Table 1.
Baseline characteristics of participants randomly assigned according to treatment group in total and stratified according to risk group
|
All participants |
Low-risk participants |
Medium-risk participants |
High–risk participants |
||||||
|---|---|---|---|---|---|---|---|---|---|
| Intervention group (n=568) | Control group (n=283) | Intervention group (n=148) | Control group (n=73) | Intervention group (n=263) | Control group (n=131) | Intervention group (n=157) | Control group (n=79) | ||
| Demographics | |||||||||
| Age (years) | 50·1 (15·0) | 49·1 (14·3) | 46·5 (14·3) | 47·6 (14·7) | 50·5 (15·3) | 49·3 (13·5) | 52·7 (14·5) | 50·1 (15·3) | |
| Sex, female | 330 (58%) | 170 (60%) | 82 (55%) | 42 (58%) | 160 (61%) | 83 (63%) | 88 (56%) | 45 (57%) | |
| Routine and manual occupations* | 287 (51%) | 149 (53%) | 61 (41%) | 26 (36%) | 137 (52%) | 65 (50%) | 89 (57%) | 58 (73%) | |
| Currently in paid employment | 350 (62%) | 174 (61%) | 112 (76%) | 50 (68%) | 158 (60%) | 83 (63%) | 80 (51%) | 41 (52%) | |
| Time off work for back pain† | 185 (53%) | 90 (52%) | 40 (36%) | 12 (24%) | 95 (60%) | 51 (61%) | 50 (63%) | 27 (66%) | |
| Back pain and function | |||||||||
| RMDQ disability score | 9·8 (5·6) | 9·7 (5·8) | 4·6 (3·5) | 4·2 (3·3) | 9·9 (4·5) | 9·8 (4·8) | 14·4 (4·6) | 14·7 (4·4) | |
| Back pain intensity | 5·3 (2·2) | 5·2 (2·2) | 3·4 (1·6) | 3·5 (1·7) | 5·5 (1·7) | 5·3 (1·8) | 7·0 (1·8) | 6·8 (2·0) | |
| Duration of back pain | |||||||||
| <1 month | 97 (17%) | 54 (19%) | 25 (17%) | 14 (19%) | 44 (17%) | 24 (18%) | 28 (18%) | 16 (20%) | |
| 1–3 months | 124 (22%) | 66 (23%) | 31 (21%) | 15 (21%) | 61 (23%) | 39 (30%) | 32 (20%) | 12 (15%) | |
| 3–6 months | 81 (14%) | 42 (15%) | 19 (13%) | 12 (16%) | 38 (14%) | 16 (12%) | 24 (15%) | 14 (18%) | |
| 6 months to 3 years | 144 (25%) | 65 (23%) | 45 (30%) | 21 (29%) | 65 (25%) | 27 (21%) | 34 (22%) | 17 (22%) | |
| >3 years | 122 (21%) | 56 (20%) | 28 (19%) | 11 (15%) | 55 (21%) | 25 (19%) | 39 (25%) | 20 (25%) | |
| Radiating leg pain | 352 (62%) | 178 (63%) | 61 (41%) | 28 (38%) | 176 (67%) | 89 (68%) | 115 (73%) | 61 (77%) | |
| Radiating pain below knee | 179 (32%) | 93 (33%) | 24 (16%) | 10 (14%) | 75 (29%) | 47 (36%) | 80 (51%) | 36 (46%) | |
| Psychological measures | |||||||||
| PCS, catastrophising score | 16·3 (10·8) | 15·9 (11·1) | 8·6 (5·8) | 8·1 (6·5) | 14·6 (8·1) | 13·6 (8·1) | 26·4 (10·6) | 26·9 (10·3) | |
| PCS ≥20 | 186 (33%) | 89 (31%) | 8 (5%) | 4 (5%) | 60 (23%) | 28 (21%) | 118 (75%) | 57 (72%) | |
| TSK, fear avoidance score | 40·3 (6·1) | 40·6 (6·3) | 36·5 (4·9) | 36·5 (5·8) | 39·2 (5·0) | 39·7 (4·7) | 45·8 (5·0) | 46·0 (5·7) | |
| HADS, anxiety subscale | 7·4 (4·1) | 7·6 (4·0) | 5·2 (2·9) | 5·4 (3·3) | 7·0 (3·7) | 7·4 (3·7) | 10·1 (4·2) | 10·1 (3·8) | |
| HADS, depression subscale | 5·8 (4·1) | 6·0 (4·1) | 3·1 (2·7) | 3·0 (2·5) | 5·5 (3·3) | 6·0 (3·8) | 8·9 (4·3) | 8·9 (3·7) | |
| General health | |||||||||
| Widespread pain‡ | 186 (33%) | 104 (37%) | 33 (22%) | 16 (22%) | 93 (35%) | 56 (43%) | 60 (38%) | 32 (41%) | |
| SF12, physical component | 37·0 (10·4) | 36·4 (10·6) | 45·9 (8·6) | 46·0 (9·1) | 35·7 (9·5) | 35·1 (8·6) | 30·8 (7·6) | 29·6 (8·2) | |
| SF12, mental component | 48·2 (11·9) | 47·8 (11·7) | 53·7 (7·3) | 53·0 (8·1) | 49·6 (11·5) | 48·6 (11·3) | 40·6 (12·5) | 41·5 (12·3) | |
Data are mean score (SD) or number (%). RMDQ=Roland and Morris Disability Questionnaire. PCS=Pain Catastrophizing Scale. TSK=Tampa Scale of Kinesiophobia. HADS=Hospital Anxiety and Depression Scale. SF12=Short Form 12.
*
Based on major groups 5–9 of the UK Standard Occupation Classification (2000) for current or most recent paid employment (inclusive of 36 missing data [26 in intervention group and ten in control group]).
†
Responders who reported being currently in paid employment at baseline and taking time off during the 12 months before baseline.
‡
Based on the American College of Rheumatology's definition.33