The preference-based multiple sclerosis index (PBMSI) can accurately measure health-related quality of life for people with multiple sclerosis (MS), according to results published in the Multiple Sclerosis Journal.
The results indicated that the PBMSI does not have the same limitations as other currently-used health-related quality of life measures for MS.
The PBMSI is a brief patient-reported outcome measure of health-related quality of life that consists of 5 items: walking, fatigue, mood, concentration, and roles and responsibilities. For each item, patients can choose from 3 response options. The scoring algorithm ranges from 0 (dead) to 1 (perfect health).
The study included participants from 3 MS clinics in Montreal. The researchers used polychoric correlation coefficients and factor analysis to assess structural validity. They formulated hypotheses about the strength of correlations between the PBMSI and other health-related quality of life measures, including the RAND-36 Item Health Survey, the Short Form-6 dimension (SF-6D), and the EuroQol-5 dimensions (EQ-5D).
The mean scores for the PBMSI, EQ-5D, and SF-6D were 0.25, 0.81, 0.68, respectively. The PBMSI demonstrated no floor effects. The PBMSI did have a slight ceiling effect where 9% (n=10) of participants had a score of 1.0, but this value was less than the cut-off of 15%.
The correlation between the PBMSI and EQ-5D was 0.37, and the correlation between the PBMSI and SF-6D was 0.66. The researchers found that the association between the PBMSI and the patient-generated index was low to moderate (r=.32, P =.001), and the correlations between the PBMSI and physical tests were moderate.
“The domains and items for the PBMSI were developed based on interviews with people with MS, ensuring that the measure had content validity in this clinical population,” the researchers wrote.
Kuspinar A, Mayo NE. Validation of the preference-based multiple sclerosis index [published online August 2, 2018]. Mult Scler. doi:10.1177/1352458518792423