Characteristics | ECRHS I | ECRHS II | ECRHS III |
N (%) or mean (SD) | N (%) or mean (SD) | N (%) or mean (SD) | |
Symptomatic study arm | 544 (14.8) | – | – |
Women | 1956 (53.3) | – | – |
Age in years | 34.3 (7.1) | 43.0 (7.0) | 54.3 (7.1) |
Height in cm | 170.6 (9.4) | 170.3 (9.4) | 169.4 (9.5) |
Weight in kg | 69.5 (13.5) | 74.0 (15.1) | 77.9 (16.1) |
BMI | |||
Continuous, in kg/m2 | 23.8 (3.7) | 25.4 (4.3) | 27.1 (4.9) |
Underweight | 453 (12.3) | 222 (6.1) | 119 (3.2) |
Normal weight | 2097 (57.1) | 1676 (45.8) | 1224 (33.3) |
Overweight | 892 (24.3) | 1298 (35.5) | 1481 (40.3) |
Obese | 231 (6.3) | 461 (12.6) | 849 (23.1) |
Smoking status | |||
Non-smoker | 1651 (45.0) | 1576 (42.9) | 1518 (41.3) |
Ex-smoker | 818 (22.3) | 1119 (30.5) | 1500 (40.8) |
Current smoker | 1204 (32.8) | 978 (26.6) | 655 (17.8) |
Secondhand smoke exposure, yes | 1939 (52.9) | 1321 (36.1) | 680 (18.6) |
Current asthma, yes† | 378 (10.5) | 491 (13.8) | 570 (16.2) |
Age completed full-time education | |||
<17 years | 675 (21.5) | – | – |
17–20 years | 1205 (38.4) | – | – |
>20 years | 1256 (40.1) | – | – |
Physical activity. Active status‡ | – | 1363 (52.2) | – |
Any long-term limiting illness, yes§ | – | 405 (17.1) | – |
Lung function | |||
FVC (mL) | 4516 (988) | 4354 (980) | 3964 (948) |
FEV1 (mL) | 3702 (798) | 3485 (790) | 3006 (753) |
FEV1/FVC (%) | 82.3 (6.9) | 80.3 (6.5) | 75.8 (6.5) |
Lung function (z-scores)¶ | |||
FVC z-score | 0.01 (0.95) | 0.02 (1.00) | −0.08 (0.94) |
FEV1 z-score | −0.01 (1.06) | −0.03 (1.08) | −0.34 (1.04) |
FEV1/FVC z-score | −0.06 (1.03) | −0.10 (1.00) | −0.48 (0.89) |
*Some variables had missing values. Number of missing values for ECRHS I: 10 in secondhand smoke exposure, 78 in current asthma, and 537 in age completed full-time education. Number of missing values for ECRHS II: 18 in secondhand smoke exposure, 118 in current asthma, 1062 in physical activity and 1300 in any long-term limiting illness. Number of missing values for ECRHS III: 14 in secondhand smoke exposure and 163 in current asthma.
†Current asthma was defined as having reported physician-diagnosed asthma and at least one of the following: asthma-like symptoms (wheeze, nocturnal chest tightness, attacks of breathlessness after activity/at rest/at night-time), asthma attacks, use of inhaled/oral medicines for breathing problems (in the last 12 months), or current use of inhalers, aerosols or tablets for asthma.
‡Individuals were categorised as being active if they exercised with a frequency of two or more times a week and with a duration of about 1 hour a week or more.
§The following illnesses were considered: hypertension, heart disease, diabetes, cancer or stroke.
¶Lung function z-scores were derived using Global Lung Initiative 2012 equations.
BMI, body mass index; FEV1, volume expired in the first second; FVC, forced vital capacity.