Is there a link between lung function and asthma symptoms?
Published online: April 26, 2019
The main goal of asthma treatment is to control the disease. Measures of asthma control include testing how well a patient’s lungs are working and how severe the patient’s symptoms are. The forced expiratory volume in 1 second (FEV1) test measures lung function. It shows how much air a patient can forcefully exhale in 1 second. The percentage of predicted FEV1 (FEV1%pred) compares how much the patient can exhale with how much a person without lung disease could exhale. The Asthma Control Questionnaire (ACQ) measures how severe a patient’s symptoms are. Questions in the ACQ ask about the patient’s symptoms during the past week.
Researchers often use FEV1%pred and the ACQ to test lung function and asthma symptoms in clinical trials. These tests help to show how well a treatment can control asthma. However, researchers disagree about how well the results of these tests are linked. In a new study published in The Journal of Allergy and Clinical Immunology: In Practice, Dr. Patrick Sullivan and colleagues investigated whether there is a link between the clinical measure of lung function (using FEV1%pred) and patient-reported asthma symptoms (ACQ scores).
The study included data from 1,748 patients in Colorado, USA, who had taken part in an earlier survey-based study of asthma control and outcomes. All patients were older than 12 years of age and had asthma symptoms more than twice a week. The researchers compared the FEV1%pred and ACQ results collected in the earlier study. They found that there was a weak link between having worse FEV1%pred scores and worse ACQ scores, but the link was stronger when the researchers also considered other patient traits (age, gender, income, race, education level, ethnicity, and smoking status).
The main takeaway of this study is that clinical lung function tests such as FEV1%pred may not measure the same thing as patient symptoms. If lung function improves in a study, we may not see a matching improvement in asthma symptoms; similarly, if the patient feels better, we may not see a matching improvement in lung function. Therefore, researchers need to both assess lung function and measure patient symptoms in future clinical studies to show how well a treatment is controlling a patient’s asthma because both tests measure different aspects of asthmatic disease.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.