title: Rasch analysis of the motor function measure in patients with congenital muscle dystrophy and congenital myopathy.
abstract: OBJECTIVE
  To monitor treatment effects in patients with congenital myopathies and congenital muscular dystrophies, valid outcome measures are necessary. The Motor Function Measure (MFM) was examined for robustness, and changes are proposed for better adequacy.
  
  
  METHODS
  Observational study based on data previously collected from several cohorts.
  
  
  METHODS
  Nineteen departments of physical medicine or neuromuscular consultation in France, Belgium, and the United States.
  
  
  METHODS
  Patients (N=289) aged 5 to 77 years.
  
  
  METHODS
  None.
  
  
  METHODS
  A Rasch analysis examined the robustness of the MFM across the disease spectrum. The 3 domains of the scale (standing position and transfers, axial and proximal motor function, and distal motor function) were independently examined with a partial credit model.
  
  
  RESULTS
  The original 32-item MFM did not sufficiently fit the Rasch model expectations in either of its domains. Switching from a 4- to a 3-category response scale in 18 items restored response order in 16. Various additional checks suggested the removal of 7 items. The resulting Rasch-scaled Motor Function Measure with 25 items for congenital disorders of the muscle (Rs-MFM25(CDM)) demonstrated a good fit to the Rasch model. Domain 1 was well targeted to the whole severity spectrum-close mean locations for items and persons (0 vs 0.316)-whereas domains 2 and 3 were better targeted to severe cases. The reliability coefficients of the Rs-MFM25(CDM) suggested sufficient ability for each summed score to distinguish between patient groups (0.9, 0.8, and 0.7 for domains 1, 2, and 3, respectively). A sufficient agreement was found between results of the Rasch analysis and physical therapists' opinions.
  
  
  CONCLUSIONS
  The Rs-MFM25(CDM) can be considered a clinically relevant linear scale in each of its 3 domains and may be soon reliably used for assessment in congenital disorders of the muscle.
authors: Hospices Civils de Lyon, Hôpital Femme-Mère-Enfant, L'Escale, Service de Médecine Physique et de Réadaptation Pédiatrique, Bron, France; Université de Lyon, Lyon, France; Université Lyon I, Villeurbanne, France; CNRS UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Equipe Biostatistique Santé, Pierre-Bénite, France; National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD. Electronic address: carole.vuillerot@gmail.com.
authors: Carole
authors: C
authors: Vuillerot
authors: Hospices Civils de Lyon, Pôle Information Médicale, Évaluation, Recherche, Lyon, France.
authors: Pascal
authors: P
authors: Rippert
authors: Cliniques Universitaires Saint-Luc, Centre de Référence des maladies neuromusculaires, Université Catholique de Louvain, Brussels, Belgium.
authors: Virginie
authors: V
authors: Kinet
authors: Cliniques Universitaires Saint-Luc, Centre de Référence des maladies neuromusculaires, Université Catholique de Louvain, Brussels, Belgium.
authors: Anne
authors: A
authors: Renders
authors: Clinical Research Center, National Institutes of Health, Bethesda, MD.
authors: Minal
authors: M
authors: Jain
authors: Clinical Research Center, National Institutes of Health, Bethesda, MD.
authors: Melissa
authors: M
authors: Waite
authors: Physical Therapy Department, The Children's Hospital of Philadelphia, Philadelphia, PA.
authors: Allan M
authors: AM
authors: Glanzman
authors: Hospices Civils de Lyon, Hôpital Femme-Mère-Enfant, L'Escale, Service de Médecine Physique et de Réadaptation Pédiatrique, Bron, France.
authors: Francoise
authors: F
authors: Girardot
authors: Centre Hospitalo-Universitaire de Montpellier, Hôpital Arnaud de Villeneuve, Montpellier, France.
authors: Dalil
authors: D
authors: Hamroun
authors: Université de Lyon, Lyon, France; Université Lyon I, Villeurbanne, France; CNRS UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Equipe Biostatistique Santé, Pierre-Bénite, France; Hospices Civils de Lyon, Service de Biostatistique, Lyon, France.
authors: Jean
authors: J
authors: Iwaz
authors: Université de Lyon, Lyon, France; Université Lyon I, Villeurbanne, France; CNRS UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Equipe Biostatistique Santé, Pierre-Bénite, France; Hospices Civils de Lyon, Service de Biostatistique, Lyon, France.
authors: René
authors: R
authors: Ecochard
authors: AP-HP, Hôpitaux Universitaires Paris-Ile-de-France Ouest, Pôle pédiatrique, Centre de Référence Maladies Neuromusculaires (GNMH), Hôpital Raymond Poincaré, Garches, St Quentin, France; Université Versailles Saint-Quentin, St Quentin, France.
authors: Susana
authors: S
authors: Quijano-Roy
authors: Hospices Civils de Lyon, Hôpital Femme-Mère-Enfant, L'Escale, Service de Médecine Physique et de Réadaptation Pédiatrique, Bron, France.
authors: Carole
authors: C
authors: Bérard
authors: Hospices Civils de Lyon, Hôpital Femme-Mère-Enfant, L'Escale, Service de Médecine Physique et de Réadaptation Pédiatrique, Bron, France.
authors: Isabelle
authors: I
authors: Poirot
authors: National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD. Electronic address: carsten.bonnemann@nih.gov.
authors: Carsten G
authors: CG
authors: Bönnemann
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology*; D009136:Muscular Dystrophies / Q000151:congenital / Q000503:physiopathology* / Q000534:rehabilitation; D011187:Posture; D011594:Psychometrics; D015203:Reproducibility of Results; D016896:Treatment Outcome; D055815:Young Adult
keywords: Congenital muscular dystrophy; Congenital myopathy; Disability evaluation; Outcome measures; Rehabilitation