Psychometric properties of palliative care outcome measures: a multi-centre study

Background: Periodic evaluation of the psychometric properties of palliative care outcome measures is essential to ensure accurate assessment of patient outcomes and to support ongoing improvements in care quality. This study aimed to assess the psychometric properties of three tools: the Integrated Palliative Care Outcome Scale (IPOS), the Symptom Assessment Scale (SAS), and the Palliative Care Problem Severity Score (PCPSS). Methods: We conducted a multicentre study using de-identified data collected from 378 participants. Internal consistency was assessed using Cronbach’s alpha for all tools, and confirmatory factor analysis was performed for the IPOS. Convergence and discriminant validity were examined for the SAS and PCPSS by analysing the correlations between similar and dissimilar items, respectively. Lastly, known-groups comparison validity was assessed. Results: Of the 378 participants, 54.5% were male, and most (77.5%) had cancer. Internal consistency was good for the IPOS total (α = 0.81), acceptable for the SAS (α = 0.70), and marginal for the PCPSS (α = 0.65). A strong correlation was observed between the pain construct of SAS and PCPSS (r = 0.74). Both the PCPSS and SAS effectively discriminated symptoms between palliative care phases and settings of care in known-group comparisons. The physical domain of the IPOS demonstrated good discriminative ability in differentiating symptoms between cancer and non-cancer patients. Our data confirmed the three theoretical domains of the IPOS—physical, emotional, and informational. Conclusion: The IPOS demonstrated higher reliability using internal consistency, whereas SAS and PCPSS showed good validity in known group comparisons. These findings may inform the selection of context-appropriate palliative care outcome measures.