German translation and validation of the "freezing of gait questionnaire" in patients with Parkinson's disease.

Background. Freezing of Gait (FOG) is a disabling parkinsonian symptom. The Freezing of Gait Questionnaire (FOG-Q) reliably detects FOG in patients with Parkinson's disease (PD). Objectives. The aim of this study was to develop a German translated version of the FOG-Q and to assess its validity. Methods. The translation was accomplished using forward-backward-translation. The construct validity of the FOG-Q was examined in twenty-seven German native speaking PD patients. Convergent validity was assessed by correlating the FOG-Q with the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) II-III, the Parkinson Disease Questionnaire 39 (PDQ-39), and the Timed Up and Go Test (TUG). Divergent validity was assessed by correlating the FOG-Q with the MDS-UPDRS I. The internal consistency was measured using Cronbach's alpha (Cα). Results. A good internal structure of the FOG-Q was found (Cα = 0.83). Significant moderate correlations between the FOG-Q and the MDS-UPDRS item 2.13 (freezing) (r s = 0.568, P = 0.002) and between the FOG-Q and the PDQ-39 subscale mobility (r s = 0.516, P = 0.006) were found. The lack of correlation with the MDS-UPDRS I demonstrated good divergent validity. Conclusion. The German FOG-Q is a valid tool to assess FOG in German native speaking PD patients.