TABLE 4.
Moderator Effects of SMT vs. Recommended Interventions for Function. Within-study Interaction (β) and 95% CI With the Intervention Effects of Random-effect Models Adjusted for Baseline Using REML, Separating Between-study and Within-study Variation Are Presented
| Standardized Mean Difference of Combined Function Scales | Follow-up 1 mo β (95% CI) m; n | 3 mo β (95% CI) m; n | 6 mo β (95% CI) m; n | 12 mo β (95% CI) m; n |
| Demographic moderators | ||||
| Sex:(reference: male) | –0.03 (–0.16 to 0.10) 9; 1876 | 0.06 (–0.09 to 0.21) 10; 1837 | (–0.15 to 0.18) 8; 1439 | –0.02 (–0.17 to 0.14) 9; 1775 |
| Age∗: (reference: <65 years’ old) | –0.03 (–0.17 to 0.12) 9; 1876 | –0.06 (–0.25 to 0.13) 10; 1835 | –0.23 (–0.45 to –0.01) 8; 1437 | –0.32 (–0.57 to –0.07) 9; 1773 |
| Body mass index: (reference: <30) | –0.07 (–0.26 to 0.12) 6; 1047 | –0.18 (–0.42 to 0.07) 7; 1139 | –0.06 (–0.30 to 0.17) 7; 1225 | 0.15 (–0.14 to 0.44) 6; 1055 |
| Ethnicity: white vs. other (reference: other than white) | –0.19 (–0.55 to 0.17) 4; 691 | 0.07 (–0.39 to 0.53) 5; 707 | –0.23 (–0.65 to 0.19) 4; 630 | 0.03 (–0.38 to 0.44) 3; 469 |
| Lifestyle factors | ||||
| Physical activity: (reference: three or less a week) (reference: one or less a week) | –0.002 (–0.008 to 0.002) 4; 511–0.11 (–0.33 to 0.11) 4; 511 | –0.002 (–0.009 to 0.004) 6; 739–0.05 (–0.27 to 0.18) 6; 739 | –0.13 (–0.40 to 0.14) 4; 659–0.13 (–0.34 to 0.09) 4; 659 | 0.00 (–0.01 to 0.01) 5; 676–0.10 (–0.33 to 0.14) 5; 676 |
| Smoker: smoker (reference: nonsmoker) | 0.24 (0.00 to 0.48) 5; 873 | 0.22 (–0.02 to 0.47) 6; 1075 | 0.14 (–0.11 to 0.38) 6; 1050 | 0.29 (0.02 to 0.56) 4; 801 |
| DZ converted to a MD on the 24-point RMDQ scale | 1.08 | 1.11 | 0.72 | 1.54 |
| Alcohol use | † | † | † | † |
| Sociodemographics | ||||
| Marital status: (reference: not involved in relation) | –0.12 (–0.29 to 0.05) 6; 1066 | –0.09 (–0.29 to 0.12) 6; 1016 | –0.08 (–0.26 to 0.10) 6; 1005 | –0.12 (–0.33 to 0.10) 4; 777 |
| Employment status: (reference: not employed) | 0.10 (–0.08 to 0.27) 7; 1657 | –0.17 (–0.39 to 0.04) 8; 1665 | 0.06 (–0.16 to 0.27) 7; 1377 | –0.06 (–0.36 to 0.23) 8; 1606 |
| Level of education: (reference: low or middle) | –0.17 (–0.37 to 0.01) 6; 1398 | –0.11 (–0.29 to 0.08) 7; 1363 | –0.07 (–0.27 to 0.13) 5; 796 | –0.14 (–0.35 to 0.05) 5; 1106 |
| Income | † | † | † | † |
| Nature and severity of LBP | ||||
| Duration of LBP∗: >1 y (reference: <1 y) | 0.07 (–0.29 to 0.43) 5; 861 | 0.02 (–0.30 to 0.34) 6; 910 | 0.19 (–0.02 to 0.39) 6; 1031 | 0.13 (–0.25 to 0.52) 5; 848 |
| DZ converted to a MD on the 24-point RMDQ scale | 0.35 | 0.10 | 1.06 | 0.78 |
