YEARS algorithm for suspected PE: the three items and how they're counted
The YEARS algorithm counts three items in a person with suspected pulmonary embolism (PE): clinical signs of deep vein thrombosis, hemoptysis (coughing up blood), and PE being the most likely explanation for the symptoms. Each present item counts 1, for a YEARS item count of 0 to 3. The algorithm then reads a D-dimer result against one of two D-dimer levels: one for a count of 0, and a different one for a count of 1 to 3. A person with hemoptysis alone has a count of 1.
This page doesn't interpret the result. The two D-dimer levels appear in the exact expression the calculator uses, below; this page doesn't say what the result means. It explains the item count and how the inputs fit together.
Not a medical device. Not a diagnosis or dosing recommendation.
What is the YEARS algorithm?
YEARS is a simplified clinical decision rule for suspected acute pulmonary embolism, published by Tom van der Hulle, Whitney Y. Cheung, Stephanie Kooij and colleagues in The Lancet in 2017. It's also called the YEARS rule, YEARS criteria or YEARS study algorithm.
The 2017 abstract describes a rule that uses different D-dimer levels depending on the items present, built "to be fast, to be compatible with clinical practice, and to reduce the number of CTPA investigations in all age groups." CTPA is CT pulmonary angiography, a scan of the lung arteries.
Magent's calculator returns the item count, the D-dimer it used, the D-dimer level that applies to that count, and two true/false result fields. This page explains the item count and which D-dimer level applies to which count. It doesn't interpret the result.
The YEARS logic
years_items = clinical_signs_dvt + hemoptysis + pe_most_likely (0 to 3)
D-dimer level used:
years_items = 0 -> the higher of the two published levels
years_items = 1 to 3 -> the lower of the two published levels
result fields compare d_dimer_ng_ml with that level (strictly below vs not)Exact expression the calculator uses:
PE excluded iff (years_items == 0 and d_dimer_ng_ml < 1000) or (years_items >= 1 and d_dimer_ng_ml < 500); years_items counts clinical_signs_dvt, hemoptysis, and pe_most_likelyThe items aren't weighted. One item and three items use the same D-dimer level.
The three items
| Item | Input | Counts 1 when |
|---|---|---|
| Clinical signs of deep vein thrombosis | clinical_signs_dvt (true/false) | true |
| Hemoptysis | hemoptysis (true/false) | true |
| PE is the most likely explanation | pe_most_likely (true/false) | true |
Plus one number:
| Input | Unit | Range |
|---|---|---|
d_dimer_ng_ml | ng/mL fibrinogen-equivalent units (FEU) | 0–20,000 |
How to apply YEARS
- Count the items. Clinical signs of DVT, hemoptysis, PE most likely. Each present item counts 1.
- Note which D-dimer level applies. A count of 0 uses one level; any count from 1 to 3 uses the other.
- Compare the D-dimer. The comparison is strict: a D-dimer exactly equal to the level is treated the same as one above it.
- Read the fields. Magent returns
pe_excludedandctpa_indicated. This page doesn't say what to do with either.
The D-dimer unit matters
Magent's calculator takes D-dimer in ng/mL fibrinogen-equivalent units (FEU), as in the paper. Results reported in other units, such as D-dimer units (DDU) or mg/L, aren't the same number and aren't what this calculator expects.
What the calculator returns
Magent's calculator returns years_items (0–3), d_dimer_ng_ml, d_dimer_threshold_ng_ml (the level that applied), pe_excluded, ctpa_indicated and a row for each item.
Worked examples
These use Magent's own expected item counts for the calculator.
Example 1: no items
- Clinical signs of DVT: no. Hemoptysis: no. PE most likely: no.
- YEARS items = 0. The count-0 D-dimer level applies.
Example 2: clinical signs of DVT alone
- Clinical signs of DVT → 1.
- YEARS items = 1. The count-1-to-3 D-dimer level applies.
