Objective: In the current research, the development of a new scale for assessing the voice symptoms affecting communicative participation of the patients with Adductor laryngeal dystonia.
Methods/Design: The research was preceded in two phases: 1. The items were generated, and the scale was developed. 2. The patients with this disorder completed the scale to establish validity (content, convergent, construct) and reliability (test-retest and internal consistency). Ninety-four patients with AdLD and Primary Muscle Tension Dysphonia (P-MTD) comprised the sample for this research, with each group consisting of 47 participants. After the primary development of the voice symptoms AdLD scale (VSAdLDS), ten participants were asked to complete the VSAdLDS.
Results: Except for two items, all the items had an acceptable Content Validity Ratio (CVR). Corrected Item-Total Correlation (CITC) led to the elimination of 13 items for item analysis. A moderate value was obtained for the convergent validity of this scale and Voice Activity and Participation Profile-Persian (VAPPP) (r = 0.532, p = 0.02). The evidence of clinical validity was proved by the higher values of Persian VSAdLDS in participants with AdLD than in patients with P-MTD (df = 92, p < 0.001). Internal consistency value was satisfactory (α = 0.77, p < 0.001). Test-retest reliability was also obtained to be of a high value (ICC = 0.90, p < 0.001).
Conclusions: The Persian VSAdLDS is a tool with satisfactory reliability and validity values. Performing research on a larger sample size and the association of the scores of this instrument with other types of assessment is suggested.