title: Using lifestyle factors to identify individuals at higher risk of inflammatory polyarthritis (results from the European Prospective Investigation of Cancer-Norfolk and the Norfolk Arthritis Register--the EPIC-2-NOAR Study).
abstract: OBJECTIVE
  To investigate the association of lifestyle factors with risk of inflammatory polyarthritis (IP) and rheumatoid arthritis (RA).
  
  
  METHODS
  The European Prospective Investigation of Cancer, Norfolk, UK (EPIC-Norfolk) gathered lifestyle data from participants aged 40-79 years from 1993 to 1997. Individuals who subsequently developed IP were identified by linkage with the Norfolk Arthritis Register. A Cox proportional hazard model was developed, and a score assigned to each risk factor to calculate the odds of developing IP.
  
  
  RESULTS
  25 455 EPIC participants were followed for a median (IQR) of 14.2 (12.9, 15.3) years; 184 developed incident IP (138 cumulatively fulfilled criteria for RA; 107 were seropositive). Pack-years of smoking were associated with increased risk of IP and RA in men (HR 1.21 (95% CI 1.08 to 1.37) per 10-pack-years) and seropositive IP (HR 1.24 (95% CI 1.10 to 1.41)) for all. Diabetes mellitus was associated with increased risk of IP (HR 2.54 (95% CI 1.26 to 5.09)), while alcohol (HR 0.86 (95% CI 0.74 to 0.99) per unit/day) and higher social class (HR 0.36 (95% CI 0.15 to 0.89) for professionals vs manual workers) were associated with reduced risk. Body mass index was associated with seronegative IP (HR 2.75 (95% CI 1.39 to 5.46) for obese vs normal-weight participants). In women, parity (HR 2.81 (95% CI 1.37 to 5.76) for ≥2 vs no children) was associated with increased risk, and breast feeding (HR 0.66 (95% CI 0.46 to 0.94) for every 52 weeks of breast feeding) was inversely associated with risk. Risk factors from the model were used to generate a 'risk score'. A total of 1159 (8.4%) women had scores reflecting a >3-fold increased risk of IP over those with a score of 0.
  
  
  CONCLUSIONS
  Several easily ascertained clinical and lifestyle factors can be used to stratify populations for risk of IP.
authors.affiliation: Arthritis Research UK Epidemiology Unit, Manchester Academic Health Sciences Centre, University of Manchester, , Manchester, UK.
authors.forename: Manjari
authors.initials: M
authors.lastname: Lahiri
authors.forename: Robert N
authors.initials: RN
authors.lastname: Luben
authors.forename: Catharine
authors.initials: C
authors.lastname: Morgan
authors.forename: Diane K
authors.initials: DK
authors.lastname: Bunn
authors.forename: Tarnya
authors.initials: T
authors.lastname: Marshall
authors.forename: Mark
authors.initials: M
authors.lastname: Lunt
authors.forename: Suzanne M M
authors.initials: SM
authors.lastname: Verstappen
authors.forename: Deborah P M
authors.initials: DP
authors.lastname: Symmons
authors.forename: Kay-Tee
authors.initials: KT
authors.lastname: Khaw
authors.forename: Nick
authors.initials: N
authors.lastname: Wareham
authors.forename: Ian N
authors.initials: IN
authors.lastname: Bruce
mesh_terms: D000328:Adult; D000368:Aged; D001168:Arthritis / Q000453:epidemiology*; D001172:Arthritis, Rheumatoid / Q000453:epidemiology*; D015331:Cohort Studies; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008019:Life Style; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries / Q000706:statistics & numerical data; D012307:Risk Factors
keywords: Epidemiology; Rheumatoid Arthritis; Smoking