Cross-cultural adaptation and validation of the Localised Scleroderma Quality of Life Instrument (LoSQI): an international study

Abstract

Juvenile localised scleroderma (jLS) is a rare disease which impacts negatively on health-related quality of life (HRQoL). We aimed to undertake the cross-cultural adaptation and validation of a novel disease-specific HRQoL measure, the Localised Scleroderma Quality of Life Instrument (LoSQI). In phase I, cross-cultural adaptation was completed using established methodology involving forward/backward translation and cognitive interviews to develop a final version in each language. In phase II, validation was performed using the translated versions. Statistical analyses addressed confirmatory factor analysis, item-level analysis and construct validity. There were 236 participants included in the study (162 participants from 20 sites in the cross-cultural adaptation phase; 213 patients from 36 sites in the validation phase; with 139 participants taking part in both phases). Of the phase II participants 67% were female with a median age at diagnosis of 7.3 years and median disease duration of 16.3 months. Linear scleroderma of the limb/trunk was the most common subtype (41%) and methotrexate (55%) was the most used systemic immunomodulation. Cross-cultural adaptation was completed in 16 languages. Six languages required minor modification after pre-testing. Harmonisation across languages identified some overlap between certain item pairs. The recall period and response periods were found to be appropriate. Participant feedback was positive with 97% approving the utility of the measure and 95% finding it easy to complete. Confirmatory factor analysis further supported the use of two subscales, consistent with a prior quantitative assessment: Pain and Physical Functioning, and Body Image and Social Support. The construct validity findings align with prior research, showing moderate to strong correlations between both LoSQI subscales and skin HRQoL measure (CDLQI). Weaker or no associations with physician-reported disease activity supports that the measure reflects patient- and parent-reported impact rather than clinical activity. The LoSQI has been successfully translated into 16 language versions. Qualitative and quantitative evidence support the validity of the versions of the LoSQI indicating its usefulness as a patient-reported outcome (PRO) to evaluate meaningful impacts of localized scleroderma which may be overlooked by generic tools in both clinical care and research.