Table 1 Relative risk (RR) and 95 % confidence interval (CI) for new-onset or recurrent LBP among young male soldiers (18–21 years), by severity of disease at recruitment for the follow up period and per 1 year

Category 1 - Low Back Pain rates in a healthy population of new recruits

AU (5,914)

49 (0.083 %)

1.6 (1.2–2.1)

<.001

MU (52,330)

240 (0.046 %)

0.9 (0.9–1.3)

NS

CU (101,051)

510 (0.050 %)

1

Total category 1

159,295

799 (0.050 %)

Category 2 - LBP rates in a population with minor clinical findings

AU (1,350)

26 (1.93 %)

2.6 (1.6–3.6)

<.001

MU (12,470)

64 (0.51 %)

0.7 (0.5–0.9)

<.001

CU (22,001)

165 (0.75 %)

1

NS

Total category 2

35281

255 (0.71 %)

Category 3 - LBP rates in a population with positive medical history and no significant radiology findings

AU (457)

22 (4.81 %)

2.4 (1.4–3.5)

<.001

MU (3,213)

54 (1.68 %)

0.9 (0.6–1.25)

NS

CU (3,031)

60 (1.98 %)

1

Total category 3

6701

136 (2.03 %)

Category 4 - LBP rates in a population with positive medical history and minimal radiologic findings

AU (381)

43 (11.29 %)

2.2 (1.5–2.8)

<.001

MU (1,749)

74 (4.23 %)

0.8 (0.6–1.1)

NS

CU (1,459)

76 (5.21 %)

1

Total category 4

3589

193 (5.38 %)