Table 1 Characteristics of the cohort at index date
From: Blood neutrophil counts are associated with exacerbation frequency and mortality in COPD
All | Normal index BNC | Elevated index BNC | Significance | |
|---|---|---|---|---|
n | 7220 | 4465 (62%) | 2462 (34%) | |
Age | 75 (65, 81) | 72 (64, 80) | 74 (67, 82) | P < 0.001 |
Male Gender | 3470 (48%) | 2149 (48%) | 1171 (48%) | P = 0.67 |
BMI | 28 (24, 31) | 28 (24, 31) | 28 (23, 32) | P = 0.63 |
ICS usea | 4525 (63%) | 2680 (60%) | 1635 (66%) | P < 0.001 |
LABA only | 146 (2%) | 101 (2%) | 42 (2%) | P = 0.14 |
LAMA only | 555 (8%) | 339 (8%) | 196 (8%) | P = 0.61 |
LABA & LAMA | 168 (2%) | 103 (2%) | 58 (2%) | P = 0.96 |
SABA | 6068 (84%) | 3672 (82%) | 2137 (87%) | P < 0.001 |
Current smokers | 3494 (48%) | 2104 (47%) | 1264 (51%) | P = 0.02 |
Ex-smokers | 3300(46%) | 2071 (46%) | 1078 (44%) | |
Spirometry | P < 0.001 | |||
FEV1 (Litres) | 1.58 (1.11, 1.98) | 1.64 (1.23, 1.91) | 1.49 (1.00, 1.87) | |
GOLD 2017 | P = 0.002 | |||
A | 332 (8%) | 243 (9%) | 82 (6%) | |
B | 2174 (51%) | 1464 (54%) | 646 (46%) | |
C | 132 (3%) | 99 (4%) | 30 (2%) | |
D | 1620 (38%) | 888 (33%) | 634 (46%) | |
Index total white cell count (cells/μL) | 8300 (6900, 1030) | 7300 (6300, 8300) | 10,800 (9700, 12,600) | P < 0.001 |
Index BNC (cells/μL) | 5200 (4000, 7000) | 4300 (3600, 5100) | 7600 (6600, 9400) | P < 0.001 |
Index eosinophil count (cells/μL) | 180 (90, 290) | 200 (120, 300) | 150 (60, 280) | P < 0.001 |
< 150 | 2960 (41%) | 1518 (34%) | 1206 (49%) | |
> 150; < 300 | 2521 (35%) | 1765 (40%) | 720 (30%) | |
> 300; < 500 | 1253 (17%) | 869 (19%) | 369 (15%) | |
> 500 | 486 (7%) | 313 (7%) | 167 (7%) | |
Exacerbation frequency (year to index date) | P < 0.001 | |||
0 | 2679 (37%) | 1797 (40%) | 792 (32%) | |
1 | 1653 (23%) | 1075 (24%) | 535 (22%) | |
2 | 1033 (14%) | 606 (14%) | 380 (15%) | |
3 or more | 1855 (26%) | 987 (22%) | 755 (31%) | |
Severe exacerbation (year to index date) | 577 (8%) | 162 (4%) | 334 (14%) | |
Exacerbation frequency (year from index date) | P < 0.001 | |||
0 | 2989 (41%) | 1870 (42%) | 988 (40%) | |
1 | 1549 (21%) | 1019 (23%) | 493 (20%) | |
2 | 1005 (14%) | 649 (15%) | 329 (13%) | |
3 or more | 1677 (23%) | 927 (21%) | 652 (26%) | |
Severe exacerbation (year from index date) | 633 (9%) | 245 (5%) | 322 (13%) | |
Crude mortality rate (per 100 person-years) | 10.0 | 7.9 | 14.0 | P < 0.001 |