Baseline characteristics by longitudinal blood eosinophil group over 12 months for the 99 patients with sufficient data
| Rarely eosinophilic | Intermittently eosinophilic | Predominantly eosinophilic | p-value++ | |
| Patients | 26 | 19 | 59 | |
| Continuous variables | ||||
| Age | 62.7±8.63 | 67.9±6.87 (n=16) | 68.0±9.05 (n=57) | 0.034 |
| Smoking history pack-years | 46.3±22.8 | 64.9±43.2 (n=16) | 51.0±28.6 (n=57) | 0.098 |
| Body mass index kg·m–2 | 28.2 (8.15) | 27.9 (5.69) (n=16) | 25.9 (4.73) (n=57) | 0.280 |
| Fat-free body mass % | 53.5 (21.5) (n=25) | 49.3 (18.3) (n=16) | 48.8 (22.4) (n=56) | 0.886 |
| White blood cells count ×109 L–1 | 8.30 (3.30) (n=25) | 7.65 (1.65) (n=16) | 7.30 (2.00) (n=57) | 0.060 |
| Blood eosinophils count ×109 L–1 | 0.10 (0.10) (n=25) | 0.20 (0.10) (n=16) | 0.30 (0.20) (n=57) | NA |
| Blood eosinophils % | 1.35 (1.45) (n=25) | 2.12 (1.09) (n=16) | 4.08 (3.05) (n=57) | NA |
| Blood neutrophils count ×109 L–1 | 5.20 (2.55) (n=25) | 4.80 (0.50) (n=16) | 4.30 (1.75) (n=57) | 0.030 |
| Fibrinogen g·L–1 | 4.70 (1.40) (n=23) | 4.75 (0.97) (n=14) | 4.80 (0.90) (n=51) | 0.905 |
| C-reactive protein mg·L–1 | 4.00 (7.50) | 5.00 (5.75) (n=16) | 5.00 (7.00) (n=57) | 0.966 |
| Sputum eosinophils %# | 0.43 (2.89) (n=18) | 0.82 (1.78) (n=7) | 2.81 (7.40) (n=40) | 0.070 |
| Sputum neutrophils %# | 9.77 (64.0) (n=18) | 62.3 (63.4) (n=7) | 38.0 (71.6) (n=40) | 0.223 |
| FEV1 % | 47.7 (25.6) | 43.9 (22.4) (n=16) | 47.5 (26.0) (n=57) | 0.661 |
| ΔFEV1 % of baseline¶ | 3.79 (27.3) (n=19) | 10.8 (23.2) (n=15) | 5.03 (21.4) (n=45) | 0.375 |
| FEV1 reversibility % of pre-bronchodilator FEV1+ | 7.69 (15.0) (n=24) | 17.9 (16.6) (n=13) | 12.6 (12.5) (n=46) | 0.355 |
| KCO % | 74.2 (31.0) (n=25) | 68.3 (26.7) (n=16) | 69.3 (30.3) (n=53) | 0.526 |
| TLCO % | 62.0 (41.1) (n=25) | 57.8 (28.8) (n=16) | 56.3 (27.7) (n=53) | 0.407 |
| CAT score | 15.5 (10.0) | 20.5 (13.0) (n=16) | 16.0 (9.00) (n=57) | 0.101 |
| 6MWT distance m | 300 (199) (n=25) | 323 (172) (n=16) | 327 (164) (n=56) | 0.914 |
| EXACT-PRO score | 36.0 (14.0) (n=23) | 36.5 (7.00) (n=14) | 36.0 (15.0) (n=46) | 0.607 |
| Exacerbation rate in year before study | 2.00 (3.00) | 2.00 (3.00) (n=16) | 2.00 (2.00) (n=57) | 0.941 |
| Exacerbation rate in first year of study | 2.47 (3.22) | 1.02 (2.00) (n=16) | 2.04 (3.95) (n=57) | 0.197 |
| Eosinophilic exacerbation rate in first year of study | 0.00 (0.99) | 0.00 (0.99) (n=16) | 1.38 (2.99) (n=57) | <0.001 |
| Follow-up in first year of study years | 1.01 (0.02) | 1.01 (0.01) (n=16) | 1.01 (0.02) (n=57) | 0.448 |
| Categorical variables | ||||
| Sex | ||||
| Male | 12 (46) | 9 (56) | 34 (60) | 0.547 |
| Female | 14 (54) | 7 (44) | 23 (40) | |
| Current smoker§ | ||||
| Yes | 15 (58) | 4 (25) | 24 (42) | 0.125 |
| No | 11 (42) | 12 (75) | 33 (58) | |
| Use of ICS at enrolmentƒ | ||||
| Yes | 21 (81) | 15 (94) | 51 (89) | 0.468 |
| No | 5 (19) | 1 (6) | 6 (11) | |
| Sputum eosinophils >3%# | ||||
| Yes | 2 (11) | 0 (0) | 19 (48) | 0.003 |
| No | 16 (89) | 7 (100) | 21 (53) | |
| Blood eosinophils ≥2% | ||||
| Yes | 7 (28) | 9 (56) | 55 (96) | NA |
| No | 18 (72) | 7 (44) | 2 (4) | |
| Bacteria present## | ||||
| Yes | 12 (55) | 6 (50) | 26 (50) | 0.952 |
| No | 10 (45) | 6 (50) | 26 (50) | |
| Virus present¶¶ | ||||
| Yes | 4 (19) | 0 (0) | 10 (20) | 0.288 |
| No | 17 (81) | 12 (100) | 40 (80) |
Data are presented as n for patient numbers, mean±sd or median (interquartile range) for continuous variables, or n (%) for categorical variables, unless otherwise stated. FEV1: forced expiratory volume in 1 s; KCO: transfer coefficient of the lung for carbon monoxide; TLCO: transfer factor of the lung for carbon monoxide; CAT: COPD Assessment Test; 6MWT: 6-min walk test; ICS: inhaled corticosteroid; NA: not appropriate. #: sputum eosinophil and neutrophil percentage at baseline is reported (“baseline” is equal to enrolment if good quality data (squamous cell contamination <30%) is present at enrolment or the next (pre-exacerbation) stable visit with quality data within 4 months of enrolment); ¶: calculated as FEV1 at month 12×100/FEV1 at enrolment; +: calculated as (post-bronchodilator FEV1–pre-bronchodilator FEV1)/pre-bronchodilator FEV1×100; §: smoking status report derived from American Thoracic Society Division of Lung Disease questionnaire ATS-DLD-78A; ƒ: ICS use was coded as “Yes” if one of the following medications/inhalers was on the list: Symbicort, Seretide, QVAR, Fostair, beclomethasone, beclomethasone/formoterol, beclomethasone dipropionate, Clenil, fluticasone/salmeterol or budesonide/formoterol; ##: sputum sampling, measured by culture (includes Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae, Staphylococcus aureus and Pseudomonas aeruginosa); ¶¶: sputum sampling, measured by PCR (includes adenovirus, enterovirus, influenza, coronavirus, metapneumovirus, bocavirus, parainfluenza, respiratory syncytial virus and rhinovirus); ++: test for differences between the three longitudinal eosinophil groups (Kruskal–Wallis test for continuous variables; Chi-squared test for categorical variables).