A diagnostic algorithm for persistence of very early inflammatory arthritis: the utility of power Doppler ultrasound when added to conventional assessment tools.

Objectives: The aim of this study was to assess the value of power Doppler ultrasound (PDUS) in combination with routine management in a cohort of patients with very early inflammatory arthritis (IA).
Methods: 50 patients with < or =12 weeks of inflammatory symptoms with or without signs had clinical, laboratory and imaging assessments. Diagnosis was recorded at 12 months. Assuming a 15% pre-test probability of IA, post-test probabilities for various assessments were calculated and used to develop a diagnostic algorithm.
Results: All patients positive for rheumatoid factor (RF) and/or cyclic citrullinated peptide (CCP) developed persistent IA, so the added value of PDUS was assessed in the seronegative (RF and CCP negative) group. The probability of IA in a seronegative patient was 6%. The addition of clinical and radiographic features raised the probability of IA to 30% and, with certain ultrasound features, this rose to 94%.
Conclusions: In seronegative patients with early IA, combining PDUS with routine assessment can have a major impact on the certainty of diagnosis.