Neuromuscular training with injury prevention counselling to decrease the risk of acute musculoskeletal injury in young men during military service: a population-based, randomised study

Table 4 Incidence per 1,000 person-days of different types of musculoskeletal injuries and hazard ratios for changes in incidence between the intervention and control companies during prestudy and study periods in moderately to highly fit conscripts^a,b

Variable	Company	Prestudy period (n= 333/291)^c		Study period (n= 315/298)^c		Age-adjusted HR (95% CI)	HR adjusted model^d (95% CI)
		Number	Incidence	Number	Incidence
Acute injuries, all	Int	160	3.05	85	1.88	0.77 (0.49 to 1.22)	0.74 (0.46 to 1.18)
	Ctrl	88	2.31	86	2.00
Lower extremity	Int	82	1.56	56	1.24	0.88 (0.51 to 1.51)	0.82 (0.46 to 1.45)
	Ctrl	52	1.37	55	1.28
Knee	Int	27	0.51	26	0.57	1.18 (0.51 to 2.75)	1.22 (0.49 to 3.01)
	Ctrl	22	0.58	21	0.49
Ankle	Int	17	0.32	12	0.26	0.53 (0.18 to 1.51)	0.50 (0.17 to 1.46)
	Ctrl	12	0.32	20	0.46
Upper extremity	Int	37	0.70	16	0.35	0.43 (0.17 to 1.09)	0.37 (0.14 to 0.99)
	Ctrl	15	0.39	20	0.46
Total number of off-duty days^e	Int	600	11.4	339	7.5	0.46 (0.22 to 0.97)	0.43 (0.19 to 0.97)^f
	Ctrl	218	5.7	424	9.8
Discharged from military service^g	Int	10	0.19	19	0.42	1.06 (0.34 to 3.27)	1.13 (0.36 to 3.58)^f
	Ctrl	8	0.21	20	0.46
		Follow-up days
	Int	52,542		45,316
	Ctrl	38,052		43,054

^aHR, hazard ratio; 95% CI, 95% confidence interval; Int, intervention company; Ctrl, control company. HRs were calculated by using the Cox proportional hazard model if not otherwise mentioned. Statistical significance level was set at P < 0.05. HRs are based on the interaction term of each study group (intervention or control), and study period was entered into the model to analyse the difference in the change in incidence between the groups. ^bTwo highest tertiles of conscripts according to physical fitness (Conscript's physical fitness index > 14.04 points); ^cnumber of conscripts in the intervention and control companies per study period; ^dadjusted for age, urbanisation level of the home residence, smoking, alcohol intake, earlier musculoskeletal symptoms, orthopaedic surgeries, chronic disabilities due to earlier musculoskeletal injuries, school success, previous physical activity and waist circumference (n = 10 adjusting variables); ^ebecause of acute injuries, rate ratio was obtained from negative binomial model; ^fnot adjusted for waist circumference, since 15 discharged individuals had missing information; ^gafter the 2-week run-in period.

ISSN: 1741-7015