Taking the patient and the patient's perspective into account to improve outcomes of care of patients with musculoskeletal diseases.

Patient-reported outcome measures are commonly used in the assessment of patients with musculoskeletal diseases. The present review provides an overview of historic and recent developments, including core set recommendations for assessing patient-reported outcomes in patients with fibromyalgia, osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis. The evidence supporting commonly used patient-reported outcomes measures is reviewed. Furthermore, various methodological approaches that can be utilized to evaluate validity and measurement precision of patient reported outcomes are introduced. Commonly used methods based on the classical test theory as well as modern approaches based on item response theory will be discussed. The review finally describes the increasing use of item response theory-based approaches used in patient-reported outcomes assessment in the musculoskeletal diseases.