title: [Comparison of the clinical features of idiopathic pulmonary fibrosis in Japan and the U.S.A., based on disease severity].
abstract: OBJECTIVE
  The aim of this study was to assess the clinical characteristics of idiopathic pulmonary fibrosis (IPF) in patients with stage I disease severity based on the criteria of the Japanese Respiratory Society (JRS), which correspond to moderate or severe U.S.A. criteria.
  
  
  METHODS
  In 46 consecutive patients with IPF who were admitted to our institution from June 2003 through September 2009, 27 were given diagnoses of stage I disease severity based on JRS criteria. These 27 were classified into 3 groups: Group A (stage I disease severity according to the JRS criteria, corresponding to mild on U.S.A. criteria, n=17), group B (stage I disease severity according to JRS criteria, corresponding to moderate or severe on U.S.A. criteria, n=10), and group C (stage I disease severity based on the JRS criteria, corresponding to severe U.S.A. criteria, n=6). We compared these groups using demographic and spirometric tests, the 6-minute walking test (6MWT), estimated systolic pulmonary arterial pressure (esPAP), and survival rates in each group.
  
  
  RESULTS
  stage I disease severity according to the JRS criteria corresponded to the following grade based on U.S.A. criteria: mild, 17 cases; moderate, 4 cases; severe, 6 cases. The values of lowest SpO2 and %DLco in group B and group C were significantly lower than those in group A, and values of the Hugh-Jones score and esPAP were higher than those in group A. In addition, the survival rate in group B and group C was significantly worse than that in group A. The survival rate in patients with stage I disease severity who showed desaturation on exertion with %DLco < or = 50%, was significantly worse than in those who showed SpO2 > or = 90% on exertion with %DLco >50% (23.7 16.5 months vs. 16.6 +/- 11.3 months; P = 0.002).
  
  
  CONCLUSIONS
  This study suggested that IPF patients with stage I disease severity according to JRS criteria included the grades of moderate and severe according to U.S.A. criteria. This suggests that we should revise the classification of disease severity for IPF in Japan.
authors.affiliation: Department of Respiratory Medicine, Toho University Omori Medical Center.
authors.forename: Keishi
authors.initials: K
authors.lastname: Sugino
authors.forename: Takafumi
authors.initials: T
authors.lastname: Ito
authors.forename: Yoko
authors.initials: Y
authors.lastname: Muramatsu
authors.forename: Keita
authors.initials: K
authors.lastname: Sato
authors.forename: Susumu
authors.initials: S
authors.lastname: Sakamoto
authors.forename: Sakae
authors.initials: S
authors.lastname: Homma
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000145:classification* / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D007564:Japan; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011669:Pulmonary Wedge Pressure; D012720:Severity of Illness Index; D015996:Survival Rate; D014481:United States