Background: Juvenile idiopathic arthritis (JIA) is the most common type of chronic arthritis in children under the age of 16. Administrative health data or billing claims can be used for longitudinal studies on chronic disease, and there have been studies conducted on JIA, the most common chronic arthritis in children. Using administration health data and billing data. Majority of such studies using administrative data have been focused on North American and Europe, and there are only few studies that have been conducted in Asia.

Objectives: This study aims to identify the disease pattern including prevalence and incidence of the patients diagnosed with JIA in accordance with diseases diagnostic code and catastrophic illness certificate code using the claims data of the Health Insurance Review and Assessment Service (HIRA), the representative secondary data in Korea.

Methods: We conducted a retrospective analysis using the national claims data of the HIRA. Our study population includes JIA patients who have records of diagnostic code in the format of the International Classification of Disease, 10 ^th revision (ICD-10-code) M08 and catastrophic illness certificate code V133, between January 1, 2010 and December 31, 2019. We calculated annual prevalence and incidence per 100,000 individuals for study periods. The denominators for prevalence and incidence were the census population and the at-risk population defined as the population without respective populations by sex for subgroup analysis. Other disease patterns, including the ratio of each diagnostic code, disease duration, and number of patients and sex ratio at the age of diagnosis, were explored.

Results: The study population was 1,729 patients (934, 54.0% male and 795, 46.0 % female). Annually cumulative prevalence was 8.8 (range: 7.0-16.9) per 100,000 people on average while annually cumulative incidence are 2.2 (1.8 – 2.8) for patients aged under 16. Annually cumulative prevalence were 9.1 (7.0-17.0) and 8.5 (6.7-16.7) per 100,000 people on average while annually cumulative incidence were 2.3 (1.7-2.9) and 2.1 (1.9-2.6), for male and female respectively. The average age of diagnosis were 10.6 years (Standard deviation, sd: 5.0) and 11.8 (4.1) with the significant difference for male and female, respectively. The average disease duration of patients were 1,339.2 days (sd: 1,007.0) and 1,377.2(994.2) without the significant difference for male and female, respectively.

Conclusion: This is the first study presenting disease patterns including prevalence and incidence in patients identified with JIA using population-based big claims data in Korea. The annual prevalence for study periods slowly decreased while the annual incidence reached a peak specifically in 2016 when the health insurance reimbursement policy of JIA treatment has been changed. The results of subgroup analyses with the four age groups showed higher prevalence and incidence as age increases in both male and female. And the number of patients at the age of diagnosis also increased as age increased. The reason for these patterns might be because the increase in physical activities can be related to the prevalence and incidence of JIA.

REFERENCES: [1] Thierry S. Fautrel B, Lemelle I, Guillemin F. Prevalence and incidence of juvenile idiopathic arthritis: A systemic review. Joint Bone Spine 2014;81:112-7.

[2] Fujikawa S, Okuni M. Clinical analysis of 570 cases with juvenile rheumatoid arthritis: Results of a nationwide retrospective survey in Japan. Axct Paediatr Jap 1997;39:245-9.

Acknowledgements: This study was sponsored from Pfizer Pharmaceuticals Korea Ltd (X9001310).

Disclosure of Interests: Dae Chul Jeong The authors do not have an actual or potential conflict of interest and do not have any interest to declare with regard to this work. This study was sponsored by Pfizer Pharmaceuticals Korea Ltd. (X9001310: JIA Claims data N15)., Jong Gyun Ahn The authors do not have an actual or potential conflict of interest and do not have any interest to declare with regard to this work. This study was sponsored by Pfizer Pharmaceuticals Korea Ltd. (X9001310: JIA Claims data N15)., Eun Jeong Min The authors do not have an actual or potential conflict of interest and do not have any interest to declare with regard to this work. This study was sponsored by Pfizer Pharmaceuticals Korea Ltd. (X9001310: JIA Claims data N15)., Young Dae Kim The authors do not have an actual or potential conflict of interest and do not have any interest to declare with regard to this work. This study was sponsored by Pfizer Pharmaceuticals Korea Ltd. (X9001310: JIA Claims data N15)., Soo-Hyun Lee SH Lee is employed by Pfizer., The authors do not have an actual or potential conflict of interest and do not have any interest to declare with regard to this work. This study was sponsored by Pfizer Pharmaceuticals Korea Ltd. (X9001310: JIA Claims data N15)., Joo-young Jo JY Jo is employed by Pfizer., The authors do not have an actual or potential conflict of interest and do not have any interest to declare with regard to this work. Funding: This study was sponsored by Pfizer Pharmaceuticals Korea Ltd. (X9001310: JIA Claims data N15).