There are a few moments you pat yourself on the back in Emergency Medicine. The good save. Shared decision-making that goes well. And, the small victory when you’ve utilized an evidence-based pathway for pulmonary embolism, and received positive results for the leviathan of over-utilization and over-diagnosis: the CT pulmonary angiogram.
Well, it’s time to deduct about 1.25 fingers from that pat on the back you give yourself, because, unfortunately, radiology PE overcalls may be more rampant than initially thought.
This is a retrospective, single-center study reviewing a year’s worth of CTPA for pulmonary embolism, a total of 937 studies. Of the studies included, 174 (18.6%) were initially read as positive. Then, each positive study was reviewed by a panel of three, specially trained chest radiologists, with their consensus read used as the gold standard for diagnosis. And so: 45 (25.9%) were subsequently judged to be incorrectly read by the original radiologist – a quarter of positive studies! – with those patients almost certainly consigned to at least short-term anticoagulation as a result.
In a light moment in the discussion, the authors helpfully contribute the following commentary:
Furthermore, many pulmonary CTA examinations in our institution are ordered by the emergency department before assessment by the admitting medical team.
My heart goes out to the poor Scottish EM physicians, for whom their radiology colleagues apparently have quite the low opinion for appropriate testing. However, the authors’ attention may be better spent further discussing their own false-positive rate, which is double the ~11% rate of other similar reviews. They also do not provide any accompanying data on the rate of false-negatives, although, in theory, these should be less clinically important.
So, think twice about doing your little happy dance for a positive CT – if your pretest likelihood was low, and the PE is subsegmental, there’s a substantial chance the stars have aligned in just the wrong constellation.
“Overdiagnosis of Pulmonary Embolism by Pulmonary CT Angiography”
http://www.ncbi.nlm.nih.gov/pubmed/26204274