Version July 2025
| Size of effect | Definition |
| Small/slight | Pain scales: Mean 5 to 10 mm improvement on a 100 mm visual analogue scale (VAS), or equivalent |
| Back-specific functional status: Mean 5 to 10 mm improvement on the Oswestry Disability Index (ODI), 1 to 2 points on the Roland Morris Disability Questionnaire (RMDQ), or equivalent | |
| All outcomes: Standardized mean difference (SMD) 0.2 to 0.5 | |
| Moderate | Pain scales: Mean 10 to 20 mm improvement on a 100 mm VAS, or equivalent |
| Back-specific functional status: Mean 10 to 20 mm improvement on the ODI, 2 to 5 points on the RMDQ, or equivalent | |
| All outcomes: SMD 0.5 to 0.8 | |
| Large/substantial | Pain scales: Mean >20 mm improvement on a 100 mm VAS, or equivalent |
| Back-specific functional status: Mean >20 mm improvement on the ODI, >5 points on the RMDQ, or equivalent | |
| All outcomes: SMD >0.8 |
