Appendix 6.
Regression analysis separately for each potential baseline predictor with bothersomeness at one-year follow-up as the dependent variable.
Variable R² Co-efficient (95% CI)
p value Demographics
Age .02 0.98 (0.96 to 1.00) .03
Sex .00 0.97 (0.52 to 1.80) .92
Pain Characteristics
Baseline pain intensity (NRS) .07 1.46 (1.21 to 1.77) <.001 Baseline disability (RMDQ) .01 1.07 (1.00 to 1.15) .05 Duration of CLBP (months)4 .00 1.00 (1.00 to 1.00) .28 100% of pain in low back
region
.01 1.75 (0.94 to 3.23) .08
Aggravated by activity (StEP)1 .01 2.36 (0.80 to 6.97) .12 Aggravated by position (StEP)1 .01 1.63 (0.69 to 3.86) .27 Baseline bothersomeness .05 3.34 (1.71 to 6.52) <.001
Interventions
No intervention4 .00 1.53 (0.73 to 3.22) .26
Manual therapy4 .00 0.68 (0.35 to 1.34) .27
Exercise4 .03 0.37 (0.18 to 0.72) .004
Psychological4 .00 1.03 (0.28 to 3.79) .96
Pharmacological4 .00 1.35 (0.62 to 2.97) .45
Injection4 .03 3.68 (1.51 to 8.96) .004
Surgery4 .00 1.81 (0.45 to 7.25) .40
Acupuncture4 .02 3.36 (1.11 to 10.20) .03
Multidisciplinary rehabilitation4
Collinear
Variable R² Co-efficient (95% CI)
p value Pain Sensitivity
Pain sensitivity clusters
Cluster 1 .01 Reference .39
Cluster 2 0.92 (0.48 to 1.77) .80
Cluster 3 0.48 (0.17 to 1.40) .18
Sensory testing PCs12
PC1 .00 1.01 (0.98 to 1.04) .56
PC2 .00 1.00 (1.00 to 1.00) .49
PC3 .00 1.08 (0.88 to 1.33) .46
PC4 .02 0.96 (0.92 to 0.99) .01
PC5 .00 0.98 (0.93 to 1.02) .28
PPT (wrist) .00 1.00 (1.00 to 1.00) .51
PPT (lumbar) .00 1.00 (1.00 to 1.00) .32
CPT (wrist) .00 1.01 (0.97 to 1.05) .64
CPT (lumbar) .00 1.01 (0.99 to 1.04) .34
HPT (wrist) .00 1.00 (0.92 to 1.08) .94
HPT (lumbar) .00 0.98 (0.90 to 1.05) .52
MDT (wrist)3 .01 1.04 (0.97 to 1.11) .24
MDT (lumbar)3 .04 1.05 (1.02 to 1.08) .002
Two-point discrimination .00 0.98 (0.85 to 1.14) .82 Baseline CPM pressure11 .00 1.00 (1.00 to 1.00) .94
CPM change score11 .00 1.02 (0.79 to 1.32) .88 Temporal summation1 .00 1.38 (0.66 to 2.88) .39 Pinprick hyperalgesia .01 0.61 (0.28 to 1.31) .20
Movement Dimension Pain response
following repeated movement subgroups
NIP .00 Reference .99
FB 1.04 (0.51 to 2.11) .92
BB 0.97 (0.33 to 2.82) .96
FB& BB 0.87 (0.33 to 2.33) .79
Forward bending time1 .02 1.05 (1.01 to 1.08) .01 Backward bending time1 .01 1.03 (0.98 to 1.07) .24 Communicative behaviours,
forward bending
.01 1.32 (0.84 to 2.06) .22
Protective behaviours, forward bending
.00 1.02 (0.94 to 1.11) .58
Communicative behaviours, backward bending
.01 1.98 (0.84
to
4.67) .12 Protective behaviours,
backward bending
.04 1.20 (1.07 to 1.35) .002
Variable R² Co-efficient (95% CI)
p value Psychological Dimension
Psychological clusters
