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Table 4 ITT and CACE model estimates of treatment difference at 3, 6 and 12 months

From: Treatment compliance and effectiveness of a cognitive behavioural intervention for low back pain: a complier average causal effect approach to the BeST data set

Ā 

ITT covariate model

Standardised effect at 12 monthsā€ 

CACE covariate model

Standardised effect at 12 monthsā€”

Ā 

Mean treatment difference (95% CI)*

p value

Mean treatment difference (95% CI)ā€ 

p value

Roland Morris Questionnaire (points)

3Ā months

1.1 (0.39, 1.77)

0.002

..

1.1 (0.04, 2.22)

0.042

..

6Ā months

1.4 (0.72, 2.16)

<0.001

..

1.9 (0.87, 2.98)

<0.001

..

12Ā months

1.3 (0.55, 2.07)

0.001

0.31

1.6 (0.51, 2.74)

0.004

0.43

Modified Von Korff disability (%)

3Ā months

4.6 (0.75, 8.52)

0.029

..

5.4 (-0.38, 11.15)

0.067

..

6Ā months

8.3 (4.32, 12.35)

<0.001

..

11.1 (5.30, 16.83)

<0.001

..

12Ā months

8.6 (4.58, 12.64)

<0.001

0.42

12.1 (6.07, 18.17)

<0.001

0.60

Modified Von Korff pain (%)

3Ā months

6.9 (3.53, 10.29)

<0.001

..

8.8 (3.84, 13.82)

0.001

..

6Ā months

8.2 (4.48, 11.97)

<0.001

..

11.2 (5.89, 16.61)

<0.001

..

12Ā months

7.00 (3.26, 10.74)

<0.001

0.37

10.4 (4.64, 16.10)

<0.001

0.60

EQ-5D

3Ā months

0.08 (0.033, 0.117)

<0.001

..

0.09 (0.020, 0.161)

0.012

..

6Ā months

0.04 (-0.007, 0.080)

0.098

..

0.06 (-0.011, 0.121)

0.102

..

12Ā months

0.05 (0.010, 0.097)

0.015

0.13

0.07 (0.008, 0.141)

0.029

0.36

  1. *Based on a linear regression model adjusted for age, sex, severity of back pain, centre and baseline value.
  2. ā€ Based on a latent class model with outcome adjusted for age, sex, severity of back pain, centre and baseline value and compliance adjusted for age and baseline modified Von Korff pain score.
  3. ā€”Standardised effect size is the unadjusted mean difference (standardised mean difference) between the groups divided by the pooled SD at baseline.