Table 1

Characteristics of participants with and without post-BD airflow obstruction in the development and validation samples

Characteristics in middle-age*Post-BD airflow obstruction aged 50s (n (%))†
Development cohort (TAHS, N=2407)‡Validation cohort (ECRHS, N=1407)§
No (n=2299)Yes (n=108)No (n=1317)Yes (n=95)
Sex (% male)1086 (49)60 (55)641 (49)53 (56)
Age (mean years (SD))§
Questionnaire42.6 (0.5)42.7 (0.6)43.8 (2.5)43.8 (2.6)
Post-BD spirometry52.7 (0.8)52.4 (0.7)55.2 (2.5)55.3 (2.5)
Post-BD spirometry at age 50s (mean (SD))
Post-BD FEV1 (L)3.33 (0.7)2.67 (0.7)3.10 (0.7)2.47 (0.7)
Post-BD FVC (L)4.16 (0.9)4.29 (1.0)3.94 (0.9)3.99 (1.0)
Post-BD FEV1/FVC (ratio)0.80 (0.05)0.63 (0.07)0.79 (0.05)0.62 (0.05)
z-score (SD)0.14 (0.7)–2.30 (0.7)–0.03 (0.8)–2.33 (0.6)
Symptoms at age 40s (n (%))
Current wheezing327 (15)52 (47)203 (15)47 (49)
Chronic cough159 (7.1)24 (22)88 (7)21 (22)
Chronic sputum130 (5.8)16 (15)78 (6)15 (16)
Breathlessness
MRC-1 (none)2026 (91)78 (72)1087 (82)69 (73)
MRC-2141 (6.3)20 (18)179 (14)19 (20)
MRC-3/466 (3.0)11 (10)51 (4)7 (7)
Chest tightness343 (15)37 (34)197 (15)32 (34)
Smoking (n (%); mean (SD); median (IQR); range†)
Never smoker1094 (49)22 (20)566 (43)25 (26)
Past smoker698 (31)24 (22)405 (31)31 (33)
Pack-years6.4 (1.7, 16)2.0 (0.3, 17)10.0 (4, 20)10.0 (5, 20)
Current smoker441 (20)63 (58)346 (26)39 (41)
Cigs per day14.0 (10)19.8 (10)14.1 (10)19.7 (11)
Duration26.0 (6)27.4 (3)26.1 (5)27.1 (4)
Age of onset16.3 (5)15.6 (3)17.5 (5)16.6 (3)
Pack-years17.4 (7, 28)27.0 (18, 38)21.9 (11, 30)31.0 (22, 39)
Current at age 50s290 (13)53 (49)234 (18)36 (38)
Quit by age 50s221 (10)16 (15)147 (11)7 (7)
Asthma at age 40s (n (%))
No asthma or wheezy breathing1459 (65)34 (31)961 (73)29 (31)
Wheezy breathing only134 (6)12 (11)166 (13)22 (23)
Self-reported asthma.
Remitted382 (17)22 (20)80 (6)12 (13)
Active, early onset88 (4)15 (14)33 (2.5)12 (13)
Active, late onset170 (8)26 (24)77 (6)20 (21)
Employment at age 40s (n (%))
Legislators, managers257 (12)12 (11)121 (9)10 (11)
Professionals474 (21)11 (10)248 (19)18 (19)
Technicians, associates263 (12)13 (12)198 (15)14 (15)
Trade workers277 (12)15 (14)106 (8)8 (8)
Clerks, services534 (24)24 (28)240 (18)19 (20)
Machine operators130 (6)9 (8)46 (4)4 (4)
Labourers, cleaners, other147 (7)15 (14)62 (5)4 (4)
House persons, other139 (6)10 (9)74 (6)5 (5)
Employed (unspecified)6 (0.3)0208 (16)§12 (13)
Non-work other6 (0.3)01 (0.1)1 (1)
  • *Post-BD airflow obstruction defined by post-BD FEV1/FVC<5th percentile (z-score<–1.645).

  • †Summary data expressed by n (%) unless by mean (SD), for example, smoking intensity/duration/start age or median (IQR), for example, pack-years. Ranges for continuous predictors: smoking intensity 0–60; duration 0–37; age-of-onset 6–41; pack-years 0–108 (ever-smokers).

  • ‡TAHS participant numbers refer to those aged in their 50s who underwent post-BD spirometry.

  • §ECRHS validation of participants aged 50 to up to 60 years (validation numbers for ages 50 up to 55 years not shown). Self-reported but unspecified employment was higher in ECRHS, as current job in the work history calendar was used with some missing (online supplemental Methods E1,E2).

  • BD, bronchodilator; ECRHS, European Community Respiratory Health Survey; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; LLN, lower limit of normal; MRC, Medical Research Council breathlessness scale; TAHS, Tasmanian Longitudinal Health Study.