Comorbidities and risk of mortality among hospitalized patients with idiopathic pulmonary fibrosis in Spain from 2002 to 2014

Background: To describe and compare the comorbid conditions, the in-hospital mortality (IHM) and the length of hospital stay (LOHS) among idiopathic pulmonary fibrosis (IPF) patients and non-IPF-matched patients hospitalized in Spain. We assess the performance of the Charlson Comorbidity Index[CCI] and the Elixhauser Comorbidity Index[ECI] to predict IHM in IPF and we identify the specific predictive factors of IHM in patients suffering IPF. Methods: We identified patients with IPF hospitalized in years 2002, 2006, 2010 and 2014. Cases of IPF were matched with non-IPF controls by sex, age, province of residence and year. Data were collected from the Spanish National Hospital Discharge Database. Results: We identified 10,285 hospitalizations with IPF, evidencing an increase in the number of IPF patients from 2002 to 2014. Overtime the prevalence of comorbidities included in the CCI significantly increased in patients with IPF, exception made of myocardial infarction and dementia. The prevalence of comorbidities included in the ECI, except paralysis and peptic ulcer disease excluding bleeding, increased significantly overtime. LOHS was longer among IPF patients than non-IPF controls and decreased significantly from 2002 to 2014. IHM was significantly higher in patients with IPF (adjustedOR 1.97; 95% CI 1.77-2.19). Area under the ROC curves showed that ECI model had a better performance to predict IHM than CCI. Conclusions: The incidence of hospitalizations for IPF increased significantly from 2002 to 2014. We observed an increase overtime of most of the comorbidities included in CCI and ECI. LOHS and IHM were higher in patients with IPF than in non-IPF controls.