Clinical impact of hospitalization in patients with idiopathic pulmonary fibrosis: A retrospective cohort study.

BackgroundAlthough hospitalization in idiopathic pulmonary fibrosis (IPF) is associated with poor outcomes, it occurs during the disease course and may lead to overestimation of its prognostic impact when analyzed as a fixed exposure.ObjectivesWe aimed to evaluate the association between hospitalization and transplantation-free survival in patients with IPF by modeling hospitalization as a time-dependent exposure and applying a standardized definition of respiratory-related hospitalization.DesignThis was a retrospective cohort study conducted at Asan Medical Center, a tertiary referral center in Seoul, South Korea.MethodsA total of 223 patients with IPF were included. Hospitalization was treated as a time-dependent exposure in Cox regression models. Changes in pulmonary function and exercise capacity before and after hospitalization were assessed using linear mixed-effects models.ResultsSeventy patients (31%) experienced hospitalization during follow-up, whereas 153 (69%) did not. Hospitalized patients had significantly worse lung function and exercise capacity at baseline compared with non-hospitalized patients. When modeled as a time-dependent exposure, hospitalization was strongly associated with increased risk of transplantation or death (adjusted hazard ratio: 8.87, 95% confidence interval [CI]: 5.57-14.11;