Table 1.
Characteristics of subjects with asthma–COPD overlap syndrome and those with COPD alone
| Characteristicsa | ACOS | COPD alone | P-value |
|---|---|---|---|
| Unweighted sample, n | 48 | 149 | – |
| Weighted estimate, n | 662,424 | 2,165,367 | – |
| Demographics | |||
| Age (year), mean (SE) | 56 (1.4) | 58 (1.1) | 0.23 |
| Male sex | 75 (53–88) | 67 (58–75) | 0.47 |
| Race/ethnicity | 0.74 | ||
| Non-Hispanic white | 88 (78–94) | 91 (85–94) | |
| Non-Hispanic black | 8 (4–18) | 5 (3–9) | |
| Hispanics | 1 (0–3) | 1 (0–3) | |
| Others | 3 (1–7) | 3 (1–8) | |
| Primary health insurance | 0.80 | ||
| Medicare | 10 (5–21) | 12 (8–19) | |
| Medicaid | 3 (1–12) | 2 (1–4) | |
| Private | 73 (53–86) | 68 (59–76) | |
| No insurance | 2 (0–10) | 5 (3–10) | |
| Others | 12 (4–32) | 12 (7–20) | |
| Medical history | |||
| Body mass index (kg/m2), mean (SE) | 30.1 (1.1) | 27.2 (0.5) | 0.03 |
| Smoking status | |||
| Current smoker | 48 (33–64) | 59 (47–70) | 0.34 |
| Pack-years, mean (SE) | 32 (3.3) | 36 (2.2) | 0.30 |
| ≥10 pack-years | 79 (63–89) | 83 (74–90) | 0.58 |
| Symptoms | |||
| Cough | 33 (17–53) | 37 (29–45) | 0.72 |
| Sputum | 34 (19–53) | 31 (22–42) | 0.78 |
| Wheezing | 72 (48–88) | 35 (27–45) | 0.01 |
| Shortness of breath on exertion | 60 (42–75) | 70 (61–78) | 0.34 |
| Comorbidities | |||
| Coronary heart diseasesb | 10 (3–30) | 15 (9–24) | 0.43 |
| Diabetes | 11 (4–25) | 11 (7–18) | 0.92 |
| Hypertension | 36 (22–53) | 41 (31–52) | 0.62 |
| Renal failure | 9 (2–37) | 2 (1–6) | 0.38 |
| Health care utilization | |||
| Having a routine place for health care | 91 (79–97) | 94 (90–97) | 0.55 |
| Number of health care visits in the past year, mean (SE) | 2 (0.2) | 2 (0.2) | 0.51 |
| Number of health care visits for wheezing in the past year, mean (SE) | 1 (0.5) | 1 (0.3) | 0.64 |
| Overnight hospital stay in the past year | 9 (3–23) | 14 (9–23) | 0.37 |
| Medications for wheezing | 58 (37–77) | 32 (19–49) | 0.01 |
| Oral corticosteroids | 3 (1–21) | 1 (0–5) | 0.47 |
| Inhaled corticosteroids | 5 (1–19) | 0 (0–0) | 0.18 |
| Laboratory tests | |||
| White blood cell count (cells/μL), mean (SE) | |||
| Total | 7,349 (297) | 7,972 (178) | 0.09 |
| Neutrophils | 4,538 (256) | 4,909 (148) | 0.25 |
| Lymphocytes | 1,951 (87) | 2,194 (79) | 0.04 |
| Eosinophils | 272 (44) | 236 (13) | 0.45 |
| Spirometry, mean (SE) | |||
| Baseline FVC (L) | 3.9 (0.2) | 4.0 (0.1) | 0.85 |
| Baseline FEV1 (L) | 2.4 (0.1) | 2.4 (0.1) | 0.97 |
| Baseline PEF (L/min) | 383 (25) | 377 (9) | 0.81 |
| Baseline FEV1 % predicted | 58 (53–62) | 61 (57–64) | 0.32 |
| Baseline FEV1/FVC% | 60 (58–62) | 59 (57–61) | 0.54 |
| Post-bronchodilator FVC (L) | 4.2 (0.2) | 4.0 (0.1) | 0.50 |
| Post-bronchodilator FEV1 (L) | 2.6 (0.1) | 2.5 (0.1) | 0.40 |
| Post-bronchodilator PEF (L/min) | 430 (27) | 402 (10) | 0.33 |
| Post-bronchodilator FEV1 % predicted | 63 (59–67) | 63 (60–67) | 0.92 |
| Post-bronchodilator FEV1/FVC% | 62 (59–65) | 61 (59–63) | 0.50 |
| GOLD stage | 0.07 | ||
| I | 2 (0–16) | 17 (10–25) | |
| II | 84 (73–91) | 63 (50–74) | |
| III | 14 (6–27) | 19 (12–30) | |
| IV | 0 (0–0) | 1 (0–6) | |
Notes:
a
Data are expressed as % (95% confidence interval) unless otherwise indicated.
b
Coronary heart diseases include ischemic heart disease, angina, myocardial infarction, and heart failure.
Abbreviations: ACOS, asthma–COPD overlap syndrome; COPD, chronic obstructive pulmonary disease; GOLD, the Global initiative of chronic Obstructive Lung Disease; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; PEF, peak flow; SE, standard error.