Table 2.
Primary Outcomes
| Observed unadjusted Mean (SD) |
Slope (95%CI) | Adjusted Mean difference (95% CI) |
||||||
|---|---|---|---|---|---|---|---|---|
| SMT 0 | SMT 6 | SMT 12 | SMT 18 | per 6 SMT sessions | SMT 0 vs SMT 6 | SMT 0 vs SMT 12 | SMT 0 vs SMT 18 | |
| Pain intensity (0-100 scale) | ||||||||
| 0 wk | 52.2 (16.3) | 51.0 (18.2) | 51.6 (17.5) | 51.5 (16.8) | ||||
| 6 wk | 34.5 (18.4) | 32.3 (15.8) | 27.1 (14.7) | 30.2 (19.0) | 1.8 (0.3, 3.2)* | 1.7 (−2.6, 5.9) | 7.2 (2.8, 11.6)* | 4.1 (−0.5, 8.6) |
| 12 wk | 37.9 (20.4) | 32.7 (19.4) | 29.0 (20.8) | 31.4 (19.8) | 2.2 (0.6, 3.8)* | 4.5 (−0.6, 9.6) | 8.6 (3.2, 14.0)* | 6.1 (1.0, 11.2)* |
| 18 wk | 35.7 (19.5) | 31.4 (18.4) | 30.3 (19.3) | 29.3 (19.7) | 2.0 (0.4, 3.5)* | 3.6 (−1.3, 8.5) | 5.1 (0.2, 10.0) | 6.1 (1.2, 11.0)* |
| 24 wk | 34.9 (20.6) | 32.5 (19.8) | 33.7 (20.5) | 32.1 (20.5) | 0.6 (−1.0, 2.3) | 1.7 (−3.4, 6.9) | 0.8 (−4.4, 6.0) | 2.4 (−2.9, 7.6) |
| 39 wk | 36.2 (21.0) | 32.8 (21.5) | 30.2 (21.7) | 31.6 (21.5) | 1.6 (−0.2, 3.3) | 2.8 (−2.8, 8.4) | 5.8 (0.5, 11.2) | 4.3 (−1.2, 9.9) |
| 52 wk | 36.5 (21.8) | 30.7 (22.4) | 31.9 (22.5) | 28.7 (20.5) | 2.2 (0.4, 4.0)* | 5.4 (−0.4, 11.1) | 4.6 (−1.2, 10.3) | 7.6 (2.0, 13.2)* |
| 6 to 52 wk† | 1.7 (0.4, 3.0)* | 3.1 (−1.0, 7.1) | 5.3 (1.2, 9.3)* | 5.0 (0.8, 9.2)* | ||||
| Functional disability (0-100 scale) | ||||||||
| 0 wk | 45.2 (21.8) | 44.8 (24.0) | 46.1 (23.4) | 45.2 (21.8) | ||||
| 6 wk | 27.0 (20.2) | 28.5 (20.3) | 25.8 (19.3) | 30.1 (20.9) | 0.6 (−2.3, 1.0) | 1.7 (−6.8, 3.4) | 1.5 (−3.7, 6.6) | −3.1 (−8.3, 2.1) |
| 12 wk | 29.2 (23.7) | 24.8 (18.6) | 22.0 (20.7) | 23.4 (20.5) | 2.0 (0.3, 3.8)* | 4.2 (−1.0, 9.4) | 7.5 (1.7, 13.3)* | 5.8 (0.2, 11.3) |
| 18 wk | 26.1 (21.4) | 23.5 (19.4) | 22.1 (21.5) | 22.4 (19.2) | 1.3 (−0.4, 2.9) | 2.2 (−2.8, 7.2) | 4.1 (−1.5, 9.7) | 3.6 (−1.5, 8.7) |
| 24 wk | 27.1 (25.2) | 25.6 (21.7) | 24.0 (20.4) | 24.1 (20.3) | 1.1 (−0.7, 2.9) | 1.4 (−4.5, 7.2) | 3.4 (−2.4, 9.3) | 2.9 (−2.9, 8.8) |
| 39 wk | 26.2 (22.8) | 24.5 (22.6) | 21.7 (20.5) | 24.1 (22.7) | 0.9 (−0.9, 2.8) | 1.4 (−4.3, 7.1) | 4.7 (−0.7, 10.2) | 2.0 (−3.9, 7.9) |
| 52 wk | 28.0 (23.7) | 22.6 (22.4) | 22.4 (21.2) | 19.1 (18.7) | 2.7 (1.0, 4.4)* | 5.2 (−0.5, 10.9) | 5.9 (0.1, 11.8) | 8.8 (3.3, 14.4)* |
| 6 to 52 wk† | 0.9 (−0.3, 2.2) | 1.5 (−2.1, 5.1) | 3.9 (−0.0, 7.7) | 2.4 (1.5, 6.3) | ||||
SMT, spinal manipulative therapy group.
Primary endpoints were prespecified as pain intensity and functional disability at 12 and 24 weeks. Unadjusted group means are from original data without imputation; slopes and group differences are computed from imputed data adjusted for the baseline covariates. Positive signs of slopes and mean differences were computed to favor higher doses of manipulation. A two-tailed test of statistical significance was pre-specified at the .025 to account for two primary outcomes and used for all statistical tests.
*
P < .025
†
Longitudinal profile using generalized estimating equations.