Shortening the SWAL-QOL: Is it possible to create a valid short form?

PURPOSE: Dysphagia is highly prevalent in movement disorders resulting in marked decrements to quality of life. The Swallowing-related Quality of Life Questionnaire (SWAL-QOL) provides critical information about the impact of dysphagia on quality of life (QOL) but is long and cumbersome. We examined whether the SWAL-QOL could be shortened, while maintaining the properties of the original scale.

METHODS

We used a combinatoric approach to reduce the 30 items that inform the QOL domains to 10 items and the 14 items that inform the symptom-profile to five items in Parkinson's disease (PD). We tested the concurrent validity of the short-form in Progressive Supranuclear Palsy (PSP) and Cerebellar Ataxia (CA), and over time.

RESULTS

Our sample included individuals with PD (n = 304), PSP (n = 33), and CA (n = 26) (age 65.7 [27-89]; 34% female). Correlations between the candidate short forms and the original QOL items ranged from 0.95 to 0.98 and for the symptom-profile from 0.91 to 0.95. Cronbach's alpha for the final 10-item short-form was 0.85 and for the 5-item symptom-profile was 0.74. Correlations between the short-form and original QOL domains were 0.98 in PSP and 0.98 in CA, and between the short and original symptom-profile were 0.98 in PSP and 0.96 in CA. Correlations between the short and original QOL items over time was 0.97 in PD, 0.99 in PSP, and 0.98 in CA and for the symptom-profile was 0.94 in PD, 0.95 in PSP, and 0.96 in CA.

CONCLUSIONS

We identified a 15-item SWAL-QOL with strong concurrent validity in movement disorder populations.