Research in context
Evidence before this study
We did not do a systematic search on this topic. However, on the basis of several prospective management studies, patients with clinically suspected pulmonary embolism should be managed according to a validated diagnostic algorithm consisting of clinical decision rule such as the Wells' rule, which predicts the pretest probability of pulmonary embolism, a D-dimer test, and eventually a multirow detector computed tomography pulmonary angiography (CTPA). By using such a diagnostic algorithm, pulmonary embolism can be excluded without CTPA in 20–30% of patients, thereby omitting radiation exposure. In a meta-analysis, the 3-month risk of venous thromboembolism in patients managed without CTPA is 0·65% (95% CI 0·38–1·11). Importantly, most CTPA results are still negative for pulmonary embolism, indicating that many patients are exposed to unnecessary radiation. An age-adjusted D-dimer threshold (age × 10 ng/mL for patients >50 years) has been validated prospectively, reporting an absolute reduction of 11·6% (95% CI 10·5–12·9) in the need for CTPA. Only patients aged 50 years or older, and foremost those older than 75 years benefit from this strategy whereas the exposure to unnecessary radiation might be more relevant to younger individuals, particularly women. Therefore, one of the remaining challenges is to further reduce the number of CTPA without reducing the safety of diagnostic management.
Additionally, despite firm evidence of its safety and efficiency, several studies reported that adherence to recommended diagnostic algorithms outside clinical studies is poor. This finding might be partly due to its complexity, and insufficient time at busy emergency departments, which hampers the use of sequential tests. Improved adherence to the algorithm has been shown to significantly decrease the mean number of diagnostic tests used along with—and more importantly—the number of diagnostic failures. For instance, one study reported a failure rate of 7·7% in patients who were managed inappropriately compared with only 1·2% in patients managed appropriately.
Added value of this study
In this study, a novel and simplified diagnostic algorithm for suspected acute pulmonary embolism (the YEARS algorithm) has been prospectively investigated. The YEARS algorithm consists of only three items of the original Wells' clinical decision rule—ie, clinical signs of deep vein thrombosis, haemoptysis, and whether pulmonary embolism is the most likely diagnosis—were found to be the most predictive for pulmonary embolism. This simplified clinical decision rule was combined with variable D-dimer threshold depending on the presence of one of these items. In patients in whom none of the items were present, a D-dimer test threshold of 1000 ng/mL was used whereas a D-dimer threshold of 500 ng/mL was used when one or more items were present.
Our study showed that the YEARS algorithm is safe during 3 months of follow-up in all patients who had pulmonary embolism excluded. In patients managed without CTPA, the 3-month risk of venous thromboembolism was well comparable to the risk reported by a meta-analysis after the current standard algorithm was used. The advantage of the YEARS algorithm is an absolute reduction of 14% of CTPA compared with the current standard algorithm and, importantly, an 8·7% reduction compared with the age-adjusted D-dimer threshold. In this context, patients younger than 50 years also benefit from the YEARS algorithm.
Implications of all the available evidence
There are two main advantages of the YEARS algorithm. First, the YEARS algorithm leads to an absolute 14% decrease in the number of CTPA examinations that is applicable to all ages. This decrease is a major step forward in reducing unnecessary radiation exposure in patients with suspected pulmonary embolism. Second, the YEARS algorithm leads to a simpler and more efficient diagnostic management of patients with suspected pulmonary embolism than standard diagnostic algorithms such as the Christopher Study algorithm, which is likely to improve the adherence to correct diagnostic management of suspected pulmonary embolism and thereby lead to better safety and efficiency in daily clinical practice.