Demographic characteristics of the cohort by symptom status
| Asthma symptoms (n = 244†) | No asthma symptoms (n = 129†) | |
|---|---|---|
| †Valid cases vary between variables. | ||
| ‡Only woodworkers, n = 328. | ||
| §Pearson χ2 test of overall smoking status between subjects with and without asthma symptoms: χ2 = 27.4, p < 0.0001. | ||
| ¶Workers using mainly pine (Pinus sylvestris). | ||
| ††Workers using mainly beech. | ||
| ‡‡Workers using mainly wood composite, e.g. chipboard, MDF board, etc. | ||
| §§Daily PEF variation >20% or PEF period variation >30%. | ||
| *p<0.05; **p<0.01. | ||
| General characteristics | ||
| Female, n (%) | 65 (26.6) | 32 (24.8) |
| Age, years, median (interquartile range) | 35 (17.0) | 41 (18.3)** |
| Unskilled workers, n (%) | 114 (47.3) | 64 (51.6) |
| Non-smokers, n (%)§ | 67 (27.8) | 54 (43.5)** |
| Ex smokers, n (%) | 24 (10.0) | 27 (21.8)** |
| Smokers, <20/cig/day, n (%) | 61 (25.3) | 28 (21.0) |
| Smokers, ⩾20/cig/day, n (%) | 89 (36.9) | 17 (13.7)** |
| Exposure characteristics | ||
| Woodworkers, n (%) | 196 (80.3) | 106 (82.2) |
| Pine¶, n (%)‡ | 88 (45.4) | 51 (48.6) |
| Beech††, n (%)‡ | 6 (3.1) | 6 (5.7) |
| Wood composite‡‡, n (%)‡ | 35 (18.0) | 23 (21.9) |
| Years in the wood industry, median (interquartile range) | 7 (8.5) | 8 (10.3) |
| Wood dust, <0.80 mg/m3, n (%)‡ | 46 (24.1) | 38 (36.5) |
| Wood dust, 0.80–0.99 mg/m3, n (%)‡ | 37 (19.4) | 17 (16.3) |
| Wood dust, 1.00–1.39 mg/m3, n (%)‡ | 59 (30.9) | 29 (27.9) |
| Wood dust, >1.39 mg/m3, n (%)‡ | 49 (25.7) | 20 (19.2) |
| Health characteristics | ||
| BHR, n (%) | 54 (23.9) | 3 (2.4)** |
| Atopy, n (%) | 130 (55.3) | 38 (30.2)** |
| Increased PEF variation§§, n (%) | 78 (45.6) | 25 (22.9)** |