPAs (11%), and missing only 7 PEs (5%). Further saving would have resulted from avoiding D-dimer testing in low risk PERC negative patients, and high risk patients.
Conclusion The use of a PE algorithm incorporating multiple clinical assessment tools results in a pathway which can help rationalise the number of CTPAs performed and D-dimers requested, without significantly increasing the proportion of missed PEs.
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Singh B, et al. Pulmonary embolism rule-out criteria (PERC) in pulmonary embolism–revisited: a systematic review and meta-analysis. Emerg Med J 2013;30(9):701–6.