1997 ACR classification criteria for SLE

Classification criteria are agreed checklists, used so that research studies include comparable patients. They support a clinician's overall judgement but do not replace it. SLE can involve the skin, mouth, joints, blood, kidneys and nervous system, as well as the linings of the heart and lungs, and the 1997 criteria list eleven items that reflect this. A patient is classified as having SLE when at least four are present, in any combination. The items do not have to occur at the same time.

The mnemonic SOAP BRAIN MD recalls the items: serositis (the lining of the lungs or heart is inflamed), oral ulcers, arthritis in two or more joints that does not destroy the bone, photosensitivity (rash after sun exposure), blood abnormalities on a full blood count (for example haemolytic anaemia, in which red cells are destroyed too early), renal abnormalities (persistent proteinuria, meaning protein in the urine), a positive ANA (anti-nuclear antibody, an antibody against components of the cell nucleus), immunological abnormalities (for example anti-dsDNA antibodies, which target double-stranded DNA), neurological abnormalities (for example seizures), malar rash (a butterfly-shaped redness across the cheeks and the bridge of the nose) and discoid rash (red, scaly, sharply outlined patches).

A positive ANA is itself one of the eleven items, not an extra requirement. Score by counting recognised items, not by how typical the features sound: a malar rash is very characteristic but only counts as one. Fatigue, Raynaud phenomenon (cold-triggered colour change in the fingers) and a family history are not on the list, so they add nothing to the count. No single item is mandatory, so renal disease, a malar rash and neurological features are optional.

The newer 2019 criteria differ: they need a positive ANA at least once, one or more clinical features, and 10 or more weighted points.