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

Background: Non-traumatic anterior knee pain affects one in every five adolescents. Despite the commonality of the condition, there are no patient-reported outcome measures developed specifically for this population. The aim of this study was to identify domains and develop a preliminary item bank for adolescents with non-traumatic anterior knee pain.

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 were 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.