Table 2– Clinical features of subjects with chronic obstructive pulmonary disease (COPD) and asthma compared to those with COPD alone
COPDCOPD and asthmaEffect sizep-value
Females1335 (42.8)252 (56.0)1.59 (1.29–1.95)<0.001
African–American627 (20.1)167 (37.1)1.74 (1.39–2.18)<0.001
Bronchodilator responsiveness1120 (36.1)177 (39.4)1.19 (0.97–1.47)0.10
Absolute BDR L0.09±0.160.11±0.160.02±0.0080.03
BODE score2.9±2.13.1±2.00.25±0.10.02
SGRQ score39.7±21.547.4±22.76.81±1.1<0.001
Exacerbations per year0.7±1.21.2±1.60.56±0.06<0.001
Severe exacerbations646 (20.7)153 (34.0)1.70 (1.36–2.12)<0.001
Hay fever442 (17.8)186 (50.3)4.66 (3.68–5.90)<0.001
High school graduates1828 (58.6)261 (58.0)1.10 (-0.19–0.39)0.54
Maternal asthma162 (7.0)57 (19.0)2.22 (1.59–3.12)<0.001
Paternal asthma123 (5.9)47 (17.5)2.64 (1.82–3.83)<0.001
  • Data are presented as n (%) or mean±sd, unless otherwise stated. Effect size data are presented as OR (95% CI) or β±se. Linear and logistic regression models were adjusted for age, race, sex and pack-years. BDR: bronchodilator response (>200 mL and 12% change in forced expiratory volume in 1 s); BODE: body mass index, airflow obstruction, dyspnoea and exercise capacity; SGRQ: St George’s Respiratory Questionnaire.