Effect Estimates for Comparison of Cohorts (SPLIT vs Usual Care) for Primary and Secondary Outcomes Over the 6-Month Follow-Up
| Crude ß/OR (95% CI)a | P Value | Adjusted ß/OR (95% CI)a | P Value | |
|---|---|---|---|---|
| Back-related disability (RMDQ, 0 to 24) | ||||
| Raw score | −5.19 (−6.09 to −4.29) | ≤.001 | −2.94 (− 3.63 to −2.24) | ≤.001 |
| Achieved MIC, yes vs nob | 7.07 (3.31 to 15.08) | ≤.001 | 8.67 (3.98 to 18.89) | ≤.001 |
| Poor disability, yes vs noc | 0.07 (0.003 to 0.13) | ≤.001 | 0.24 (0.15 to 0.38) | ≤.001 |
| Pain intensity (NPRS, 0 to 10) | ||||
| Raw score | −1.76 (−2.18 to −1.35) | ≤.001 | −0.88 (−1.18 to −0.57) | ≤.001 |
| Achieved MIC, yes vs nob | 3.55 (1.94 to 6.48) | ≤.001 | 3.50 (1.88 to 6.49) | ≤.001 |
| Perceived effect of treatment (GPES, −5 to +5) | ||||
| Raw score | 1.50 (1.08 to 1.91) | ≤.001 | 1.40 (0.97 to 1.82) | ≤.001 |
| Achieved MIC, yes vs nob | 4.66 (2.39 to 9.12) | ≤.001 | 4.40 (2.22 to 8.71) | ≤.001 |
| HRQoL (EQ-5D-3L, 0 to 1) | ||||
| Raw score | 0.19 (0.16 to 0.23) | ≤.001 | 0.11 (0.08 to 0.14) | ≤.001 |
EQ-5D-3L = EuroQoL 5 dimensions 3 levels; GPES = Global Perceived Effect Scale; HRQoL = health-related quality of life; MIC = minimal important change; NPRS = Numeric Pain Rating Scale; OR = odds ratio; RMDQ = Roland-Morris Disability Questionnaire; SPLIT = stratified primary care for low back pain; UC = usual care.
↵a For continuous outcomes (RMDQ, NPRS, GPES, and EQ-5D-3L raw scores over time), crude/adjusted ß values were derived via a linear mixed-effects model for the comparison of UC vs SPLIT. For categorical outcomes (achieved MIC of RMDQ, NPRS, and GPES, along with poor disability), crude/adjusted OR values were derived via a logistic mixed-effects model for the comparison of UC vs SPLIT. Adjusted ß/OR and 95% CI values were adjusted for age, duration of low back pain episode, referred leg pain, and baseline STarT Back Screening Tool psychosocial subscale, NPRS, RMDQ, and EQ-5D-3L values.
↵b Based on established MIC criteria: ≥30% decrease from baseline for RMDQ and NPRS and a GPES score ≥3.
↵c Based on a cutoff RMDQ score ≥7.