The color of phlegm in patients with bronchiectasis, a lung disease, can indicate the level of inflammation in their lungs and predict their future outcomes, according to a new study presented at the European Respiratory Society International Congress in Milan, Italy [1]. This research, which involved nearly 20,000 patients from 31 countries, is the first to show that the color of phlegm, also known as sputum, can provide clinically relevant information that reflects prognoses and can help guide treatment decisions.
Bronchiectasis is a chronic condition that cannot be cured. It occurs when one or more of the small airways in the lungs, called bronchi, widen, leading to an accumulation of excess mucus that can make the lungs more susceptible to infections. Over time, this can cause progressive damage to the lungs. The causes of bronchiectasis can include lung infections such as pneumonia or whooping cough, cystic fibrosis, underlying immune system problems, or an allergy to certain types of fungi. It is one of the three most common chronic inflammatory airway diseases, along with asthma and chronic obstructive pulmonary disease (COPD). The prevalence of bronchiectasis ranges from 67 to 566 cases per 100,000 people in Europe, North America, the UK, and the USA, and it can affect individuals of any age, although symptoms typically appear in middle age [2].
Dr. Megan Crichton, a postdoctoral researcher at the University of Dundee in the UK, presented the findings from the study. She explained that a productive cough is one of the main characteristics of bronchiectasis, with nearly 75% of patients producing sputum daily. When patients develop chest infections, the color of their sputum darkens due to the release of a protein called myeloperoxidase (MPO) from inflamed cells. As a result, sputum color can serve as a biomarker for inflammation.
The study involved 13,484 out of 19,324 patients who regularly coughed up sputum and were enrolled in the European bronchiectasis registry, EMBARC. The researchers followed these patients for up to five years to assess the number and severity of exacerbations they experienced, as well as mortality rates. Sputum was classified into four levels based on color and texture: mucoid (clear, frothy, and grey-colored), mucopurulent (creamy yellow), purulent (darker yellow or green with a thicker texture), and severe purulent (darker green turning into brown, sometimes with streaks of blood). Among the sputum-producing patients, 40% had mucoid sputum, 40% had mucopurulent sputum, 18% had purulent sputum, and 1% had severe purulent sputum.
The researchers found that patients with more purulent sputum had an increased risk of exacerbations, hospitalizations, and death. For every 1-point increase in sputum purulence, there was a 12% higher risk of death. These findings suggest that sputum color can reflect prognosis and serve as a useful indicator for disease progression.
Dr. Crichton stressed the importance of implementing this biomarker into clinical practice, as sputum samples can be easily collected and sputum color can be readily interpreted. She believes that using sputum color as a means of self-monitoring and self-management can empower patients and improve their quality of life.
The researchers are now focusing on introducing the sputum color chart into clinical practice and determining the best way to help patients use it to monitor their disease severity. These additional findings will be reported to raise awareness among patients, clinicians, and researchers.
According to Professor Carlos Robalo Cordeiro, President of the European Respiratory Society, the study findings offer doctors and patients a non-invasive method for monitoring their symptoms. If implemented in clinical practice, the use of sputum color as an indicator could significantly improve disease management and enable earlier intervention when symptoms worsen.
In conclusion, the study demonstrates the potential of sputum color as a valuable biomarker for bronchiectasis. Monitoring sputum color can provide valuable insights into the level of inflammation in the lungs and help predict future outcomes. By incorporating this information into clinical practice, healthcare professionals can make more informed treatment decisions and improve the monitoring of bronchiectasis patients.
