Bronchodilator reversibility in asthma and COPD: findings from three large population studies
Bibliographic record
Abstract
Bronchodilator response (BDR) testing is used as a diagnostic method in obstructive airway diseases. The aim of this investigation was to compare different methods for measuring BDR in participants with asthma and chronic obstructive pulmonary disease (COPD) and to study to the extent to which BDR was related to symptom burden and phenotypic characteristics. Forced expiratory volume in 1 s (FEV 1 ) and forced vital capacity (FVC) were measured before and 15 min after 200 μg of salbutamol in 35 628 subjects aged ≥16 years from three large international population studies. The subjects were categorised in three groups: current asthma (n=2833), COPD (n=1146) and no airway disease (n=31 649). Three definitions for flow-related reversibility (increase in FEV 1 ) and three for volume-related reversibility (increase in FVC) were used. The prevalence of bronchodilator reversibility expressed as increase FEV 1 ≥12% and 200 mL was 17.3% and 18.4% in participants with asthma and COPD, respectively, while the corresponding prevalence was 5.1% in those with no airway disease. In asthma, bronchodilator reversibility was associated with wheeze (OR 1.36, 95% CI 1.04–1.79), atopy (OR 1.36, 95% CI 1.04–1.79) and higher exhaled nitric oxide fraction, while in COPD neither flow- nor volume-related bronchodilator reversibility was associated with symptom burden, exacerbations or health status after adjusting for pre-bronchodilator FEV 1 . Bronchodilator reversibility was at least as common in participants with COPD as those with asthma. This indicates that measures of reversibility are of limited value for distinguishing asthma from COPD in population studies. However, in asthma, bronchodilator reversibility may be a phenotypic marker.
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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 | 0.008 | 0.015 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".