title: Being overweight or obese and risk of developing rheumatoid arthritis among women: a prospective cohort study.
abstract: OBJECTIVE
  To examine the relationship between being overweight or obese and developing rheumatoid arthritis (RA) in two large prospective cohorts, the Nurses' Health Study (NHS) and Nurses' Health Study II (NHSII).
  
  
  METHODS
  We followed 109 896 women enrolled in NHS and 108 727 in NHSII who provided lifestyle, environmental exposure and anthropometric information through biennial questionnaires. We assessed the association between time-varying and cumulative Body Mass Index (BMI) in WHO categories of normal, overweight and obese (18.5-<25, 25.0-<30, ≥30.0 kg/m(2)) and incident RA meeting the 1987 American College of Rheumatology (ACR) criteria. We estimated HRs for overall RA and serologic subtypes with Cox regression models adjusted for potential confounders. We repeated analyses restricted to RA diagnosed at age 55 years or younger.
  
  
  RESULTS
  During 2 765 195 person-years of follow-up (1976-2008) in NHS and 1 934 518 person-years (1989-2009) in NHSII, we validated 1181 incident cases of RA (826 in NHS, 355 in NHSII). There was a trend toward increased risk of all RA among overweight and obese women (HR (95% CI) 1.37 (0.95 to 1.98) and 1.37 (0.91, 2.09), p for trend=0.068). Among RA cases diagnosed at age 55 years or younger, this association appeared stronger (HR 1.45 (1.03 to 2.03) for overweight and 1.65 (1.34 to 2.05) for obese women (p trend <0.001)). Ten cumulative years of being obese, conferred a 37% increased risk of RA at younger ages (HR 1.37 (1.11 to 1.69)).
  
  
  CONCLUSIONS
  Risks of seropositive and seronegative RA were elevated among overweight and obese women, particularly among women diagnosed with RA at earlier ages.
authors: Division of Rheumatology, Immunology & Allergy, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
authors: Bing
authors: B
authors: Lu
authors: Division of Rheumatology, Immunology & Allergy, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA.
authors: Linda T
authors: LT
authors: Hiraki
authors: Division of Rheumatology, Immunology & Allergy, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
authors: Jeffrey A
authors: JA
authors: Sparks
authors: Division of Rheumatology, Immunology & Allergy, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
authors: Susan
authors: S
authors: Malspeis
authors: Division of Rheumatology, Immunology & Allergy, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA.
authors: Chia-Yen
authors: CY
authors: Chen
authors: Division of Rheumatology, Immunology & Allergy, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
authors: J Adebukola
authors: JA
authors: Awosogba
authors: Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA.
authors: Elizabeth V
authors: EV
authors: Arkema
authors: Division of Rheumatology, Immunology & Allergy, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
authors: Karen H
authors: KH
authors: Costenbader
authors: Division of Rheumatology, Immunology & Allergy, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
authors: Elizabeth W
authors: EW
authors: Karlson
mesh_terms: D000328:Adult; D000367:Age Factors; D000886:Anthropometry / Q000379:methods; D001172:Arthritis, Rheumatoid / Q000453:epidemiology / Q000209:etiology*; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009726:Nurses / Q000706:statistics & numerical data; D009765:Obesity / Q000150:complications / Q000453:epidemiology; D050177:Overweight / Q000150:complications* / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology
keywords: Ant-CCP; Epidemiology; Rheumatoid Arthritis; Rheumatoid Factor