Biomarkers in the Yale Center for Asthma and Airways Disease (YCAAD), Severe Asthma Research Programme (SARP) and New York University/Bellevue Asthma Registry (NYUBAR) cohorts by YKL-40 asthma cluster
| Total cohort | Cluster 1 | Cluster 2 | Cluster 3 | Cluster 4 | p-value | |
| YCAAD | ||||||
| Subjects | 156 | 76 (49) | 30 (19) | 20 (13) | 30 (19) | |
| Sputum YKL-40 ng·mL−1# | 15 (0–40) | 10 (0–37) | 10 (0–26) | 28 (5–58) | 32 (8–43) | 0.16 |
| Serum IgE IU·mL−1 | 91 (25–277) | 77 (23–220) | 85 (17–328) | 163 (48–341) | 72 (30–351) | 0.40 |
| FENO ppb | 28 (19–53) | 25 (18–55) | 43 (23–60) | 20 (15–35) | 32 (21–50) | 0.02 |
| Absolute blood eosinophil count cells·μL−1 | 165 (86–335) | 136 (84–276) | 170 (101–322) | 192 (86–399) | 170 (91–338) | 0.69 |
| Eosinophils in sputum %# | 3 (1–7) | 2 (1–5) | 4 (2–8) | 2 (1–4) | 5 (2–12) | 0.08 |
| Neutrophils in sputum %# | 37 (27–48) | 34 (27–44) | 37 (24–45) | 46 (34–55) | 43 (29–50) | 0.15 |
| Macrophages in sputum % | 55 (42–65) | 60 (51–67) | 51 (42–67) | 47 (35–55) | 44 (35–58) | <0.01 |
| SARP | ||||||
| Subjects | 167 | 84 (50) | 57 (34) | 14 (8) | 12 (7) | |
| Serum IgE IU·mL−1 | 116 (34–301) | 73 (24–191) | 177 (60–354) | 162 (18–262) | 270 (200–333) | 0.03 |
| FENO ppb | 25 (16–50) | 21 (11–52) | 29 (23–63) | 27 (16–40) | 52 (16–111) | 0.04 |
| Blood eosinophils % | 3 (2–5) | 2.5 (1.8–4.0) | 4.0 (2.0–6.0) | 5.1 (4.0–7.5) | 4.5 (2.3–9.8) | <0.01 |
| NYUBAR | ||||||
| Subjects | 341 | 205 (60) | 97 (28) | 15 (4) | 24 (7) | |
| Serum IgE IU·mL−1 | 129 (41–345) | 119 (31–328) | 197 (74–443) | 130 (52–278) | 94 (46–173) | 0.02 |
Data are expressed as n, n (%) or median (interquartile range). FENO: exhaled nitric oxide fraction. #: data available for n=113 (C1, n=54; C2, n=17; C3, n=18; C4, n=24).