Aim: To describe the development and clinimetric properties of a new scale to evaluate changes in the impact of drooling in children with developmental disabilities.
Method: After examining the properties of potential items, 10 items were retained for inclusion in the final Drooling Impact Scale. The clinimetric properties of the scale were evaluated using data from two convenience samples of children attending a saliva-control clinic: a stable group (n=31, 22 males, nine females; mean age 10y 7mo, SD 4y 5mo, range 3y 6mo-18y 3mo; cerebral palsy [CP] n=17, intellectual disability n=10; non-ambulatory n=13, nonverbal n=12) and an intervention group (n=49, 29 males, 20 females; mean age 11y, SD 3y 6mo, range 3y 4mo-16y 10mo; CP n=31, intellectual disability n=15; non-ambulatory n=27, nonverbal n=28). To assess validity, changes in scores on the Drooling Impact Scale over time were compared with a carer's global rating of change using Pearson's correlations and t-tests. A concordance correlation coefficient was used to compute the level of agreement between assessments 1 month apart in stable children. Effect size, standardized response mean, Guyatt responsiveness statistic, and an unpaired t-test were used to estimate responsiveness.
Results: The correlation between the global rating and change in Drooling Impact Scale scores was 0.69 (p<0.001). The concordance correlation coefficient was 0.85. An effect size of 1.8, standardized response mean of 1.5, Guyatt responsiveness statistic of 1.4, and mean group difference of 23.5 (95% confidence interval 17.4-29.6) were obtained.
Interpretation: The Drooling Impact Scale is a valid and reliable subjective measure that is responsive to change.