Player characteristics, exposure, injury, cost data and cost differences between the ‘11+ Kids’ intervention and control groups
| Outcome | Intervention | Control | Total |
| No of players (N) | 614 | 388 | 1002 |
| No of girls (% of total) | 45 (7.3) | 29 (7.5) | 74 (7.4) |
| Teams (N) | 37 | 25 | 62 |
| Age (years) | 11.0 (1.2) | 10.6 (1.1) | 10.9 (1.2) |
| Body height (m) | 1.46 (0.09) | 1.44 (0.08) | 1.45 (0.08) |
| Body mass (kg) | 37.2 (7.7) | 36.1 (7.0) | 36.8 (7.5) |
| BMI (kg/m2) | 17.2 (2.6) | 17.2 (2.3) | 17.2 (2.5) |
| Exposure time (hours) | 43 777 | 32 596 | 76 373 |
| Total No of injuries (N) | 42 | 57 | 99 |
| Medically treated injuries (N) | 20 | 33 | 53 |
| Total No of injured players (N) | 20 | 32 | 52 |
| No of players with one injury (N) | 20 | 31 | 51 |
| No of players with two injuries (N) | 0 | 1 | 1 |
| No of injuries by time loss (N) (% of total) | |||
| No time loss | 1 (5.0) | 3 (9.1) | 4 (7.5) |
| 1–3 days | 0 (0) | 3 (9.1) | 3 (5.7) |
| 4–7 days | 6 (30.0) | 1 (3.0) | 7 (13.2) |
| 8–28 days | 10 (50.0) | 14 (42.4) | 24 (45.3) |
| >28 days | 3 (15.0) | 12 (36.4) | 15 (28.3) |
| Sum of days lost to injury (days) | 355 | 910 | 1265 |
| Mean lay-off time (95% CI) (days) | 17.7 (11.9, 23.6) | 27.6 (17.9, 37.3) | 23.9 (17.5, 30.3) |
| Comparison between groups | Intervention | Control | |
| IID and HR (95% CI) | IID 0.96 (0.71, 1.30) | IID 1.75 (1.35, 2.27) | HR 0.50 (0.29, 0.86) |
| Costs per player* (95% CI) (CHF) | 16.28 (9.80, 23.94)† | 39.40 (22.96, 58.06) | CD −23.12 (−39.09,–7.14) |
| Costs per injured player (95% CI) (CHF) | 238.02 (154.61, 335.68)† | 268.20 (179.11, 371.49) | CD −30.19 (−166.13, 105.75) |
| Costs per 1000 hours of exposure (95% CI) (CHF) | 228.34 (137.45, 335.77)† | 469.00 (273.30, 691.11) | CD −240.66 (−406.89,–74.32) |
*Per player season.
†Taking into account CHF4.02 intervention costs per player in the study setting.
CD, cost difference between the ‘11+ Kids’ intervention and control groups in Swiss Francs; CHF, Swiss Francs; HR, Hazard R atio between the ‘11+ Kids’ intervention and control groups; IID, injury incidence density per 1000 hours of exposure.