YEARS Algorithm Definition of "PE Not Likely"
In the YEARS algorithm, pulmonary embolism is considered "not likely" (and can be safely excluded without imaging) when patients have ZERO YEARS clinical items AND a D-dimer <1000 ng/mL, OR when patients have one or more YEARS items AND a D-dimer <500 ng/mL. 1, 2
The Three YEARS Clinical Items
The YEARS algorithm uses only three clinical criteria from the Wells score: 1, 2
- Clinical signs or symptoms of deep vein thrombosis (unilateral leg swelling, pain on palpation)
- Hemoptysis (coughing up blood)
- Pulmonary embolism is the most likely diagnosis (no alternative diagnosis is more likely)
Specific Exclusion Criteria
PE is excluded and no CTPA is needed when: 1, 2
- Zero YEARS items present (all three questions answered "no") AND D-dimer <1000 ng/mL
- OR one or more YEARS items present (any question answered "yes") AND D-dimer <500 ng/mL
All other patients require CT pulmonary angiography. 1, 2
Safety and Validation
The YEARS algorithm was prospectively validated in 3,465 patients with suspected PE, demonstrating: 2
- Failure rate of 0.61% (95% CI 0.36-0.96%) among 2,946 patients in whom PE was ruled out at baseline
- Six fatal PE cases (0.20%, 95% CI 0.07-0.44%) during 3-month follow-up among those left untreated
- Negative predictive value >99% when combined with the specified D-dimer thresholds 3
Efficiency Advantage
The YEARS algorithm reduces unnecessary CTPA by 14% absolute reduction compared to the conventional Wells score with fixed D-dimer threshold of 500 ng/mL. 2
- CTPA avoided in 48% of patients using YEARS versus 34% with conventional Wells approach 2
- In primary care settings, PE can be safely ruled out in 80.6% of patients using YEARS 4
- Emergency department visit time reduced by approximately 60 minutes with YEARS implementation 5
Critical Implementation Points
The YEARS algorithm requires simultaneous assessment of all three clinical items and D-dimer measurement—not sequential testing. 1, 2 This parallel approach is what enables the efficiency gains and shorter turnaround times. 5
The higher D-dimer threshold (1000 ng/mL) applies ONLY to patients with zero YEARS items—this reflects the lower pre-test probability in this subgroup and safely excludes more patients from imaging. 1, 2
Common Pitfalls to Avoid
- Do not apply the 1000 ng/mL threshold to patients with any positive YEARS items—these patients require the standard 500 ng/mL cutoff 1, 2
- Do not use YEARS in high-risk patients with hemodynamic instability—these patients require immediate imaging regardless of clinical probability or D-dimer 1
- Ensure D-dimer assays used are highly sensitive (ELISA or equivalent with ≥95% sensitivity)—point-of-care assays with lower sensitivity should not be used with YEARS 1