The minimal clinically important change in the motor section of the Burke-Fahn-Marsden Dystonia Rating Scale for generalized dystonia: Results from deep brain stimulation

• Published in: Parkinsonism & related disorders 2021-12, Vol.93, p.85-88
• Main Authors: Esther Cubo, Miravite, Joan, Calvo, Sara, Cooper, Kathryn, Raymond, Deborah, Ooi, Hwai Yin, Lubarr, Naomi, Bressman, Susan, Saunders-Pullman, Rachel
• Format: Article
• Language: English
• Subjects: Adult; Aged; Apoptosis Regulatory Proteins; Burke-Fahn-Marsden dystonia rating scale; Deep brain stimulation; Deep Brain Stimulation - statistics & numerical data; DNA-Binding Proteins; Dystonia; Dystonia - genetics; Dystonia - surgery; Female; Globus Pallidus - surgery; Health Status Indicators; Humans; Male; Middle Aged; Minimal Clinically Important Difference; Molecular Chaperones; Rating scale; Reference Values; Treatment Outcome
• ISSN: 1353-8020; 1873-5126
• DOI: 10.1016/j.parkreldis.2021.11.016

The minimal clinically important difference (MCID) describes the smallest change in an outcome that is considered clinically meaningful. The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) is the most frequently rating scale assessing the efficacy of deep brain stimulation therapy (DBS) for dystonia. To expand our understanding, we evaluated the MCID thresholds for the BFMDRS motor subscale (MS) using physician-reported outcomes. We assessed the MCID thresholds for the BFMDRS using movement disorder specialist ratings of videotapes from patients with genetically determined dystonia (Tor1A and THAP1) who underwent bilateral globus pallidum internum (GPi) DBS. We calculated the effect size of the BFMDRS-MS change and determined the MCID thresholds using the Clinical Global Impression of Change (CGIC). Twelve participants with a median age at DBS of 44.5 (range:27–68) had baseline and follow-up BFMDRS-MS with a median post-DBS follow-up of 5.5 years. Based on descriptive analysis, patients with good improvement after DBS according to the CGIC [8/12 (67%)] had a median BFMDRS-MS score reduction of 77% [Interquartile range (IQR):66.2;91.0) with an effect size of 0.39, and those with non-improvement [4/12 (33%)], had a median BFMDRS-MS score reduction of 62% (IQR:36.6;83.6). Our MCID estimates can be utilized in clinical practice in judging clinical relevance. However, further larger, powered studies are needed to simultaneously determine and compare MCID using patient and physician-reported outcomes in segmental and generalized dystonia in genetic and non-genetic populations. •There is an ongoing need to assess Deep Brain Stimulation (DBS) meaningful clinical benefits in genetically determined populations with dystonia.•We described the minimal clinically important difference (MCID) thresholds for the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) motor scores (MS) for DBS therapy using physician-reported outcomes.•In this descriptive analysis, patients with good improvement after DBS had a median BFMDRS-MS score reduction of 77% with an effect size of 0.39.•Further larger studies are needed to determine the MCID using patient and physician-reported outcomes.