Example 3: all three items
- Clinical signs of DVT → 1; hemoptysis → 1; PE most likely → 1.
- YEARS items = 3. The same count-1-to-3 level applies as in Example 2.
YEARS reference values
These are Magent's expected item counts. With no items, the count is 0 and the count-0 level is used. Signs of DVT alone gives a count of 1, and all three items give a count of 3. Both use the count-1-to-3 level.
History of the YEARS algorithm
The algorithm comes from Tom van der Hulle, Whitney Y. Cheung, Stephanie Kooij, Ludo F. M. Beenen, Thomas van Bemmel and colleagues, Simplified diagnostic management of suspected pulmonary embolism (the YEARS study): a prospective, multicentre, cohort study, The Lancet, 2017 (volume 390, issue 10091, pages 289–297).
The abstract explains the motivation: existing diagnostic algorithms for suspected PE are often not used correctly, "leading to overuse of computed tomography pulmonary angiography (CTPA)."
The study was "a prospective, multicentre, cohort study in 12 hospitals in the Netherlands, including consecutive patients with suspected pulmonary embolism." Patients were assessed with the three YEARS items (clinical signs of deep vein thrombosis, haemoptysis, and whether pulmonary embolism was the most likely explanation) together with D-dimer concentrations. In total, "3616 consecutive patients with clinically suspected pulmonary embolism were screened."
When it's used
The 2017 study included consecutive patients with suspected pulmonary embolism. Magent's record notes that the study excluded pregnancy, and the calculator doesn't apply a pregnancy-adapted version.
Where it's used
The study took place in 12 hospitals in the Netherlands.
Who uses it
In the study, patients were assessed with the YEARS items and a D-dimer at the same time, per the abstract.
Limits of the calculation
- It counts three items and compares a D-dimer. It doesn't diagnose or confirm PE.
- All three items are the caller's call. Magent doesn't decide whether PE is the most likely explanation.
- D-dimer must be in ng/mL FEU.
- It has no pregnancy input and isn't the pregnancy-adapted YEARS.
- It isn't the Wells PE score or the PERC rule.
- This page doesn't say what the result means.
Clinical decisions belong to a qualified clinician who knows the patient.
How it differs from related calculators
Glossary
- PE: pulmonary embolism, a blood clot in the lung arteries.
- DVT: deep vein thrombosis, a clot in a deep vein, usually in the leg.
- Hemoptysis: coughing up blood.
- D-dimer: a blood test for a protein fragment released when a clot breaks down.
- FEU: fibrinogen-equivalent units, one of the ways D-dimer is reported.
- CTPA: CT pulmonary angiography, a scan of the lung arteries.
Common mistakes
- Weighting the items. Each item counts 1, and one item is treated the same as three.
- Using the wrong D-dimer unit. The calculator expects ng/mL FEU.
- Treating a D-dimer equal to the level as below it. The comparison is strictly "below."
- Using it in pregnancy. The original study excluded pregnancy.
- Confusing YEARS with Wells. They have different items and work differently.
Source
van der Hulle T, Cheung WY, Kooij S, et al. Simplified diagnostic management of suspected pulmonary embolism (the YEARS study): a prospective, multicentre, cohort study. Lancet. 2017;390(10091):289-297. DOI: 10.1016/S0140-6736(17)30885-1
Frequently asked questions
What are the YEARS criteria?
Clinical signs of deep vein thrombosis, hemoptysis, and PE being the most likely explanation, each counted once, plus a D-dimer.
What D-dimer level does YEARS use?
The exact expression above uses one level when no items are present and a lower one when one or more are present. This page doesn't say what a result means.
Are the YEARS items weighted?
No. Each counts 1, and any count from 1 to 3 is treated the same.
What unit does the YEARS D-dimer use?
ng/mL fibrinogen-equivalent units (FEU), as in the 2017 paper.
Who developed the YEARS algorithm?
Tom van der Hulle and colleagues, in a 2017 study in The Lancet.