ObjectiveThe accessibility issue of orphan drugs in China is prominent. Based on real-world data from a tier-one city in Northeast China, this study aims to analyze the current usage and affordability of orphan drugs for rare diseases.MethodsThe data was sourced from the health insurance claims data of a certain city from 2018 to 2021, including a total of 16 orphan drugs. The utilization of orphan drugs is assessed using four indicators: frequency of medical insurance claims, medication cost, defined daily doses (DDDs), and defined daily drug cost (DDDc). Affordability is measured using the concept of catastrophic health expenditure (CHE).ResultsBetween January 2018 and December 2021, there were a total of 2,851 medical insurance claims in the city, with a total medication costs of $3.08 million. Overall, during the study, there was a year-on-year increase in the utilization frequency of individual rare disease drugs in the city, with DDDs rising from 140.22 in 2018 to 3983.63 in 2021. Additionally, the annual medication costs of individual drugs showed a consistent upward trend, increasing from $10,953.53 in 2018 to $120,491.36 in 2021. However, the DDDc of individual drugs decreased from $398.12 in 2018 to $96.65 in 2021.The number of sales and the amount of sales for orphan drugs in community pharmacies have significantly increased. Prior to medical insurance coverage, out of the 16 orphan drugs, 9 drugs had annual treatment costs exceeding CHE for urban residents, and 15 drugs had annual treatment costs exceeding CHE for rural residents. After medical insurance coverage, there were no drugs with out-of-pocket costs exceeding CHE for urban residents, while 8 drugs had out-of-pocket costs exceeding CHE for rural residents. Furthermore, both before and after medical insurance coverage, the four treatment drugs for idiopathic pulmonary arterial hypertension were more affordable compared to the four treatment drugs for multiple sclerosis.ConclusionThe usage frequency of orphan drugs in a certain city increased gradually, but the disease burden remained heavy. More policy support should be provided to the priority rare disease populations, and the rare disease medical security and diagnosis and treatment systems should be improved.