Demographic data
| Variable | All (n=373) | Group A (n=146) | Group B (n=227) | P value |
| Age (years) | ||||
| Median (range) | 20 (14–30) | 19 (14–30) | 20 (14–30) | 0.15 |
| Sex | ||||
| Male | 344 (92.2%) | 136 (93.1%) | 208 (91.6%) | 0.59 |
| Female | 29 (7.7%) | 10 (6.9%) | 19 (8.4%) | |
| Smoking | ||||
| Yes | 37 (9.9%) | 17 (11.6%) | 20 (8.8%) | 0.37 |
| No | 336 (90.1%) | 129 (88.4%) | 207 (91.2%) | |
| Affected side | ||||
| Right | 153 (41.0%) | 63 (43.2%) | 90 (39.6%) | 0.5 |
| Left | 220 (59.0%) | 83 (56.8%) | 137 (60.4%) |