Background
Methods
Study design and participants
Study procedure
Measurement
Statistical analyses
Identification of pain trajectories
Identifying possible predictors
Missing data and evaluation of loss to follow-up
Results
Study population
Whole sample | No follow-up | Follow-up | p value | |
---|---|---|---|---|
N | 1377 | 260 | 1117 | |
Gender (female) | 58.7 | 53.1 | 60.0 | 0.042 |
Age, mean (SD) | 47.0 (13.5) | 45.0 (13.6) | 47.5 (13.5) | 0.008 |
Education (high vocational/ university) | 60.4 | 57.3 | 61.1 | 0.261 |
Radiating pain into the leg | 39.9 | 41.9 | 39.4 | 0.453 |
Radiating pins and needles | 27.0 | 26.5 | 27.1 | 0.848 |
Time since complaints 1st started | 11.4 (12.0) | 11.2 (11.7) | 11.4 (12.1) | 0.792 |
Duration of current episode (years) | 2.1 (4.8) | 2.4 (4.8) | 2.1 (4.8) | 0.423 |
SF-6D baseline score | 0.74 (0.11) | 0.75 (0.11) | 0.74 (0.11) | 0.691 |
ODI baseline score | 23.4 (15.7) | 24.6 (16.6) | 23.2 (15.5) | 0.265 |
Concomitant complaints present | 53.8 | 54.2 | 53.7 | 0.881 |
Pain avoidant | 70.9 | 72.8 | 70.5 | 0.490 |
Previous specialist visit | 62.1 | 57.3 | 63.2 | 0.078 |
Previous visit neurologist | 22.5 | 25.0 | 21.9 | 0.287 |
Previous visit orthopaedic surgeon | 21.2 | 23.1 | 20.8 | 0.413 |
Previous visit rehabilitation | 4.9 | 6.2 | 4.7 | 0.317 |
Previous visit pain clinic | 7.5 | 6.5 | 7.7 | 0.522 |
Medication (categorical)* | 0.477 | |||
None (ref.) | 32.8 | 28.8 | 33.8 | |
Rarely | 24.5 | 25.0 | 24.4 | 0.327 |
Regularly not daily | 28.2 | 30.8 | 27.7 | 0.139 |
Daily | 14.5 | 15.4 | 14.2 | 0.280 |
Previous physiotherapy* | 0.987 | |||
Treated no effect (ref.) | 64.6 | 65.0 | 64.5 | |
Treated effect | 6.6 | 6.5 | 6.6 | 0.939 |
Not treated | 28.8 | 28.5 | 28.9 | 0.875 |
Previous manual therapy* | 0.899 | |||
Treated no effect (ref.) | 28.8 | 29.2 | 28.7 | |
Treated effect | 6.4 | 5.8 | 6.5 | 0.649 |
Not treated | 64.8 | 65.0 | 64.7 | 0.934 |
Previous chiropractic* | 0.034 | |||
Treated no effect (ref.) | 13.6 | 18.5 | 12.4 | |
Treated effect | 2.6 | 3.5 | 2.8 | 0.136 |
Not treated | 83.8 | 79.6 | 84.4 | 0.013 |
Previous medication* | 0.735 | |||
Treated no effect (ref.) | 19.5 | 18.5 | 19.7 | |
Treated effect | 2.8 | 3.5 | 2.7 | 0.440 |
Tot treated | 77.7 | 78.1 | 77.6 | 0.691 |
Previous pain clinic* | 0.046 | |||
Treated no effect (ref.) | 6.0 | 3.8 | 6.5 | |
Treated effect | 0.9 | 1.9 | 0.6 | 0.015 |
Not treated | 93.1 | 94.2 | 92.8 | 0.114 |
Previous surgery* | 0.333 | |||
Treated no effect (ref.) | 1.7 | 1.9 | 1.7 | |
Treated effect | 2.0 | 0.8 | 2.2 | 0.181 |
Tot treated | 96.3 | 97.3 | 96.1 | 0.829 |
Previous other treatment* | 0.789 | |||
Treated no effect (ref.) | 16.6 | 15.8 | 16.8 | |
Treated effect | 4.4 | 3.8 | 4.6 | 0.783 |
Not treated | 78.9 | 80.4 | 78.6 | 0.643 |
Work status* | 0.126 | |||
No work (ref.) | 22.3 | 22.7 | 22.3 | |
Not physical work | 51.6 | 46.5 | 52.6 | 0.423 |
Physical work | 26.1 | 30.8 | 25.1 | 0.331 |
Type of treatment* | 0.064 | |||
Manual Medicine (MM, ref.) | 20.0 | 21.4 | 19.7 | |
Orthomanual Medicine (OMM) | 76.9 | 74.0 | 77.6 | 0.461 |
Both MM and OMM | 1.8 | 1.3 | 1.8 | 0.529 |
Other treatment | 1.3 | 3.1 | 0.9 | 0.024 |
