Burden, Trends, Associated Diseases and Predictions of Alopecia Areata in China, Japan, South Korea, and Globally: A GBD 2023 Analysis

Abstract

Background

Alopecia areata (AA) causes non-scarring hair loss and substantial psychosocial burden, yet its trends, comorbidities, and future burden in East Asia remain underexplored.

Methods

Global Burden of Disease(GBD) Study 2023 data from 1990–2023 were analyzed for the world, China, Japan, and South Korea. Age-standardized incidence (ASIR), prevalence (ASPR), and disability-adjusted life-year (DALY) rates were assessed by region, sex, and age. Joinpoint regression quantified temporal trends. Ecological correlations with associated diseases and socio-demographic Index (SDI) were examined. Burden through 2046 was projected using United Nations population estimates.

Results

In 2023, Japan and South Korea had higher ASIR and ASPR than China and global averages. Females bore greater burden; incidence peaked in young-to-middle-aged adults. Global age-standardized rates(ASRs) declined (1990–2023), while rates remained stable in China and persistently high in Japan and South Korea. AA correlated with atopic dermatitis, iron deficiency anemia, and thyroid disorders. Higher SDI was associated with lower incidence in Japan, South Korea, and globally, but not in China. Substantial cases are projected through 2046.

Conclusion

AA burden varies by region, sex, and age, and will continue to be a major public health issue. Clinicians should be particularly attentive to women and East Asian patients. While the etiology appears multifactorial, causality remains to be confirmed at the individual level. Nevertheless, these findings support more vigilant screening and tailored prevention in high-risk East Asian populations.

Introduction

Alopecia areata (AA) is an immune-mediated, non-scarring hair loss disorder with clinical manifestations ranging from localized patchy hair loss to alopecia totalis or alopecia universalis. Epidemiological studies have suggested that the lifetime incidence of AA is approximately 2.11% worldwide.^1,2 The prevalence of AA varies by ethnicity, sex, and age, with some of the highest estimates reported among Asian populations.^3,4 Although AA is not generally associated with mortality, it can cause substantial psychological distress, impaired social functioning, and reduced quality of life.^5,6

The pathogenesis of AA is complex and involves multiple factors. Genetic susceptibility plays a significant role, with several human leukocyte antigen alleles (HLA), including HLA-DRB104 and HLA-DRB116, have been associated with an increased risk of AA.⁷ AA is also recognized as an autoimmune disorder, with collapse of hair follicle immune privilege considered a central pathogenic event, leading to immune-mediated attack of the hair follicle by autoreactive T cells.⁸ In addition, endocrine status, psychological factors, and environmental exposures have been implicated in the development or progression of AA.^9–12Although the epidemiological characteristics of AA have attracted increasing attention with improved disease recognition and expanding treatment options, reliable epidemiological data in Asian populations remain relatively limited This gap is particularly important given the reported ethnic differences in AA epidemiology, with a higher prevalence observed in Asian populations than in White populations.¹³ China, Japan, and South Korea are among the most populous and economically important countries in East Asia; however, the lack of harmonized, longitudinal, multinational assessments has hindered the development of region-specific prevention strategies and evidence-based allocation of healthcare resources.

The Global Burden of Disease (GBD) Study provides a standardized framework for comparing disease burden at the global, regional, and national levels. It enables the assessment of health loss across time, age, sex, and location.¹⁴ Published GBD-based analyses of AA have largely relied on data available through 2021.^15,16 However, systematic comparisons of AA burden between the global population and East Asian countries remain limited, particularly those integrating long-term temporal trends, associated disease profiles, socioeconomic development, and future burden projections.

China, Japan, and South Korea are neighboring countries in East Asia with shared historical and cultural ties. However, they differ substantially in population structure, socioeconomic development, healthcare accessibility, diagnostic practices, and lifestyle patterns. Comparing the burden of AA in these countries to the global average can provide insights into the epidemiological characteristics of alopecia areata in East Asia and help identify priorities for future disease surveillance and public health management. Therefore, using GBD 2023 data to systematically evaluated the incidence, prevalence, and DALY burden of AA in the global population, China, Japan, and South Korea from 1990 to 2023. We further assessed temporal trends, sex- and age-specific differences, the burden profiles of selected associated diseases, and the relationship between the Socio-demographic Index and AA burden. We projected the future burden of AA from 2024 to 2046.

