Interstitial lung disease and risk of mortality: 11-year nationwide population-based study

Patients with interstitial lung disease (ILD) constitute a substantial disease burden. Although ILD outcomes have been investigated, the risk of death due to ILD has not been studied in the light of confounders and comorbidities. In this nationwide, 11-year longitudinal, population-based study, we aimed to discover if ILD is an independent risk factor for mortality.

Data on 1 031 392 (2.2%) randomly selected subjects from 47 279 373 Korean residents were collected from the 2002 Korean National Health Insurance database. The ILD group comprised patients with an initial diagnosis of ILD between January 2003 and December 2007. Each patient was followed until 2013. We used Cox proportional hazard regression analyses to calculate the risk of death adjusted for comorbidities and confounders.

ILD developed in 783 of the 303 385 subjects during the 5-year period (51 per 100 000 person-years). Death occurred in 157 (23.2%) cases and 272 controls (10.4%). ILD was significantly associated with the risk of death (hazard ratio 2.1, 95% confidence interval [CI] 1.6-2.7) and for those aged 40-59, 60-69 and 70 years. A high proportion of patients with ILD died due to respiratory causes.

ILD patients had a significantly higher risk of death than matched controls, after adjustment for potential confounders and comorbidities.