Pulmonary Embolism Rule-out Criteria vs D-dimer testing in low-risk patients for pulmonary embolism: a retrospective study

Study objectives: The Pulmonary Embolism Rule-out Criteria (PERC) score has shown excellent negative predictive value; however, its use in the European population with high prevalence of PE is controversial. In Europe, PERC is not part of routine practice. For low-risk patients, guidelines recommend D-dimer testing, followed if positive by imaging study. We aimed to study the rate of diagnosis of PE after D-dimer testing in PERC-negative patients that could have been discharged if PERC was applied.

Method: This was a multicenter retrospective study in Paris, France. We included all patients with a suspicion of PE who had D-dimer testing in the emergency department, low pre-test probability, and a negative PERC score (that was retrospectively calculated). Patients with insufficient record to calculate PERC score were excluded. The primary end point was the rate of PE diagnosis before discharge in this population. Secondary end points included rate of invasive imaging studies and subsequent adverse events.

Results: We screened 4301 patients who had D-dimer testing, 1070 of whom were PERC negative and could be analyzed. The mean age was 35 years and 46% were men. D-dimer was positive (>500 ng/L) in 167 (16%) of them; CTPA or V/Q scan was performed in 153 (14%) cases. PE was confirmed in 5 cases (total rate 0.5%, 95% confidence interval 0.1%-1.1%). Fifteen patients (1%) experienced non-severe adverse events.

Conclusion: D-dimer testing in PERC-negative patients led to a diagnosis of PE in 0.5% of them, with 15% of patients undergoing unnecessary irradiative imaging studies.