Materials and Methods

Data Source

The GBD Study 2023 provided us with data regarding new AA cases, prevalent cases, DALYs, and ASRs for AA incidence, prevalence, and DALYs based on differences in sex, age groups, and location from 1990 to 2023. Incidence, prevalence, DALYs, and their rates were reported with 95% uncertainty intervals (UIs). Age-standardized rates were expressed per 100,000 population. Study regions, demographic stratification, and population data.

The geographical units included the global population, China, Japan, and South Korea. Analyses were conducted for both sexes combined, males, and females. For age-specific analyses, we used the age groups defined by the GBD Study, and cross-sectional comparisons were based on 2023 data. GBD estimates were obtained from the Global Health Data Exchange (GHDx) Results Tool (https://ghdx.healthdata.org/gbd-results-tool).

Population data were obtained from the United Nations World Population Prospects 2024 (https://population.un.org), which provides estimates and projections at both global and national levels. Population estimates were utilized for the period from 1990 to 2023, while population projections under the medium-variant scenario were applied for the years 2024 to 2046. These data were used to estimate and project the number of incident cases, prevalent cases, and DALYs associated with AA.

Cross-Sectional Analysis in 2023

Burden assessment and subgroup analyses.

In 2023, we collected data on the number of incident cases, prevalent cases, and DALYs, together with the ASIR, ASPR, and ASR of DALYs, for the global population, China, Japan, and South Korea. These indicators were compared across locations to characterize regional differences in the burden of AA. Additionally, we conducted sex-stratified analyses to examine the differences in the burden of AA between males and females. Age-specific incidence rates in 2023 were used to describe the age-distribution patterns of AA across locations and between sexes.

To evaluate the consistency of estimates across various GBD iterations, validation datasets were downloaded separately from GBD 2021 and GBD 2023 and compared using identical extraction specifications.

Joinpoint Regression Analysis

Temporal trends in age-standardized rates of AA from 1990 to 2023 were analyzed using the Joinpoint Regression Program, version 6.0.1 (National Cancer Institute, Bethesda, MD, USA). This program identifies changes in trends over time by fitting a series of connected linear segments and estimating the calendar years at which statistically significant changes in slope occur.¹⁷

The calendar year was used as the independent variable, while the age-standardized rate served as the dependent variable. Log-linear models were fitted to estimate the annual percent change (APC) for each segment and the average annual percent change (AAPC) over the entire study period.¹⁸ The optimal number and location of joinpoints were determined automatically by the software. A two-sided P value of less than 0.05 was considered statistically significant.

Associated Disease Burden Profile

To understand the broader epidemiological context of diseases potentially linked to AA, we extracted the ASPRs of atopic dermatitis, anxiety disorders, depressive disorders, iron deficiency anemia, and thyroid disorders from 1990 to 2023. We used temporal trend plots to illustrate the burden profiles of these selected conditions across the study locations.

Spearman’s rank correlation coefficient was calculated between the ASPR of AA and the ASPR of each associated disease. These analyses were ecological time-series correlations based on aggregated location-year data and were not intended to establish individual-level associations or causal relationships. The inherent autocorrelation in time-series data may lead to underestimated uncertainty in the correlation estimates, and although we applied appropriate adjustments, residual autocorrelation cannot be completely ruled out.

Ecological Association Between SDI and ASIR

SDI data for the global population, China, Japan, and South Korea from 1990 to 2023 were matched with the corresponding ASIR estimates for AA by location and year. SDI–ASIR trajectory plots were constructed to illustrate changes in the burden of AA incidence across different levels of socioeconomic development.

Pearson and Spearman correlation coefficients were calculated to evaluate linear and monotonic associations, respectively. Additionally, linear regression models were used to estimate the change in ASIR associated with each 0.1-unit increase in SDI. Since both SDI and ASIR changed over time, these analyses should be interpreted as ecological temporal rather than causal effects of socioeconomic development.

