title: Progression of pneumoconiosis in coal miners after cessation of dust exposure: a longitudinal study based on periodic chest X-ray examinations in Hokkaido, Japan.
abstract: BACKGROUND
  The progression rate of pneumoconiosis in retired coal miners over ten years has not been studied in Japan.
  
  
  METHODS
  A retrospective longitudinal study was undertaken using chest X-rays of 1091 pneumoconiosis subjects in Hokkaido, Japan between 1985 and 2005.
  
  
  RESULTS
  The final numbers of subjects were 207 (19% of the entry) after 1 decade and 85 (8%) after 2 decades. Sixty-two percent of 207 subjects after 1 decade and 29% of 85 showed progression in 2 decades. Thirty-one percent of ILO category 1 and 55% of category 2 subjects showed progression to complicated pneumoconiosis after 1 decade, and 6% (4 of 64) of category 1 and 6% (5 of 77) of category 2 subjects progressed to complicated pneumoconiosis during 2 decades.
  
  
  CONCLUSIONS
  The progression of pneumoconiosis was observed after the cessation of dust exposure, especially during the first 10 years.
authors.affiliation: Clinical Research Center for Pneumoconiosis, Hokkaido Chuo Rosai Hospital (Workmen's Accident Compensation Hospital), Japan Labor Health and Welfare Organization, Iwamizawa. ranrankk@cello.ocn.jp
authors.forename: Kiyonobu
authors.initials: K
authors.lastname: Kimura
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ohtsuka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kaji
authors.forename: Ikuo
authors.initials: I
authors.lastname: Nakano
authors.forename: Ichiro
authors.initials: I
authors.lastname: Sakai
authors.forename: Koichi
authors.initials: K
authors.lastname: Itabashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Igarashi
authors.forename: Kenzo
authors.initials: K
authors.lastname: Okamoto
mesh_terms: D000368:Aged; D003032:Coal Mining / Q000639:trends*; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008400:Mass Chest X-Ray / Q000639:trends*; D008875:Middle Aged; D011009:Pneumoconiosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology*; D012189:Retrospective Studies; D013997:Time Factors