Mortality in Patients Admitted for Concurrent COPD Exacerbation and Pneumonia

Response to the letter

We read with interest the comments by Dr. E. Hernandez-Garduno on our recently published manuscript (1,2). We agree with most of the points he raised and would like to clarify our findings in accord with his comments. In our study, we confirmed that chest imaging was performed during the admission, but we did not have access to the report of the imaging. In addition, we did not have access to any lung function testing reports. We consider lack of access to lung function as an important limitation of our study. However, we also believe that the clinical definition that we used in this research is reflective of real-world medical practice. In fact, a study in a general practice showed that only 50% of patients clinically diagnosed with COPD underwent pulmonary function testing (3). Dr. Hernandez-Garduno raised a very important question, namely, whether the increased mortality in pneumonia with COPD (PCOPD) is due to the pneumonia or to associated comorbid conditions. Our study clearly showed that the prevalence of significant comorbid conditions and thus, Charlson Comorbidity Index was higher in patients with PCOPD compared to patients with acute exacerbation of COPD (AECOPD) or pneumonia (PNA) alone. To further explore the interaction between pneumonia and COPD, we did include the interaction in our initial analysis; however, it did not show statistical significance and, thus, we did not include the interaction term in our table. In line with the conclusion by Dr. Hernandez-Garduno, with or without the interaction term, it is still impossible to draw a causative conclusion about the effects of pneumonia versus those of COPD on mortality in patients who are hospitalized for PCOPD.