Number of treatment sessions | 3.4 (1.6) | 2.7 (1.6) | 3.5 (1.6) | 0.000 |
McKenzie | 14.2 | 12.6 | 14.6 | 0.434 |
Treated.differently | 4.4 | 5.4 | 4.2 | 0.428 |
Missing data loss to follow-up
Defining subgroups with distinct pain trajectories
Mean NDI and ODI | Class 1 (N = 226, 20%) | Class 2 (N = 578, 52%) | Class 3 (N = 313, 28%) | |||
---|---|---|---|---|---|---|
NRS (SD) | ODI (SD) | NRS (SD) | ODI (SD) | NDI (SD) | ODI (SD) | |
Baseline | 6.9 (1.2) | 24.8 (15.8) | 7.0 (1.1) | 26.4 (15.4) | 3.5 (1.1) | 15.5 (12.7) |
6 weeks | 5.2 (2.2) | 17.6 (14.5) | 4.0 (2.4) | 15.0 (14.4) | 2.5 (1.9) | 8.6 (9.7) |
12 weeks | 5.7 (2.4) | 19.7 (15.6) | 2.9 (2.3) | 11.0 (11.4) | 2.6 (2.2) | 8.7 (10.8) |
18 weeks | 5.7 (2.1) | 18.9 (16.3) | 2.6 (2.2) | 8.1 (10.2) | 2.5 (2.2) | 8.6 (10.4) |
26 weeks | 6.7 (1.2) | 19.4 (14.7) | 1.8 (1.4) | 6.1 (7.3) | 2.2 (1.7) | 8.0 (9.9) |
Baseline-26 wk. change | 0.2 (3%) | 5.4 (22%) | 5.2 (74%) | 20.3 (77%) | 1.3 (37%) | 7.5 (48%) |
Predictors
Predictor variables | LCGA classes of 1117 patients classified | Univariate analyses | |||||
---|---|---|---|---|---|---|---|
Class 1 | Class 2 | Class 3 | Class 2 versus Class 1 | ||||
Not improved | Improved | Low NRS | p value | OR | 95% CI of OR | ||
N | 226 | 578 | 313 | Lower | Upper | ||
Gender (female) | 30.1 | 42.2 | 43.1 | 0.002 | 0.589 | 0.424 | 0.818 |
Age, mean (SD) | 47.6 (14.4) | 47.4 (13.8) | 47.5 (12.2) | 0.845 | 0.999 | 0.988 | 1.010 |
Education (high vocational/ university) | 60.1 | 57.8 | 67.9 | 0.448 | 0.883 | 0.641 | 1.217 |
Radiating pain into the leg | 43.8 | 42.9 | 29.7 | 0.817 | 0.964 | 0.707 | 1.315 |
Radiating pins and needles | 31.0 | 28.0 | 22.7 | 0.407 | 0.932 | 0.788 | 1.102 |
Time since complaints 1st started | 11.6 (12.3) | 11.4 (12.2) | 11.4 (11.6) | 0.855 | 0.999 | 0.986 | 1.011 |
Duration of current episode (years) | 3.2 (6.2) | 1.9 (4.8) | 1.7 (3.6) | 0.003 | 0.958 | 0.932 | 0.986 |
SF-6D baseline score | 0.73 (0.11) | 0.73 (0.10) | 0.78 (0.10) | 0.523 | 0.613 | 0.137 | 2.746 |
ODI baseline score | 24.8 (15.8) | 26.4 (15.4) | 15.5 (12.7) | 0.525 | 1.004 | 0.992 | 1.015 |
Concomitant complaints present | 58.8 | 51.4 | 54.3 | 0.048 | 0.731 | 0.535 | 0.998 |
Pain avoidant | 73.5 | 73.6 | 62.1 | 0.938 | 0.986 | 0.697 | 1.397 |
Previous specialist visit | 52.2 | 64.2 | 69.3 | 0.002 | 1.640 | 1.201 | 2.240 |
Previous visit neurologist | 28.3 | 20.9 | 19.2 | 0.026 | 0.819 | 0.687 | 0.976 |
Previous visit orthopedic surgeon | 28.8 | 19.7 | 16.9 | 0.006 | 0.847 | 0.753 | 0.953 |
Previous visit rehabilitation | 7.1 | 5.0 | 2.2 | 0.255 | 0.912 | 0.779 | 1.068 |
Previous visit pain clinic | 8.8 | 8.5 | 5.4 | 0.866 | 0.991 | 0.888 | 1.105 |
Medication (categorical) | |||||||
None (ref.) | 26.1 | 28.9 | 48.2 | 0.231 | |||
Rarely | 23.9 | 24.6 | 24.3 | 0.738 | 0.929 | 0.603 | 1.430 |
Regularly not daily | 35.4 | 28.4 | 20.8 | 0.113 | 0.724 | 0.486 | 1.080 |
Daily | 14.6 | 18.2 | 6.7 | 0.640 | 1.124 | 0.688 | 1.837 |
Previous physiotherapy | |||||||
Treated no effect (ref.) | 72.6 | 63.5 | 60.4 | 0.037 | |||
Treated effect | 3.1 | 5.9 | 10.5 | 0.069 | 2.170 | 0.943 | 4.998 |
