Speech Pathology-Specific Questionnaire for Persons with Multiple Sclerosis (SMS): adaptation, validation and...

Speech and voice disorders are among the least well-described clinical manifestations of Multiple Sclerosis (MS) although their estimated prevalence reaches 40-50%. The aim of the present study was adaptation and validation of the Speech Pathology-Specific Questionnaire for Persons with Multiple Sclerosis (SMS) into the Polish language to be used as part of the diagnostic procedure to quantify important speech-related changes and to improve individual tailoring of therapeutic activities.

The study included a total number of 178 participants. The study group consisted of 107 patients diagnosed with Multiple Sclerosis, mean age 42.8±11.6 years and the Control Group were 71 healthy sex and age matched normophonic subjects, mean age 44.2±12.5 years with no neurological symptoms. Translated version of SMS was administered to all participants of the study. Voice Handicap Index (VHI) questionnaire was used for comparison purposes. Test-retest reproducibility, internal consistency, floor and ceiling effects, discriminant validity and construct validity of the Polish SMS were investigated. Preliminary assessment of diagnostic value of SMS was conducted on the basis of the results recorded in duration-related quartiles of the Study Group.

High value of Intraclass Correlation Coefficient (ICC= 0 .930) obtained for the test-retest indicates a good level of reproducibility of the Polish SMS. High Cronbach's alpha (α=0.94) proves the test's good internal consistency. There were no floor and ceiling effects for the SMS test score in the Study Group and they were negligible in the Control Group. A significant difference in mean SMS total scores between patients and controls (14.22 points vs. 6.06 points) shows discriminant validity of SMS. Similar differences were observed for all the subscales of the test (in t test: p<0.001). A statistically significant correlation was found for the SMS score and its all subscales, as well as between all the subscales of the test proving good construct validity of the test. Similarly, statistically significant correlations were observed for the total score of SMS and VHI (r=.817, p <0.001) as well as between the particular subscales of SMS test and the subscales of VHI. There was a statistically significant difference in the mean total score of SMS in the distinguished quartiles of the Study Group with the highest values (20 points) recorded in the group of patients suffering from MS for over 15 years.

The psychometric properties of the Polish version of Speech Pathology-Specific Questionnaire indicate that it is a valid patient-reported outcome measure suitable for the assessment of speech-language pathology aspects on the population of Multiple Sclerosis patients and can be used as an complementary diagnostic tool in clinical practice.