Responsiveness and Interpretability of the Portuguese Version of the Quebec Back Pain Disability Scale in Patients With Chronic Low Back Pain
Bibliographic record
Abstract
STUDY DESIGN: A prospective cohort study with a 6-week follow-up of patients with chronic low back pain undergoing physiotherapy. OBJECTIVE: To examine the responsiveness of the Portuguese version of the Quebec Back Pain Disability Scale (QBPDS-PT), and to determine the minimal clinically important difference, minimal detectable change (MDC), and floor/ceiling effects. SUMMARY OF BACKGROUND DATA: Measuring change over time is critical to assess the effectiveness of a physiotherapy intervention or to distinguish individual differences in response to treatment. METHODS: One hundred thirty-two patients were recruited from 16 outpatient clinics in 7 different regions of Portugal. A final sample of 120 patients completed the QBPDS-PT twice: at the baseline and after 6 weeks of physiotherapy treatment. The patient global impression of change scale was used as an external criterion measure to distinguish between improved or nonimproved patients' scores between baseline and follow-up. The responsiveness of the QBPDS-PT was assessed through correlation coefficient and receiver operating characteristics curves. The minimal clinically important difference was estimated by the receiver operating characteristics curve method and the MDC through the standard error of measurement. RESULTS: The scale revealed moderate responsiveness (ρ = 0.426 and area under the curve = 0.741; 95% confidence interval: 0.645-0.837). The MDC achieved 19 points, whereas the minimal clinically important difference was found to be 6.5 points (area under the curve = 0.741, sensitivity = 72%, specificity = 71%). A floor effect was founded with 15.8% of the participants reporting values within the MDC at the lower end of the available range of scores. For the highest baseline scores of QBPDS-PT (≥34 points) the optimal cutoff point was found to be 10.5 points (area under the curve = 0.738, sensitivity = 73%, specificity = 67%). CONCLUSION: The QBPDS-PT demonstrated moderate levels of responsiveness, and is recommended to measure change in disability in patients with chronic low back pain after physiotherapy intervention. LEVEL OF EVIDENCE: N/A.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.016 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".