A psychometric validation of two brief measures to assess palliative need in patients severely affected by multiple sclerosis

Abstract

Context: Most patient-reported outcome measurement tools in multiple sclerosis (MS) are geared toward less severely affected patients. Palliative care outcome measures have not been validated in patients with MS.

Objectives: To assess the psychometric properties of the Core-Palliative Care Outcome Scale (Core-POS) and POS-MS-Symptoms (POS-MS-S) in patients severely affected by MS.

Methods: Secondary analyses were conducted on data from a Phase II trial of palliative care in MS. Patients completed assessments using the following five scales: Core-POS, POS-MS-S, the Multiple Sclerosis Impact Scale, the United Kingdom Neurological Disability Scale, and the Expanded Disability Status Scale. Data quality, scaling assumptions, acceptability, internal consistency, and construct validity of the Core-POS and POS-MS-S were determined using standard psychometric methods.

Results: The 46 participants had a mean ±SD age of 52.8 ±10.6 years. The mean Expanded Disability Status Scale score was 7.9 ± 1.2. Missing data were low (0 and 0.2% for the Core-POS and POS-MS-S, respectively), and floor and ceiling effects were absent. Internal consistency was good (Cronbach's alpha for the Core-POS and POS-MS-S were 0.72 [95% CI 0.56-0.84] and 0.81 [95% CI 0.72-0.89], respectively). Construct validity was consistent with a priori hypotheses 17 of 20 times.

Conclusion: Psychometric analyses confirm that the Core-POS and POS-MS-S are acceptable, reliable, and valid in patients severely affected by MS.

Keywords: Multiple sclerosis; Palliative Care Outcome Scale (POS); outcome assessment; palliative care; psychometric validation; terminal care.