Subjects in cluster H (neutrophilic disease with severe obstruction and low periostin levels) have high sputum neutrophil counts with fixed airflow obstruction (low prebronchodilator and postbronchodilator FEV1) associated with very high symptom scores (median ACQ7, 3.3-3.4) and low serum periostin levels. Here, POSTN is linked to functional neutrophil defect.