The patellofemoral pain and osteoarthritis subscale of the KOOS (KOOS-PF): development and validation using the COSMIN checklist
Bibliographic record
Abstract
BACKGROUND: Patellofemoral pain and osteoarthritis are prevalent and associated with substantial pain and functional impairments. Patient-reported outcome measures (PROMs) are recommended for research and clinical use, but no PROMs are specific for patellofemoral osteoarthritis, and existing PROMs for patellofemoral pain have methodological limitations. This study aimed to develop a new subscale of the Knee injury and Osteoarthritis Outcome Score for patellofemoral pain and osteoarthritis (KOOS-PF), and evaluate its measurement properties. METHODS: Items were generated using input from 50 patients with patellofemoral pain and/or osteoarthritis and 14 health and medical clinicians. Item reduction was performed using data from patellofemoral cohorts (n=138). We used the COnsesus-based Standards for the selection of health Measurements INstruments guidelines to evaluate reliability, validity, responsiveness and interpretability of the final version of KOOS-PF and other KOOS subscales. RESULTS: From an initial 80 generated items, the final subscale included 11 items. KOOS-PF items loaded predominantly on one factor, pain during activities that load the patellofemoral joint. KOOS-PF had good internal consistency (Cronbach's α 0.86) and adequate test-retest reliability (intraclass correlation coefficient 0.86). Hypothesis testing supported convergent, divergent and known-groups validity. Responsiveness was confirmed, with KOOS-PF demonstrating a moderate correlation with Global Rating of Change scores (r 0.52) and large effect size (Cohen's d 0.89). Minimal detectable change was 2.3 (groups) and 16 (individuals), while minimal important change was 16.4. There were no floor or ceiling effects. CONCLUSIONS: The 11-item KOOS-PF, developed in consultation with patients and clinicians, demonstrated adequate measurement properties, and is recommended for clinical and research use in patients with patellofemoral pain and osteoarthritis.
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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 | 0.021 | 0.028 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".