Appendix 4.
Regression analysis separately for each potential baseline predictor with disability at one- year follow-up as the dependent variable, adjusting for baseline disability (n=266).
Variable Co-efficient (95% CI)
p value Baseline disability (RMDQ) 0.59 (0.47 to 0.72) <.001
Demographics
Age 0.03 (-0.01 to 0.07) .13
Sex 0.24 (-0.80 to 1.28) .65
Pain Characteristics
Baseline pain intensity (NRS) 0.16 (-0.13 to 0.44) .28 Duration of CLBP (months)4 0.00 (0.00 to 0.00) .49 100% of pain in low back region 0.69 (-0.34 to 1.71) .19 Aggravated by activity (StEP)1 0.90 (-0.56 to 2.35) .23 Aggravated by position (StEP)1 0.78 (-0.52 to 2.09) .24 Baseline bothersomeness 0.66 (-0.39 to 1.70) .22
Interventions
No intervention4 0.50 (-0.84 to 1.84) .46
Manual therapy4 -0.11 (-1.19 to 0.98) .84
Exercise4 -0.10 (-3.10 to -1.10) <.001
Psychological4 0.04 (-2.18 to 2.27) .97
Pharmacological4 1.32 (-0.07 to 2.71) .06
Injection4 1.94 (0.13 to 3.75) .04
Surgery4 1.15 (-1.60 to 3.90) .41
Acupuncture4 1.78 (-0.50 to 4.05) .13
Multidisciplinary rehabilitation4 -0.92 (-6.88 to 5.04) .76
Variable Co-efficient (95% CI)
p value Pain Sensitivity
Pain sensitivity clusters
Cluster 1 Reference .25
Cluster 2 -0.96 (-2.10 to 0.18) .10 Cluster 3 -0.52 (-2.08 to 1.04) .52
Sensory testing PCs12
PC1 0.03 (-0.02 to 0.08) .20
PC2 0.00 (-0.00 to 0.00) .56
PC3 -0.13 (-0.50 to 0.24) .48
PC4 0.06 (-0.13 to -0.00) .05
PC5 -0.04 (-0.11 to 0.03) .29
PPT (wrist) 0.00 (0.00 to 0.00) .90
PPT (lumbar) 0.00 (0.00 to 0.00) .86
CPT (wrist) 0.03 (-0.04 to 0.10) .36
CPT (lumbar) 0.05 (0.00 to 0.10) .05
HPT (wrist) 0.03 (-0.10 to 0.16) .66
HPT (lumbar) 0.03 (-0.10 to 0.16) .69
MDT (wrist)3 0.05 (-0.07 to 0.17) .42
MDT (lumbar)3 0.08 (0.02 to 0.14) .01
Two-point discrimination 0.01 (-0.23 to 0.26) .90
Baseline CPM presure11 0.00 (0.00 to 0.00) .84
CPM change score11 -0.27 (-0.70 to 0.17) .22
Temporal summation1 0.29 (-1.01 to 1.58) .66
Pinprick hyperalgesia 0.03 (-1.38 to 1.44) .96
Movement Dimension Pain response following
repeated movement subgroups
NIP Reference .50
FB -0.19 (-1.43 to 1.04) .76
BB -1.37 (-3.15 to 0.42) .13
FB&BB -0.46 (-2.07 to
1.14) .57 Forward bending time1 0.13 (0.06 to 0.19) <.001 Backward bending time1 0.01 (-0.08 to 0.09) .89 Communicative behaviours, forward
bending
0.21 (-0.70 to 1.12) .65 Protective behaviours, forward
bending
0.05 (-0.09 to 0.19) .48 Communicative behaviours,
backward bending
0.87 (-0.96 to 2.69) .35 Protective behaviours, backward
bending
0.22 (0.01 to 0.43) .04
Variable Co-efficient (95% CI)
p value Psychological Dimension
Psychological clusters
Cluster 1 Reference .02
Cluster 2 1.06 (-0.19 to 2.30) .10 Cluster 3 2.53 (0.80 to 4.26) .004
DASS depression 0.06 (0.00 to 0.12) .04
DASS anxiety 0.02 (-0.05 to 0.09) .60
DASS stress 0.02 (-0.04 to 0.08) .50 DASS combined total (also PC1) 0.02 (-0.01 to 0.04) .19
FABQ-W8 0.02 (-0.02 to 0.06) .36
FABQ-PA 0.08 (-0.01 to 0.17) .07
PCS rumination1 0.12 (0.01 to 0.23) .04
PCS magnification1 0.16 (-0.02 to 0.35) .08
PCS helplessness1 0.14 (0.05 to 0.23) .003
PCS total1 0.06 (0.01 to 0.10) .01
PSEQ -0.06 (-0.11 to -0.01) .03
Psychological PC21 0.70 (0.27 to 1.13) .002
AEQ
classification2
Adaptive Reference .09
Distress endurance 1.47 (0.03 to 2.91) .04 Eustress endurance -0.17 (-1.47 to 1.13) .79 Fear-avoidance 0.07 (-1.77 to 1.91) .94
TSS1 0.73 (0.42 to 1.03) <.001
BES 0.37 (-0.13 to 0.86) .15
Psychological PC3 0.85 (0.42 to 1.28) <.001
CPAQ-8 pain willingness 0.04 (-0.07 to 0.14) .51 CPAQ-8 activity engagement -0.01 (-0.12 to 0.10) .84 CPAQ-8 total (also PC4) 0.01 (-0.06 to 0.08) .78
