In a new study, researchers at Lund University in Sweden suggested that females could be an independent risk factor for chronic obstructive pulmonary disease (COPD), with the risk of developing the disease possibly twice as high among women as it is for men. The study, “Incidence of airflow limitation in subjects 65-100 years of age,” was published in The European Respiratory Journal.

COPD is a broad term used to describe chronic lung diseases that lead to impairment of lung airflow. According to the World Health Organization (WHO), COPD will become the third leading cause of death worldwide by 2030. Currently, the real incidence of COPD remains largely unknown, especially due to the few existing studies that have examined who is at risk of developing the disease.

These studies have used outdated and unreliable diagnostic methods no longer recommended by European Respiratory Society (ERS) or the American Thoracic Society (ATS). Specifically, these older methods, which rely on spirometry data to interpret lung function, do not take into account the age or sex of patients, factors that are known or suspected to influence pulmonary function. Established risk factors include smoking and air pollution.

Now, a team led by Dr. Johannes Luoto used more advanced diagnostic criteria, where factors such as age and gender were taken into consideration before evaluation and interpretation of spirometry results in order to identify possible COPD risk factors. The team assessed a population of 2,300 people who were between 65 and 100 years old.

The results showed that, using the more modern method Lower Limit of Normal (LNN) significantly affected the observations made by researchers. Although previous studies had suggested that women’s airways could be more sensitive, no older diagnostic method had shown with certainty that the female gender was indeed a risk factor for COPD.

“We see a clear increased risk for women contracting COPD compared with the risk for men,” Luoto said in a press release.  “And it applies even when other risk factors, such as smoking and age, are taken into consideration. Researchers and the doctors involved have not yet agreed on the method that is to be used in practice. Further studies are needed to compare the methods.”