But are acute respiratory events associated with a decline in lung function in smokers without airway obstruction?
Exacerbations of chronic obstructive pulmonary disease (COPD) are associated with accelerated lung function loss in patients who have established COPD. The greatest loss occurs in patients who have mild disease.
Self-reported acute respiratory event data were examined on the first 2000 patients who returned for a second visit to COPDGene, a study of more than 10,000 current and former smokers, some with COPD, 5 years after enrollment.
Researchers at the University of Alabama at Birmingham and the Birmingham VA Medical Center, Medicine/Pulmonary, Allergy and Critical Care, and other centers defined exacerbations (and acute respiratory events in patients who did not have established COPD) as acute respiratory symptoms that require antibiotics or systemic steroids.
Severe events were defined by the need for hospitalization; patients were grouped by COPD severity based on Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines.
Linear mixed models were used to fit forced expiratory volume in 1 second (FEV1) decline based on reported exacerbations or acute respiratory events.
Exacerbations were associated with excess FEV1 decline in patients with COPD. The greatest effect in occurred in GOLD 1, where each exacerbation was associated with an additional 23 mL/year decline and each severe exacerbation with an additional 87 mL/year decline. GOLD 2 and 3 patients had statistically significant but smaller effects.
The researchers found that acute respiratory events are not associated with additional FEV1 decline in patients who do not have airflow obstruction.
The study was published online on October August 24, 2016 in the American Journal of Respiratory and Critical Care Medicine.