Seasonal and Regional Variations in Chronic Obstructive Pulmonary Disease Exacerbation Rates in Adults without Cardiovascular Risk Factors
Bibliographic record
Abstract
RATIONALE: Colder temperatures have been shown to increase hospitalization and mortality rates in adults with chronic obstructive pulmonary disease (COPD) and cardiac disease. Seasonal influences on exacerbation rates in adults with severe COPD but without significant cardiovascular disease are unclear. In addition, regional variations in COPD exacerbations in North America have not yet been explored. OBJECTIVES: In this study, we sought to determine the seasonal and regional variability in exacerbation rates in those with COPD but without significant cardiovascular risk factors. METHODS: We studied adults without cardiovascular risk factors from STATCOPE (Simvastatin in the Prevention of COPD Exacerbations) and placebo arm of MACRO (Azithromycin for the Prevention of Exacerbations of COPD) studies. Forty-five study sites were divided into climate regions in Canada and the United States; seasons were defined as winter, spring, summer, and fall. The primary outcome was the rate of COPD exacerbation. Secondary outcomes included time to first exacerbation, severity of exacerbations, all-cause mortality, and antibiotic and steroid use. RESULTS: We analyzed 1,175 subjects with a mean age of 63.3 ± 8.6 years, forced expiratory volume in 1 second of 41.5 ± 17.1% predicted, and 53.6 ± 29.4 pack-years of smoking history. The COPD exacerbation rate was higher in winter (0.13 exacerbations/person-month) than in spring, summer, and fall (0.11, 0.079, and 0.10 exacerbations/person-month, respectively) (P < 0.001). Summer had the highest proportion of severe exacerbations (40.5%) compared with spring, fall, and winter (32.6%, 34.7%, and 33.1%, respectively) (P = 0.004). Mortality was highest in spring and winter (34% and 30%, respectively). There was significant regional variability in the time to first exacerbation, with the Southeast and West having longer median times to first exacerbation (350 and 342 d, respectively, compared with 184 d in other regions) (P < 0.001). CONCLUSIONS: Significant seasonal and regional variability exist in the rate and severity of exacerbations and overall mortality in adults with COPD without cardiovascular disease.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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".