MAAS3 -0.25 (-0.85 to 0.35) .41
Perceived risk of persistent pain1 0.26 (-0.05 to 0.58) .10
FreBAQ 0.00 (-0.08 to 0.08) .98
Health Dimension
Total diagnosed comorbidities 0.20 (-0.05 to 0.45) .12 Musculoskeletal comorbidities 0.38 (-0.59 to 1.34) .44 Functional pain comorbidities 0.23 (-0.39 to 0.85)) .46 Other diagnosed comorbidities 0.29 (-0.08 to 0.66) .12 Other comorbid symptoms 0.05 (-0.20 to 0.29) .72 Number of body chart squares
filled-in
0.02 (-0.02 to 0.07) .32 Manchester CWP classification 0.77 (-0.41 to 1.96) .20 Baseline COOP/WONCA overall
health rating
0.59 (0.03 to 1.15) .04
BMI 0.09 (-0.01 to 0.20) .08
Variable Co-efficient (95% CI) p
value Lifestyle and Social Dimensions
PSQI9 -0.02 (-0.15 to 0.10) .71
Smoking status
Non-smoker Reference
Ex-smoker 0.16 (-0.38 to 0.70) .56
Smoker 0.57 (-0.25 to 1.40) .17
Moderate and vigourous physical activity per week5
0.00 (0.00 to 0.00) .52 Years in education10 -0.17 (-0.32 to -0.03) .02
Compensation status5 0.67 (-0.74 to 2.07) .35
Currently at work -1.68 (-2.88 to -0.47) .01
Manual v. sedentary occupation12
Not working Reference
Sedentary -0.42 (-2.16 to 1.33) .64
Manual 0.91 (-1.05 to 2.87) .36
Job satisfaction13 -0.01 (-0.21 to 0.20) .95
Life events 0.02 (-0.32 to 0.37) .90
MPI social support7 0.11 (-0.22 to 0.44) .52
MPI punishing6 0.43 (0.03 to 0.82) .04
MPI solicitous6 0.07 (-0.30 to 0.44) .71
MPI distracting6 0.04 (-0.37 to 0.44) .86
Note. 1 missing in one case, 2 missing in two cases, 3 missing in three cases, 4 missing in four cases, 5 missing in six cases, 6 missing in eight cases, 7 missing in nine cases, 8 missing in 10 cases, 9 missing in 11 cases, 10 missing in 13 cases, 11 missing in 14 cases, 12 missing in 16 cases, 13 missing in 39 cases
NRS – numeric rating scale, RMDQ – Roland Morris Disability questionnaire, StEP – Standardised Evaluation of Pain, PC – principal component, Sensory testing PC1 - principal component score derived from thermal pain sensitivity, PC2 - principal component score derived from pressure pain sensitivity, PC3 - principal component score derived from conditioned pain modulation change score, temporal summation and pinprick hyperalgesia, PC4 - principal component score derived from mechanical detection thresholds, PC5 - principal component score derived from two-point discrimination and vibration perception, PPT – Pressure pain threshold, CPT – cold pain threshold, HPT - Heat pain threshold, MDT – Mechanical detection threshold, CPM – Conditioned pain
modulation, NIP – No increased pain following repeated bending, FB – Pain increased
following repeated forward bending only, BB – Pain increased following repeated back bending only, FB&BB – Pain increased following repeated forward and backward bending, DASS – Depression Anxiety Stress scales, FABQ-W – Fear-Avoidance Beliefs questionnaire (Work subscale), FABQ-PA - Fear-Avoidance Beliefs questionnaire (Physical activity subscale), PCS – Pain Catastrophising scale, PSEQ – Pain Self-efficacy questionnaire, Psychological PC2 – principal component score derived from FABQ-PA, PCS and PSEQ scores, AEQ – Avoidance Endurance questionnaire, TSS – Thought Suppression subscale, BES – Behavioural Endurance subscale, Psychological PC3 - mean of TSS and BES scores, CPAQ-8 – Chronic Pain Acceptance questionnaire (Short form), MAAS – Mindful Attention Awareness scale, FreBAQ – Fremantle Back Awareness questionnaire, CWP – Chronic widespread pain, BMI – Body mass index, PSQI – Pittsburgh Sleep Quality index, MPI - Multidimensional Pain Inventory
