2019 EULAR/ACR SLE Classification Criteria Calculator
2019 EULAR/ACR SLE Classification Criteria Calculator
Score the 2019 EULAR/ACR criteria with the ANA entry requirement, the one-criterion-per-domain rule and the attribution rule all enforced, not just described.
2019 EULAR/ACR SLE criteria
Entry + 10 domains → 0–51ANA 1:640 on HEp-2; all features attributed to lupus. Leucopenia 3.1 × 10⁹/L, a malar rash of acute cutaneous lupus, synovitis in four joints, C3 and C4 both low, anti-dsDNA positive on a high-specificity assay. No fever, no neuropsychiatric or serosal features, no renal involvement, no antiphospholipid antibodies
Entry criterion, then ten weighted domains
- Entry
- positive ANA at 1:80 or above by HEp-2 immunofluorescence, or an equivalent assay, on at least one occasion
- Domain rule
- only one criterion — the highest weighted — counts per domain
- Attribution rule
- a criterion is not counted if there is a more likely explanation than SLE
- Clinical rule
- at least one of the seven clinical domains must contribute
- Timing
- criteria need not occur simultaneously; the score is cumulative over the recorded history
- Maximum
- 51 points — 39 clinical and 12 immunological
Worked example
ANA 1:640 on HEp-2; all features attributed to lupus. Leucopenia 3.1 × 10⁹/L, a malar rash of acute cutaneous lupus, synovitis in four joints, C3 and C4 both low, anti-dsDNA positive on a high-specificity assay. No fever, no neuropsychiatric or serosal features, no renal involvement, no antiphospholipid antibodies
Entry criterion met — ANA 1:640 is ≥1:80
Haematological: leucopenia → 3; mucocutaneous: acute cutaneous lupus → 6
Musculoskeletal: joint involvement → 6 — clinical subtotal 3 + 6 + 6 = 15
Complement: low C3 and low C4 → 4; SLE-specific antibody: anti-dsDNA → 6 — immunological subtotal 10
15 + 10 = 25 of 51
At least one clinical criterion is present, and 25 ≥ 10 → classifies as SLE
The 2019 EULAR/ACR criteria in full
| Type | Domain | Criterion | Weight |
|---|---|---|---|
| Clinical | Constitutional | Fever > 38.3 °C | 2 |
| Clinical | Haematological | Leucopenia < 4 × 10⁹/L | 3 |
| Clinical | Haematological | Thrombocytopenia < 100 × 10⁹/L | 4 |
| Clinical | Haematological | Autoimmune haemolysis | 4 |
| Clinical | Neuropsychiatric | Delirium | 2 |
| Clinical | Neuropsychiatric | Psychosis | 3 |
| Clinical | Neuropsychiatric | Seizure | 5 |
| Clinical | Mucocutaneous | Non-scarring alopecia | 2 |
| Clinical | Mucocutaneous | Oral ulcers | 2 |
| Clinical | Mucocutaneous | Subacute cutaneous or discoid lupus | 4 |
| Clinical | Mucocutaneous | Acute cutaneous lupus | 6 |
| Clinical | Serosal | Pleural or pericardial effusion | 5 |
| Clinical | Serosal | Acute pericarditis | 6 |
| Clinical | Musculoskeletal | Joint involvement | 6 |
| Clinical | Renal | Proteinuria > 0.5 g/24 h | 4 |
| Clinical | Renal | Renal biopsy class II or V lupus nephritis | 8 |
| Clinical | Renal | Renal biopsy class III or IV lupus nephritis | 10 |
| Immunological | Antiphospholipid antibodies | Anti-cardiolipin, anti-β2GPI or lupus anticoagulant | 2 |
| Immunological | Complement proteins | Low C3 or low C4 | 3 |
| Immunological | Complement proteins | Low C3 and low C4 | 4 |
| Immunological | SLE-specific antibodies | Anti-dsDNA or anti-Sm | 6 |
The three rules that change the answer
| Rule | What it means | What goes wrong without it |
|---|---|---|
| ANA ≥1:80 at least once | Obligatory entry criterion | An ANA-negative patient with nephritis and anti-Sm gets a score. The criteria say they cannot be classified at all |
| Highest criterion per domain only | Leucopenia (3) plus thrombocytopenia (4) is 4, not 7 | Domain-rich presentations inflate. A patient with alopecia, oral ulcers, discoid and acute cutaneous lupus scores 6, not 14 |
| No more likely explanation | Attribute each feature before counting it | Sepsis, drugs and thrombotic microangiopathy all supply criteria. This is the rule the authors call “central” |
| At least one clinical criterion | Serology alone never classifies | Anti-dsDNA + low C3 and C4 + antiphospholipid antibodies is 12 points, and would classify a healthy blood donor |
What changed from the 1997 ACR and 2012 SLICC criteria
| 1997 ACR revised | 2012 SLICC | 2019 EULAR/ACR | |
|---|---|---|---|
| Structure | 11 items, any 4 classify | 17 items, any 4 including ≥1 clinical and ≥1 immunological | Weighted, 2 to 10 points each, threshold 10 |
| Entry criterion | None | None | ANA ≥1:80 — obligatory |
| Items weighted? | No — a malar rash counts as much as nephritis | No | Yes |
| Biopsy-proven nephritis | One of the 11 | Classifies alone with a positive ANA or anti-dsDNA | 10 points on its own for class III/IV — reaches the threshold alone |
| Attribution | Not formalised | Not formalised | Formalised: no criterion counts if better explained |
The rules that decide the answer, and why this page enforces them
The 2019 EULAR/ACR criteria look like a points table and behave like a small rulebook. The points table is the easy part: ten domains, seven clinical and three immunological, with criteria weighted from 2 to 10, and a patient classifies at 10 or more. The rules are where scores go wrong, and there are four of them. A positive ANA at 1:80 or higher is an obligatory entry criterion — without it the criteria cannot be applied at all. Within each domain, only the highest-weighted criterion counts. At least one clinical criterion is required. And no criterion is counted at all if there is a more likely explanation than lupus.
