Table 4 Analysis of high and low ODI^a strata (n = 347)

ODI at BL^b

6.3

3.1, 9.5

< 0.001

ODI at BL in two groups: Low ( = < 12) & High (> 12)

 Low

—

—

 High

16

11, 21

< 0.001

SBT category: Low vs. Medium/High (independent variable)

 Low

—

—

 Medium/High

-1.0

-6.4, 4.3

0.7

Type back pain: LBP vs. Referred/Radicular (independent variable)

 LBP

—

—

 Referred/Radicular

0.62

-3.9, 5.1

0.8

Linear change during first 6 months

0.24

-1.7, 2.2

0.8

ODI at BL in two groups: Low ( = < 12) & High (> 12) * Linear change during first 6 months

 High * Linear change during first 6 months

-6.5

-9.4, -3.6

< 0.001

SBT category: Low vs. Medium/High * Linear change during first 6 months

 Medium/High * Linear change during first 6 months

1.5

-1.8, 4.7

0.4

Type back pain: LBP vs. Referred/Radicular * Linear change during first 6 months

 Referred/Radicular * Linear change during first 6 months

-0.26

-3.0, 2.5

0.9

SBT category: Low vs. Medium/High * ODI at BL in two groups: Low ( = < 12) & High (> 12) * Linear change during first 6 months

 Medium/High * High * Linear change during first 6 months

-7.1

-11, -3.2

< 0.001

ODI at BL in two groups: Low ( = < 12) & High (> 12) * Type back pain: LBP vs. Referred/Radicular * Linear change during first 6 months

 High * Referred/Radicular * Linear change during first 6 months

1.2

-2.3, 4.6

0.5

Quadratic change during first 6 months

-0.07

-0.37, 0.22

0.6

ODI at BL in two groups: Low ( = < 12) & High (> 12) * Quadratic change during first 6 months

 High * Quadratic change during first 6 months

0.79

0.36, 1.2

< 0.001

SBT category: Low vs. Medium/High * Quadratic change during first 6 months

 Medium/High * Quadratic change during first 6 months

-0.21

-0.71, 0.28

0.4

Type back pain: LBP vs. Referred/Radicular * Quadratic change during first 6 months

 Referred/Radicular * Quadratic change during first 6 months

0.03

-0.39, 0.44

> 0.9

SBT category: Low vs. Medium/High * ODI at BL in two groups: Low ( = < 12) & High (> 12) * Quadratic change during first 6 months

 Medium/High * High * Quadratic change during first 6 months

0.95

0.35, 1.5

0.002

ODI at BL in two groups: Low ( = < 12) & High (> 12) * Type back pain: LBP vs. Referred/Radicular * Quadratic change during first 6 months

 High * Referred/Radicular * Quadratic change during first 6 months

-0.22

-0.74, 0.31

0.4

Difference between ODI at 6 and 12 months

-0.89

-4.3, 2.5

0.6

ODI at BL in two groups: Low ( = < 12) & High (> 12) * Difference between ODI at 6 and 12 months

 High * Difference between ODI at 6 and 12 months

-4.2

-9.1, 0.77

0.10

SBT category: Low vs. Medium/High * Difference between ODI at 6 and 12 months

 Medium/High * Difference between ODI at 6 and 12 months

1.1

-4.6, 6.8

0.7

Type back pain: LBP vs. Referred/Radicular * Difference between ODI at 6 and 12 months

 Referred/Radicular * Difference between ODI at 6 and 12 months

1.6

-3.2, 6.3

0.5

SBT category: Low vs. Medium/High * ODI at BL in two groups: Low ( = < 12) & High (> 12) * Difference between ODI at 6 and 12 months

 Medium/High * High * Difference between ODI at 6 and 12 months

2.9

-3.8, 9.7

0.4

ODI at BL in two groups: Low ( = < 12) & High (> 12) * Type back pain: LBP vs. Referred/Radicular * Difference between ODI at 6 and 12 months

 High * Referred/Radicular * Difference between ODI at 6 and 12 months

-1.6

-7.6, 4.4

0.6

 SBT category: Low vs. Medium/High * ODI at BL in two groups: Low ( = < 12) & High (> 12)

 Medium/High * High

9.1

2.7, 16

0.006

ODI at BL in two groups: Low ( = < 12) & High (> 12) * Type back pain: LBP vs. Referred/Radicular

 High * Referred/Radicular

1.6

-4.0, 7.3

0.6

random intercept (sd)

7.8

correlation random effects

-0.50

random linear slope (sd)

1.2

residuals (sd)

8.1

AIC

10,189

BIC

10,46