Studies have shown that chronic bronchitis occurs in 18% to 45% of patients with COPD and is associated with a higher risk for exacerbations and hospitalizations as well as an accelerated decline in lung function. However, chronic bronchitis has not been well described in patients with advanced emphysema. “The data regarding mortality in this patient population are conflicting,” says Victor Kim, MD. “Few studies have assessed the effects of chronic bronchitis on hospitalization rates in those with advanced emphysema.”
A Novel Concept
Severe chronic bronchitis is a novel concept, according to Dr. Kim, MD, lead author of a study published in the journal COPD that investigated this relationship. “We defined severe chronic bronchitis as the presence of cough and sputum along with chest trouble based on patient responses to the St. George’s Respiratory Questionnaire (SGRQ), a measure of health-related quality of life (HRQOL),” he says.
Patients who had been randomized to medical therapy in the National Emphysema Treatment Trial were grouped by Dr. Kim and colleagues into those with or without chronic bronchitis. “The classic definition of chronic bronchitis is based on affirmative answers to questions about the presence of cough and sputum for 3 months out of the year for at least 2 consecutive years,” Dr. Kim explains. Participants were then categorized into those with severe chronic bronchitis or no severe chronic bronchitis based on the presence of chest trouble. Associations between chronic bronchitis and severe chronic bronchitis with all-cause mortality and time to all-cause hospitalization were assessed. Lung function and SGRQ scores over time were also compared between groups.
“Emphysema and chronic bronchitis are generally thought to exist on opposite ends of the spectrum, with most patients falling somewhere in the middle,” says Dr. Kim. “But our study showed that patients who have emphysema by every clinical criteria—including physical exams, lung function studies, and CAT scans—can still endorse cough and phlegm; this fits our severe chronic bronchitis definition.” Study participants with and without chronic bronchitis had similar survival rates (about 60 months) and time-to-hospitalization (about 25 months). However, those with severe chronic bronchitis had substantially worse survival (47.7 vs 65.7 months) and time-to-hospitalization (18.5 vs 26.7 months) than those without severe chronic bronchitis. Patients with severe chronic bronchitis also had significantly worse HRQOL scores.
According to Dr. Kim, it is important for future research to determine the causes of chronic bronchitis in patients with COPD. Until these data emerge, Dr. Kim says that the identification of cough and phlegm in patients with COPD should heighten a provider’s suspicion for exacerbations. “It should spark the consideration of more aggressive medical therapy to lower the risk for these exacerbations.” he says.