Table 1.
Baseline Characteristics
| SMT 0 (n = 95) | SMT 6 (n=99) | SMT 12 (n = 97) | SMT 18 (n = 100) | All (n=391) | |
|---|---|---|---|---|---|
| Sociodemographic information | |||||
| Age (yr) | 40.9 (14.1) | 41.4 (14.8) | 41.8 (14.0) | 41.2 (13.8) | 41.3 (14.1) |
| Female (%) | 49 | 49 | 49 | 52 | 50 |
| Non-white or Hispanic (%) | 14 | 18 | 11 | 16 | 15 |
| Married (%) | 37 | 28 | 41 | 36 | 36 |
| College degree (%) | 58 | 63 | 51 | 53 | 56 |
| Income < $20,000/ yr (%) | 31 | 27 | 19 | 28 | 26 |
| Smoker (%) | 17 | 13 | 6 | 8 | 11 |
| Expectations | |||||
| Confidence in treatment success | |||||
| Spinal Manipulation (1-6 scale)* | 3.6 (1.2) | 3.8 (1.1) | 3.7 (1.2) | 3.8 (1.1) | 3.7 (1.2) |
| Light massage (1-6 scale)* | 3.4 (1.2) | 3.5 (1.2) | 3.4 (1.2) | 3.5 (1.2) | 3.5 (1.2) |
| Previous treatment | |||||
| Spinal Manipulation (%) | 71 | 70 | 74 | 72 | 72 |
| Light massage (%) | 52 | 56 | 43 | 54 | 51 |
| Low back pain complaint | |||||
| Pain intensity (0-100 scale)† | 52.2 (16.3) | 51.0 (18.2) | 51.6 (17.5) | 51.5 (16.8) | 51.6 (17.2) |
| Functional disability (0-100 scale)† | 45.2 (21.8) | 44.8 (24.0) | 46.1 (23.4) | 45.2 (21.8 | 45.3 (22.7) |
| Pain unpleasantness (0-100 scale)† | 41.7 (19.5) | 41.1 (21.1) | 40.3 (22.8) | 42.4 (22.2 | 41.4 (21.4) |
| Days with pain (last 4 wk) | 24.8 (4.8) | 24.1 (5.5) | 23.3 (5.7) | 24.1 (4.6) | 24.1 (5.2) |
| Days with disability (last 4 wk) | 7.4 (8.1) | 6.7 (7.5) | 6.8 (7.5) | 6.5 (7.2) | 6.8 (7.6) |
| Duration (yr) | 11.6 (9.5) | 11.2 (9.8) | 11.7 (10.4) | 12.5 (9.5) | 11.8 (9.8) |
| Health status | |||||
| SF-12 physical health component‡ | 43.0 (9.5) | 43.8 (8.9) | 44.3 (8.4) | 42.3 (8.8) | 43.3 (8.9) |
| SF-12 mental health component‡ | 50.2 (10.5) | 48.6 (10.5) | 47.6 (11.2) | 49.4 (9.6) | 48.9 (10.5) |
| Health State (0-100 visual analog scale)‡ | 70.1 (17.2) | 72.1 (13.8) | 73.5 (14.4) | 68.2 (17.4) | 70.9 (15.8) |
| Other Comorbidity (%) | 58 | 57 | 52 | 54 | 55 |
| Fear-Avoidance Beliefs Questionnaire | |||||
| Work beliefs (0-100 scale)‡ | 36.6 (23.2) | 32.0 (23.4) | 31.0 (18.9) | 32.2 (21.4) | 32.9 (21.8) |
| Activity beliefs (0-100 scale)‡ | 55.0 (20.1) | 53.8 (23.1) | 56.4 (17.7) | 58.8 (19.8) | 56.0 (20.3) |
| Oral medication use (times in last 4 wk) | |||||
| Prescription | 0.9 (3.6) | 0.3 (1.1) | 0.6 (2.6) | 0.3 (1.5) | 0.5 (2.4) |
| Non-prescription | 7.6 (10.0) | 8.9 (10.8) | 9.5 (10.0) | 7.6 (9.4) | 8.4 (10.1) |
Mean (SD) or percentage. SMT, spinal manipulation.
*
Six-point Likert scale with 1 indicating lowest and 6 indicating highest confidence.
†
Lower scores favorable. Low back pain intensity and functional disability evaluated with Modified Von Korff scales.
‡
Higher scores favorable. Short Form 12 Health Survey (SF-12) scores are standardized to the US general population (mean=50, SD=10).