The Deep Brain Stimulation Impairment Scale: A useful complement in assessment of well-being and functioning in DBS-patients - Results from a large multicentre survey in patients with Parkinson's disease

Background: Deep Brain Stimulation (DBS) has been proven to alleviate motor symptoms in Parkinson's Disease (PD). Regarding non-motor symptoms, however, inconsistencies have been reported, on whether DBS causes reductions in well-being and functioning. To assess motor and non-motor impairment in DBS-patients, the Deep Brain Stimulation Impairment Scale (DBS-IS) has been developed. Yet, the extent to which the DBS-IS detects impairment in DBS-patients and thus could serve as a useful tool that complements the PDQ-39 (gold standard) in assessment of well-being and functioning in PD-patients has not been shown. Objectives: By comparing DBS and non-DBS-patients we aimed to identify DBS-specific symptoms. We thereby aimed to show in how far the DBS-IS complements the PDQ-39 in assessing well-being and functioning in PD patients under DBS. Methods: In a cross-sectional study, 186 DBS-patients were matched (for age, disease duration and sex) to 186 non-DBS-patients (N = 372) and the two groups were compared regarding well-being and functioning: Impairment was assessed via DBS-IS and overall Quality of Life (QoL) was assessed via PDQ-39. Additionally, we analyzed differences in impairment between age and disease duration clusters. Results: DBS-patients showed significantly higher total impairment (DBS-IS) and significantly higher impairment on the subscales Postural Instability and Gait difficulties and speaking difficulties than non-DBS-patients. Impairment increased with age and disease duration and, overall, differences in impairment rose by age. Overall QoL (PDQ-39) was non-significantly lower in DBS-patients. Conclusion: Since there is evidence that the PDQ-39 misses some DBS-specific symptoms, the DBS-IS is recom-mended to complement the PDQ-39 when assessing DBS-patients