Short-term air pollution exposure and exacerbation events in mild to moderate COPD: a case-crossover study within the CanCOLD cohort
Bibliographic record
Abstract
Background Infections are considered as leading causes of acute exacerbations of chronic obstructive pulmonary disease (COPD). Non-infectious risk factors such as short-term air pollution exposure may play a clinically important role. We sought to estimate the relationship between short-term air pollutant exposure and exacerbations in Canadian adults living with mild to moderate COPD. Methods In this case-crossover study, exacerbations (‘symptom based’: ≥48 hours of dyspnoea/sputum volume/purulence; ‘event based’: ‘symptom based’ plus requiring antibiotics/corticosteroids or healthcare use) were collected prospectively from 449 participants with spirometry-confirmed COPD within the Canadian Cohort Obstructive Lung Disease. Daily nitrogen dioxide (NO 2 ), fine particulate matter (PM 2.5 ), ground-level ozone (O 3 ), composite of NO 2 and O 3 (O x ), mean temperature and relative humidity estimates were obtained from national databases. Time-stratified sampling of hazard and control periods on day ‘0’ (day-of-event) and Lags (‘−1’ to ‘−6’) were compared by fitting generalised estimating equation models. All data were dichotomised into ‘warm’ (May–October) and ‘cool’ (November–April) seasons. ORs and 95% CIs were estimated per IQR increase in pollutant concentrations. Results Increased warm season ambient concentration of NO 2 was associated with symptom-based exacerbations on Lag−3 (1.14 (1.01 to 1.29), per IQR), and increased cool season ambient PM 2.5 was associated with symptom-based exacerbations on Lag−1 (1.11 (1.03 to 1.20), per IQR). There was a negative association between warm season ambient O 3 and symptom-based events on Lag−3 (0.73 (0.52 to 1.00), per IQR). Conclusions Short-term ambient NO 2 and PM 2.5 exposure were associated with increased odds of exacerbations in Canadians with mild to moderate COPD, further heightening the awareness of non-infectious triggers of COPD exacerbations.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".