J Korean Med Sci.  2019 Mar;34(8):e55. 10.3346/jkms.2019.34.e55.

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

Affiliations
  • 1Department of Rheumatology, Hanyang University Hospital for Rheumatic Diseases, Seoul, Korea. sungyk@hanyang.ac.kr
  • 2Biostatistical Consulting and Research Lab, Medical Research Collaborating Center, Hanyang University, Seoul, Korea.
  • 3College of Pharmacy, Chung-Ang University, Seoul, Korea.
  • 4Department of Information Statistics, Andong National University, Andong, Korea.

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.

Keyword

Inflammatory Myopathy; Prevalence; Incidence; Comorbidity

MeSH Terms

Comorbidity
Dermatomyositis
Female
Humans
Incidence*
Korea*
Lung Diseases, Interstitial
Myositis*
National Health Programs
Polymyositis
Prevalence*
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