title: What's in season for rheumatoid arthritis patients? Seasonal fluctuations in disease activity.
abstract: OBJECTIVE
  To examine whether a seasonal fluctuation exists with rheumatoid arthritis (RA) activity and to analyse seasonal effects of varying components that express disease activity in RA patients.
  
  
  METHODS
  A group of 1665 RA patients (mean age 57.2 yrs, mean disease duration 9.9 yrs) whose data were available for 10 consecutive phases from a large observational cohort study conducted at our institution from October 2000 to April 2005, bi-annually, were evaluated. Ten criteria were analysed to assess RA disease activity.
  
  
  RESULTS
  All criteria revealed decrease in disease activity during fall and increase in disease activity during spring, except for the physician's global assessment of disease activity in which significant differences were not observed between the two seasons.
  
  
  CONCLUSIONS
  We found definite seasonal differences in RA patients, both subjectively and objectively. RA disease activity was higher in spring and lower during fall. Seasonal changes may play an important role in evaluating disease activity of RA patients and should be taken into account when examining these patients.
authors.affiliation: Institute of Rheumatology, Tokyo Women's Medical University, 10-22 Kawada-cho, Shinjuku-ku, Tokyo 162-0054 Japan. iikuni@ior.twmu.ac.jp
authors.forename: N
authors.initials: N
authors.lastname: Iikuni
authors.forename: A
authors.initials: A
authors.lastname: Nakajima
authors.forename: E
authors.initials: E
authors.lastname: Inoue
authors.forename: E
authors.initials: E
authors.lastname: Tanaka
authors.forename: H
authors.initials: H
authors.lastname: Okamoto
authors.forename: M
authors.initials: M
authors.lastname: Hara
authors.forename: T
authors.initials: T
authors.lastname: Tomatsu
authors.forename: N
authors.initials: N
authors.lastname: Kamatani
authors.forename: H
authors.initials: H
authors.lastname: Yamanaka
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D012621:Seasons; D012720:Severity of Illness Index; D014041:Tokyo / Q000453:epidemiology