Impact of the ICD-11 on the accuracy of clinical coding in Korea.

Background: ICD-11 was officially released at the World Health Assembly on 25 May 2019. Objective: To find effective ways to increase the accuracy of coding for diagnostic terms in Korea for a stable transition from Korean modification of ICD-10 (7th Revision of Korean Classification of Disease, KCD-7) to ICD-11. Method: A total of 27 skilled Korean health information managers performed KCD-7 and ICD-11 coding simultaneously (line coding [56]; case coding [17]). Accuracy rates and percentage agreements were calculated, and granularity and difficulty of the ICD-11 were rated by participants. Results: The average accuracy rate of line coding was 71.6 % in ICD-11 and 80.2% in KCD-7, which was similar to results in other studies. The mean percentage agreements for ICD-11 and KCD-7 for line coding were 64.2% and 72.1%, respectively; while for case coding it was 15.3% and 26.6%. Selection criteria for the case scenarios may have influenced the low agreements in case coding. Cluster coding, changes of terms in ICD-11 and removal of codes used in ICD-10 contributed to low agreement in ICD-11 (46.6% of participants reported that granularity of ICD-11 was similar to ICD-10, while 36.9% reported that ICD-11 had finer granularity). In terms of difficulty, 15.3% of participants found line coding difficult and 10.9% found case coding difficult. Conclusion: Provision of more detailed reference guidelines and efficient training for coding professionals by the World Health Organization would enable ICD-11 to be an excellent tool for gathering relevant information about diseases in Korea.