Table 1

Percentage prevalences of self-reported asthma, phlegm, chronic bronchitis, and current smoking in the 1976–8 cohort and the 1991–4 cohort

1976–8 (n=1034)1991–4 (n=1104)
Women (n=533)Men (n=501)Women (n=581)Men (n=523)
Self-reported asthma1-150 1.7 (0.6 to 2.8)1.2 (0.2 to 2.2)4.7 (3.0 to 6.4)4.8 (3.0 to 6.7)
 20–25 years3.00.75.84.0
 26–30 years1.71.95.23.9
 31–35 years0.51.13.95.7
Occasional phlegm1-151 15.4 (12.3 to 18.4)16.4 (13.1 to 19.6)11.5 (8.9 to 14.1)17.9 (14.6 to 21.2)
 20–25 years14.913.37.713.1
 26–30 years8.415.211.516.7
 31–35 years22.519.912.920.4
Chronic bronchitis1-151 7.1 (4.9 to 9.3)9.2 (6.7 to 11.7)5.9 (4.0 to 7.9)10.9 (8.2 to 13.6)
 20–25 years6.04.03.86.1
 26–30 years3.49.74.710.3
 31–35 years11.812.97.613.1
Current smokers1-152 60.4 (56.3 to 64.6)62.1 (57.8 to 66.3)44.0 (39.9 to 48.1)46.5 (42.2 to 50.8)
 20–25 years58.355.337.536.0
 26–30 years58.464.247.449.0
 31–35 years64.265.644.149.0
  • 1-150 Asthma is more prevalent in the 1991–4 cohort than in the 1976–8 cohort among women (p=0.009) as well as men (p=0.002). There are no significant sex differences.

  • 1-151 Occasional phlegm and chronic bronchitis are more prevalent among men than women in the 1991–4 cohort (p<0.005). There is no sex difference in the 1976–8 cohort nor any difference between cohorts. There is a modest increase with age in occasional phlegm and chronic bronchitis, reaching statistical significance only by pooling women and men (1976–8: p<0.01, 1991–4: p<0.03).

  • 1-152 The prevalence of smoking is significantly reduced from 1976–8 to 1991–4 (p<0.001). There is no sex difference in smoking prevalence in either cohort.