Cross-sectional quantitative validation of the paediatric Localized Scleroderma Quality of Life Instrument (LoSQI): A disease-specific patient-reported outcome measure

Background: The Localized Scleroderma Quality of Life Instrument (LoSQI) is a disease-specific patient-reported outcome (PRO) measure designed for children and adolescents with localized scleroderma (LS; morphea). This tool was developed using rigorous PRO methods and previously cognitively tested in a sample of paediatric patients with LS. Objective: The purpose of this study was to evaluate the psychometric properties of the LoSQI in a clinical setting. Methods: Cross-sectional data from four specialized clinics in the US and Canada were included in the analysis. Evaluation included reliability of scores, internal structure of the survey, evidence of convergent and divergent validity, and test–retest reliability. Results: One hundred and ten patients with LS (age: 8–20 years) completed the LoSQI. Both exploratory and confirmatory factor analysis supported the use of two sub-scores: Pain and Physical Functioning, and Body Image and Social Support. Correlations with other PRO measures were consistent with pre-specified hypotheses. Limitations: This study did not evaluate longitudinal validity or responsiveness of scores. Conclusion: Results from a representative sample of children and adolescents with LS continue to support the validity of the LoSQI when used in a clinical setting. Future work to evaluate the responsiveness is ongoing.