Item generation for a new patient-reported outcome measure: The non-traumatic anterior knee pain (AKP)-YOUTH scale

Question Which domains are important to develop a preliminary item bank for a new patient-reported outcome measure relating to adolescents with non-traumatic anterior knee pain? Design Multiple methods: semi-structured interviews, Participants Twenty-one adolescents with anterior knee pain participated in semi-structured interviews which explored their experience of living with knee pain. Following thematic analysis, we generated an item bank based on the domains which emerged from the impact their knee pain had on their daily life. Ten clinical experts provided input on the preliminary item bank via an online survey. Cognitive interviews were conducted using the think-aloud approach with ten adolescents to evaluate the comprehensibility and face validity of the items. Results From the interviews we identified four overarching domains where adolescents were impacted by their knee pain: knee symptoms, limitations in physical activity/sport, limitations in social activities, and emotional impact of pain. Eighteen items was initially developed and expanded to 23 following clinical expert input. The cognitive interviews with adolescents demonstrated that the items were comprehensive, understandable, and relevant for adolescents. Conclusion This study developed an item bank of 23 items. These spanned four domains of impact for adolescents with anterior knee pain. The items had good face validity and were deemed relevant and understandable for adolescents with knee pain. Further steps are needed to validate and reduce the items for the non-traumatic anterior knee pain (AKP)-YOUTH scale.