| Radiation: leg pain (reference: no leg pain) | –0.16 (–0.40 to 0.80) 3; 660 | 0.04 (–0.18 to 0.27) 5; 911 | –0.01 (–0.22 to 0.21) 4; 820 | –0.08 (–0.33 to 0.17) 4; 681 |
| Previous LBP treatment received: (reference: no) | 0.09 (–0.11 to 0.29) 5; 884 | 0.11 (–0.12 to 0.34) 5; 871 | 0.02 (–0.21 to 0.15) 5; 812 | 0.12 (–0.14 to 0.39) 4; 637 |
| Previous Physio for LBP: (reference: no) | –0.08 (–0.63 to 0.48) 3; 426 | 0.04 (–0.33 to 0.40) 5; 696 | 0.18 (–0.19 to 0.56) 4; 615 | 0.11 (–0.27 to 0.50) 4; 634 |
| Previous SMT for LBP: (reference: no) | –0.11 (–0.49 to 0.26) 4; 616 | –0.07 (–0.46 to 0.32) 6; 885 | 0.14 (–0.20 to 0.49) 5; 795 | 0.52 (0.09 to 0.95) 4; 631 |
| DZ converted to a MD on the 24 point RMDQ scale | –0.49 | –0.36 | 0.74 | 2.93 |
| Previous medication for LBP: (reference: no) | –0.02 (–0.22 to 0.19) 5; 887 | –0.11 (–0.33 to 0.09) 6; 903 | –0.20 (–0.41 to 0.004) 4; 790 | –0.11 (–0.39 to 0.17) 6; 877 |
| Comorbidities | † | † | † | |
| Psychological factors | ||||
| Depression∗: (reference: no depression) | 0.28 (–0.03 to 0.58) 4; 1075 | 0.33 (–0.02 to 0.69) 5; 1066 | 0.13 (–0.26 to 0.51) 3; 505 | 0.02 (–0.39 to 0.43) 4; 825 |
| Treatment preference/expectations∗ | † | † | † | † |
| Primary/secondary outcomes at baseline as moderator | ||||
| Baseline function scales combined (z score) | –0.04 (–0.17 to 0.09) 10; 1939 | +0.01 (–0.10 to 0.13) 11; 1892 | –0.04 (–0.17 to 0.08) 9; 1490 | –0.05 (–0.17 to 0.07) 10; 18,266 |
| Baseline pain dichotomized∗: (reference: baseline pain <50) | –0.20 (–0.36 to –0.04) 10; 1932 | –0.20 (–0.37 to –0.03) 11; 1882 | –0.22 (–0.39 to –0.06) 9; 1506 | –0.14 (0.33 to 0.04) 10; 1806 |
| –0.90 | –0.92 | –1.00 | –0.64 | |
| MCS per 10 points change | –0.00 (–0.10 to 0.10) 5; 1204 | –0.03 (–0.16 to 0.08) 6; 1358 | 0.09 (–0.07 to 0.25) 5; 864 | 0.00 (–0.12 to 0.12) 4; 1069 |
| PCS per 10 points change | 0.03 (–0.17 to 0.23) 5; 1204 | –0.06 (–0.18 to 0.06) 6; 1358 | –0. 13 (–0.32 to 0.07) 5; 864 | 0.00 (–0.22 to 0.21) 4; 1069 |
CI indicates confidence interval; DZ, difference in Z-score; LBP, low back pain; m, number of studies; MCS, mental component summary of SF 36; MD, mean difference; n, number of participants; PCS, physical component summary of SF 36; REML, restricted maximum likelihood; RMDQ, Roland Morris Disability questionnaire; SMT, spinal manipulative therapy. A negative interaction coefficient indicates a more positive/less negative effect of SMT vs. recommended therapies for the index group (e.g., females) as compared to the reference group (e.g., males).
β (95% CI), within-study interaction and confidence interval of the interaction term: the difference in z score for the specific moderator for function for SMT vs. recommended therapies.
Confirmatory moderator analysis.
Not enough data.