Table 2.
Primary and secondary outcomes for treatment groups and treatment comparisons (adjusted mean difference) for all time periods
| Outcome | Amoxicillin | Placebo | ANCOVA | Linear mixed effects‡ | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No* | Mean (SD) | No | Mean (SD) | No† | Mean (95% CI) | P value | Mean (95% CI) | P value | |||||
| RMDQ: | |||||||||||||
| Baseline | 88 | 12.7 (4.7) | 90 | 12.8 (3.7) | — | — | — | — | — | ||||
| 3 months | 85 | 10.3 (5.8) | 87 | 12.4 (4.4) | 180 | −1.9 (−3.2 to −0.7) | 0.003 | −1.9 (−3.3 to −0.5) | 0.006 | ||||
| 6 months | 83 | 9.9 (5.9) | 78 | 11.7 (5.2) | 179§ | −1.5 (−2.9 to 0.0)¶ | 0.047 | −1.6 (−3.2 to −0.1) | 0.04 | ||||
| 9 months | 77 | 9.7 (6.4) | 79 | 11.1 (5.4) | 179§ | −1.6 (−3.1 to 0.0)¶ | 0.049 | −1.7 (−3.3 to −0.1) | 0.04 | ||||
| 12 months | 85 | 9.0 (6.2) | 84 | 10.7 (5.6) | 180 | −1.6 (−3.1 to 0.0) | 0.04 | −1.7 (−3.3 to −0.1) | 0.04 | ||||
| ODI: | |||||||||||||
| Baseline | 88 | 31.9 (11.4) | 89 | 31.8 (10.3) | — | — | — | — | — | ||||
| 3 months | 86 | 26.6 (14.7) | 85 | 30.4 (10.7) | 179§ | −3.8 (−6.7 to −0.9)** | 0.01 | −4.1 (−7.0 to −1.2) | 0.006 | ||||
| 12 months | 85 | 24.4 (15.0) | 84 | 28.9 (14.0) | 179§ | −4.8 (−8.3 to −1.4)** | 0.007 | −5.1 (−8.5 to 1.6) | 0.004 | ||||
| Back pain intensity††: | |||||||||||||
| Baseline | 88 | 6.4 (1.2) | 90 | 6.3 (1.5) | — | — | — | — | — | ||||
| 3 months | 85 | 5.2 (2.3) | 85 | 5.4 (1.9) | 179§ | −0.3 (−0.8 to 0.3)** | 0.33 | −0.4 (−0.8 to 0.1) | 0.13 | ||||
| 6 months | 83 | 5.1 (2.2) | 77 | 5.5 (2.2) | 178§ | −0.5 (−1.1 to 0.1)¶** | 0.11 | −0.5 (−1.0 to 0.0) | 0.03 | ||||
| 9 months | 78 | 5.2 (2.4) | 77 | 5.0 (2.3) | 178§ | 0.0 (−0.7 to 0.6)¶** | 0.97 | 0.0 (−0.5 to 0.5) | 0.88 | ||||
| 12 months | 85 | 4.7 (2.3) | 84 | 5.2 (2.3) | 179§ | −0.6 (−1.3 to 0.0)** | 0.06 | −0.7 (−1.2 to −0.2) | 0.005 | ||||
| EQ5D-5L: | |||||||||||||
| Baseline | 89 | 0.55 (0.19) | 91 | 0.54 (0.18) | — | — | — | — | — | ||||
| 3 months | 85 | 0.60 (0.22) | 83 | 0.54 (0.21) | 180 | 0.06 (0.00 to 0.11)** | 0.04 | 0.06 (0.00 to 0.11) | 0.05 | ||||
| 12 months | 84 | 0.65 (0.22) | 83 | 0.58 (0.22) | 180 | 0.07 (0.02 to 0.12)** | 0.01 | 0.07 (0.01 to 0.13) | 0.015 | ||||
| Leg pain intensity (0-10): | |||||||||||||
| Baseline | 89 | 3.2 (2.6) | 90 | 3.2 (2.6) | — | — | — | — | — | ||||
| 3 months | 85 | 3.1 (2.8) | 84 | 3.4 (2.6) | 168 | −0.3 (−0.9 to 0.4)¶** | 0.42 | — | — | ||||
| 12 months | 85 | 2.8 (2.7) | 82 | 3.5 (2.8) | 166 | −0.8 (−1.4 to −0.1)¶** | 0.03 | — | — | ||||
ANCOVA=analysis of covariance; EQ5D-5L=EuroQol’s health related quality of life (score from −0.59 to 1; higher scores indicate better quality of life); ODI=Oswestry Disability Index (score from 0 to 100; higher scores indicate more severe pain and disability); RMDQ=Roland-Morris Disability Questionnaire (score from 0 to 24; higher scores indicate more severe pain and disability).
Number of answered questionnaires of outcome.
Number of cases included in the analyses after multiple imputations.
Interaction between time and treatment at 12 months with simple contrasts.
Some patients excluded from analysis because the imputation model did not manage to impute all missing variables.
Retrospective analyses not described in the registry.
Estimates smaller than recommended thresholds for clinical important change within groups (ODI 13-20; low back pain intensity numerical rating scale 2-3; leg pain intensity numerical rating scale 2-3.5; EQ5D-5L 0.11-0.30).
Linear mixed effects model includes all time points (week 0-13).