Outcome Measures for Evaluating the Effect of a Multidisciplinary Intervention on Axial Symptoms of Parkinson's Disease

Introduction: The satisfactory symptomatic control of the axial symptoms of Parkinson's disease (PD) remains challenging. As these symptoms are an important cause of disability, new therapeutic strategies should be developed and evaluated. To do this, it is necessary to select the outcomes to be measured and reported in a clinical trial. In this study, we sought to identify the most responsive outcome measures for assessing the efficacy of a multidisciplinary intervention on the axial symptoms of PD. Methods: An exploratory prospective clinical study was conducted. PD patients engaged in a pre-defined multidisciplinary intervention program for parkinsonian patients were assessed at admission and discharge by a multidisciplinary team. The responsiveness to intervention was evaluated and the smallest sample size needed to enable statistically significant results for an expected 30% change from baseline for each outcome was calculated. Results: Twenty-two patients were included in the study. The effect size detected varied between 0.04 and 0.83. The Movement Disorder Society—Unified Parkinson's Disease Rating Scale (MDS-UPDRS) total score and each subsection, the N-FOG questionnaire, the 10-m walk test, and Frenchay Dysarthria Assessment-2 Edition (FDA-2) showed a medium to large effect size. Sample size calculations for 90% power and assuming 30% change from baseline ranged from eight to 180 participants. The outcome measures that require a small number of participants to enable statistically significant results were the FDA-2 rating scale (n = 4 participants), the MDS-UPDRS total score (n = 9), the 10-m walk test (n = 9), and the MDS-UPDRS motor examination (n = 10). Conclusions: The MDS-UPDRS part III and total score and the 10-m walk test were the outcomes with the best responsiveness to a multidisciplinary intervention and required a small number of participants to enable statistically significant results. Further studies are needed to clarify the suitability of the Timed Up and Go test.