Impact of Diabetes Mellitus On In-Patient Mortality From Pneumonia Over 25 Years in a Portuguese Tertiary Care Hospital

Introduction Pneumonia is among the most important causes of morbidity and mortality in Portugal. Diabetes mellitus (DM) is a risk factor for the development of pneumonia and has an adverse effect on the patients' outcome. This study aimed to evaluate the evolution of in-hospital mortality from pneumonia in patients with DM over 25 years. Materials and methods Hospital admissions due to pneumonia were retrospectively assessed between 1989 and 2014 in patients with and without DM. Evolution of the annual number of admissions, length of stay, and in-hospital mortality was evaluated. Results A total of 1,356,502 hospitalizations were evaluated, of which 44,301 were due to pneumonia (20.3% had DM). The proportion of hospitalizations due to pneumonia was higher among patients with DM (7.2% vs 2.9%, p < 0.001). In this group, the proportion of female patients was higher (46.7% vs 41.3%, p < 0.001). Patients with a diagnosis of DM had a longer hospital stay (11 (7-20) vs 10 (6-19)). In-hospital mortality was higher among patients with DM (p < 0.001) across the study periods up to 2008. However, mortality has progressively decreased, with no significant differences observed in the last study period (p = 0.446). After adjusting for age and sex, mortality rates remained similar up to 2008 but were lower among patients with DM in the last study period (OR = 0.89, 95% CI 0.81-0.97, p = 0.012). Conclusions In-hospital pneumonia mortality among patients with DM decreased throughout time and was comparable to that of non-DM patients in the final study period.