Frequency and severity of COPD exacerbations and future risk of exacerbations and mortality: an observational cohort study in Canada
Bibliographic record
Abstract
OBJECTIVES: To estimate the risk of subsequent exacerbations, in relation to history of exacerbations, in a cohort of older chronic obstructive pulmonary disease (COPD) patients in Canada. METHODS: Using provincial claims data from Ontario, Canada, patients with COPD aged≥65 years (identified between 2004 and 2018; followed up to 2020) were categorised into one of four mutually exclusive groups: no exacerbation; only one moderate; only one severe; or two or more exacerbations of any severity (moderate or severe) during the baseline period. The index date was the first documentation of a COPD diagnosis code; the subsequent 12 months served as the baseline period. Adjusted risks of subsequent exacerbations (any severity and severe exacerbation, separately) by the end of postbaseline year 1, 2 and 3 were estimated, accounting for differences in patient and disease characteristics and competing risk of death. RESULTS: A total of 591 686 patients were included. The majority (89.8%) had no exacerbation at baseline, 3.1% had one moderate exacerbation only, 3.6% had one severe exacerbation only and 3.6% had two or more exacerbations of any severity. Adjusted risks of a subsequent exacerbation of any severity by the end of year 3 were 28.6% (95% CI, 28.5% to 28.7%) with no baseline exacerbation; 56.6% (95% CI, 56.1% to 57.1%), one severe; 58.4% (95% CI, 58.0% to 58.8%), one moderate; and 77.5% (95% CI, 77.2% to 77.8%) two or more exacerbations. Adjusted risks of a subsequent severe exacerbation by the end of year 3 were 20.1% (95% CI, 20.0% to 20.2%) with no baseline exacerbation; 34.9% (95% CI, 34.5% to 35.4%), one moderate; 46.7% (95% CI, 46.2% to 47.2%), one severe; and 59.6% (95% CI, 59.3% to 60.0%) two or more exacerbations. CONCLUSIONS: Having a history of a single severe or two or more exacerbations of any severity is associated with a higher risk of future exacerbations, with observed exacerbation rates and severity that are constant over time. Even one moderate exacerbation over a year is associated with poorer outcomes, compared with the absence of exacerbation, and moderate exacerbations should be managed accordingly.
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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 | 0.004 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".