Future Projection Analysis

Age-specific incidence, prevalence, and DALY rates from 1990 to 2023 were modeled separately by location, sex, measure, and age group using linear regression and extrapolated to 2024–2046. Projected absolute burden was calculated by applying the predicted age-specific rates to the corresponding age- and sex-specific population projections from the United Nations World Population Prospects 2024 and summing across age groups:

Both-sex absolute burden was obtained by summing male and female estimates. ASIRs, ASPRs, and age-standardized rates of DALYs were modeled separately using official GBD 2023 age-standardized estimates from 1990 to 2023 and linearly extrapolated to 2046; these rates were used only to describe future standardized-rate trends and not to derive absolute burden. Projections should be interpreted as trend-based scenarios rather than deterministic forecasts.

All statistical analyses were performed using R (v4.4.3), with significance set at p-value < 0.05.

Results

AA Burden in 2023 in China, Japan, South Korea and Globally

Table 1 presents the numbers of incident cases, prevalent cases, and DALYs, along with the corresponding ASIR, ASPR, and ASR of DALYs for alopecia areata in China, Japan, South Korea, and the global population in 2023. In China, there were 1,091,571 incident cases (95% UI,1,058,457–1,125,507),621,916 (95% UI,603,141–643,433) prevalence and 20,222 (95% UI,13,168–28,294) DALYs. In Japan, there were 146,853 incident cases (95% UI, 142,739–151,416),84,099 (95% UI,81,829–87,013) Prevalence and 2,717 (95% UI,1,779–3,782) DALYs. In South Korea, there were 64,707 incident cases (95% UI,62,883–66,865),36,935 (95% UI,35,774–38,084) Prevalence and 1,195 (95% UI,748–1,677) DALYs. Globally, there were 6,274,912 incident cases (95% UI,6,108,514–6,450,742),3,559,681 (95% UI,3,461,749–3,662,700) Prevalence and 115,808 (95% UI,75,580–160,541) DALYs.

Table 1.

The ASR and Number of Alopecia Areata Cases in China, Japan, South Korea and Globally in 2023

Region	Measure	Numbers (95% UI)	ASR (Per 100 000; 95% UI)
China	Incidence	1,091,571 (1,058,457–1,125,507)	71.08 (68.89–73.19)
	Prevalence	621,916 (603,141–643,433)	40.22 (39.01–41.52)
	DALYs	20,222 (13,168–28,294)	1.32 (0.86–1.84)
Japan	Incidence	146,853 (142,739–151,416)	111.75 (108.56,-115.31)
	Prevalence	84,099 (81,829–87,013)	63.25 (61.23–65.36)
	DALYs	2,717 (1,779–3,782)	2.07 (1.34–2.91)
South Korea	Incidence	64,707 (62,883–66,865)	110.96 (107.71–114.63)
	Prevalence	36,935 (35,774–38,084)	62.81 (60.86–64.96)
	DALYs	1,195 (748–1,677)	2.06 (1.27–2.93)
Global	Incidence	6,274,912 (6,108,514–6,450,742)	75.47 (73.49–77.58)
	Prevalence	3,559,681 (3,461,749–3,662,700)	42.75 (41.61–44)
	DALYs	115,808 (75,580–160,541)	1.39 (0.91–1.93)

Abbreviations: ASR, age-standardized rate; DALY, disability-adjusted life-year; UI, Uncertainty interval.

In 2023, the burden of AA varied substantially by region (Table 1 and Figure 1A). Japan had the highest ASIR at 111.75 per 100,000 (95% UI, 108.56 −115.31 per 100,000), closely followed by South Korea at 110.96 per 100,000 (95% UI, 107.71 −114.63 per 100,000). These values were substantially higher than the ASIRs in China, 71.08 per 100,000 (95% UI,68.89–73.19per 100,000), and globally, 75.47 per 100,000 (95% UI,73.49–77.58per 100,000). The ASPR was also highest in Japan 63.25per 100,000 (95% UI,61.23–65.36per 100,000) and South Korea 62.81per 100,000 (95% UI,60.86–64.96per 100,000), compared with China 40.22per 100,000 (95% UI,39.01–41.52per 100,000) and the global population 42.75per 100,000 (95% UI,41.61–44per 100,000). ASR of DALYs followed a similar distribution, with higher rates in Japan 2.07per 100,000 (95% UI,1.34–2.91per 100,000) and South Korea 2.06per 100,000 (95% UI,1.27–2.93per 100,000) than in China 1.32per 100,000 (95% UI,0.86–1.84per 100,000) and globally 1.39per 100,000 (95% UI,0.91–1.93per 100,000). These findings suggest that the burden of alopecia areata is relatively high in high-income East Asian countries.

