In a new study, researchers at the Hospital of Anhui Medical University explored the phenotypes of viruses and bacteria involved in chronic obstructive pulmonary disease (COPD) pathogenesis, and their impact on the length of stay (LOS) in hospitalized patients and on the COPD Assessment Test (CAT) Scale. The research paper, entitled “Respiratory infectious phenotypes in acute exacerbation of COPD: an aid to length of stay and COPD Assessment Test,” was recently published in the International Journal of Chronic Obstructive Pulmonary Disease.
Viral and bacterial infections are important comorbidities in COPD patients and play a significant role in acute exacerbation events of the disease (AECOPD), which can lead to a more severe loss of lung function, recurrent hospitalizations and decreased patient survival. Despite its importance in clinical outcomes of COPD and LOS, there are still gaps in knowledge regarding the spectrum of virus and bacteria involved in AECOPD.
In the study, researchers enrolled 81 patients with a diagnosed COPD exacerbation, defined as an acute event with consequent worsening of respiratory symptoms that lead to changes in medication. Scientists evaluated lung function through spirometry following inhalation of 400 μg of salbutamol, and the parameters FVC (forced vital capacity), FEV1 (Forced Expiratory Volume during the first second), and FEV1/FVC ratio. Patients were also asked to complete the CAT, and their clinical characteristics such as exacerbation history and LOS were registered. Furthermore, the team performed a series of virological and bacteriological assays from patient samples.
Results showed that 38 patients (47%) presented positive results for virus assays, with 12 patients showing multiple viral infections. In total, 21 revealed to be positive for influenza virus, 11 tested positive for enterovirus/rhinovirus, 9 for coronavirus, 6 for bocavirus, 5 for metapneumovirus, 3 for parainfluenza virus types (1, 2, 3, and 4) and 3 for respiratory syncytial virus. Regarding bacterial infections, a total of 17 patients presented positive results. The most common bacterial infection was Pseudomonas aeruginosa (6 patients), Acinetobacter baumannii (5 patients), Klebsiella (4 patients), and Escherichia coli and Streptococcus pneumoniae each testing positive for 1 patient. Of the patients testing positive for bacteria or viruses, seven had co-infection with both.
Researchers evaluated if there was a relationship between respiratory infection phenotypes and the clinical outcomes in LOS and the CAT scale. Results showed that, indeed, different infection profiles result in different lengths of LOS and AECOPD health status. Co-infection of virus and bacteria led to more severe symptoms and longer LOS for recovery. CAT results, used to assess patient disease burden, supported the researcher’s theory that co-infection, which leads to more inflammation, results in higher CAT scores. A correlation between CAT and LOS was found, confirming the CAT scale as an important tool to assess the impact of AECOPD symptoms.
Two of the patients with confirmed influenza infection died during the study, leading the scientists to suggest that respiratory influenza viral infection contributes to the mortality of COPD exacerbations. This suggestion, however, needs further confirmation.