Introduction: Stable state blood eosinophil counts (BEC) should be used to guide inhaled corticosteroid (ICS) treatment in COPD as BEC may drop during acute illness. Expedient treatment decisions are challenged by the availability and stability of BEC; a reliable surrogate would be helpful.
Aims: The blood eosinophils in COPD (BECCOPD) study is assessing whether the highest of ?3 BEC within 24 months (historical BEC) is a surrogate for stable state BEC. We investigated the variability between historical and stable state BEC, and two prospective stable state BECs.
Methods: Patients were recruited from primary and secondary care. Stable state BEC were collected on study entry and after at least 3 months. We compared the agreement between study entry BEC, and historical and second stable state BEC.
Results: 295 participants were recruited, 196 included in this analysis. Mean (SD) age 71 (7), mean FEV1% predicted 55 (23). 52% were male, median eMRCD 3 (3-4). Agreement between BEC samples is tabulated below.
| Historical BEC | Historical BEC | Stable state BEC | Stable state BEC | ||
| <0.1 | 0.1+ | <0.1 | 0.1+ | ||
| Study entry BEC | <0.1 | 11 | 19 | 16 | 14 |
| Study entry BEC | 0.1+ | 4 | 162 | 18 | 148 |
| Agreement | 173/196 | 88% | 164/196 | 84% | |
| <0.3 | 0.3+ | <0.3 | 0.3+ | ||
| Study entry BEC | <0.3 | 107 | 49 | 142 | 14 |
| Study entry BEC | 0.3+ | 8 | 32 | 14 | 26 |
| Agreement | 139/196 | 71% | 168/196 | 86% |
Conclusion: Historical BEC showed good agreement at the 0.1 threshold and is a reasonable surrogate when a stable state BEC is unavailable. Historical BEC offered reasonable performance at the 0.3 threshold but with greater variation.
Acknowledgements: The BECCOPD study is funded by GSK via the supported studies program.