Introduction: Interstitial lung diseases (ILDs) are associated with a high economic burden, yet prospective data of the German healthcare system are sparse. Objective: We assessed average ILD-related costs of pharmacological and non-pharmacological (hospitalizations, outpatient, rehabilitation, physiotherapy, and medical aids) interventions in ILD. Methods: We used data from the multicenter, observational, prospective Exploring Clinical and Epidemiological Characteristics of Interstitial Lung Diseases registry to evaluate adjusted per capita costs and cost drivers for ILD-related healthcare costs over 4 years, using generalized estimating equation regression models. Results: Idiopathic pulmonary fibrosis (IPF) had the highest annual pharmacological costs >EUR 21,000, followed by connective tissue disease-associated ILD (CTD-ILD) averaging EUR 6,000. Other idiopathic interstitial pneumonias and hypersensitivity pneumonitis averaged below EUR 2,400 and sarcoidosis below EUR 400. There were no significant differences in pharmacological costs over time. Trends in non-pharmacological costs were statistically significant. At year 1, CTD-ILD had the highest costs (EUR 7,700), while sarcoidosis had the lowest (EUR 2,547). By year 4, these declined to EUR 3,218 and EUR 232, respectively. Regarding cost drivers, the ILD subtype had the greatest impact with 75 times higher pharmacological costs in IPF and 4 times higher non-pharmacological costs in CTD-ILD, compared to the reference. Pulmonary hypertension (PH) and gastroesophageal reflux disease (GERD) triggered higher pharmacological costs, and higher values of forced vital capacity % predicted were associated with lower pharmacological and non-pharmacological costs. Conclusion: Stabilizing lung function and reducing the impact of PH and GERD are crucial in reducing the economic burden of ILD. There is an urgent need for effective treatment options, especially in CTD-ILD.

Keywords:
Diffuse parenchymal lung disease, Healthcare expenditure, Direct costs, Interstitial lung disease management, Healthcare spending
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