Development and Psychometric Evaluation of the Laryngeal Palpation Pain Scale (LPPS)

One of the most important assessment and therapy methods for patients with muscle tension dysphonia (MTD) and other voice disorders is laryngeal palpation. However, there is no comprehensive scale for measuring pain during laryngeal palpation. The goal of the present study was to develop and validate a new scale to evaluate pain during palpation for patients with MTD.

The present study consisted of two phases: (1) Development of the Laryngeal Palpation Pain Scale (LPPS) based on an in-depth literature review, the palpatory evaluation of MTD patients, interviews with experts in the field of voice disorders, and consultation with a registered pain expert, and (2) evaluation of the validity and reliability of the LPPS. The validity of the LPPS was investigated using qualitative and quantitative content validity, qualitative face validity, discriminant validity, and convergent validity. Content validity of the LPPS was assessed by experts' opinions (10 speech-language pathologists and five laryngologists), and face validity was investigated using the opinions of speech-language pathologists. The reliability of the LPPS was determined using test-retest and inter-rater reliability.

The item generation phase of the study led to the development of a scale to assess pain during palpation that included eleven locations in the neck region for palpatory assessment. These 11 items were divided into 13 different items (neck locations) based on the opinions of the experts. The content validity ratio values of all scale items were higher than 0.78. The content validity index (CVI) value for each of the items of the scale was higher than 0.79 and for the entire scale CVI (S-CVI) was 0.915. The results of the reliability of the LPPS items were satisfactory with weighted kappa values ranging from 0.655 to 1 for the test-retest and 0.77-1 for the inter-rater reliability. Convergent validity of the LPPS was shown with a significant positive correlation (r = 0.68) between the LPPS and the pain severity of vocal tract discomfort (P < 0.001). Moreover, MTD patients had more pain severity than the control group in all items of the LPPS (P < 0.05) except for the submental item (P = 0.89). These results indicate that the LPPS can differentiate MTD patients from healthy subjects. The final version of the LPPS includes 13 potential pain locations. The severity of pain at each of these locations is determined on a numeric pain rating scale of zero (no pain) to ten (the most severe pain).

The study showed that the LPPS is a valid and reliable scale to assess pain in MTD patients during palpation evaluations. More studies are recommended for further psychometric evaluation of the LPPS including responsiveness to change (the use in before-and-after intervention studies) and concurrent validity of the LPPS. The LPPS can be used for clinical and research purposes.