title: Defining Quality of Life Levels to Enhance Clinical Interpretation in Multiple Sclerosis: Application of a Novel Clustering Method.
abstract: BACKGROUND
  To enhance the use of quality of life (QoL) measures in clinical practice, it is pertinent to help clinicians interpret QoL scores.
  
  
  OBJECTIVE
  The aim of this study was to define clusters of QoL levels from a specific questionnaire (MusiQoL) for multiple sclerosis (MS) patients using a new method of interpretable clustering based on unsupervised binary trees and to test the validity regarding clinical and functional outcomes.
  
  
  METHODS
  In this international, multicenter, cross-sectional study, patients with MS were classified using a hierarchical top-down method of Clustering using Unsupervised Binary Trees. The clustering tree was built using the 9 dimension scores of the MusiQoL in 2 stages, growing and tree reduction (pruning and joining). A 3-group structure was considered, as follows: "high," "moderate," and "low" QoL levels. Clinical and QoL data were compared between the 3 clusters.
  
  
  RESULTS
  A total of 1361 patients were analyzed: 87 were classified with "low," 1173 with "moderate," and 101 with "high" QoL levels. The clustering showed satisfactory properties, including repeatability (using bootstrap) and discriminancy (using factor analysis). The 3 clusters consistently differentiated patients based on sociodemographic and clinical characteristics, and the QoL scores were assessed using a generic questionnaire, ensuring the clinical validity of the clustering.
  
  
  CONCLUSIONS
  The study suggests that Clustering using Unsupervised Binary Trees is an original, innovative, and relevant classification method to define clusters of QoL levels in MS patients.
authors.affiliation: *EA3279 Self-Perceived Health Assessment Research Unit and Department of Public Health, Nord University Hospital, APHM, Aix-Marseille University †Department of Mathematics, Faculté des Sciences de Luminy, Aix-Marseille University, Marseille, France ‡Institute of Clinical Neurosciences, Hospital Regional Universitario Carlos Haya, Málaga, Spain §Neurological Rehabilitation Center Quellenhof, Bad Wildbad, Germany ∥Departments of Neurology and CRMBM CNRS6612, Timone University Hospital, APHM, Marseille, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Michel
authors.forename: Karine
authors.initials: K
authors.lastname: Baumstarck
authors.forename: Laurent
authors.initials: L
authors.lastname: Boyer
authors.forename: Oscar
authors.initials: O
authors.lastname: Fernandez
authors.forename: Peter
authors.initials: P
authors.lastname: Flachenecker
authors.forename: Jean
authors.initials: J
authors.lastname: Pelletier
authors.forename: Anderson
authors.initials: A
authors.lastname: Loundou
authors.forename: Badih
authors.initials: B
authors.lastname: Ghattas
authors.forename: Pascal
authors.initials: P
authors.lastname: Auquier
mesh_terms: D000328:Adult; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000523:psychology*; D011594:Psychometrics; D011788:Quality of Life; D011795:Surveys and Questionnaires