Validity and Reliability of the Thai Version of the Freezing of Gait Questionnaire in Individuals With Parkinson's disease

Objective To evaluate the validity and reliability of the Thai version of the Freezing of Gait Questionnaire (FOG-Q) in individuals with Parkinson's disease (PD). Methods The FOG-Q was translated into Thai according to the standard process. Fifty-six individuals with PD participated in the study. The content validity was assessed using the content validity index (CVI). The construct validity was evaluated by correlating Thai FOG-Q with Thai version of the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) items 2.13 and 3.11, Thai version of the Falls Efficacy Scale-International (FES-I), Timed Up and Go test (TUG) and Berg Balance Scale (BBS) using Spearman's correlation coefficient (rS). The correlation between Thai FOG-Q and clinical characteristics, for example, duration of PD and modified Hoehn and Yahr (mH&Y) stage was evaluated. Internal consistency and test-retest reliability were evaluated with Cronbach's alpha (C alpha) and intraclass correlation coefficient (ICC), respectively. Results The Thai FOG-Q had high content validity (CVI=0.96). The mean FOG-Q score was 9.0 +/- 4.9. The construct validity showed a strong positive correlation with MDS-UPDRS item 2.13 (rS=0.81), and moderate correlations with MDS-UPDRS item 3.11, FES-I, and TUG (rS=0.42-0.60). A negative correlation with BBS was found (rS=-0.32). It had a moderate correlation with mH&Y stage (rS=0.40). The Thai FOG-Q had good internal consistency (C alpha=0.87) with excellent test-retest reliability (ICC=0.91). Conclusion The Thai FOG-Q has excellent validity and reliability. It is a useful instrument for the evaluation of FOG in individuals with PD.