title: Associations between demographic and disease-related variables and disability over the first five years of inflammatory polyarthritis: a longitudinal analysis using generalized estimating equations.
abstract: OBJECTIVE
  To investigate whether the relationship between demographic and disease-related variables and disability is constant during the first five years of inflammatory polyarthritis (IP) and to identify the contribution from involvement of specific joint areas to overall disability.
  
  
  METHODS
  684 patients referred to the Norfolk Arthritis Register were followed for five years using the Health Assessment Questionnaire (HAQ). The relationship between disability and demographic and clinical variables was analyzed using a multi-level modelling approach.
  
  
  RESULTS
  Female gender, older age at symptom onset (> or = 64 years), joint involvement at six specific sites, joint tenderness and the number of deformed joints were all independently associated with disability (HAQ > or = 1.00). Similar results were obtained using a more stringent cut-off (HAQ > or = 1.50) or when analysis was restricted to the 325 patients who satisfied the 1987 ARA list criteria for rheumatoid arthritis.
  
  
  CONCLUSIONS
  Disability, as measured by the HAQ, was associated with a large number of independent factors over the first five years of disease.
authors.affiliation: ARC Epidemiology Unit, University of Manchester Medical School, Manchester, UK.
authors.forename: N
authors.initials: N
authors.lastname: Wiles
authors.forename: G
authors.initials: G
authors.lastname: Dunn
authors.forename: E
authors.initials: E
authors.lastname: Barrett
authors.forename: A
authors.initials: A
authors.lastname: Silman
authors.forename: D
authors.initials: D
authors.lastname: Symmons
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000453:epidemiology / Q000503:physiopathology*; D003710:Demography; D004185:Disability Evaluation; D004739:England / Q000453:epidemiology; D005163:Factor Analysis, Statistical; D005260:Female; D006304:Health Status; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012042:Registries; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires