A paper published in the international Journal of COPD, entitled “Respiratory infectious phenotypes in acute exacerbation of COPD: an aid to length of stay and COPD Assessment Test,” indicated how parameters such as respiratory infectious phenotypes, the COPD Assessment Test (CAT), and length of stay (LOS) influence exacerbation of patients with chronic obstructive pulmonary disease (COPD).

Chronic obstructive pulmonary disease is identified by inflamed lung airways that cause obstructed airflow throughout the lungs. In the U.S., it affects some 32 million people and is the third leading cause of death, carrying a social and economic burden that is expected to increase in coming decades. Even though causes of COPD are not fully understood, it is believed that long-term exposure to irritating gasses or particulate matter, most often from chemicals, tobacco smoking, air pollution, and fumes, contribute to the development of COPD.

Respiratory infections are known to play a key role in triggering a sudden worsening of COPD symptoms (exacerbation), but the types of respiratory tract viruses and bacteria common in the disease are not as well understood. To provide a better understanding of the connection between respiratory infections and exacerbations, the researchers examined respiratory infectious phenotypes and their influence on two instrument criteria: 1) length of stay (LOS), and 2) COPD Assessment Test (CAT) scale during exacerbations of COPD. The parameter LOS typically indicates more fragile patients who require increased attention, and CAT provides consistency and test-retest reliability.

In this study, a total of 81 eligible patients with COPD participated. The patients were randomized by type of infection into several groups: 1) bacterial infection, 2) viral infection, 3) co-infection with both species viruses/bacteria, and 4) non-infectious groups. Then, data related to LOS, CAT, and demographic information were recorded and analyzed. The results suggested that 38 patients confirmed infection with viruses, 17 with bacteria, and 7 patients with both viruses/bacteria. Typical viruses found in patients include influenza, enterovirus/rhinovirus, coronavirus, bocavirus, metapneumovirus, parainfluenza virus types 1, 2, 3, and 4, and respiratory syncytial virus. Common identified bacteria include Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella, Escherichia coli, and Streptococcus pneumoniae.

Researchers conclude these findings demonstrate that exacerbations in COPD are often caused by respiratory infection with viruses and bacteria. When co-infection with both species viruses/bacteriais involved, severe acute exacerbations characterized by longer LOS result. Analysis of data confirmed positive correlation between CAT and LOS, and CAT could predict longer LOS with both infections bacteria/viruses. Finally, influenza is ranked as most common virus, which killed two infected patients during the study, and thus is potentially a public health threat. However, whether infection with influenza could be attributed to mortality of COPD exacerbations is not yet clear and requires future investigation.