On September 17, the New Zealand Medical Institute published a paper by Richard Beasley in the Annals of the American Thoracic Society titled “Prevalence and Clinical Characteristics of Persistent Airflow Limitation in the NOVELTY Cohort“.
This large-scale study, based on the NOVELTY observational longitudinal cohort, explores the prevalence, clinical characteristics, and prognostic significance of Persistent Airflow Limitation (PAL) in patients with asthma and Chronic Obstructive Pulmonary Disease (COPD).
The study included 9081 patients aged 12 years and older from primary and secondary healthcare institutions in 18 countries, comprising 4754 asthma patients, 1147 asthma patients with comorbid COPD, and 3180 COPD patients.
The study defined PAL using two criteria: the lower limit of normal range as per the European Respiratory Society/American Thoracic Society (ERS/ATS) and the fixed ratio of 0.7 as per the Global Initiative for Chronic Obstructive Lung Disease (GOLD).
The results showed that the prevalence of PAL at baseline was 24.2% and 29.2% in asthma patients, 63.3% and 74.1% in asthma patients with comorbid COPD, and 65.4% and 75.8% in COPD patients.
The study found that patients with PAL had a significantly increased symptom burden and a higher frequency of moderate to severe acute exacerbations. In asthma patients, PAL was associated with higher levels of blood eosinophils and exhaled nitric oxide (FeNO) values, with 60% of asthma patients with PAL being never-smokers.
The study also found that 84% of baseline PAL patients still met the PAL criteria after three years, indicating that it is a stable pathological feature. Regardless of the initial diagnosis by the physician, PAL is an important marker for increased risk of moderate to severe acute exacerbations and poor symptom control during the three-year follow-up.
The study concluded that persistent airflow limitation is a stable pathological feature associated with more severe disease and poor prognosis, holding significant clinical predictive value for adult patients diagnosed with asthma and/or COPD. These findings emphasize the importance of assessing and monitoring airflow limitation in the management of asthma and COPD.