A couple of years (ha ha!) ago, the results of the YEARS study were unveiled, a culmination of various ideas towards incorporating pretest probability into the use of the D-dimer for “ruling out” pulmonary embolism. The ideas were not unique to this research group in the Netherlands, but the implementation was – and many awaited some independent confirmation of their results.
This is a step towards that independent confirmation, a multi-center observational evaluation of the YEARS protocol. In this study, these authors collected the data necessary to determine the workup and outcomes via YEARS, but clinical practice was left unchanged. This is of particular importance because, unfortunately, this leaves a glaring hole in their enrollment criteria – YEARS did not have any carve outs for patients in whom D-dimer was not part of the evaluation for PE, whereas in these EDs, patients with high pretest likelihood typically went straight to imaging without D-dimers.
Overall, then, in these 17 Emergency Departments, 1,789 low- and intermediate-risk patients were evaluated for PE, with an overall prevalence of 4%. There were 7 (0.3%) patients determined to have potentially missed PE by three month chart review and follow-up phone calls, with a default assignment of “no PE” for the handful lost to follow-up. In their sample, usual practice led 45% undergoing CTPA and 9% undergoing V/Q. With YEARS criteria implemented, the imaging rate would have been 33% – at the cost of an additional 6 missed PEs. This miss rate, however, is still below the threshold of testing equipoise, balancing the morbidity of anticoagulation versus the morbidity of missing PE.
This is a helpful piece of evidence in support of YEARS, even if it leaves major questions unanswered regarding its use in high-pretest probability patients, to say the least. The imaging reduction estimation, as well, should be considered to be overstated by an observational trial, as the adoption of apparently aggressive new protocols would likely be slower than this theoretical maximum.
One small step forward.
“Multicenter Evaluation of the YEARS Criteria in Emergency Department Patients Evaluated for Pulmonary Embolism”
https://www.ncbi.nlm.nih.gov/pubmed/29603819