Table 2

 Lung function levels (% predicted) in quintile groups for each study

Quintile 1Quintile 2Quintile 3Quintile 4Quintile 5
*Percentage predicted values were calculated using Hankinson’s equation49 with the assumption that the men in the study had a mean height of 170 cm and women had a mean height of 160 cm, and the mean age was 46 years.
    Van Den Eeden13*⩽6667–7980–9394–104⩾104
    Van Den Eeden13*⩽6061–7576–8586–99⩾100