BACKGROUND: Chronic pain continues for more than 12 weeks despite medication or treatment. Chronic pain is the main symptom of muscle and joint problems, rarely explained by damage to the muscle and joints alone. Activity in the central nervous system (CNS; nerves, spinal cord, and brain) pathways governs our ability to describe pain intensity and our emotional response to pain. Musculoskeletal conditions (e.g., inflammatory arthritis, osteoarthritis, low back pain, fibromyalgia) share altered CNS pathways, acknowledged by recent classifications of 'primary' and 'nociplastic' pain. Clinically useful tools to diagnose and measure activity and reveal abnormalities in these CNS pathways are needed to improve clinical decisions and accelerate new treatment development. Laboratory pain sensitivity testing and brain imaging confirm the CNS as a primary contributor to pain. These assessments are less acceptable or unfeasible for clinical practice. Simpler clinical pain sensitivity assessments are being developed. The investigators simple Central Aspects of Pain (CAP) questionnaire detects some people with pain sensitivity and knee, rheumatoid arthritis or low back pain. Combining the CAP questionnaire reflecting emotional processing and simpler pain sensitivity assessment, combining two different dimensions should be better than either approach alone. PURPOSE: To optimise diagnosis and measurement of CNS as the primary contribution to chronic musculoskeletal pain by using the CAP questionnaire and simpler pain sensitivity assessments to ensure timely, effective diagnosis and treatment. OBJECTIVES: 1. Assess the ease, ability and performance of the combined CAP questionnaire and simpler pain sensitivity assessments to identify CNS as the primary contributor to chronic pain across musculoskeletal conditions. 2\. Use the CAP questionnaire alone or with substitute measures of activity in CNS pathways, demographic, and clinical variables to indicate pain levels at six and twelve weeks. 3\. Understand the relationship between CAP and simpler pain sensitivity assessment with laboratory pain sensitivity assessments as a tool to inform the current CNS activity contributing to pain. 4\. Evaluate associations between the CAP questionnaire and simpler pain sensitivity assessments with patient outcomes.