Cross sectional analysis: differences in forced expiratory volume in one second (FEV1) in ml associated with increases in the number of apples eaten per week at phase I (from no apples per week) within smoking categories3-150
| Smoking group | No. | 1 per week | 2–4 per week | ⩾5 per week | Test of trend | Test of heterogeneity | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Difference | 95% CI | Difference | 95% CI | Difference | 95% CI | ||||||||
| Never smoked | 333 | –150.3 | –398.8 to 98.3 | 16.8 | –173.9 to 207.4 | 47.9 | –149.9 to 245.8 | p = 0.241 | p = 0.941 | ||||
| Ex-smoker † | 625 | –19.2 | –198.4 to 160.0 | 84.6 | –50.7 to 219.8 | 108.7 | –33.8 to 251.2 | p = 0.083 | |||||
| Cigar/pipe smoker‡ | 227 | 113.5 | –181.5 to 408.5 | 168.3 | –27.4 to 364.0 | 132.9 | –106.1 to 372.0 | p = 0.190 | |||||
| Current cigarette smoker¶ | 892 | 134.6 | 4.2 to 264.9 | 102.6 | 3.6 to 201.6 | 195.0 | 54.9 to 335.1 | p = 0.012 | |||||
↵3-150 All associations adjusted for age, height, body mass index, social class, work exercise, leisure exercise and total calorie intake.†Association adjusted for length of time since quitting smoking.‡Association adjusted for the number of cigars smoked per day and the number of ounces of tobacco smoked per week. ¶Association adjusted for the number of cigarettes smoked per day (mixed smokers excluded).