Juvenile idiopathic arthritis (JIA), the most common rheumatic disease in children, is a broad term for chronic arthritis (≥6 weeks) of unknown cause that develops before the age of 16 years [1,2]. The International League of Associations for Rheumatology (ILAR) classifies JIA into seven subtypes [3]: systemic, oligoarticular, polyarticular with and without rheumatoid factor (RF), psoriatic, enthesitis-related, and undifferentiated (Supplementary Table 1). In other words, JIA has more subtypes than adult rheumatoid arthritis (RA). For example, some subtypes, such as systemic JIA and enthesitis-related arthritis (ERA), have adult analogs (adult-onset Still’s disease [AOSD] and spondyloarthritis, respectively) [4,5]. However, oligoarticular JIA, the most common subtype of JIA (40%~50% of all JIA cases), does not have an adult analog [5]. Accurate diagnosis of the JIA subtypes is important because the clinical course and outcomes vary by subtype [1]. The treatment of JIA used to focus on symptom control using non-steroidal anti-inflammatory drugs (NSAIDs) and steroids. However, since the introduction of biologic disease-modifying anti-rheumatic drugs (bDMARDs), the treatment paradigm has shifted to the prevention of major complications, such as growth retardation, permanent joint destruction, and uveitis [4,5].

In the past, the prevalence and incidence of JIA in Korea were held to be very low, precluding the development of epidemiological data [2]. However, a recent JIA study conducted in Korea by Min et al. [6] showed that the prevalence (15.9 per 100,000 population) and incidence (2.2 per 100,000 population) were higher than previously expected. These figures were lower than those in Western countries (32.6 and 8.3 per 100,000 population, respectively) [3], but they fall between those of Japan (10.0~15.0 and 1.0 per 100,000 population, respectively) [4] and Taiwan (18.0 and 5.2 per 100,000 population, respectively) [5,7].

Table 1 summarizes the basic epidemiological data from Korea, Japan, and Taiwan. The sex ratios and age at diagnosis did not differ significantly between Korea and Taiwan. Systemic JIA was the most common subtype in Japan, and ERA was the most common subtype in Taiwan. The JIA study by Min et al. [6] was informative but failed to present detailed data, such as clinical symptoms or laboratory results. In fact, JIA research in Korea, including epidemiology, lags behind that in other countries. For example, Japan and Taiwan have established and use their own JIA guidelines [4,5], but Korea has not yet established its own guidelines.

In this issue of the Journal of Rheumatic Diseases, Ahn et al. [8] presents a real-world analysis of treatment patterns for JIA in Korea, particularly regarding bDMARDs. In their study, 31% (541/1,728) of patients with JIA received bDMARDs, which is higher than in the UK (20%) and lower than in Canada (45%) [9]. Of the 541 patients prescribed bDMARDs, 15% discontinued treatment due to disease remission, and 14% had to switch to a second bDMARD due to the ineffectiveness of the first bDMARD. The study by Ahn et al. [8] is the first nationwide, population-based study to investigate JIA treatment patterns in Korea using claims data from Health Insurance Review and Assessment (HIRA). This study is expected to support decision-making regarding the prescriptions of bDMARDs in real-world clinical settings. However, due to the inherent limitations of HIRA data, it could not distinguish among the JIA subtypes or evaluate disease severity, comorbidities, or patient-reported outcomes.

Table 2 compares studies on biologic treatments in Korea, Japan, and Taiwan. Japanese studies [10,11] reported that 21% (1,280/6,191) of patients with JIA receive bDMARDs, and a Taiwanese study [7] reported that 19% (326/1,696) of patients receive bDMARDs. In Korea and Taiwan, etanercept (ETN) was the most prescribed bDMARD, but in Japan, tocilizumab (TCZ) was the most prescribed, which might reflect the relatively high prevalence of systemic JIA in Japan [4]. Other parameters, including discontinuation and switching rates, did not differ significantly among countries. However, one prominent difference among the three countries is clear: the median interval from JIA diagnosis to the first bDMARD prescription in Korea (37 months) is much longer than in Japan (~6 months, guidelines) and Taiwan (9 months). In other words, Korean patients with JIA seem to wait longer to receive advanced treatments than patients in Japan or Taiwan. These delays may reflect differences in insurance reimbursement policies, specialist referral systems, or treatment practice patterns between Korea and other countries.

Fortunately, useful nationwide studies in Korea, such as the study by Ahn et al. [8], have recently been published. These studies suggest the potential for advances in JIA research in Korea. However, they also highlight the challenges Korea faces in research and clinical practice, such as a critical shortage of specialists (i.e., pediatric rheumatologists), inadequate infrastructure (e.g., nationwide registries and multi-center research platforms), and insufficient data. Addressing these difficulties will require not only the efforts of individual researchers but also institutional strategies at the academic society level.

In this regard, the Korean College of Pediatric Clinical Immunology (KCPCI), established in 2006, is playing a pivotal role. Although the number of members is still insufficient, the affiliated pediatric rheumatologists are actively participating in JIA research and clinical practice. The KCPCI encourages the training of pediatric rheumatologists to improve public health and is pushing for the introduction of a government-certified specialist system. Expanding and strengthening this pool of specialists will be the most important first step in addressing subsequent challenges, such as establishing research infrastructure and securing high-quality data that can help to improve clinical outcomes for Korean children with JIA.

Supplementary data can be found with this article online at https://doi.org/10.4078/jrd.2026.0077