The 2016 ACR/EULAR Classification Criteria for Primary Sjögren’s Syndrome are a research/classification standard created by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) to identify people who can be classified as having primary Sjögren’s syndrome. They are meant for patients with symptoms or signs suggestive of Sjögren’s, and they are classification criteria, not the same thing as a clinical diagnosis.

The criteria use a weighted point system with 5 items:

• Labial salivary gland biopsy showing focal lymphocytic sialadenitis with focus score ≥ 1 = 3 points
• Anti-SSA/Ro antibody positive = 3 points
• Ocular staining score ≥ 5 in at least 1 eye, or van Bijsterveld score ≥ 4 in at least 1 eye = 1 point
• Schirmer test ≤ 5 mm/5 min in at least 1 eye = 1 point
• Unstimulated whole saliva flow rate ≤ 0.1 mL/min = 1 point

A person is classified as having primary Sjögren’s syndrome when:

• the total score is 4 or more,
• they have at least 1 symptom of ocular or oral dryness or other sufficient clinical suspicion, and
• they do not have one of the listed exclusion conditions.

Common exclusion criteria include: prior head/neck radiation, active hepatitis C, advanced HIV, sarcoidosis, amyloidosis, graft-versus-host disease, and IgG4-related disease.

So in plain language: it is a point-based system used to decide whether someone fits the formal classification for primary Sjögren’s. The biggest-weight items are positive anti-SSA/Ro and a positive labial salivary gland biopsy.