Table 1.
Patient characteristics.
| Variable | All observations | Suspected COPD | COPD not suspected | Missing values | p valuec | |||
|---|---|---|---|---|---|---|---|---|
| Participants, n (%) | 288 | (100.0) | 76 | (26.4) | 212 | (73.6) | ||
| Age in years, mean (SD) | 63.1 | (6.7) | 63.6 | (6.0) | 62.9 | (7.0) | 0.421 | |
| Male, n (%) | 146 | (50.7) | 43 | (56.6) | 103 | (48.6) | 0.232 | |
| Ethnicity, n (%) | 0.394 | |||||||
| Caucasian | 283 | (98.3) | 74 | (97.4) | 209 | (98.6) | ||
| Asian | 2 | (0.7) | 1 | (1.3) | 1 | (0.5) | ||
| Afro-Caribbean | 1 | (0.3) | 0 | (0.0) | 1 | (0.5) | ||
| Other | 2 | (0.7) | 1 | (1.3) | 1 | (0.5) | ||
| BMI kg/m2, mean (SD) | 29.2 | (5.3) | 28.5 | (5.6) | 29.5 | (5.2) | 0.188 | |
| Practice IMD decile (median, IQR) | 9 | (8,10) | 9 | (8,10) | 9 | (8,10) | n/a | |
| Smoking status (n, %) | 0.076 | |||||||
| Current smoker | 66 | (22.9) | 23 | (30.3) | 43 | (20.3) | ||
| Ex-smoker | 222 | (77.1) | 53 | (69.7) | 169 | (79.7) | ||
| Smoking pack years (median, IQR) | 20 | (8,36) | 29.3 | (15,45) | 17.4 | (7,33.5) | <0.001 | |
| Symptoms, n (%) | ||||||||
| Cough | 162 | (56.3) | 52 | (68.4) | 110 | (51.9) | 0.013 | |
| Dyspnoea | 140 | (48.6) | 42 | (55.3) | 98 | (46.2) | 0.176 | |
| Wheeze | 118 | (41.0) | 43 | (56.6) | 75 | (35.4) | 0.001 | |
| Sputum | 89 | (30.9) | 29 | (38.2) | 60 | (28.3) | 0.111 | |
| MRC breathlessness score, n (%) | 287 | 75 | 212 | 1 | 0.060 | |||
| 1 | 129 | (44.9) | 25 | (33.3) | 104 | (49.1) | ||
| 2 | 119 | (41.5) | 34 | (45.3) | 85 | (40.1) | ||
| 3 | 27 | (9.4) | 12 | (17.4) | 15 | (7.1) | ||
| 4 | 11 | (3.8) | 4 | (5.3) | 7 | (3.3) | ||
| 5 | 1 | (0.3) | 0 | (0.0) | 1 | (0.4) | ||
| FENO (median, IQR) | 21 | (13,33) | 22 | (12,36) | 21 | (14,33) | 64 | 0.568 |
| FEV1 litres, mean (SD) | 2.65 | (0.70) | 2.38 | (0.66) | 2.75 | (0.68) | 3 | <0.001 |
| FEV1 % predicted (median, IQR) | 99 | (87,109) | 87.5 | (74,98) | 104 | (92,113) | 3 | <0.001 |
| FEV1/FVC ratio (median, IQR) | 74 | (69,79) | 65 | (60,68) | 77 | (73,80.5) | 3 | <0.001 |
| FEV1/VC ratio (median, IQR) | 76 | (70,81) | 66 | (59.5,69) | 79 | (75,83) | 19 | <0.001 |
| FEF 25–75% predicted (median, IQR) | 62 | (45.5,82) | 38 | (27.3,46) | 71 | (57,90) | <0.001 | |
| Co-morbidities, n (%) | ||||||||
| Respiratory tract infection in the past 12 months | 67 | (23.3) | 18 | (23.7) | 49 | (23.1) | 0.919 | |
| Asthma | 85 | (29.5) | 34 | (44.7) | 51 | (24.1) | 0.001 | |
| Depression or anxiety | 70 | (24.3) | 17 | (22.4) | 53 | (25.0) | 0.646 | |
| Gastro-oesophageal reflux disease (GORD) | 39 | (13.5) | 8 | (10.5) | 31 | (14.6) | 0.371 | |
| Endocrine diseasea | 60 | (20.8) | 20 | (26.3) | 40 | (18.9) | 0.170 | |
| Cardiac diseaseb | 49 | (17.0) | 12 | (15.8) | 37 | (17.5) | 0.741 | |
| Chronic rhino-sinusitis | 16 | (5.6) | 2 | (2.6) | 14 | (6.6) | 0.195 | |
| Allergic rhinitis | 16 | (5.6) | 7 | (9.2) | 9 | (4.2) | 0.105 | |
| Pneumonia | 8 | (2.8) | 3 | (3.9) | 5 | (2.4) | 0.470 | |
Data are presented as n (%), mean (standard deviation) or median (interquartile range), unless otherwise stated.
IMD index of multiple deprivation (a weighted standardised measure of socioeconomic status), BMI body mass index, FEV1 forced expiratory volume in 1 s, FVC forced vital capacity.
aEndocrine disease is defined as either of diabetes mellitus or hypothyroidism.
bCardiac disease is defined as any of ischaemic heart disease, hypocholesterolaemia, myocardial infarction or atrial fibrillation.
cAll p values computed using tests appropriate for the type and distribution of each variable: t test for age, BMI, FEV1 (litres); Mann–Whitney U test for smoking pack-years, FEV1 %predicted, FEV1/FVC ratio, FEV1/VC ratio, FEF 25–75 %predicted; Chi-squared test for sex, ethnicity, smoking status, MRC breathlessness score, all symptoms and all comorbidities.