Non-chemical triggers and risk of COPD exacerbation
| Variable type | Variable description | OR | 95% CI | −2log likelihood | |
| Season | Season, ref=summer | 417 | |||
| Summer | 1.00 | 1.00 | 1.0 | ||
| Spring | 2.59 | 1.55 | 4.35 | ||
| Winter | 2.38 | 1.37 | 4.11 | ||
| Fall | 6.64 | 3.83 | 11.5 | ||
| Weather | Spent time in cold air/cold weather in past week* | 1.16 | 0.78 | 1.70 | 468 |
| Spent time in hot air/hot weather in past week* | 0.50 | 0.34 | 0.75 | 457 | |
| Local temperature (categorical)‡ | 422 | ||||
| Cold (<40°F) | 1.0 | 1.0 | 1.0 | ||
| Moderate (40–50°F) | 2.50 | 1.51 | 4.12 | ||
| Warm (>50°F) | 0.55 | 0.36 | 0.84 | ||
| Acute illness | Respiratory infection/cold in past week* | 8.14 | 4.67 | 14.2 | 396 |
| Physical activity | Total hours spent outside of the home*,§ | 0.99 | 0.99 | 1.00 | 469 |
| Exercised in past week* | 0.60 | 0.39 | 0.93 | 462 | |
*Based on self-reports from exposure questionnaires.
†Based on 7-day averages using data from NOAA collected at Worcester Regional Airport.
‡Categorical representation of variable based on cut-offs identified in restricted cubic splines.
§Estimated as the sum of total ‘hours reported outdoors’, ‘hours reported in a vehicle’ and ‘hours reported indoors but not at home’.
COPD, chronic obstructive pulmonary disease.