Leiden Clinical Prediction Rule for Undifferentiated Arthritis

Leiden Clinical Prediction Rule

Age at Symptom Onset

Sex

Distribution of Involved Joints

Morning Stiffness ≥30 Minutes

Tender Joint Count

Compression Pain (MTP/MCP Squeeze Test)

Leiden Score: 0

Low Risk

Low probability of progression to persistent or erosive arthritis. Consider watchful waiting.

Diagnoses rheumatoid arthritis in patients with recent-onset undifferentiated arthritis.

Why Use

Estimates an individual’s 1-year likelihood that undifferentiated arthritis will evolve into persistent/erosive RA, helping clinicians weigh the benefits of early DMARD initiation against the risks of overtreatment.

When to Use

Apply to adults with recent-onset clinical synovitis who do not yet meet classification criteria for any specific rheumatologic disease, including rheumatoid arthritis (RA).

Formula

Age × 0.02 + sum of all other selected points: Variable Points Age, years Multiply by 0.02 Sex Male 0 Female 1 Distribution of involved joints Small joints in hands/feet 0.5 Upper extremities only 1 Upper and lower extremities 1.5 Other 0 Symmetric distribution No 0 Yes 0.5 Duration of morning stiffness <30 min 0 30-59 min 0.5 ≥60 min 1 Number of tender joints (out of 68) <4 0 4-10 0.5 ≥11 1 Number of swollen joints (out of 66) <4 0 4-10 0.5 ≥11 1 C-reactive protein level, mg/L <5 0 5-50 0.5 ≥51 1.5 Rheumatoid factor Negative 0 Positive 1 Anti-CCP antibodies Negative 0 Positive 2

Pearls / Pitfalls

Derived and chiefly validated in Dutch early-arthritis cohorts; calibration may drift in populations with different seropositive rates or disease spectra. Obtain laboratory studies (RF, anti-CCP, CRP) and joint counts before starting DMARDs or glucocorticoids to preserve accuracy. A score ≥8 carries a 97% risk of RA within 6–12 months, whereas ≤6 yields a 70%–90 % negative predictive value for non-progression; reported AUC ranges 0.87–0.97.

Management

Low risk (score ≤6): Provide symptomatic care (e.g., NSAIDs, brief steroid taper if needed). Re-evaluate regularly; re-score if new joint involvement or laboratory abnormalities emerge. Indeterminate risk (score 6.1–7.9): Follow closely with repeat assessments. Consider early rheumatology referral and discussion of DMARD therapy. High risk (score ≥8.0): Refer to rheumatology for DMARD therapy and further management.

Advice

Use the result to support, not replace, a comprehensive clinical assessment and sound clinical judgment.

More Information

Interpretation: Score Risk Group* ≤6.0 Low >6.0 and <8.0 Indeterminate ≥8.0 High *In the validation study including 3 separate cohorts, combined negative predictive value for developing rheumatoid arthritis was 83% for scores ≤6.0, and combined positive predictive value for scores ≥8.0 was 97%.