Abstract: Objective To provide references for controlling hospitalization expenses effectively, and reduce the economic burden of patients by analyzing the trend of changes, the structural changes, and influencing factors of hospita-lization expenses for rare diseases patients. Methods Medical records data of rare diseases patients in a tertiary general hospital in Shandong Province from 2019 to 2023 were collected, and structural variation analysis, grey correlation degree method and quantile regression model were used to analyze the structural changes and influencing factors of hospitalization expenses in rare diseases patients. Results In the past 5 years, there was an overall decreasing trend for the hospitalization expenses for rare diseases patients. Inspection expenses, drug expenses and consumables expenses were the main factors that leaded to changes in expenses structure, accounting for a cumulative contribution rate of 94.41%, with an increase in inspection expenses and decreases in drug and consumables expenses. Treatment expenses and inspection expenses were the factors with the largest correlation with hospitalization expenses. The results from quantile regression models showed that first hospitalization, operation, payment method, disease type and length of stay were associated with all three quantile points(P5, P50,P95)of hospitalization expenses(P<0.05). Conclusion The composition of hospitalization expenses in rare diseases needs to be further optimized. It is necessary to emphasis on multidisciplinary collaboration, exploring new treatment methods, controlling hospitalization time, and reducing increase in hospitalization expenses. It is also needed to gradually improve multi-payment medical security mechanism, and to reduce economic burden of rare diseases patients, by incorporating the epidemiological characteristics of local rare diseases.

Key words: Rare diseases, Hospitalization expenses, Structural variation, Influencing factors, Quantile regression