Table 3.
Linear Models of SGRQ Total Score Among Participants With COPD in SPIROMICS, Ages 50 to 80 Years (n = 1,522)
| Variable | β (95% CI) |
|---|---|
| Age,a y | |
| < 65 | Reference |
| ≥ 65 | −4.2 (−5.7 to −2.6) |
| Interaction age × dyspneab | |
| Effect of severe dyspnea if age < 65 y | 16.9 (14.6-19.2) |
| Effect of severe dyspnea if age ≥ 65 y | 13.9 (11.7-16.0) |
| Mean score difference by age when dyspnea is severe | −6.2 (−8.7 to −3.7) |
| Demographic factors | |
| Sex | |
| Male | Reference |
| Female | 1.5 (0.0-3.0) |
| Race | |
| Non-Hispanic white | Reference |
| African American | 1.7 (−0.5 to 3.8) |
| Smoking status | |
| Past smoker | Reference |
| Current smoker | 3.4 (1.8-5.0) |
| BMI | |
| < 30 | Reference |
| ≥ 30 | 3.5 (1.9-5.0) |
| Respiratory factors | |
| mMRC dyspnea scorec | |
| < 2 | Reference |
| ≥ 2 | 15.3 (13.6-16.9) |
| Chronic bronchitis | |
| No | Reference |
| Yes | 6.1 (4.4-7.9) |
| Frequent exacerbations | |
| No (< 2/y) | Reference |
| Yes (≥ 2/y) | 6.3 (4.2-8.4) |
Models additionally were adjusted for FEV1 % predicted and comorbidities. mMRC = modified Medical Research Council; SGRQ = St. George’s Respiratory Questionnaire; SPIROMICS = Subpopulations and Intermediate Outcome Measures in COPD Study.
Effect of age unweighted average over both levels of dyspnea.
P = .04.
Effect of severe dyspnea unweighted average over both groups of age.