Baseline Characteristics of Potentially Eligible and Participating Patients
| Characteristic | Phase 1 | Phase 3 |
|---|---|---|
| Potentially eligible patients | ||
| Number invited (potentially eligible) | 630 | 1,017 |
| Age, mean (SD), y | 47.9 (16.8) | 49.2 (15.8) |
| Sex, female, No. (%) | 340 (54) | 570 (56) |
| Excluded, No. (%)a | 28 (4) | 47 (5) |
| Nonrespondents, No. (%) | 234 (37) | 416 (41) |
| Respondents, No. (%) | 368 (58) | 554 (55) |
| Consented to medical record review, No. (%) | 307 (83) | 421 (76) |
| Followed up at 2 mo, No. (%)b | 254 (69) | 332 (60) |
| Followed up at 6 mo, No. (%)c | 233 (63) | 314 (57) |
| Participating patients | ||
| Age, mean (SD), y | 53.0 (15.0) | 54.1 (14.8) |
| Sex, female, No. (%) | 202 (55) | 330 (60) |
| Routine/manual laborer, No. (%)d | 102 (35) | 157 (37) |
| Currently in paid employment, No. (%) | 227 (62) | 323 (59) |
| Time off work for back pain, No. (%)e | 109 (49) | 133 (42) |
| Disability: RMDQ score, mean (SD)f | 8.7 (5.9) | 8.4 (5.7) |
| Pain intensity: NRS rating, mean (SD)g | 5.3 (2.4) | 5.0 (2.6) |
| Duration of back pain episode, No. (%) | ||
| <1 month | 75 (20) | 94 (17) |
| 1–3 months | 62 (17) | 102 (18) |
| 3–6 months | 75 (20) | 111 (20) |
| 6 months to 3 years | 82 (22) | 130 (24) |
| >3 years | 74 (20) | 117 (21) |
| Leg pain, No. (%) | 279 (76) | 408 (74) |
| Risk group, No. (%) | ||
| Low | 136 (37) | 214 (39) |
| Medium | 151 (41) | 232 (42) |
| High | 81 (22) | 108 (20) |
NRS = numerical rating scale; RMDQ = Roland-Morris Disability Questionnaire.
↵a Exclusions: 8 patients in phase 1 and 23 patients in phase 3 had either died or moved primary care practice; 1 and 0 were unable to respond to questions; 11 and 19 did not want to participate; 6 and 4 did not have back pain; 1 and 0 had comorbid problems that were a priority; 1 and 1 were unable to take part.
↵b Losses to follow-up at 2 months: 102 patients in phase 1 and 217 patients in phase 3 did not respond to mailing; 9 and 0 had either died or moved primary care practice since baseline; 2 and 3 did not want to continue to take part; 0 and 1 did not have back pain; 1 and 1 had comorbid problems that were a priority. All baseline participants were retained for the purposes of intention-to-treat analysis (by imputation).
↵c Losses to follow-up at 6 months: 118 patients in phase 1 and 235 patients in phase 3 did not respond to mailing; 5 and 3 had either died or moved primary care practice since 2-month follow-up; 0 and 1 had comorbid problems that were a priority; 0 and 1 did not have back pain. All baseline participants were retained for the purposes of intention-to-treat analysis (by imputation).
↵d Based on major groups 5 to 9 of the UK Standard Occupation Classification (SOC, 2000) for current or most recent paid job.
↵e Respondents who were currently in paid employment at baseline and had time off in the 12 months before baseline.
↵f On a scale of 0 to 24: 0 = no disability, 24 = maximum disability.
↵g On a scale of 0 to 10: 0 = no pain, 10 = pain as bad as could be.