The Development of the Social Functioning Scale for Patients with Parkinson's Disease

Background: Social functioning is crucial for the determinants of Parkinson's disease (PD) with dementia; however, there is no social functioning scale applicable to PD. Objective: This study aimed to develop a social functioning scale specific to PD (PDSFS) and provide a cut-off score to improve diagnosis accuracy. Methods: The items were developed through literature, interview patients, and PD expertise. After the pilot study, one hundred fifty-seven patients and 74 healthy participants were enrolled and completed the Mini-Mental State Examination, Clock Drawing Test, Activities of Daily Living, Neuropsychiatric Inventory, Adaptive Behavior Assessment System-Second Edition (ABAS-II) and part III of the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS). Results: The final PDSFS has 23 items. The exploratory factor analysis revealed three factors, including 'Family Life, Hobbies and Self-Care', 'Interpersonal Relationship and Recreational Leisure', and 'Social Bond'. The internal consistency coefficient was 0.883, and the test-retest reliability was 0.774, respectively. The total score of the PDSFS was significantly related to the total score of ABAS-II (r=0.609, p<0.001), and was not correlated with the third part of MDS-UPDRS (p=0.736). A significant intergroup difference was found (p<0.001), and the healthy controls had the highest PDSFS score, followed by non-demented PD and PD dementia. The optimal cut-off score for PD patients with dementia was 39 (sensitivity: 0.735; specificity: 0.857). Conclusions: PDSFS is a practical and psychometrically sound tool to access the social functioning of the PD population.