Cluster 1 .02 Reference .69
Cluster 2 1.82 (0.79 to 4.21) .16
Cluster 3 2.67 (0.99 to 7.22) .05
DASS depression .00 1.02 (0.99 to 1.05) .26
DASS anxiety .00 1.01 (0.97 to 1.05) .78
DASS stress .01 1.03 (1.00 to 1.06) .09
DASS combined total (also PC1)
.01 1.01 (1.00 to 1.02) .22
FABQ-W8 .01 1.02 (1.00 to 1.05) .07
FABQ-PA .00 0.99 (0.94 to 1.05) .82
PCS rumination1 .02 1.09 (1.02 to 1.16) .01
PCS magnification1 .00 1.04 (0.93 to 1.15) .51
PCS helplessness1 .02 1.06 (1.00 to 1.11) .04
PCS total1 .02 1.03 (1.00 to 1.05) .03
PSEQ .03 0.97 (0.94 to 0.99) .01
Psychological PC21 .02 1.31 (1.04 to 1.65) .02
AEQ
classification2
Adaptive .01 Reference .51
Distress endurance
1.72 (0.76 to 3.88) .19 Eustress
endurance
1.35 (0.60 to 3.02) .46 Fear-
avoidance
0.88 (0.26 to 2.98) .83
TSS1 .03 1.32 (1.10 to 1.59) .003
BES .02 1.42 (1.05 to 1.93) .02
Psychological PC3 .04 1.50 (1.15 to 1.94) .002
CPAQ-8 pain willingness .00 1.02 (0.95 to 1.08) .63 CPAQ-8 activity engagement .00 0.98 (0.92 to 1.05) .61 CPAQ-8 total (also PC4) .00 1.00 (0.96 to 1.04) .98
MAAS3 .00 0.85 (0.60 to 1.21) .38
Perceived risk of persistent pain1
.00 1.11 (0.91 to 1.35) .31
FreBAQ .00 1.01 (0.96 to 1.06) .70
Variable R² Co-efficient (95% CI)
p value Health Dimension
Total diagnosed comorbidities .01 0.89 (0.75 to 1.05) .17 Musculoskeletal comorbidities .00 0.74 (0.40 to 1.36) .33 Functional pain comorbidities .00 1.01 (0.70 to 1.45) .97 Other diagnosed
comorbidities
.01 0.80 (0.62 to 1.04) .09
Other comorbid symptoms .00 0.94 (0.81 to 1.09) .41 Number of body chart squares
filled-in
.03 1.03 (1.01 to 1.06) .01
Manchester CWP classification .01 1.49 (0.78 to 2.85) .22 Baseline COOP/WONCA
overall health rating
.03 1.54 (1.12 to 2.13) .01
BMI .01 0.95 (0.89 to 1.01) .12
Variable R² Co-efficient (95% CI)
p value
Lifestyle and Social Dimensions
PSQI9 .01 0.95 (0.88 to 1.03) .19
Smoking status
Non-smoker .02 Reference .06
Ex-smoker 0.55 (0.25 to 1.17) .12
Smoker 1.91 (0.79 to 4.64) .15
Moderate and vigourous physical activity per week5
.00 1.00 (1.00 to 1.00) .53
Years in education10 .03 0.88 (0.80 to 0.97) .01 Compensation status5 .00 1.43 (0.65 to 3.16) .37
Currently at work .01 0.62 (0.31 to 1.21) .16
Manual v.
sedentary occupation12
Not working .03 Reference .01
Sedentary 0.30 (0.12 to 0.75) .01
Manual 0.63 (0.23 to 1.74) .38
Job satisfaction13 .01 0.92 (0.82 to 1.04) .18
Life events .01 1.14 (0.92 to 1.41) .23
MPI social support7 .01 1.19 (0.96 to 1.48) .12
MPI punishing6 .01 1.18 (0.94 to 1.47) .15
MPI solicitous6 .01 1.19 (0.95 to 1.49) .13
MPI distracting6 .01 1.17 (0.91 to 1.49) .22
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 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