Not treated | 24.3 | 30.6 | 29.1 | 0.044 | 1.438 | 1.009 | 2.049 |
Previous manual therapy | |||||||
Treated no effect (ref.) | 35.4 | 27.3 | 26.5 | 0.066 | |||
Treated effect | 4.9 | 6.7 | 7.3 | 0.112 | 1.795 | 0.873 | 3.692 |
Not treated | 59.7 | 65.9 | 66.1 | 0.036 | 1.429 | 1.024 | 1.994 |
Previous chiropractic | |||||||
Treated no effect (ref.) | 20.4 | 11.1 | 9.3 | 0.003 | |||
Treated
effect | 2.7 | 2.9 | 2.6 | 0.165 | 2.036 | 0.746 | 5.563 |
Not treated | 77.0 | 86.0 | 88.2 | 0.001 | 2.053 | 1.354 | 3.113 |
Previous medication | |||||||
Treated no effect (ref.) | 27.0 | 21.3 | 11.5 | 0.224 | |||
Treated effect | 2.2 | 2.4 | 3.5 | 0.546 | 1.389 | 0.478 | 4.033 |
Tot treated | 70.8 | 76.3 | 85.0 | 0.086 | 1.367 | 0.957 | 1.952 |
Previous pain clinic | |||||||
Treated no effect (ref.) | 10.2 | 6.2 | 4.5 | 0.152 | |||
Treated effect | 0.9 | 0.7 | 0.3 | 0.787 | 1.278 | 0.216 | 7.548 |
Not treated | 88.9 | 93.1 | 95.2 | 0.055 | 1.710 | 0.989 | 2.957 |
Previous surgery | |||||||
Treated no effect (ref.) | 4.4 | 0.9 | 1.3 | 0.010 | |||
Treated effect | 2.2 | 2.1 | 2.6 | 0.040 | 4.800 | 1.074 | 21.447 |
Tot treated | 93.4 | 97.1 | 96.2 | 0.003 | 5.318 | 1.797 | 15.739 |
Previous other treatment | |||||||
Treated no effect (ref.) | 19.5 | 15.6 | 17.3 | 0.369 | |||
Treated effect | 4.0 | 3.5 | 7.0 | 0.851 | 1.086 | 0.457 | 2.581 |
Not treated | 76.5 | 81.0 | 75.7 | 0.171 | 1.323 | 0.886 | 1.974 |
Work status | |||||||
No work (ref.) | 31.4 | 21.1 | 17.9 | 0.005 | |||
Not physical work | 48.2 | 51.4 | 58.1 | 0.013 | 1.586 | 1.100 | 2.286 |
Physical work | 20.4 | 27.5 | 24.0 | 0.002 | 2.012 | 1.296 | 3.122 |
Type of treatment | |||||||
Manual Medicine (MM, ref.) | 14.6 | 21.5 | 18.6 | 0.109 | |||
Orthomanual Medicine (OMM) | 70.4 | 76.5 | 77.7 | 0.166 | 0.739 | 0.482 | 1.133 |
Both MM and OMM | 2.2 | 0.9 | 3.1 | 0.058 | 0.284 | 0.078 | 1.042 |
Other treatment | 0.4 | 1.1 | 0.7 | ||||
Number of treatment sessions | 3.7 (1.5) | 3.5 (1.6) | 3.5 (1.6) | 0.121 | 0.925 | 0.839 | 1.021 |
McKenzie | 11.1 | 13.3 | 18.2 | 0.801 | 1.065 | 0.645 | 1.733 |
Treated.differently | 6.1 | 4.6 | 2.1 | 0.008 | 1.000 | 1.000 | 1.000 |
Multivariable model
Predictor variables in multivariate model | Coefficient | OR | 95% CI of OR | |
---|---|---|---|---|
Lower | Upper | |||
Gender (female) | − 0.6271 | 0.5341 | 0.3629 | 0.7862 |
Time since complaints 1st started | 0.0145 | 1.0146 | 0.9982 | 1.0312 |
Previous specialist visit | 0.4623 | 1.5876 | 1.0645 | 2.3678 |
Previous visit pain clinic | 0.1372 | 1.1471 | 0.9982 | 1.3162 |
Previous chiropractic treatment (treated without effect is reference) | ||||
Treated effective | 0.2836 | 1.3279 | 0.4244 | 4.1546 |
Not treated | 0.5804 | 1.7868 | 1.0872 | 2.9364 |
Work status (no work is reference) | ||||
Non-physical work | 0.3539 | 1.4246 | 0.9218 | 2.2014 |
Physical work | 0.5169 | 1.6768 | 0.9900 | 2.8399 |
Duration of current episode in years (non-linear spline variable) | ||||
Duration of current episode* | − 0.5197 | 0.5947 | 0.4298 | 0.8228 |
Spline variable duration of current episode* | 1.9619 | 7.1128 | 1.9705 | 25.6750 |
Intercept | 0.5462 | 1.7266 | 0.8101 | 3.6801 |