Figure 1.

Burden of alopecia areata in China, Japan, South Korea, and globally, 2023. (A) Age-standardized rate; (B) Age-standardized prevalence rate by sex; (C) Incidence rates by sex and age group.

In 2023, ASPR of AA was generally higher in females than in males (Table 2 and Figure 1B). In Japan and South Korea, the ASPRs among females were 78.68 per 100,000 population (95% UI, 76.25–81.27per 100,000) and 78.31 per 100,000 population (95% UI, 75.69–80.97per 100,000), respectively. These estimates were approximately 1.65 times the corresponding rates among males in Japan (47.61 per 100,000; 95% UI, 45.76–49.38per 100,000) and South Korea (47.42 per 100,000; 95% UI, 45.66–49.32per 100,000). In China, the ASPR among females was 40.23 per 100,000 population (95% UI, 38.91–41.50per 100,000), only marginally higher than that among males (40.21 per 100,000; 95% UI, 39.00–41.64per 100,000). Globally, the ASPR among females was 46.85 per 100,000 population (95% UI, 45.55–48.21per 100,000), approximately 1.22 times that among males (38.45 per 100,000; 95% UI, 37.37–39.71per 100,000). These findings indicate that females may be an important population for AA surveillance and disease burden management.

Table 2.

The Sex-Stratified ASPR of Alopecia Areata in China, Japan, South Korea and Globally in 2023

Region	Male ASPR (Per 100 000; 95% UI)	Female ASPR (Per 100 000; 95% UI)
China	40.21 (39.00–41.64)	40.23 (38.91–41.50)
Japan	47.61 (45.76–49.38)	78.68 (76.25–81.27)
South Korea	47.42 (45.66–49.32)	78.31 (75.69–80.97)
Global	38.45 (37.37–39.71)	46.85 (45.55–48.21)

Abbreviations: ASPR, age-standardized prevalence rate; UI, Uncertainty interval.

Across the four locations examined, AA incidence was relatively high among young and middle-aged populations. The overall age-specific patterns were broadly similar across locations and exhibited a bimodal distribution. Incidence increased rapidly from early life, reached its primary peak in the 30–34-year age group, and subsequently declined with advancing age. It then increased again from approximately 55–59 years, reaching a smaller secondary peak at 65–69 years. Nevertheless, the magnitude of the peaks and the age groups with the highest incidence varied to some extent across locations (Table 3 and Figure 1C). In the 30–34-year age group, The peak incidence rate was highest in Japan 187.76 per 100,000; (95% UI,169.93–211.28per 100,000), followed by South Korea 186.23 per 100,000 (95% UI,167.27–209.56per 100,000), the global population 116.39 per 100,000 (95% UI,104.73–129.13per 100,000), and China112.53per 100,000 (95% UI,99.75–125.86per 100,000). In males, the peak age group was 25–29 years in Japan and South Korea, but 30–34 years in China and globally. In females, the peak age group was 65–69 years in Japan, South Korea, and globally, while China peaked at 30–34 years.

Table 3.

Peak Age Group of Alopecia Areata Incidence in 2023 by Region and Sex

Region	Sex	Peak Age Group	Peak Incidence Rate (Per 100 000; 95% UI)
China	Both	30–34 years	112.53 (99.75–125.86)
	Male	30–34 years	112.49 (99.22–127.04)
	Female	30–34 years	112.59 (99.46–126.6)
Japan	Both	30–34 years	187.76 (169.93–211.28)
	Male	25–29 years	173.31 (154.25–193.33)
	Female	65–69 years	216.59 (191.78–244.04)
South Korea	Both	30–34 years	186.23 (167.27–209.56)
	Male	25–29 years	172.7 (153.46–193.57)
	Female	65–69 years	215.84 (191.15–241.08)
Global	Both	30–34 years	116.39 (104.73–129.13)
	Male	30–34 years	111.19 (99.63–123.92)
	Female	65–69 years	128.21 (115.97–140.04)

Abbreviation: UI, Uncertainty interval.

