How patient-reported respiratory symptoms relate to lung function and inflammation in adult asthma

Introduction: Knowing which asthma symptom is related to either lung function parameters or inflammatory parameters is important in order to better understand the disease.

Objectives: The main goal was to assess the relationship between the five asthma symptoms, as reported by the patient, and lung function and inflammatory parameters.

Methods: A cross-sectional study was conducted on treated adult (>18 years) asthmatics recruited from the Liege University Hospital Asthma Clinic (Belgium) between 2018 and 2023 (n=505). The intensity of the asthma symptoms was measured by five-point Likert scales (5 expressed the highest intensity). Multiple linear regression analyses (MLRA) were performed to identify the functional and inflammatory parameters independently associated with each asthma symptom.

Results: The mean age of our patients was 51(±16) years and 58%(291) were female. The mean BMI was 27(±5.3). The mean % predicted FEV1 and % FEV1/FVC were 81%(±19) and 74%(±9.7) respectively. The mean cough, airway secretion, chest tightness, dyspnea and wheezing intensity scales were 3(±1), 2.7(±1.2), 2.9(±1.1), 3.4(±1.1) and 2.7(±1.1) respectively. MLRA showed that FEV1% pred., FeNO, blood eosinophils and sputum eosinophils significantly associated with cough intensity (p<0.05 for all). It also revealed that FEV1% pred. and FEV1/FVC% significantly associated with dyspnea (p<0.0001, p<0.01 respectively) and wheezing intensity (p<0.0001, p<0.05 respectively). Finally, only FEV1% pred. significantly associated with chest tightness intensity (p<0.001).

Conclusion: Cough associates with T2 inflammatory parameters, while chest tightness, dyspnea and wheezing associate with impaired spirometric indices.