Relationship between airway pathophysiology and airway inflammation in older asthmatics

Background and objective Asthma‐related morbidity is greater in older compared with younger asthmatics. Airway closure is also greater in older asthmatics, an observation that may be explained by differences in airway inflammation. We hypothesized that in older adult patients with asthma, neutrophil airway inflammation increases airway closure during bronchoconstriction, while eosinophil airway inflammation increases airway hyperresponsiveness (AHR). Methods Asthmatic subjects (n = 26), aged ≥55 years (68% female), were studied, and AHR to 4.5% saline challenge was measured by the response–dose ratio (%fall in forced expiratory volume in 1 s (FEV1)/mg saline). Airway closure was assessed during bronchoconstriction percent change in forced vital capacity (FVC)/percent change in FEV1 (i.e. Closing Index). Airway inflammation was assessed by induced sputum and exhaled nitric oxide (eNO). Results Mean patient age was 67 years (confidence interval: 63–71) with a mean FEV1 of 78 % predicted (confidence interval: 70–85%). AHR correlated with sputum eosinophils (r = 0.68, P = 0.005) and eNO (r = 0.71, P