We noted that previous studies based on GBD 2021 reported significantly higher ASRs of AA.^14,15 We therefore performed an additional cross-version validation. The GBD 2021 validation estimates were consistent with previously published global and Chinese GBD 2021 results and were approximately 5.0–5.6 times higher than the corresponding GBD 2023 estimates obtained using identical extraction specifications (Supplementary Table 1). These findings indicate a substantial systematic difference in AA estimates between the GBD 2021 and GBD 2023 iterations.

Trends in ASIR, ASPR, and ASR of DALYs for AA

Japan and South Korea consistently had higher ASIRs, ASPRs, and the ASR of DALYs than China and the global average throughout the study period. However, these indicators generally showed slight declines or remained relatively stable (Table 4 and Figure 2). Between 1990 and 2023, the largest overall reduction in ASIR was observed globally (−7.90%), followed by South Korea (−1.62%) and Japan (−0.88%). Similar patterns were observed for ASPR and the age-standardized rate of DALYs. Globally, ASPR and the age-standardized rate of DALYs decreased by 7.93% and 7.78%, respectively, compared with reductions of 1.63% and 1.15% in South Korea and 0.89% and 0.93% in Japan. In China, the overall changes in ASIR and ASPR were close to zero, whereas the age-standardized rate of DALYs increased slightly by 0.36%.

Table 4.

Summary of AAPC from Joinpoint Regression Analysis for ASR of Alopecia Areata in China, Japan, South Korea and Globally,1990–2023

Variables	China				Japan				South Korea				Global
	1990	2023	Overall change,%	AAPC	1990	2023	Overall change,%	AAPC	1990	2023	Overall change,%	AAPC	1990	2023	Overall change,%	AAPC
ASIR (per 100,000;95%UI)	71.08(68.92-73.19)	71.08(68.89-73.19)	0	−2.20e-05 (p<0.001)	112.75(109.53-116.29)	111.75(108.56-115.31)	−0.88	−0.027 (p<0.001)	112.79(109 0.49–116.55)	110.96(107.71-114.63)	−1.62	−0.05 (p<0.001)	81.94(79.79-84.19)	75.47(73.49-77.58)	−7.9	−0.263 (p<0.001)
ASPR (per 100,000;95%UI)	40.22(39.01-41.52)	40.22(39.01-41.52)	0	−1.60e-05 (p=0.012)	63.82(61.78−65.95)	63.25(61.23−65.36)	−0.89	−0.027 (p<0.001)	63.85(61.89−66.03)	62.81(60.86−64.96)	−1.63	−0.05 (p<0.001)	46.43(45.24-47.80)	42.75(41.61-44.00)	−7.93	−0.264 (p<0.001)
ASR of DALYs (per100,0 00;95%UI)	1.32(0.85−1.83)	1.32(0.86−1.84)	0.36 (p=0.003)	0.014	2.09(1.35–2.89)	2.07(1.34–2.91)	−0.93	−0.025 (p<0.001)	2.08(1.35–3.04)	2.06(1.27–2.93)	−1.15	−0.021 (p=0.051)	1.51(0.99−2.09)	1.39(0.91-1.93)	−7.78	−0.257 (p<0.001)

Abbreviations: ASIR, age-standardized incidence rate; ASPR, age-standardized prevalence rate; ASR, age-standardized rate; DALY, disability-adjusted life-year; AAPC, average annual percentage change; UI, Uncertainty interval.

Figure 2.

Annual percent changes for the (A) ASIR, (B) ASPR, and (C) ASR of DALYs of alopecia areata in China, Japan, South Korea, and globally from 1990 to 2023 calculated using Joinpoint regression analyses. ASIR age-standardized incidence rate, ASPR age-standardized prevalence rate, ASR age-standardized rate. *P<0.05.

