Psychometric Evaluation of the German Version of the Social Functioning in Dementia Scale (SF-DEM)

Abstract

Background: Dementia is one of the most common and most severe disorder in old age. In addition to cognitive decline and functional impairment, changes in social functioning occur in the course of dementia. Currently, there is no valid instrument in German language to assess social functioning in individuals with dementia. Objective: We aim to adapt and psychometrically evaluate a German version of the Social Functioning in Dementia Scale (SF-DEM). Methods: First, a multi-step and team-based translation process based on the TRAPD model was performed. Second, we interviewed dyads of individuals with mild dementia and caregivers to test the internal consistency, test-retest reliability, interrater reliability, construct validity, and acceptance of the German version of the SF-DEM. Results: The internal consistency of the patient-rated (α= 0.72) and the caregiver-rated (α= 0.76) SF-DEM is at an acceptable level. The interrater reliability was excellent for both versions (patients: ICC = 0.98, CI [0.95–0.99]; caregiver: ICC = 0.95, CI [0.89–0.98]) and the test-retest reliability was moderate (patients: ICC = 0.57, CI [0.26–0.77]; caregiver: ICC = 0.58, CI [0.27–0.78]). Caregiver-rated SF-DEM correlated strong with LSNS-6 (rs = 0.60, p < 0.01), QoL-AD (marriage: rs = 0.61, p < 0.01; friends: rs = 0.51, p = 0.01). In addition, the SF-DEM was accepted by the participants. Conclusion: The German SF-DEM is a valid, reliable, and acceptable instrument to assess social functioning in individuals with dementia. Further research should address the psychometric properties in individuals with more severe dementia.