Researchers at Cambridge have discovered that a lung function test to diagnose asthma is more reliable in the morning and less so throughout the rest of the day. The team used real-world data collected from 1,600 people, which was available in a database designed to speed up innovation and research. They also discovered that the test’s reliability is significantly different during winter as compared with autumn. Asthma, a lung disease that is common and can lead to wheezing or shortness of breathe (sometimes severe), has been studied by researchers in 19659002. In the UK, asthma affects around 6.5% of adults over the age of six. Inhalers and nebulisers are used to deliver medication directly into the lungs.
Most asthma attacks happen at night or in the early morning. This may be partly due to the cooler air at night and to exposure to dust mites or allergens. However, this also indicates that our circadian rhythms – our “body clocks” – likely play an important role. Researchers from the Victor Phillip Dahdaleh Heart and Lung Research Institute (a collaboration between University of Cambridge and Royal Papworth NHS Foundation Trust) wanted to investigate whether circadian rhythms could also impact our ability to detect asthma using clinical tests.
People with asthma are usually offered the spirometry, which is a test that involves inhaling deeply and then exhaling as hard as you can into a tube. This helps to measure lung function. The patient will be given salbutamol in the form of an inhaler, nebuliser or both. They’ll then retake their spirometry tests shortly after. Salbutamol opens up the airways. A positive result, that is, the difference between readings from the first and second spirometer tests, means the patient’s airways were narrower, or blocked, at the beginning. This could indicate asthma. The Electronic Patient Record Research and Innovation database (ERIN), set up by the Cambridge University Hospitals NHS Foundation Trust, allows researchers to access data on patients in a safe environment. This will help them in their research and improve patient care. The Cambridge team used this resource to analyse data of 1,600 patients referred by CUH from 2016-2023. They adjusted the results for age, sex and body mass index, smoking history and severity of initial impairments in lung function. Researchers found in a study published in Thorax (19459008) that the likelihood of the patient having a positive test result, i.e., their lungs reacting to treatment and suggesting they may have asthma, decreased by 8 percent for every hour after 8.30 am. The Lead Respiratory Scientist at RPH Dr Ben Knox Brown said that he was surprised to see the difference between the results of lung function tests during the day and night. Researchers found that autumn tests were associated with a 33% lower chance of a positive test result than winter testing. The difference may be due to a number of factors, according to Dr Akhilesh Jha. He is a Medical Research Council Clinician-Scientist at University of Cambridge, and an Honorary Respiratory Medicine Consultant at CUH. Jha stated
“Our bodies have natural rhythms — our body clocks,” . “Our immune system, for instance, performs differently throughout the day as the levels of hormones fluctuate.” These factors could affect the results of the lung function tests.
“The idea that the time of day, or the season of the year, affects our health and how we respond to treatments is something we’re seeing increasing evidence of. We know, for example, that people respond differently to vaccinations depending on whether they’re administered in the morning or afternoon. The findings of our study further support this idea and may need to be taken into account when interpreting the results of these commonly performed tests.”