Abbreviations: DALY, disability-adjusted life-year; AAPC, average annual percentage change.

Joinpoint regression further showed that, from 1990 to 2023, the global ASIR, ASPR, and age-standardized rate of DALYs all exhibited significant downward trends, with AAPCs of −0.263%, −0.264%, and −0.257%, respectively. The declines in ASIR and ASPR were more pronounced in South Korea, with AAPCs of approximately −0.050% for both indicators, than in Japan, where the corresponding AAPCs were approximately −0.027%. In contrast, the age-standardized rate of DALYs declined slightly faster in Japan (AAPC, −0.025%) than in South Korea (AAPC, −0.021%); however, the decline in South Korea did not reach statistical significance. In China, ASIR and ASPR remained largely stable, with AAPCs close to zero, whereas the age-standardized rate of DALYs showed a small but statistically significant increase (AAPC, 0.014%).

Association Between AA and Comorbidities in China, Japan, South Korea and Globally

Previous clinical studies have indicated a relatively high prevalence of several comorbid conditions among patients with alopecia areata (AA). These conditions include thyroid disorders, iron deficiency anemia, anxiety disorders, depressive disorders, and atopic dermatitis.^19–22 We therefore selected these five conditions as diseases potentially associated with AA and examined the ecological temporal correlations between their age-standardized prevalence rates (ASPRs) and the ASPR of AA from 1990 to 2023.

Figure 3A illustrates the temporal trends in the ASPRs of five selected health conditions from 1990 to 2023, both globally and specifically in China, Japan, and South Korea. Among these conditions, iron deficiency anemia exhibited one of the highest burdens and remained particularly prevalent within the global population and in the East Asian nations studied. Its ASPR declined markedly in China and South Korea over the study period, while more gradual decreases were observed in Japan and globally. Thyroid disorders also imposed a substantial burden in China and globally. In China, the ASPR of thyroid disorders fluctuated over time, with relative peaks around 2000 and 2010, followed by a modest decline and subsequent stabilization. By contrast, the burden of thyroid disorders was generally lower in Japan and South Korea than in China and the global population. The ASPRs of anxiety and depressive disorders showed increasing or fluctuating trends across the four locations, with more pronounced increases after 2019. Meanwhile, The ASPR for atopic dermatitis remained relatively stable over time and was generally higher in China and globally than in Japan and South Korea.

Figure 3.

Correlations between alopecia areata and selected associated diseases. (A) Trends in age-standardized prevalence rates of associated diseases from 1990 to 2023; (B) Ecological temporal correlation heatmap between associated diseases and alopecia areata across region groups.

The ecological temporal correlations between the ASPR of AA and those of the selected conditions varied markedly across locations (Figure 3B). In Japan, South Korea, and the globally, there was a strong positive correlation between AA and conditions such as atopic dermatitis and iron deficiency anemia. In Japan, the correlation coefficients for AA with both atopic dermatitis and iron deficiency anemia were nearly 1.00. In South Korea, the correlation coefficients were 1.00 for iron deficiency anemia and 0.99 for atopic dermatitis, whereas the corresponding coefficients were 0.99 for both conditions at the global level. AA was also strongly positively correlated with thyroid disorders in South Korea (Spearman’s ρ = 0.95) and moderately positively correlated with thyroid disorders globally (ρ = 0.52).

In China, however, the temporal relationships between AA and the selected conditions were generally weak. AA showed a moderate positive correlation with anxiety disorders (ρ = 0.49), whereas its correlations with atopic dermatitis, iron deficiency anemia, and thyroid disorders were weak or close to null. Anxiety and depressive disorders were strongly negatively correlated with AA in Japan (ρ = −0.95 and −0.91, respectively) and globally (ρ = −0.94 and −0.99, respectively). In South Korea, AA was also negatively correlated with anxiety disorders (ρ = −0.76), whereas its correlation with depressive disorders was weak.

This data represents ecological time-series associations based on aggregate information and should not be interpreted as evidence of individual-level associations or causal relationships.

