ICD-11 in Canada: Leveraging crosswalks to evaluate adoption, impact and transition strategies

The World Health Organization's (WHO's) International Statistical Classification of Diseases and Related Health Problems, Eleventh Revision (ICD-11) is a modern classification system that provides enhanced granularity and flexibility for capturing clinical and health system data. For Canada, transitioning from ICD-10-CA, the Canadian modification, to ICD-11 poses opportunities and challenges. To explore these opportunities and challenges more thoroughly, a backward crosswalk was developed to evaluate statistical continuity. This approach helped identify the benefits of ICD-11, while also highlighting potential implications for health systems, case mix, and national health indicator reporting.

To examine how bidirectional crosswalks between ICD-10-CA and ICD-11 can support Canada's transition to ICD-11; and demonstrate how these crosswalks can be utilised in a Canadian-specific use case.

14,652 ICD-11 Mortality and Morbidity Statistics (2022 release) codes were mapped to version 2022 ICD-10-CA codes. Each mapping was reviewed to determine the relationship between the ICD-11 and ICD-10-CA codes, categorising them as equivalent to, broader than or narrower than the source ICD-11 codes. The bidirectional crosswalks were applied to a Canadian use case to demonstrate level of specificity between ICD-10-CA and ICD-11 codes.

26% of the ICD-10-CA target codes were equivalent to a single ICD-11 code, 65% were broader, 9% were narrower and 0.03% had no applicable ICD-11 map. Findings from the Canadian use case showed that 55% of the ICD-11 target codes were equivalent to or narrower than their ICD-10-CA source codes in the forward crosswalk, and 57% of ICD-11 congenital anomaly concepts had greater specificity in the backward crosswalk.

The backward crosswalk assessment highlights the benefits of ICD-11's increased specificity, which has the potential to enhance healthcare data in Canada. However, these findings must be considered alongside the forward crosswalk analysis, which noted a loss in specificity.Implications for health information management practice:As demonstrated in a Canadian use case example, bidirectional crosswalks can be leveraged to better understand the impact of ICD-11 adoption.