Development and validation of the DBS-PS (Deep Brain Stimulation-Perception Scale): Assessing parkinsonian patients' expectations to prevent post-operative disappointment?

Background Recent literature suggests that taking into consideration and evaluating preoperative expectations of Parkinson's disease (PD) patients candidates to deep brain stimulation (DBS), can contribute to treatment effectiveness. However, few validated instruments investigating preoperative expectations are available. We present the development and validation of the DBS-PS (Deep Brain Stimulation – Perception Scale). Methods The DBS-PS is an 11 questions self-administered scale, with answers rated on a 10-point Likert scale (1 completely false, 10 completely true). Items were generated on the basis of patient's interviews analyzed by an expert group and reached consensus. The scale is divided into three domains: expectations for PD, expectations for social-life and leisure, expectations for intimate life. Exploratory factor analysis (EFA) completed by item response theory (IRT) analysis was conducted to validate the theoretical structure of the DBS-PS. Results 64 PD patients aged 59.18 (SD = 5.74) years with PD diagnosed since 9.36 (SD = 4.09) years completed the DBS-PS preoperatively. EFA confirmed a 3 factors scale structure (eigenvalue >1) explaining 69% of variance (factor 1: 43%; factor 2: 17%; factor 3: 9%). Reliability (Cronbach's α: 0.714 for factor 1, 0.781 for factor 2, 0.889 for factor 3) and discriminant validity (Pearson coefficient r < 0.50) were satisfactory. IRT showed good model fit, preserved unidimensionality, but some local dependences were observed. Conclusion The DBS-PS shows satisfactory psychometric properties. It is easy to administer in routine practice with preoperative PD patients. It constitutes an interesting basis for cognitive restructuring before neurosurgery, by highlighting dysfunctional cognitions and measuring the benefits of cognitive restructuring therapy.