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Prevalence and incidence of polymyositis and dermatomyositis in Japan
Akiko Ohta1, Masaki Nagai, Motoko Nishina
1Department of Public Health, Saitama Medical University Faculty of Medicine , Saitama , Japan.
Objectives:
To estimate the number of patients with polymyositis/dermatomyositis (PM/DM) in Japan and the prevalence rate and incidence rate of the disease.
Methods:
The electronic database in the nationwide registration system on intractable diseases from 2003 to 2010 was utilized to identify the number of prevalent and incident cases of PM/DM. The electronic data entry rate was used to establish the total number of registered cases.
Results:
The estimated total number of patients with PM/DM and the prevalence rate in Japan in 2010 were 17,000 and 13.2 per 100,000 population, respectively. The prevalence of PM/DM ranged from 10 to 13 per 100,000 population with a trend toward increasing over time. The incidence of PM/DM was estimated within the range 10-13 per 1,000,000 person-years, except for 2003.
Conclusions:
We report the prevalence and incidence of PM/DM recently in Japan for the first time at the nationwide population level. Because the prevalence seems to be increasing recently, continued monitoring of these epidemiologic features is required.
Insights
The estimated prevalence of polymyositis/dermatomyositis (PM/DM) in Japan was 13.2 per 100,000 people in 2010. This autoimmune disease prevalence shows an increasing trend, requiring ongoing epidemiological monitoring.
Area of Science:
- Epidemiology
- Rheumatology
- Public Health
Background:
- Polymyositis/dermatomyositis (PM/DM) are rare autoimmune diseases affecting muscles and skin.
- Understanding the epidemiology of PM/DM in Japan is crucial for healthcare planning.
Purpose of the Study:
- To estimate the national prevalence and incidence of PM/DM in Japan.
- To analyze trends in PM/DM epidemiology over time.
Main Methods:
- Utilized a nationwide registration system for intractable diseases (2003-2010).
- Calculated prevalent and incident cases using electronic data.
- Adjusted for electronic data entry rates to estimate total registered cases.
Main Results:
- In 2010, an estimated 17,000 patients had PM/DM in Japan.
- The prevalence rate in 2010 was 13.2 per 100,000 population.
- Prevalence ranged from 10-13 per 100,000, showing an increasing trend; incidence was 10-13 per million person-years (excluding 2003).
Conclusions:
- This study provides the first nationwide population-level data on PM/DM prevalence and incidence in Japan.
- The observed increasing trend in PM/DM prevalence necessitates continued epidemiological surveillance.
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