Prevalence and Incidence of Comorbidities in Patients with Atopic Dermatitis, Psoriasis, Alopecia Areata, and Vitiligo Using a Japanese Claims Database

Infectious Diseases Rheumatology and Immunology Immunology Life Sciences Oncology Cardiovascular System Medicine
comorbidities atopic dermatitis psoriasis alopecia areata vitiligo Japan health claims database

Prevalence and Incidence of Comorbidities in Japanese Patients with Dermatologic Diseases

Academic Background

Dermatologic diseases such as atopic dermatitis (AD), psoriasis, alopecia areata (AA), and vitiligo are common chronic inflammatory or autoimmune skin disorders. These conditions not only significantly impact patients’ quality of life but are also often accompanied by various comorbidities, including infections, malignancies, and cardiovascular diseases. Although numerous studies have shown associations between these dermatologic diseases and comorbidities, research on Japanese patient populations remains limited. Given Japan’s unique demographic structure and healthcare system, the comorbidity patterns in Japanese dermatologic patients may differ from those in Western countries. Therefore, researchers aimed to evaluate the prevalence and incidence of specific comorbidities in Japanese patients with these skin conditions using a retrospective cohort study based on a Japanese medical database.

Source of the Study

This study was jointly conducted by researchers from Pfizer Japan Inc. and Fukuoka University. The first authors are Yue Ma and Motohiko Chachin, and the corresponding author is Tomohiro Hirose. The paper was accepted on January 10, 2025, and published in the Journal of Dermatology, with the DOI 10.1111⁄1346-8138.17643.

Research Process

Data Source and Study Design

The study utilized the Japan Medical Data Center (JMDC) insurance claims database, which covers medical records of employees from mid- to large-sized companies in Japan and their families. The study period ranged from June 2013 to December 2020, and data from 12,136,472 individuals were analyzed. The study design was a retrospective cohort study, including patients diagnosed with AD, psoriasis, AA, or vitiligo between June 2014 and December 2020. Each dermatologic disease group was matched 1:1 with a control group without the corresponding skin condition, based on age, sex, and diagnosis time.

Study Participants and Inclusion Criteria

  • Dermatologic Disease Groups: Patients required at least two diagnostic records in different months and at least one record more than 12 months after database entry. Additionally, AD patients needed at least two treatments, including topical corticosteroids, calcineurin inhibitors, or dupilumab, within one month of diagnosis.
  • Control Groups: Patients without a diagnosis of the corresponding skin condition, matched to the disease groups by age, sex, and diagnosis month.

Study Variables and Measurement Metrics

The primary variables included the following comorbidities: - Allergic Diseases: Such as allergic rhinitis, conjunctivitis, and asthma. - Infections: Such as viral infections, fungal infections, herpes zoster, and tuberculosis. - Malignancies: Including non-melanoma skin cancer (NMSC) and lymphoma. - Cardiovascular Diseases: Such as ischemic heart disease, stroke, and venous thromboembolism (VTE).

Statistical Analysis

The study calculated the prevalence (baseline period) and incidence (follow-up period) of comorbidities. Incidence rates were expressed per 100,000 person-years (PY), and 95% confidence intervals (CIs) were calculated using the Poisson distribution. Additionally, stratified analyses were conducted by age groups (0-9, 10-19, 20-29, 30-39, 40-49, 50-59, ≥60 years).

Key Findings

Comorbidity Prevalence

The study found that the prevalence of allergic diseases was significantly higher in dermatologic disease groups compared to controls. For example: - AD Group: Allergic rhinitis (47% vs 37%), conjunctivitis (33% vs 23%), asthma (27% vs 20%). - Psoriasis Group: Allergic rhinitis (35% vs 28%), conjunctivitis (21% vs 17%). - AA Group: Allergic rhinitis (40% vs 31%), conjunctivitis (26% vs 19%). - Vitiligo Group: Allergic rhinitis (45% vs 36%), conjunctivitis (30% vs 22%).

Additionally, the prevalence of infections was significantly higher in dermatologic disease groups, particularly viral infections (AD group: 22% vs 15%) and fungal infections (psoriasis group: 17% vs 5%).

Comorbidity Incidence

  • Cardiovascular Events: The incidence of VTE was significantly higher in the AD and psoriasis groups compared to controls (AD group: 51.4⁄100,000 PY; control group: 31.7⁄100,000 PY; psoriasis group: 172.7⁄100,000 PY; control group: 92.5⁄100,000 PY).
  • Malignancies: The incidence of lymphoma was significantly higher in the AD and psoriasis groups compared to controls (AD group: 13.8⁄100,000 PY; control group: 5.7⁄100,000 PY; psoriasis group: 50.6⁄100,000 PY; control group: 17.2⁄100,000 PY).
  • Infections: The incidence of herpes zoster was significantly higher in all dermatologic disease groups compared to controls (AD group: 740.9⁄100,000 PY; control group: 397.6⁄100,000 PY; psoriasis group: 951.9⁄100,000 PY; control group: 703.6⁄100,000 PY).

Study Conclusions

This study indicates that the incidence of cardiovascular events, malignancies, and infections is significantly higher in Japanese patients with AD and psoriasis compared to those without dermatologic diseases. Notably, patients with AD and psoriasis have a significantly increased risk of lymphoma and herpes zoster. These findings provide important insights for clinicians, highlighting the need to carefully monitor the risk of comorbidities when managing these skin conditions.

Highlights of the Study

  1. Large Data Scale: The study is based on the JMDC database, including data from over 12 million individuals, providing high representativeness.
  2. Comprehensive Comorbidity Analysis: The study not only focused on cardiovascular diseases and malignancies but also detailed infections and other comorbidities.
  3. Age-Stratified Analysis: Incidence rates stratified by age groups offer more nuanced guidance for managing comorbidities in different age groups.
  4. Unique Japanese Perspective: This is the first large-scale comorbidity study on Japanese dermatologic patients, filling a gap in the field.

Significance and Value of the Study

This study provides important evidence for managing comorbidities in Japanese dermatologic patients, particularly for the long-term monitoring of AD and psoriasis patients. Furthermore, the findings suggest the need for further exploration of causal relationships between dermatologic diseases and comorbidities, offering direction for future research.