A Randomised Clinical Study of the Measurement of Xerostomia Relief

Objectives: To assess test-retest reliability and construct validity of an 11-point Visual Rating Scale (VRS); to determine test product efficacy versus water using the VRS on questions regarding moisturisation, lubrication and dry mouth relief; to compare efficacy using a 5-point Product Performance and Attributes Questionnaire (PPAQ) and the VRS.
Methods: This was a single centre, examiner-blind, four treatment arm, stratified, randomised, parallel group study. Subjects (35–84 years) with self-reported dry mouth used their assigned treatment (experimental OralBalance gel [‘Gel], biotène® Dry Mouth Oral Rinse [‘Rinse’], biotène® Moisturising Mouth Spray [‘Spray’] or tap water [‘Water’] in a 2:2:2:1 randomisation) then completed the VRS immediately and at 30, 60 (plus modified PPAQ), 90 and 120 minutes on Visit 1 and again on Visit 2, 3 days later.
Results: Of 175 subjects randomised, 170 completed the study. Intra-class correlation values (Visits 1 and 2 test-retest reliability) for moisturisation, lubrication and dry mouth relief questions were 0.695, 0.700 and 0.677. Responses to the VRS-rated questions were not wholly consistent across visits but with occasional significant differences (p<0.05) noted for each of the dry mouth products compared to Water. Overall, Gel scores were significantly higher than Water at more timepoints than the other treatments, notably for moisture and lubrication questions. Modified PPAQ analysis demonstrated lower sensitivity to detect treatment differences but less inconsistency between days than VRS. Construct validity of the VRS-rated questions assessed against the modified PPAQ question at 60 minutes demonstrated correlation values between 0.713 and 0.792. Two subjects (both Rinse) reported three treatment-related oral adverse events.
Conclusions: While OralBalance gel performed best overall, these data should be interpreted cautiously as test-retest reliability of the VRS was borderline of what is considered a consistent and reliable measurement scale. Construct validity of the VRS scale (compared to PPAQ) was acceptable. Study was funded by GSK Consumer Healthcare.