| (1) Respiratory symptoms on screening questionnaire(n = 454) | (2) Met case definition for EAA(n = 19)* | (3) Met case definition for OA(n = 66)† | (4) Controls(n = 47) | Statistical difference(1 vs 4)‡ | Statistical difference(2 vs 3 vs 4)§ | ||
| Age (years) | Mean (SD) | 44.7 (8.6) | 47.5 (7.9) | 43.4 (7.6) | 43.6 (10.5) | p = 0.417 | p = 0.176 |
| Gender | |||||||
| Men | n (%) | 419 (92.2%) | 17 (89.5%) | 59 (89.4%) | 43 (91.5%) | p = 1.000 | Not done |
| Women | 35 (7.8%) | 2 (10.5%) | 7 (10.6%) | 4 (8.5%) | |||
| Ethnicity | |||||||
| Caucasian | n (%) | 396 (87.2%) | 18 (94.7%) | 53 (80.3%) | 44 (93.6%) | p = 0.298 | p = 0.064 |
| Non-Caucasian | 58 (12.8%) | 1 (5.3%) | 13 (19.7%) | 3 (6.4%) | |||
| Smoking | |||||||
| Current | n (%) | 125 (28%) | 3 (15.8%) | 15 (22.7%) | 6 (14.3%) | p = 0.086 (current vs others) | p = 0.513 (current vs others) |
| Ex | 127 (28%) | 7 (36.8%) | 18 (27.3%) | 13 (31.0%) | |||
| Never | 197 (44%) | 9 (47.4%) | 33 (50%) | 23 (54.7%) | |||
| FEV1 (l) | Mean (SD) | 3.52 (0.76) | 2.90 (0.66) | 3.45 (0.69) | 3.91 (0.76) | ||
| FEV1 (% predicted) | Mean (SD) | 96.8 (15.8) | 83.4 (15.9) | 94.9 (14.9) | 102.8 (14.9) | p = 0.012 | p<0.001 |
| FVC (l) | Mean (SD) | 4.50 (0.93) | 3.58 (0.74) | 4.40 (0.86) | 4.99 (0.98) | ||
| FVC (% predicted) | Mean (SD) | 103.5 (15.7) | 85.1 (15.9) | 101.4 (14.9) | 110.0 (17.1) | p = 0.008 | p<0.001 |
| Works mostly in manufacturing | |||||||
| Yes | n (%) | 368 (81%) | 19 (100%) | 64 (97%) | 28 (60.9%) | p = 0.002 | p<0.001 |
| No | n (%) | 86 (19%) | 0 (0%) | 2 (3%) | 18 (39.1%) | ||
| Ever worked on machine with MWF | |||||||
| Yes | n (%) | 270 (60%) | 14 (73.7%) | 43 (65.2%) | 22 (46.8%) | p = 0.111 | p = 0.06 |
| No | n (%) | 180 (40%) | 5 (26.3%) | 23 (34.8%) | 25 (53.2%) | ||
| Duration of employment at factory (years) | Median (IQR) | 10.5 (5–15) | 9 (4–12) | 12 (6–15) | 9 (4–15) | p = 0.403 | p = 0.306 |
FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; MWF, metal working fluid.
*Eight also had OA.
†Excludes eight with EAA.
‡Analysis by t test for age, FEV1 and FVC; Mann-Whitney U test for duration of employment.
§Analysis by one-way ANOVA for age, FEV1 and FVC; Kruskal-Wallis test for duration of employment.
‡,§Categorical data analysed by χ2 test.