Economic burden and cost drivers of interstitial lung disease: a systematic review

Interstitial lung disease (ILD) consists of many subtypes, with idiopathic pulmonary fibrosis (IPF) and subtypes that manifest as progressive pulmonary fibrosis (PPF) exhibit faster progression and poorer prognosis. Recent updates in the definition of PPF and expanded approval of antifibrotic treatments warrant a comprehensive review to understand the economic impact and key cost drivers.

This systematic review aims to summarize published studies on the economic burden of ILD on patients, the healthcare system, and society, and to identify the prevailing cost drivers.

A literature search was conducted using PubMed, Scopus and Web of Science to identify full-length publications in English on the ILD economic burden, cost of illness, or cost-effectiveness studies, from inception until January 2024. The review protocol was registered with PROSPERO (CRD42024504116) and followed Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline. This review compares the direct, indirect, and overall costs across ILD subtypes and countries.

Forty studies fulfilled the inclusion criteria. Annual direct costs of ILD ranged from $1,593 (South Korea) to $177,526 (United States) per patient, while indirect costs ranged from $45 to $19,507. Hospitalisation costs ranged from $1,500 to $18,792 per admission, and end-of-life care costs were $52,614 annually per patient. Inpatient (40%-89%) and medication costs (36%-82%) were identified as the major cost drivers. The predictors of increasing costs include disease severity, presence of comorbidities, and antifibrotic use. Additionally, regional disparities and healthcare system differences influenced the economic burden.

Interstitial lung disease imposes a substantial economic impact. Early diagnosis, effective treatments targeting ILD and comorbidities, appropriate social support, and an optimized health delivery system may reduce the overall cost and improve health outcomes.