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Table 1 Characteristics of study groups at baseline and length of follow-up periods

From: Does lung function predict the risk of disability pension? An 11-year register-based follow-up study

 Obstructive spirometry n = 111Restrictive spirometry n = 95Controls n = 3180All n = 3386
Age,mean years, (SD)45.9 (7.8)46.2 (8.4)44.2 (8.3)44.3 (8.3)
Males57 (51%)60 (63%)1550 (49%)1667 (49%)
Education
 Basic36 (32%)35 (37%)686 (22%)757 (22%)
 Mid-level35 (32%)41 (43%)1219 (38%)1295 (38%)
 University40 (36%)19 (20%)1275 (40%)1334 (39%)
Doctor-diagnosed asthma25 (23%)11 (12%)187 (6%)223 (7%)
Self-reported COPD8 (7%)1 (1%)10 (0.3%)19 (1%)
Smoking
 non-smoker30 (27%)33 (35%)1557 (49%)1620 (48%)
 ex-smoker24 (22%)25 (26%)646 (20%)695 (21%)
 current smoker57 (51%)37 (39%)976 (31%)1070 (32%)
S-cotinine ≥ 100μg/l59 (53%)33 (35%)826 (26%)918 (27%)
BMI
  < 2561 (55%)18 (19%)1332 (42%)1411 (42%)
 25–29.937 (33%)30 (32%)1280 (40%)1347 (40%)
  ≥ 3013 (12%)47 (50%)567 (18%)627 (19%)
FEV1% predicted
 FEV1 ≥ 80%0 (0%)70 (74%)1996 (63%)2066 (61%)
 50 ≤ FEV1 < 80109 (98%)25 (26%)1184 (37%)1318 (39%)
 30 ≤ FEV1 < 502 (2%)0 (0%)0 (0%)2 (0.1%)
 FEV1 < 300 (0%)0 (0%)0 (0%)0 (0%)
Length of follow-up period, mean years (SD)9.4 (3.0)8.7 (3.5)9.7 (2.8)9.7 (2.8)
Co-morbidities
 137 (33%)29 (31%)1032 (33%)1098 (32%)
  ≥ 225 (23%)24 (25%)476 (15%)525 (16%)
Physically active66 (60%)45 (48%)1775 (56%)1886 (56%)
  1. FEV1 forced expiratory volume in one second, FVC forced ventilation capacity, BMI body mass index
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