Factors associated with the length of hospital stay in patients with acute exacerbations of asthma and COPD overlap syndrome

Background: A significant proportion of patients with chronic airways disease present asthma and COPD overlap syndrome (ACOS). Acute exacerbation of ACOS required hospitalisation is also assumed to be a major cause of morbidity and accounts for significant medical cost, in which hospital length of stay (LOS) is a significant marker of clinical severity and use of medical resources. This study aimed to determine the factors associated with hospital LOS in acute exacerbations of ACOS. Methods: A retrospective cohort study was conducted to assess patients with doctor diagnosed ACOS that had acute exacerbations admitted from January 2011 to December 2014. Patients with pneumonia and respiratory disorders other than asthma and COPD were excluded. Clinical characteristics, comorbidity, arterial blood gas, complete blood count, blood chemistry tests,routine sputum culture, chest radiography and medication use were assessed. Stepwise negative binomial regression was performed to identify factors associated with hospital LOS in exacerbations of ACOS. Results: A total of 146 patients were evaluated with the median LOS of 12(9-15) days. Multivariate negative binomial regression analysis identified that age starting to present respiratory symptoms (P=0.001), Charlson index of comorbidity(P=0.002), positive bacterial pathogen on sputum culture (P=0.002) and the use systemic glucocorticoid (P=0.009) were independently associated with increased hospital LOS in acute exacerbations of ACOS. Conclusion: Several factors were associated with hospital LOS in patients with acute exacerbations of ACOS which may be useful for prediction of clinical outcomes of ACOS.