The Significance of Selecting an Appropriate Patient-Reported Outcome Measure (PROM): A Cross-Cultural Adaptation of the Specific Paediatric International Documentation Committee Subjective (Pedi-IKDC) Knee Form.

Introduction: The selection of an appropriate PROM is a crucial aspect in assessing outcomes. Questionnaires that have not been designed or validated for a paediatric population are routinely used. Using a questionnaire requires translation, cultural adaptation, and testing the psychometric properties of the translated questionnaire. There is no applicable questionnaire in our country for children with knee-specific conditions in sports orthopaedics. Therefore, this study aims to translate, culturally adapt, and assess the psychometric properties of the Paediatric IKDC (Pedi-IKDC) questionnaire within the Lithuanian paediatric population.

Methods: The translation was conducted in accordance with international standards. Patients aged 11-17 years with various knee disorders participated in three surveys and completed the Pedi-IKDC, Lysholm, and PedsQL questionnaires. Interviews with patients following the translation process, in addition to floor and ceiling effects, were used to assess content validity. Cronbach alpha (α) statistics and the intraclass correlation coefficient (ICC) were applied to measure internal consistency and reproducibility, respectively. The standard error of measurement (SEM) and smallest detectable change (SDC) were calculated to assess reliability. Pearson correlations were calculated between Pedi-IKDC and Lysholm PedsQL scores to determine criteria validity. The effect size (ES) and standardised response mean (SRM) were calculated to assess the responsiveness to change.

Results: Cronbach's alpha (α) was 0.91 for the total score, 0.75 for symptoms, and 0.92 for the sport/function component. The ICC for overall scores was 0.98, with each question ranging from 0.87 to 0.98. The SEM was 2.97, and the SDC was 8.23. Lysholm and PedsQL physical functioning domain scores had moderate correlations (0.8 > r > 0.5), and the overall PedsQL score had a weak correlation (0.5 > r > 0.2) to the Pedi-IKDC score. The floor and ceiling effects were 3.3% and 1.6%, respectively. The SRM was 1.72 and the ES was 1.98.

Conclusions: The Lithuanian Pedi-IKDC version is an appropriate evaluation instrument for assessing outcomes in children with knee disorders. All of the psychometric features produced acceptable results.