Table 2.
Linear Models of SGRQ Total Score Among Participants With COPD in the COPDGene Study, Ages 50 to 80 Years (n = 4,097)
| Variable | β (95% CI) |
|---|---|
| Age,a y | |
| < 65 | Reference |
| ≥ 65 | −3.0 (−3.9 to −2.0) |
| Interaction age × dyspneab | |
| Effect of severe dyspnea if age < 65 y | 24.6 (23.2-25.9) |
| Effect of severe dyspnea if age ≥ 65 y | 21.0 (19.6-22.3) |
| Mean score difference by age when dyspnea is severe | −4.4 (−5.5 to −3.2) |
| Demographic factors | |
| Sex | |
| Male | Reference |
| Female | −0.3 (−1.2 to 0.6) |
| Race | |
| Non-Hispanic white | Reference |
| African American | 3.0 (1.9-4.1) |
| Smoking status | |
| Past smoker | Reference |
| Current smoker | 2.3 (1.3-3.2) |
| BMI | |
| < 30 | Reference |
| ≥ 30 | 2.2 (1.2-3.2) |
| Respiratory factors | |
| mMRC dyspnea scorec | |
| < 2 | Reference |
| ≥ 2 | 22.8 (21.8-23.9) |
| Chronic bronchitis | |
| No | Reference |
| Yes | 9.6 (8.5-10.6) |
| Frequent exacerbations | |
| No (< 2/y) | Reference |
| Yes (≥ 2/y) | 6.8 (5.6-8.0) |
Models additionally were adjusted for FEV1 % predicted, time with a COPD diagnosis, and comorbidities. COPDGene = Genetic Epidemiology of COPD; mMRC = modified Medical Research Council; SGRQ = St. George’s Respiratory Questionnaire.
Effect of age unweighted average over both levels of dyspnea.
P < .001.
Effect of severe dyspnea unweighted average over both groups of age.