title: The interest of gait markers in the identification of subgroups among fibromyalgia patients.
abstract: BACKGROUND
  Fibromyalgia (FM) is a heterogeneous syndrome and its classification into subgroups calls for broad-based discussion. FM subgrouping, which aims to adapt treatment according to different subgroups, relies in part, on psychological and cognitive dysfunctions. Since motor control of gait is closely related to cognitive function, we hypothesized that gait markers could be of interest in the identification of FM patients' subgroups. This controlled study aimed at characterizing gait disorders in FM, and subgrouping FM patients according to gait markers such as stride frequency (SF), stride regularity (SR), and cranio-caudal power (CCP) which measures kinesia.
  
  
  METHODS
  A multicentre, observational open trial enrolled patients with primary FM (44.1 ± 8.1 y), and matched controls (44.1 ± 7.3 y). Outcome measurements and gait analyses were available for 52 pairs. A 3-step statistical analysis was carried out. A preliminary single blind analysis using k-means cluster was performed as an initial validation of gait markers. Then in order to quantify FM patients according to psychometric and gait variables an open descriptive analysis comparing patients and controls were made, and correlations between gait variables and main outcomes were calculated. Finally using cluster analysis, we described subgroups for each gait variable and looked for significant differences in self-reported assessments.
  
  
  RESULTS
  SF was the most discriminating gait variable (73% of patients and controls). SF, SR, and CCP were different between patients and controls. There was a non-significant association between SF, FIQ and physical components from Short-Form 36 (p = 0.06). SR was correlated to FIQ (p = 0.01) and catastrophizing (p = 0.05) while CCP was correlated to pain (p = 0.01). The SF cluster identified 3 subgroups with a particular one characterized by normal SF, low pain, high activity and hyperkinesia. The SR cluster identified 2 distinct subgroups: the one with a reduced SR was distinguished by high FIQ, poor coping and altered affective status.
  
  
  CONCLUSIONS
  Gait analysis may provide additional information in the identification of subgroups among fibromyalgia patients. Gait analysis provided relevant information about physical and cognitive status, and pain behavior. Further studies are needed to better understand gait analysis implications in FM.
authors.affiliation: Locomotion Research Unit, Laval Hospital, Laval, France. bernard.auvinet@gmail.com
authors.forename: Bernard
authors.initials: B
authors.lastname: Auvinet
authors.forename: Denis
authors.initials: D
authors.lastname: Chaleil
authors.forename: Jean
authors.initials: J
authors.lastname: Cabane
authors.forename: Anne
authors.initials: A
authors.lastname: Dumolard
authors.forename: Pierre
authors.initials: P
authors.lastname: Hatron
authors.forename: Robert
authors.initials: R
authors.lastname: Juvin
authors.forename: Michel
authors.initials: M
authors.lastname: Lanteri-Minet
authors.forename: Yves
authors.initials: Y
authors.lastname: Mainguy
authors.forename: Laurence
authors.initials: L
authors.lastname: Negre-Pages
authors.forename: Fabien
authors.initials: F
authors.lastname: Pillard
authors.forename: Daniel
authors.initials: D
authors.lastname: Riviere
authors.forename: Yves-Michel
authors.initials: YM
authors.lastname: Maugars
mesh_terms: D000328:Adult; D015415:Biomarkers; D058443:Catastrophization / Q000175:diagnosis / Q000523:psychology; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology; D015897:Comorbidity; D004185:Disability Evaluation; D005260:Female; D005356:Fibromyalgia / Q000145:classification* / Q000175:diagnosis* / Q000453:epidemiology; D020233:Gait Disorders, Neurologic / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D006801:Humans; D008875:Middle Aged; D010147:Pain Measurement / Q000379:methods; D010808:Physical Examination / Q000379:methods*; D011795:Surveys and Questionnaires / Q000592:standards; D055815:Young Adult
chemical_list: D015415:Biomarkers
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