Table 1.

Distribution of lung and joint involvement according to positivity of anti-Jo1 antibodies in patients with PM/DM. Anti-Jo1 was detected by double immunodiffusion method (IT-ENA, ImmunoThink Co.) and reaffirmed by the autoimmune target test (IT-AIT, ImmunoThink Co.) with specific immunofluorescence pattern (cytoplasmic fine granular). Values are n (%) unless otherwise specified.

CharacteristicsPatients
With Anti-Jo1, n = 23Without Anti-Jo1, n = 28
Involved organs*
  Lung + joints11 (47.8)8 (28.6)
  Lung only9 (39.1)9 (32.1)
  Joints only2 (8.7)1 (3.6)
  None1 (4.3)10 (35.7)
Disease duration, yrs, mean ± SD7.39 ± 5.48.8 ± 2.9
Age, yrs, mean ± SD47.9 ± 9.442.4 ± 14.7
Sex, f/m18/524/4
  • * Lung involvement regardless of arthritis was 20 (87.0%) and 17 (60.7%) in patients with and without anti-Jo1, respectively (p = 0.037, chi-square test). Joint involvement regardless of lung lesion was 13 (56.5%) and 9 (32.1%) in patients with and without anti-Jo1, respectively (p = 0.080, chi-square test). PM: polymyositis; DM: dermatomyositis.