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. 2019 Feb 8;34(8):e55.
doi: 10.3346/jkms.2019.34.e55. eCollection 2019 Mar 4.

Incidence and Prevalence of Idiopathic Inflammatory Myopathies in Korea: a Nationwide Population-based Study

Soo-Kyung Cho  1 , Hyoungyoung Kim  1 , Jisun Myung  2 , Eunwoo Nam  2 , Sun-Young Jung  3 , Eun Jin Jang  4 , Dae-Hyun Yoo  1 , Yoon-Kyoung Sung  1
Affiliations

Incidence and Prevalence of Idiopathic Inflammatory Myopathies in Korea: a Nationwide Population-based Study

Soo-Kyung Cho et al. J Korean Med Sci. .

Abstract

Background: This study aimed to estimate the incidence and prevalence of idiopathic inflammatory myopathies (IIM) and associated comorbidities in Korea from 2006 to 2015.

Methods: IIM between 2004 to 2015 were identified using the Korean National Health Insurance Service medical claim database. The case definition required more than one visit based on diagnostic codes including juvenile dermatomyositis (JDM), dermatomyositis (DM), or polymyositis (PM) and registration in the Individual Copayment Beneficiaries Program (ICBP) for rare and intractable diseases. IIM patients with a disease-free period of 24 months before the index date were defined as incident cases. The Elixhauser comorbidity score was calculated.

Results: Using the base case definition, 1,150 prevalent patients with IIM (117 JDM, 521 DM, 512 PM) were recorded in 2006 and 2,210 (130 JDM, 1,101 DM, 869 PM) in 2015. The prevalence was estimated at 2.3-4.0 (0.9-1.2 for JDM, 1.2-2.7 for DM, 1.4-2.1 for PM)/100,000 person-year (PY). We identified 218 incident cases of IIM in 2006 (18 JDM, 98 DM, 102 PM) and 191 cases (7 JDM, 83 DM, 101 PM) in 2015. The incidence was estimated at 2.9-5.2 (0.7-1.9 for JDM, 1.8-4.0 for DM, 1.6-3.0 for PM)/1,000,000 PY. The mean age (± standard deviation) of prevalent patients with IIM was 51.2 (± 16.9) years, and the percentage of women was 72.1%. More than two-thirds of patients (70.7%) had more than two comorbidities. Twenty percent of patients had interstitial lung diseases.

Conclusion: In Korea, the incidence and prevalence of IIM were 2.9-5.2/1,000,000 PY and 2.3-4.0/100,000 PY, respectively.

Keywords: Comorbidity; Incidence; Inflammatory Myopathy; Prevalence.

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Conflict of interest statement

Disclosure: The authors have no potential conflicts of interest to disclose.

Figures

Fig. 1
Fig. 1. Prevalence trends between 2006 and 2015 in patients with inflammatory myositis.
JDM = juvenile dermatomyositis, PM = polymyositis, DM = dermatomyositis.
Fig. 2
Fig. 2. Incidence trends between 2006 and 2015 in patients with inflammatory myositis.
JDM = juvenile dermatomyositis, PM = polymyositis, DM = dermatomyositis.
Fig. 3
Fig. 3. Percentage of comorbidities of prevalent patients with inflammatory myositis in 2015.
AIDS/HIV = acquired immune deficiency syndrome/human immunodeficiency virus.
See this image and copyright information in PMC

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