Main characteristics, respiratory symptoms, and respiratory function in hairdressing apprentices and office apprentices in the two phases of the study
| Initial phase | Final phase | |||||
|---|---|---|---|---|---|---|
| Hairdressing apprentices n=297 | Office apprentices n=248 | p value | Hairdressing apprentices n=280 | Office apprentices n=250 | p value | |
| *Atopy defined by positive medical history of asthma or allergic rhinitis or medical history of atopic dermatitis. | ||||||
| †MHR: mucosal hyperresponsiveness, defined in this study as the presence of one or more of the following symptoms: fit of coughing, sneezing or runny nose, eye symptoms, and acute dyspnoea. | ||||||
| ‡Percentage of the reference values established by Knudson and colleagues.8 | ||||||
| §Only 234 hairdressing apprentices and 116 office apprentices at the initial phase and 204 hairdressing apprentices and 129 office apprentices at the final phase completed the methacholine challenge. | ||||||
| ¶Methacholine dose-response slope, defined by the percent decline in FEV1 divided by the final cumulative dose of methacholine administered. | ||||||
| Gender (% females) | 84.8 | 87.9 | 0.30 | 88.6 | 89.6 | 0.70 |
| Age (y), mean (SD) | 17.1 (1.3) | 16.8 (0.9) | 0.0004 | 19.0 (1.1) | 18.1 (1.0) | <0.0001 |
| Height (cm), mean (SD) | 163.8 (7.8) | 164.2 (7.3) | 0.54 | 164.0 (7.0) | 165.8 (7.9) | 0.03 |
| Smoking habits | ||||||
| Non-smoker (%) | 44.8 | 62.5 | <0.0001 | 38.2 | 60.1 | <0.0001 |
| Current or ex-smoker(%) | 55.3 | 37.5 | 61.8 | 39.9 | ||
| Cig/day, mean (SD) | 9.5 (6.6) | 8.9 (6.0) | 0.48 | 11.1 (5.1) | 9.2 (6.3) | 0.02 |
| Atopy* (%) | 20.2 | 24.6 | 0.22 | |||
| Symptoms | ||||||
| Morning cough (%) | 2.7 | 6.5 | 0.03 | 3.6 | 4.4 | 0.63 |
| Cough day/night (%) | 3.0 | 12.1 | <0.0001 | 3.2 | 8.8 | 0.006 |
| Morning sputum (%) | 0.7 | 4.0 | 0.008 | 1.4 | 1.2 | 0.82 |
| Wheezing (%) | 8.8 | 19.8 | 0.0002 | 10.0 | 18.8 | 0.004 |
| Dyspnoea with wheezing (%) | 7.7 | 12.5 | 0.06 | 6.1 | 11.2 | 0.03 |
| MHR† (%) | 25.3 | 42.7 | <0.0001 | 29.6 | 40.8 | 0.007 |
| Work related MHR (%) | 6.1 | 2.8 | 0.07 | |||
| Work related wheezing and/or dyspnoea according to the occupational physician (%) | 3.6 | 0 | 0.003 | |||
| Respiratory function‡ | (n=239) | (n=124) | (n=218) | (n=138) | ||
| % FVC, mean (SD) | 102.7 (11.8) | 100.7 (14.1) | 0.15 | 102.4 (10.9) | 100.1 (12.8) | 0.07 |
| % FEV1, mean (SD) | 103.1 (11.7) | 100.0 (12.9) | 0.02 | 101.8 (10.9) | 99.8 (12.0) | 0.10 |
| FEV1/FVC, mean (SD) | 89.3 (5.6) | 88.5 (5.7) | 0.21 | 88.7 (5.1) | 89.1 (6.0) | 0.54 |
| %FEF25–75%, mean (SD) | 100.5 (21.0) | 95.8 (20.1) | 0.04 | 97.4 (19.6) | 98.9 (22.3) | 0.50 |
| Methacholine challenge§ | ||||||
| BHR (15% decrease in FEV1) (%) | 33.3 | 31.9 | 0.79 | 35.3 | 24.8 | 0.04 |
| log(methacholine slope¶ + 0.02), mean (SD) | −1.51 (0.23) | −1.50 (0.26) | 0.74 | −1.51 (0.26) | −1.54 (0.20) | 0.22 |