Quantifying coding integrity and reliability of ICD-11 MMS for rare disease registration: a case study of the Chinese...

Epidemiological data on rare diseases (RDs) affect the accurate scientific assessment of these diseases and lead to many issues in policy-making, healthcare systems, and legislation. The coding system is crucial for accurately identifying and calculating the incidence rates of each RD. This study focuses on the effectiveness of collecting RD data via the ICD-11 and examines whether the ICD-11 can fully support RD statistics. The findings of this study should provide a foundation for replacing the ICD-10 with the ICD-11.

This study included 121 RDs from the first "Rare Disease Catalogue"in China. The diseases were recoded independently by two experts in the ICD-11 MMS. A comparative analysis was conducted on the distributions of chapters, code types, and index terms in the ICD-10 and ICD-11 MMS.

This study analysed 121 rare diseases (RDs) from China's first Rare Disease Catalogue. These RDs mapped to 204 ICD-10 codes (1.4% of all codes), including 76 (37.3%) non-index terms, and to 171 ICD-11 MMS codes (0.96% of all codes). The proportion of RD codes was significantly lower in ICD-11 than in ICD-10 (0.96% vs. 1.4%, P < 0.001), indicating greater dilution of RDs in ICD-11. All ICD-11 MMS codes were indexed (100% vs. 62.7% in ICD-10, P < 0.001), and 51 ICD-11 MMS codes (29.8%, P < 0.001) provided more detailed classifications. When using the ICD-11 to code RDs for subsequent statistical analyses, it is recommended that a network system of RD index terms be established in advance.

The ICD-11 can replace the ICD-10 for coding RDs. However, many RD terms do not have accurate codes and must be uniquely identified with URIs in the ICD-11. To ensure the reliability of RD-related data, establishing a local RD database for reporting data via the ICD-11 in China is essential.