Multiple linear regression of ΔFEV1 in ml/year in 234 subjects with asthma based on a mean observation period of 10 years
| Variable | Estimate (ml/year) | SE | p value |
|---|---|---|---|
| SE, standard error of the estimate; ICS, inhaled corticosteroids. | |||
| The intercept represents the mean annual decline in a non-smoking asthmatic woman without wheezing who is not treated with ICS. The estimate for different variables represents the difference in the annual decline in FEV1 between those with and those without these characteristics (this means that heavy smokers have an additional decline in FEV1 of 22.5 ml/year whereas those treated with ICS have a 17.8 ml/year lower decline in FEV1). | |||
| Intercept1 | 49.5 | 5.7 | <0.001 |
| Sex | |||
| Women | 0 | ||
| Men | 5.6 | 5.6 | 0.319 |
| Smoking | |||
| Non-smokers | 0 | ||
| Starters | 16.6 | 17.1 | 0.333 |
| Quitters | 8.6 | 7.6 | 0.259 |
| Light smokers | 2.1 | 8.7 | 0.805 |
| Heavy smokers | 22.5 | 7.3 | 0.002 |
| Wheezing | |||
| No | 0 | ||
| Yes | −13.1 | 6.0 | 0.030 |
| ICS | |||
| No | 0 | ||
| Yes | −17.8 | 7.1 | 0.013 |