American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Apr 2021
Mixed Sputum Granulocyte Longitudinal Impact on Lung Function in the Severe Asthma Research Program.
Rationale: Some reports indicate longitudinal variability in sputum differential cell counts, whereas others describe stability. Highly variable sputum eosinophil percentages are associated with greater lung function loss than persistently elevated eosinophil percentages, but elevated neutrophils are linked to more severe asthma. Objectives: To examine sputum granulocyte stability or variability longitudinally and associations with important clinical characteristics. ⋯ Longitudinal neutrophil groups showed few differences. However, a combination of predominantly ≥2% eosinophil and ≥50% neutrophil groups resulted in the lowest prebronchodilator FEV1% predicted (P = 0.049) compared with the combination with predominantly <2% eosinophils and<50% neutrophils. Conclusions: Subjects with predominantly ≥2% sputum eosinophils in combination with predominantly ≥50% neutrophils showed greater loss of lung function, whereas those with highly variable sputum eosinophils had greater healthcare use.