1. The PERC Rule

2. The paper Kline et al Journal of Thrombosis and Haemostasis 2008 Prospective Multicenter Evaluation of the Pulmonary Embolism Rule Out Criteria

3. As a background 2004 Kline PERC derivation paper ‘Clinical criteria to prevent unnecessary diagnostic testing in the Emergency Department; patients with suspected pulmonary embolism’

4. PERC rule Decision tool to support the clinician deciding not to investigate a patient for a suspected PE – Providing that the clinician had a low clinical suspicion of PE i.e. < 15%

5. The PERC rule Must in addition have all of the following 8 points Less than 50 years old Pulse rate < 100 Pulse oximetry reading > 94% whilst breathing room air No history of haemoptysis Not taking exogenous oestrogen No previous history of VTE No history of recent surgery or trauma (requiring endotracheal intubation or hospitalization in the past 4 weeks) Visually not evidence of unilateral calf swelling

6. Patients enrolled once an objective test was ordered to investigate a PE - written by or under the supervision of a board certified emergency physician – CTPA, VQ or a d-dimer

7. Data collected Patients followed up for 45 days – Telephone, mail, primary care physician, social security death index Used the presence of VTE (DVT or PE) in the next 45 days as a diagnosis of VTE

8. Results Enrolled 8138 from eligible 12213 53% patients had chest pain, 33% dyspnoea Prevelance of disease in the entire group 5.9% had PE within 45 days

9. Results In 1666 patients (20% of cohort) were – Gestalt of PE low – PERC negative Of these patients – 1% had a VTE or died within 45 days (upper 95% CI of 1.6%)

10. References Kline, J A et al. “Prospective multicenter evaluation of the pulmonary embolism rule- out criteria.” Journal of thrombosis and haemostasis JTH 6.5 (2008) : 772-780