Definitions of SLE classification criteria
| Criteria | Definition |
| Antinuclear antibodies (ANA) | ANA at a titre of ≥1:80 on HEp-2 cells or an equivalent positive test at least once. Testing by immunofluorescence on HEp-2 cells or a solid phase ANA screening immunoassay with at least equivalent performance is highly recommended |
| Fever | Temperature >38.3°C |
| Leucopenia | White blood cell count <4.0×10∧9/l |
| Thrombocytopenia | Platelet count <100×10∧9/l |
| Autoimmune haemolysis | Evidence of haemolysis, such as reticulocytosis, low haptoglobin, elevated indirect bilirubin, elevated lactate dehydrogenase (LDH) AND positive Coomb’s (direct antiglobulin) test. |
| Delirium | Characterised by (1) change in consciousness or level of arousal with reduced ability to focus, (2) symptom development over hours to <2 days, (3) symptom fluctuation throughout the day, (4) either (4a) acute/subacute change in cognition (eg, memory deficit or disorientation), or (4b) change in behaviour, mood, or affect (eg, restlessness, reversal of sleep/wake cycle) |
| Psychosis | Characterised by (1) delusions and/or hallucinations without insight and (2) absence of delirium |
| Seizure | Primary generalised seizure or partial/focal seizure |
| Non-scarring alopecia | Non-scarring alopecia observed by a clinician* |
| Oral ulcers | Oral ulcers observed by a clinician* |
| Subacute cutaneous or discoid lupus | Subacute cutaneous lupus erythematosus observed by a clinician*: Annular or papulosquamous (psoriasiform) cutaneous eruption, usually photodistributed Discoid lupus erythematosus observed by a clinician*: Erythematous-violaceous cutaneous lesions with secondary changes of atrophic scarring, dyspigmentation, often follicular hyperkeratosis/haematological(scalp), leading to scarring alopecia on the scalp If skin biopsy is performed, typical changes must be present. Subacute cutaneous lupus: interface vacuolar dermatitis consisting of a perivascular lymphohistiocytic infiltrate, often with dermal mucin noted. Discoid lupus: interface vacuolar dermatitis consisting of a perivascular and/or periappendageal lymphohistiocytic infiltrate. In the scalp, follicular keratin plugs may be seen. In longstanding lesions, mucin deposition and basement membrane thickening may be noted |
| Acute cutaneous lupus | Malar rash or generalised maculopapular rash observed by a clinician If skin biopsy is performed, typical changes must be present: interface vacuolar dermatitis consisting of a perivascular lymphohistiocytic infiltrate, often with dermal mucin noted. Perivascular neutrophilic infiltrate may be present early in the course |
| Pleural or pericardial effusion | Imaging evidence (such as ultrasound, X-ray, CT scan, MRI) of pleural or pericardial effusion, or both |
| Acute pericarditis | ≥2 of (1) pericardial chest pain (typically sharp, worse with inspiration, improved by leaning forward), (2) pericardial rub, (3) electrocardiogram (EKG) with new widespread ST-elevation or PR depression, (4) new or worsened pericardial effusion on imaging (such as ultrasound, X-ray, CT scan, MRI) |
| Joint involvement | EITHER (1) synovitis involving two or more joints characterised by swelling or effusion OR (2) tenderness in two or more joints and at least 30 min of morning stiffness |
| Proteinuria >0.5 g/24 hours | Proteinuria >0.5 g/24 hours by 24 hours urine or equivalent spot urine protein-to-creatinine ratio |
| Class II or V lupus nephritis on renal biopsy according to ISN/RPS 2003 classification | Class II: mesangial proliferative lupus nephritis: purely mesangial hypercellularity of any degree or mesangial matrix expansion by light microscopy, with mesangial immune deposit. A few isolated subepithelial or subendothelial deposits may be visible by immune-fluorescence or electron microscopy, but not by light microscopy Class V: membranous lupus nephritis: global or segmental subepithelial immune deposits or their morphological sequelae by light microscopy and by immunofluorescence or electron microscopy, with or without mesangial alterations |
| Class III or IV lupus nephritis on renal biopsy according to International Society of Nephrology/ Renal Pathology Society (ISN/RPS) 2003 | Class III: focal lupus nephritis: active or inactive focal, segmental or global endocapillary or extracapillary glomerulonephritis involving <50% of all glomeruli, typically with focal subendothelial immune deposits, with or without mesangial alterations Class IV: diffuse lupus nephritis: active or inactive diffuse, segmental or global endocapillary or extracapillary glomerulonephritis involving ≥50% of all glomeruli, typically with diffuse subendothelial immune deposits, with or without mesangial alterations. This class includes cases with diffuse wire loop deposits but with little or no glomerular proliferation |
| Positive antiphospholipid antibodies | Anticardiolipin antibodies (IgA, IgG, or IgM) at medium or high titre (>40 A phospholipids (APL), GPL or MPL units, or >the 99th percentile) or positive anti-β2GP1 antibodies (IgA, IgG, or IgM) or positive lupus anticoagulant |
| Low C3 OR low C4 | C3 OR C4 below the lower limit of normal |
| Low C3 AND low C4 | Both C3 AND C4 below their lower limits of normal |
| Anti-dsDNA antibodies OR anti-Smith (Sm) antibodies. | Anti-dsDNA antibodies in an immunoassay with demonstrated ≥90% specificity for SLE against relevant disease controls OR anti-Sm antibodies |
ISN/RPS International Society of Nephrology/Renal Pathology Society
*This may include physical examination or review of a photograph.
dsDNA, double-stranded DNA; SLE, systemic lupus erythematosus.