Impact of reference equations on lung function and outcomes in fibrotic interstitial lung disease
Bibliographic record
Abstract
Background The impact of applying different lung function reference equations and interpretation methods in fibrotic interstitial lung disease (ILD) is poorly understood. We aimed to evaluate disease severity classification, trajectories and prognostic significance of percent-predicted and z-scores of forced vital capacity (FVC) and diffusing capacity of the lung for carbon monoxide ( D LCO ) using the Global Lung Function Initiative (GLI) reference equations in patients with fibrotic ILD, compared to registry-recorded values. Methods Serial lung function measurements of 5026 patients from three prospective registries were used to calculate percent-predicted and z-scores using 2012- and 2023-GLI FVC reference equations and 2017-GLI D LCO reference equations, which were compared with registry-recorded values. Differences for baseline and longitudinal assessments, classification for lung function impairment severity and progression, and association with transplant-free survival and performance of the ILD-Gender-Age-Physiology model with external validation were assessed. Results Baseline FVC and D LCO percent-predicted values were consistently higher using the 2012- and 2023-GLI FVC and 2017-GLI D LCO reference equations compared to registry-recorded values. The agreements for all percent-predicted reference equations were good for lung function severity classification (unweighted κ for FVC 0.69–0.76, D LCO 0.70), but only moderate for the counterpart z-scores (FVC 0.41–0.50, D LCO 0.45). The largest 1-year declines were observed using the 2023-GLI FVC reference equations and the 2017-GLI D LCO reference equations. Lower baseline GLI and registry-recorded FVC and D LCO values were associated with worse transplant-free survival and had similar performance for risk stratification, except for a lack of association of baseline 2023-GLI FVC percent-predicted and z-scores for adjusted analyses in the non-White cohort. Conclusions Use of different lung function reference equations and interpretation methods may impact disease severity classification and longitudinal trajectory in patients with fibrotic ILD, although prognostic significance is similar, except for 2023-GLI FVC in non-White patients.
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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 | 0.033 | 0.073 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".