Item development and pre-testing of an Osteoarthritis Conceptualisation Questionnaire to assess knowledge and beliefs in people with knee pain.

Many people with osteoarthritis hold beliefs that physical activity is unhelpful or dangerous for their joints, despite high-level evidence suggesting otherwise. Recent advances in scientific understanding of osteoarthritis have led to new treatments that target an individual's understanding both of their condition and the importance of best-practice management strategies, such as physical activity. Conceptual change has been proposed as an important mechanism by which cognitive interventions, such as pain science education, may reduce pain and improve function. There are currently no specific assessments of osteoarthritis conceptualisation to determine the effectiveness of cognitive interventions in effecting conceptual change in people with knee osteoarthritis. Therefore, we aimed to develop an item bank, as the first phase of developing a questionnaire to assess people's conceptualisations about their knee osteoarthritis and the role of physical activity in managing their osteoarthritis. Using a guideline-informed mixed method design, a panel of experts identified domains relevant to conceptualisation about knee osteoarthritis and physical activity (knowledge, beliefs, understanding) based upon available evidence. The panel created 33 provisional items. Qualitative and quantitative pretesting were used to explore how people with knee osteoarthritis understood the provisional items. Eighteen people with knee osteoarthritis completed cognitive interviews about their comprehension of the wording/grammar of each provisional item. The provisional item bank was field tested with 100 people with knee osteoarthritis. Readability was adequate with a Flesch reading ease score of 57.7. Although 14.7% used the 'Strongly agree' response option, only 3.4% of responses used the 'Strongly disagree' option, suggesting possible response bias. Predictive quality testing identified relevant modifications to the questionnaire instructions. The panel of experts appraised the qualitative data to assess whether and how items should be modified to address the problems identified, resulting in a final item bank of 45 items that can be evaluated for psychometric properties in future research.