PERC (Pulmonary Embolism Rule-Out Criteria)

PERC (Pulmonary Embolism Rule-Out Criteria) is a set of criteria established for patients with chest pain or dyspnea in outpatient settings (ie. primary care settings or emergency departments).

PERC Criteria are defined as the following:

• Age <50 years
• HR <100 BPM
• Oxygen Saturation ≥ 95%
• No hemoptysis
• No estrogen use
• No prior DVT or PE
• No unilateral leg swelling
• No surgery/trauma requiring hospitalizing in the last 4 weeks

The criteria were validated in 2008 based on a multicenter, prospective cohort study of emergency department patients whose suspected diagnosis was pulmonary embolism. It was a rather large study of 8138 patients, 85% of these patient’s chief complaint was dyspnea or chest pain.

Of these patients, 1666 patients (20%) met the PERC criteria and the clinician reported low suspicion for PE. As a diagnostic test, low suspicion and PERC (-) patients had a sensitivity of 97.4% and specificity of 21.9%.

What does it mean?

Well many patients present to their PCP or the ED with complaints of dyspnea or chest pain. In a certain population, however, it is probably not necessary to spend resources, time, risk of false positives and possible exposure to radiation to test for pulmonary embolism. The combination of gestalt estimate of low suspicion for PE and PERC(-) reduces the probability of PE to below 2% in about 20% of outpatients with suspected PE.

What does it not mean?

It is important to recall the PERC criteria were evaluated in combination with the treating physician’s clinical suspicion for PE. Like all rule out criteria, the PERC criteria does not diminish the clinician’s decision making but rather confirms and strengthens it.