Overview of the approach to suspected inflammatory arthritis in adults

Arthritis is a common symptom of many inflammatory rheumatological conditions and until the arthritis is categorised or the diagnosis is confirmed, specialists often refer to early presentations as 'suspected inflammatory arthritis'. In the early stages of disease, it may be classified in broad terms as:

• monoarticular arthritis—inflammation affecting a single joint
• oligoarticular arthritis—inflammation affecting 2 to 4 joints
• polyarticular arthritis—inflammation affecting 5 or more joints.

This is a useful classification because the most likely diagnoses for monoarticular, oligoarticular and polyarticular presentations vary. Investigation and management are directed by the most likely diagnosis and the most serious diagnoses to exclude. This classification also applies to children and adolescents but is associated with different diseases to those seen in adults; see Diagnosis of musculoskeletal symptoms in children and adolescents for more details.

Sometimes it may take months for a formal rheumatological diagnosis to be reached because there is much crossover of inflammatory and noninflammatory symptoms.