Further development of a patient-reported outcome measure to assess the impact of oral secretion problems in people living with MND.

Objective: Oral secretion problems are common yet poorly managed in people living with MND (plwMND). A validated patient-reported outcome for measuring saliva symptoms in this patient group would facilitate better monitoring of individuals. This study aimed to assess the validity, reliability and sensitivity to change of a revised version of the clinical saliva score for MND (CSS-MNDr). Methods: Data were collected as part of a longitudinal, observational saliva management study. The CSS-MNDr, ALS Functional Rating Scale, a Global Rating of Change questionnaire and saliva-specific modified Likert scale were completed at each study visit, each of which probed the severity of saliva symptoms. Construct validity, test-retest reliability and sensitivity of the CSS-MNDr were assessed and the minimal important difference of the instrument was estimated. Results: The CSS-MNDr showed excellent test-retest reliability (intraclass correlation coefficient >0.9). Construct validity showed the CSS-MNDr performed as expected, with bulbar-onset participants scoring significantly higher than those who reported limb-onset across all visits (group mean scores). Strong correlation of total scores with the ALSFRS-R saliva question was demonstrated (-0.8), with the thick subscore correlating less well (-0.5). A minimal important difference in the range of -2.5 to -3.6 over 3 months was estimated for worsening symptoms. Conclusions: The CSS-MNDr has been validated as a reliable patient reported outcome for measuring saliva problems in plwMND. With separate scores for thick and thin secretion problems, the CSS-MNDr is the most comprehensive tool for assessing salivary problems in plwMND reported to date.