Table 4

Comparison of spirometry data for patients with IP and the general population

Mean (SD) or n (%)Mean (SD) or n (%)Difference: β (95% CI) or OR (95% CI)Difference: β (95% CI) or OR (95% CI)
VariableN/nGeneral population (N=1492)IP patients (N=373)Adjusted for smokingAdjusted for smoking and BMI
Demographic characteristics
 Age, years1492/37362 (11)62 (11)
 Gender, female1492/3731012 (68%)253 (68%)
Smoking status
  Never767 (51.4%)125 (33.5%)
  Past607 (40.7%)195 (52.3%)
  Current118 (7.9%)53 (14.2%)
 BMI, kg/m21490/37326.6 (4.1)27.9 (5.0)
Abnormal lung function test
 Medication for respiratory symptoms1492/37341 (2.8%)45 (12.1%)
 FEV11492/3732.36 (0.71)2.28 (0.69)−0.08 (−0.13 to −0.02)−0.06 (−0.11 to −0.01)
 FVC1492/3732.82 (0.87)2.88 (0.86)0.06 (−0.01 to 0.13)0.08 (0.01 to 0.15)
 Obstructive lung disease1124/27755 (4.9%)32 (11.6%)2.01 (1.26 to 3.22)2.05 (1.27 to 3.29)
 Restrictive lung disease1296/287227 (17.5%)42 (14.6%)0.76 (0.53 to 1.10)0.71 (0.49 to 1.03)
  • N=general population/n=patients with IP with available data.

  • BMI, body mass index; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; IP, inflammatory polyarthritis.