Table 3

Percentage of population with lung function below the lower limit of normal in “healthy” population for the Health Survey for England reference curves using different estimates of the 5th percentile by sex and age group

Age yrsPresent model#Mean – 1.645σ
FEV1FVCFEV1FVC
Males
 16–244.05.04.54.0
 25–345.85.05.03.9
 35–446.36.05.36.3
 45–543.55.14.36.6
 55–643.13.86.96.9
 65–746.46.412.110.8
 ≥755.15.18.515.3
 All5.05.25.65.9
Females
 16–245.56.13.03.7
 25–344.65.73.23.2
 35–446.34.44.94.1
 45–545.15.45.65.9
 55–645.36.76.57.9
 65–745.55.210.99.1
 ≥755.73.813.810.7
 All5.45.45.55.4
  • σ: sd of residuals

  • FEV1: forced expiratory volume in one second

  • FVC: forced vital capacity

  • #: lower limit of normal=eb0+b1A+b2A2+b3ln H

  • coefficient values given in table 2