| Characteristic | Translocation frequency/100 cell equivalents | |||||
| Pilots (n = 83) | Comparison group (n = 50) | |||||
| n (%) | Mean (SD) | p Value* | n (%) | Mean (SD) | p Value | |
| Age at blood draw | ||||||
| ⩽40 | 13 (15.7%) | 0.27 (0.19) | 0.003 | 9 (18.0%) | 0.17 (0.13) | 0.02† |
| 41–45 | 25 (30.1%) | 0.29 (0.29) | 16 (32.0%) | 0.35 (0.38) | ||
| 46–50 | 16 (19.3%) | 0.48 (0.36) | 14 (28.0%) | 0.40 (0.36) | ||
| >50 | 29 (34.9%) | 0.49 (0.36) | 11 (22.0%) | 0.28 (0.28) | ||
| Smoking status | ||||||
| Never | 67 (80.7%) | 0.37 (0.32) | 0.26 | 43 (86.0%) | 0.31 (0.33) | 0.79 |
| Ever | 16 (19.3%) | 0.48 (0.38) | 7 (14.0%)‡ | 0.34 (0.29) | ||
| Pack-years§ | ||||||
| 0 | 67 (80.7%) | 0.37 (0.32) | 0.58 | 43 (86.0%) | 0.31 (0.33) | 0.84 |
| ⩽1 | 5 (6.0%) | 0.53 (0.43) | 4 (8.0%) | 0.37 (0.35) | ||
| >1 | 11 (13.3%) | 0.45 (0.37) | 3 (6.0%) | 0.30 (0.26) | ||
| Cumulative red bone marrow x ray dose score | ||||||
| <0.5 | 33 (39.8%) | 0.25 (0.20) | 0.02 | 27 (54.0%) | 0.31 (0.33) | 0.45 |
| 0.5–1.9 | 39 (47.0%) | 0.48 (0.33) | 16 (32.0%) | 0.32 (0.38) | ||
| ⩾2.0 | 11 (13.3%) | 0.52 (0.49) | 7 (14.0%) | 0.31 (0.13) | ||
| Military flying | ||||||
| No | 25 (30.1%) | 0.31 (0.26) | 0.11 | 50 (100%) | 0.32 (0.32) | – |
| Yes | 58 (69.9%) | 0.43 (0.36) | 0 | – | – | |
*p Value (likelihood ratio χ2 statistic) from separate univariate negative binomial regression models treating smoking status (ever vs never smokers) and military flying (yes vs no) as categorical variables, and age, pack-years and cumulative red bone marrow x ray dose score as continuous variables (p value for the linear term unless otherwise noted); †p value for the quadratic term. p = 0.38 for the linear term only; ‡includes one current smoker with 1.75 pack-years; §pack-years coded as 0 for never smokers.
SD, standard deviation.