Let’s Get Together and Ignore PERC

The “Pulmonary Embolism Rule-Out Criteria” does not, as it implies, “rule out” PE.  It does, however, generally carve out a cohort for whom objective testing may be obviated, with the implication the costs and harms from false-positives and from anticoagulation outweigh the morbidity from missed PE. It is fairly well popularized and incorporated into guidelines for PE – and, well, at the least, physicians in an academic center, on the cutting edge of medical knowledge and education, should be applying appropriately.

Or not.

This is a prospective study enrolling undifferentiated Emergency Department patients with chest pain and shortness of breath. Research staff approached patients with these general chief complaints and collected the baseline variables needed for PERC, Wells, and other baseline clinical and historical data.  They collected data on 3,204 patients, 17.5% of whom were PERC-negative. Of these, 25.5% underwent some testing for pulmonary embolism – inclusive of D-dimer, CTPA, or V/Q scanning. Then, two – 0.4% – PERC-negative patients were ultimately diagnosed with a PE. The authors also present comparative data for the PERC-positive population, with the expected higher-frequency of testing and diagnosis associated with the absence of low-risk features.

PERC is, of course, an imperfect tool, an unavoidable consequence of any decision instrument narrowing a complex clinical decision down to a handful of variables. But, at the least, patients meeting PERC ought nearly all fall into the bucket of “why were you really considering PE in the first place?”, with few exceptions. For nearly a quarter of these to start down the rabbit hole of testing for PE is low-value and harmful medical practice at a population level, regardless of the potential magnitude of individual benefit for those true positives ultimately identified.

AOr, more concisely, this is nuts.

“Pulmonary Embolism Testing among Emergency Department Patients who are Pulmonary Embolism Rule-out Criteria Negative”

http://onlinelibrary.wiley.com/doi/10.1111/acem.13270/full

2 thoughts on “Let’s Get Together and Ignore PERC”

  1. PERC is only useful in the context of low pretest prob. Doesn’t look like the study took that into account.

    1. It does – in the fine print, they mention there were five patients who were Wells’ moderate but PERC-, and they were excluded.

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