A validation study of the modified Chinese version of the integrated palliative care outcome scale (IPOS) among patients with advanced illness in Hong Kong

Abstract

Background: In order to conduct holistic person-centred assessment, monitoring and research in progressive illness, a valid tool is required that captures the specific symptoms and concerns faced by patients and families. While the Integrated Palliative care Outcome Scale (IPOS) is widely used, its cultural applicability for Chinese populations remains unestablished. Methods: This psychometric validation study aimed to culturally adapt the IPOS and evaluate its psychometric properties in Chinese-speaking populations. Conducted in oncology and palliative care settings in Hong Kong, the study comprised two phases. Phase I: Traditional Chinese IPOS translation with face/content validity testing through cognitive interviews(7 patients with advanced illness, 6 caregivers, 15 healthcare professionals) and expert panel meeting. Phase II: psychometric testing with 236 patient-caregiver dyads and 21 professionals. Analyses included exploratory/confirmatory factor analyses, convergent validity with Edmonton Symptom Assessment System (ESAS) item pairs, divergent validity with State Hope Scale (SHS), predictive validity with EuroQoL5-dimensional 5-level Scale(EQ-5D-5L)/Palliative Performance Scale-version2(PPSv2), known-group validity, reliability, responsiveness and feasibility. Results: The Modified Traditional Chinese IPOS(MC-IPOS) was formed with swelling of limbs and difficulty in sleeping added, demonstrated high face/content validity. EFA extracted 5 factors with CFA indicating marginally acceptable indices(CFI=.91, RMSEA/SRMR=.06); the 1-factor(scree plot suggested) and theoretical 3-factor solutions exhibited poor fit, leading to further item-level analysis. Convergent validity was established with significant correlations(.35≤ρ≤.79) to ESAS item pairs; divergent validity unconfirmed. Known-group validity was evidenced by significant score differences(total scores and 17/19 item scores) observed between stable and unstable/deteriorating patients. Specific MC-IPOS items can predict corresponding EQ-5D-5L items, while PPSv2 can predict most MC-IPOS items. Internal consistency(α=.86) was good, inter-rater reliability was acceptable(>80% items.2w≤.61 across all dyads/timepoints), and test-retest reliability(70% items kw≥.60) was good. MC-IPOS was responsive in improved group(z=-2.49, p