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 3 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^a

Variable	Company	Prestudy period (n= 508/436)^b		Study period (n= 501/467)^b		Age-adjusted HR (95% CI)	HR adjusted model^c (95% CI)
		Number	Incidence	Number	Incidence
Acute injuries, all	Int	246	3.16	150	2.14	0.74 (0.52 to 1.06)	0.75 (0.51 to 1.09)
	Ctrl	149	2.73	155	2.44
Lower extremity	Int	136	1.75	90	1.28	0.84 (0.55 to 1.30)	0.82 (0.52 to 1.31)
	Ctrl	91	1.67	96	1.51
Knee	Int	50	0.64	48	0.68	1.05 (0.55 to 2.00)	1.32 (0.65 to 2.67)
	Ctrl	35	0.64	38	0.60
Ankle	Int	37	0.48	17	0.24	0.38 (0.17 to 0.86)	0.34 (0.15 to 0.78)
	Ctrl	21	0.38	37	0.58
Upper extremity	Int	53	0.68	31	0.44	0.57 (0.28 to 1.16)	0.52 (0.24 to 1.12)
	Ctrl	26	0.48	31	0.49
Total number of off-duty days^d	Int	917	11.8	546	7.8	0.46 (0.26 to 0.83)	0.55 (0.29 to 1.04)
	Ctrl	419	7.7	677	10.7
Discharged from military service^e	Int	34	0.44	42	0.60	0.78 (0.41 to 1.51)	0.81 (0.42 to 1.57)^f
	Ctrl	26	0.48	52	0.82
Follow-up days
	Int	77,871		70,222
	Ctrl	54,620		63,494

^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. ^bNumber of conscripts in the intervention and control companies per study period; ^cadjusted 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, waist circumference and conscript's physical fitness index (n = 11 adjusting variables); ^dbecause of acute injuries, rate ratio was obtained using a negative binomial model; ^eafter the 2-week run-in period; ^fnot adjusted for waist circumference or physical fitness level, since 36 discharged individuals had missing information.

ISSN: 1741-7015