Table 3. Secondary Outcomes Among Participants With Chronic Low Back Paina.
| Overall Effect | Intervention Group, Mean (95% CI) | Control Group, Mean (95% CI) | Between-Group Difference, Mean (95% CI)b | P Value | Risk Difference (95% CI) | NNT |
|---|---|---|---|---|---|---|
| Functioning Score c , d | ||||||
| Facet joint trial, No. of participants | 125 | 126 | ||||
| Overall | 0.04 (−3.02 to 3.10) | .98 | ||||
| 3 mo | 26.03 (23.01 to 29.06) | 28.67 (26.06 to 31.84) | −2.45 (−5.93 to 1.03) | .17 | ||
| 6 mo | 25.38 (22.45 to 28.30) | 27.15 (24.07 to 30.23) | −0.60 (−4.13 to 2.92) | .74 | ||
| 9 mo | 25.74 (22.74 to 28.73) | 24.52 (21.49 to 27.54) | 2.26 (−1.29 to 5.82) | .21 | ||
| 12 mo | 24.59 (21.39 to 27.79) | 25.04 (21.77 to 28.31) | 1.48 (−2.09 to 5.06) | .42 | ||
| Sacroiliac joint trial, No. of participants | 116 | 112 | ||||
| Overall | 0.42 (−2.99 to 3.82) | .81 | ||||
| 3 mo | 27.72 (24.50 to 30.95) | 29.09 (25.47 to 2.71) | −4.20 (−8.39 to −0.00) | .05 | ||
| 6 mo | 25.99 (22.91 to 29.05) | 24.99 (21.45 to 28.52) | 0.07 (−4.16 to 4.30) | .97 | ||
| 9 mo | 28.40 (25.05 to 31.75) | 23.45 (20.00 to 6.91) | 4.45 (0.14 to 8.77) | .04 | ||
| 12 mo | 27.29 (23.89 to 30.69) | 24.49 (20.74 to 28.23) | 2.11 (−2.25 to 6.47) | .34 | ||
| Combination trial, No. of participants | 103 | 99 | ||||
| Overall | 1.90 (−2.96 to 6.76) | .44 | ||||
| 3 mo | 28.00 (24.65 to 31.35) | 33.63 (29.88 to 37.37) | −4.66 (−10.21 to 0.89) | .10 | ||
| 6 mo | 30.24 (26.14 to 34.34) | 28.61 (24.80 to 32.43) | 4.44 (−1.18 to 0.06) | .12 | ||
| 9 mo | 30.73 (26.83 to 34.63) | 28.70 (24.48 to 32.91) | 3.55 (−2.17 to 9.26) | .22 | ||
| 12 mo | 31.20 (27.20 to 35.20) | 24.67 (20.88 to 28.45) | 6.44 (0.61 to 12.26) | .03 | ||
| Global Perceived Recovery e | ||||||
| No. With Treatment Success/Total No. (%) | No. With Treatment Success/Total No. (%) | Relative Risk (95% CI) f | P Value | Risk Difference (95% CI) | NNT | |
| Facet joint trial, No. of participants | 125 | 126 | ||||
| 3 wk | 32/108 (29.63) | 5/101 (4.95) | 5.41 (2.29 to 10.34) | <.001 | 24.68 (15.08 to 34.27) | 4 |
| 6 wk | 35/119 (29.41) | 11/118 (9.32) | 2.71 (1.37 to 4.68) | .005 | 20.09 (10.37 to 29.81) | 5 |
| 3 mo | 43/119 (36.13) | 27/114 (23.68) | 1.35 (0.81 to 2.05) | .24 | 12.45 (0.81 to 24.09) | 8 |
| 6 mo | 46/113 (40.70) | 39/108 (36.11) | 1.04 (0.64 to 1.12) | .85 | 4.59 (−8.21 to 17.41) | NA |
| 9 mo | 41/106 (38.67) | 42/105 (40.00) | 0.81 (0.48 to 0.57) | .35 | −1.33 (−14.50 to 11.86) | NA |
| 12 mo | 44/103 (42.71) | 40/102 (39.22) | 0.90 (0.55 to 1.33) | .65 | 3.49 (−9.95 to 16.96) | NA |
| Sacroiliac joint trial, No. of participants | 116 | 112 | ||||
| 3 wk | 28/94 (29.78) | 9/88 (10.23) | 2.83 (1.39 to 4.89) | .01 | 19.55 (8.35 to 30.77) | 5 |
| 6 wk | 43/110 (39.09) | 10/95 (10.53) | 3.71 (2.00 to 5.74) | <.001 | 28.56 (17.55 to 39.58) | 4 |
| 3 mo | 43/110 (39.10) | 19/88 (21.59) | 1.87 (1.13 to 2.71) | .02 | 17.51 (4.97 to 30.03) | 6 |
| 6 mo | 46/103 (44.66) | 29/88 (32.95) | 1.26 (0.83 to 1.84) | .21 | 11.71 (−2.03 to 25.44) | NA |
| 9 mo | 36/101 (35.64) | 25/78 (32.05) | 1.13 (0.67 to 1.70) | .62 | 3.59 (−10.35 to 17.54) | NA |
| 12 mo | 49/102 (48.03) | 24/76 (31.78) | 1.46 (0.92 to 2.02) | .10 | 16.25 (2.20 to 30.72) | NA |
| Combination trial, No. of participants | 103 | 99 | ||||
| 3 wk | 17/77 (22.07) | 4/56 (7.14) | 2.23 (0.73 to 5.52) | .15 | 14.93 (3.48 to 25.40) | 6 |
| 6 wk | 25/90 (27.77) | 7/82 (8.54) | 2.41 (0.99 to 4.90) | .05 | 19.23 (8.19 to 30.30) | 5 |
| 3 mo | 30/88 (34.09) | 13/80 (16.25) | 1.99 (0.99 to 3.37) | .06 | 17.84 (5.06 to 30.63) | 5 |
| 6 mo | 30/85 (35.29) | 28/75 (37.33) | 0.76 (0.39 to 1.30) | .36 | −2.04 (−16.97 to 12.90) | NA |
| 9 mo | 29/82 (35.36) | 21/68 (30.88) | 1.11 (0.57 to 1.82) | .73 | 4.48 (−10.61 to 19.57) | NA |
| 12 mo | 26/75 (34.66) | 22/61 (36.06) | 0.91 (0.46 to 1.52) | .76 | −1.40 (−17.65 to 14.76) | NA |
Abbreviations: NA, not applicable; NNT, number needed to treat.
The other secondary outcomes are presented in eTable 2 in Supplement 2.
Values presented (for mean differences) are model estimates of linear mixed-effects models with a random intercept, and adjusted for outcome at baseline and age, sex, body mass index, education, smoking, marital status, back pain complaint history, and participant expectations. Regression coefficients can be interpreted as mean differences between interventions at a certain follow-up point compared with baseline.
Measured by Oswestry Disability Index (score range, 0-100); a higher score indicates worse functioning.
The overall effect measures provide information over the total follow-up time of 12 mo, instead of the time × treatment effects.
Measured by the Global Perceived Effect scale (range, 1-7); a score of 1 to 2 indicates success.
Relative risk was estimated based on the method of Zhang et al.31