Table 4

Relative risk reduction and numbers-needed-to-treat analyses for non-contact anterior cruciate ligament injury

Reference	Non-contact ACL injury in group	Female athletes per group	Non-contact ACL incidence rates*	RRR (95% CI)	NNT to benefit (NNTB)†, NNT to harm (NNTH)‡ (95% CI)
Hewett et al
Control	5	463	0.11	100	93 NNTB
Intervention	0	366	0	(NA)	(50 NNTB to 723)
Myklebust et al
Control	18	942	0.09	38.8	135 NNTB
Intervention (first year only)	10	855	0.03	(−0.9, 62.9)	(53 NNTB to ∞ to 255 NNTH)
Mandelbaum et al
Control	67	3818	0.24	81.9	70 NNTB
Intervention (first and second year total)	6	1885	0.04	(60.9, 91.6)	(52 NNTB to 106)
Olsen et al
Control	5	778	0.06	80.7	193 NNTB
Intervention	1	808	0.01	(−15.3, 96.8)	(89 NNTB to ∞ to 1079 NNTH)
Petersen et al
Control	5	142	0.21	100	28 NNTB
Intervention	0	134	0	(NA)	(16 NNTB to 205)
Pfeiffer et al
Control	3	862	0.04	−49.4	582 NNTH
Intervention	3	577	0.08	(−233.4, 33.1)	(188 NNTB to ∞ to 114 NNTH)
Gilchrist et al
Control	10	583	0.18	86.3	68 NNTB
Intervention	2	852	0.06	(51.5, 96.1)	(39 NNTB to 265)
Steffen et al
Control	2	947	0.03	−32.4	1462 NNTH
Intervention	3	1073	0.05	(−171.1, 35.4)	(277 NNTB to ∞ to 201 NNTH)
Kiani et al
Control	5	729	0.08	100	146 NNTB
Intervention	0	777	0	(NA)	(78 NNTB to 1153)
LaBella et al
Control	6	755	0.48	65.9	191 NNTB
Intervention	2	737	0.10	(−13.5, 89.7)	(80 NNTB to ∞ to 470 NNTH)
Total
Control	126	10019	0.14	73.4	108 NNTB
Intervention	27	8064	0.04	(62.5, 81.1)	(86 NNTB to 150)

*Relative incidence rate (per 1000 A*h).
†NNT to benefit (NNTB) represents a beneficial preventive effect of the intervention.
‡NNT to harm (NNTH) indicates harmful effect of the intervention. Infinity (∞) means no beneficial or harmful effects.