That last rule is the one the authors single out. They write that “the concept that all criteria are only to be counted if SLE is thought to be the most likely cause of the manifestation (ie, no other more likely cause exists) is central to these new EULAR/ACR criteria”. It matters because almost every criterion on the list has a common non-lupus cause. Fever is usually infection. Cytopenias are commonly drug-induced, and a patient on azathioprine or mycophenolate is being given a reason for leucopenia by their own treatment. Proteinuria is more often diabetic than lupus nephritis in an unselected clinic. Low complement is consumed in sepsis, in thrombotic microangiopathy and in cryoglobulinaemia. Score all of those uncritically and a patient with an incidental ANA and a bad admission reaches 10 points without having lupus at all. This page therefore asks the attribution question explicitly and refuses to return a classification when the answer is no.
The domain rule is the one most calculators get wrong quietly, and it is enforced here by the shape of the inputs rather than by a warning. Each domain is a single selector, so a patient with non-scarring alopecia, oral ulcers, discoid lesions and an acute malar rash scores 6 — the highest mucocutaneous criterion — and not 14. A patient with both leucopenia and thrombocytopenia scores 4, not 7. And in the renal domain the biopsy classes supersede the proteinuria item rather than adding to it, which is why a class IV lupus nephritis is 10 points and not 14. The one place the rule is generous is timing: “criteria need not occur simultaneously”, so the score is built from the whole recorded history, not from one clinic visit. A patient in remission today still carries the pericarditis they had three years ago.
Three of the ten domains are laboratory-only, and two of those are the ones a chemical pathology report can settle. The complement domain distinguishes a low C3 or C4 (3 points) from both being low (4 points), so it is worth checking both rather than one — the C3 and C4 converters will put a result into the units your laboratory’s reference interval is quoted in, which is where most of the confusion lives. The SLE-specific antibody domain requires anti-dsDNA to be measured in an assay with at least 90% specificity against non-SLE controls — a detail that matters because ELISA anti-dsDNA is considerably less specific than Crithidia or Farr, and a weakly positive ELISA is not automatically 6 points. And the renal domain rewards a biopsy heavily, which is the criteria saying plainly that in suspected lupus nephritis the biopsy is worth more than any amount of serology. This supports a clinician’s judgement rather than replacing it. It is arithmetic on the figures entered, and it knows nothing about the patient in front of you.
Frequently asked questions
What is the entry criterion for the 2019 EULAR/ACR SLE criteria?
A positive ANA at a titre of 1:80 or higher on HEp-2 cells, or an equivalent assay, on at least one occasion. It is obligatory: a persistently ANA-negative patient cannot be classified by these criteria at all, however many other features they have.
How many points are needed to classify SLE?
Ten or more, and at least one of them must come from a clinical domain. Serological points alone — anti-dsDNA, low complement and antiphospholipid antibodies together reach 12 — never classify.
Do two criteria in the same domain both count?
No. Only the highest-weighted criterion in each domain counts. Leucopenia (3) plus thrombocytopenia (4) contributes 4, not 7, and alopecia plus oral ulcers plus discoid plus acute cutaneous lupus contributes 6, not 14.
What is the attribution rule?
A criterion is not counted if there is a more likely explanation than SLE. The authors describe this as “central” to the criteria. Drug-induced cytopenias, fever from infection, diabetic proteinuria and complement consumed in a microangiopathy all look like criteria and none of them should be scored.
Must all the criteria be present at the same time?
No — “criteria need not occur simultaneously”. The score is cumulative across the recorded history, so features documented years apart all count. A patient in remission today may still classify on what is in their notes.
What is the maximum possible score?
51 points — the sum of the highest-weighted criterion in each of the ten domains, which is 39 clinical and 12 immunological. Class III or IV lupus nephritis on biopsy is worth 10 on its own and reaches the classification threshold by itself, provided the entry criterion is met.
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References
- Aringer M, Costenbader K, Daikh D, et al. 2019 European League Against Rheumatism/American College of Rheumatology classification criteria for systemic lupus erythematosus. Ann Rheum Dis. 2019;78(9):1151–9.
- Aringer M, Costenbader K, Daikh D, et al. 2019 European League Against Rheumatism/American College of Rheumatology classification criteria for systemic lupus erythematosus. Arthritis Rheumatol. 2019;71(9):1400–12.
- Petri M, Orbai AM, Alarcón GS, et al. Derivation and validation of the Systemic Lupus International Collaborating Clinics classification criteria for systemic lupus erythematosus. Arthritis Rheum. 2012;64(8):2677–86.
- Hochberg MC. Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum. 1997;40(9):1725.
- Fanouriakis A, Kostopoulou M, Andersen J, et al. EULAR recommendations for the management of systemic lupus erythematosus: 2023 update. Ann Rheum Dis. 2024;83(1):15–29.
Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.