Epidemiology and comorbidities in idiopathic pulmonary fibrosis: a nationwide cohort study

Abstract

Background: Idiopathic pulmonary fibrosis (IPF) is frequently accompanied by comorbidities, with the management of these comorbidities crucial for clinical outcomes. This study investigated the prevalence, incidence, changes over time, and clinical impact of comorbidities in IPF patients, based on nationwide claims data in South Korea.

Methods: This retrospective cohort study utilised nationwide health claim data in South Korea between 2011 and 2019. Patients with IPF were defined as those with ICD-10 code J84.1 and Rare Intractable Disease code V236 who made at least one claim per year. Patients were classified by sex, age, pirfenidone use and burden of comorbidities, and differences among groups were determined.

Results: The yearly prevalence rate of IPF increased from 7.50 to 23.20 per 100,000 people, and the yearly incidence rate increased from 3.56 to 7.91 per 100,000 person-years over time. The most common respiratory comorbidity was chronic obstructive pulmonary disease (37.34%), followed by lung cancer (3.34%), whereas the most common non-respiratory comorbidities were gastro-oesophageal reflux disease (70.83%), dyslipidaemia (62.93%) and hypertension (59.04%). The proportion of some comorbidities differed by sex, age and use of pirfenidone. The proportion of lung cancer was higher in patients treated with pirfenidone, whereas the proportion of anxiety and depression were lower in patients not treated with pirfenidone. Charlson comorbidity index ≥ 4 was associated with increases in hospitalisations and total medical costs.

Conclusions: The yearly prevalence and incidence of IPF and comorbidities in Korea increased over time. These comorbidities affected the use of pirfenidone and medical resources.

Keywords: Comorbidity; Idiopathic pulmonary fibrosis; Incidence; Pirfenidone; Prevalence.

Fig. 1

Annual prevalence and incidence rates of idiopathic pulmonary fibrosis from 2011 to 2019 in South Korea. The red solid line shows the incidence/100,000 person-years (left y-axis) and the blue dotted line shows the prevalence/100,000 people (right y-axis). Both prevalence and incidence rates showed statistically significant annual increases (p < 0.001 by Poisson regression analysis)

Fig. 2

Prevalence of comorbidities in patients with idiopathic pulmonary fibrosis at the time of diagnosis (blue), 1 year after diagnosis (orange) and 3 years after diagnosis (grey). We presented the change of prevalence at three different time points of respiratory comorbidities (A) and non-respiratory comorbidities (B) Abbreviations: GERD, gastro-oesophageal reflux disease; COPD, chronic obstructive pulmonary disease