Relationship Between the Burden of AA and SDIs

Our analysis revealed distinct regional patterns in the association between SDI and AA burden. From 1990 to 2023, the SDI increased globally and in China, Japan, and South Korea. China experienced a marked rise in SDI, whereas the ASIR of AA remained largely stable Japan and South Korea remained in the high-SDI and high-ASIR range throughout the study period; however, their ASIRs declined gradually as SDI increased further. A similar pattern was observed globally, with ASIR decreasing progressively as SDI increased (Figure 4A and B).

Figure 4.

Correlations between the burden of alopecia areata and SDIs in China, Japan, South Korea, and globally. (A) SDI-ASIR trajectories of alopecia areata from 1990 to 2023; (B) Region-specific SDI-ASIR trajectories of alopecia areata; (C) Spearman correlations between SDI and ASIR of alopecia areata.

Abbreviations: ASIR, age-standardized incidence rate; SDI, social development index.

The relationships between the SDI and ASIR also showed marked regional heterogeneity (Figure 4C). No significant association was observed in China (Spearman’s ρ = 0.15, P = 0.388). By contrast, Japan and South Korea showed perfect negative Spearman correlations between SDI and ASIR (ρ = −1.00 for both, P < 0.001), and a similarly strong negative association was observed globally (ρ = −0.99, P < 0.001).

These findings suggest that countries with higher SDI levels may have a greater absolute burden of AA incidence, as observed in Japan and South Korea; however, further increases in SDI over time were generally associated with declining ASIRs in Japan, South Korea, and globally. The absence of a significant association in China indicates that the relationship between socioeconomic development and AA incidence is region-specific and likely influenced by differences in healthcare access, diagnostic practices, population structure, environmental exposures, and other contextual factors.

Predicted Patterns and Trends in AA Burden from 2024 to 2046

By 2046, the global AA burden was predicted to increase to 3,934,208 prevalent cases and 127,619 DALYs. Further, the predicted ASRs of incidence, prevalence, and DALYs were 69.22, 39.19, and 1.28 per 100,000, respectively. In China, the AA burden was predicted to decrease to 572,880 prevalent cases and 18,422 DALYs. The ASRs of incidence, prevalence, and DALYs were predicted to be 71.08,40.22 and 1.32 per 100,000, respectively, by 2046. In Japan, the AA burden was predicted to decrease to 70,708 prevalent cases and 2,282 DALYs; the ASRs of incidence, prevalence, and DALYs were predicted to be 111.03, 62.83, and 2.06 per 100,000, respectively, by 2046. In South Korea, the AA burden was predicted to decrease to 31,303 prevalent cases and 1,015 DALYs, and the ASRs of incidence, prevalence, and DALYs were predicted to be 109.72, 62.10, and 2.06 per 100,000, respectively, by 2046 (Table 5 and Figure 5).

Table 5.

Prediction of the ASR and Number of Alopecia Areata Cases in China, Japan, South Korea and Globally in 2046

Region	China	Japan	South Korea	Global
Incident numbers	1,001,145	123,281	54,473	6,919,556
Prevalent numbers	572,880	70,708	31,303	3,934,208
DALYs numbers	18,422	2,282	1,015	127,619
ASIR (per 100,000)	71.08	111.03	109.72	69.22
ASPR (per 100,000)	40.22	62.83	62.10	39.19
ASR of DALYs (per 100,000)	1.32	2.06	2.06	1.28

Abbreviations: ASIR, age-standardized incidence rate; ASPR, age-standardized prevalence rate; ASR, age-standardized rate; DALY, disability-adjusted life-year.

Figure 5.

Predicted case numbers and ASR of alopecia areata in China, Japan, South Korea, and globally from 1990 to 2046. (A) Incidence; (B) prevalence; (C) DALYs. Gray bars indicate observed trends from 1990 to 2023, Blue bars indicate projectedk trends from 2024 to 2046, and vertical dashed lines mark the transition between observation and projection periods, red line show ASR and linear extrapolation.

Abbreviations: ASIR, age-standardized incidence rate; ASPR, age-standardized prevalence rate; ASR, age-standardized rate; DALY, disability-adjusted life-year.

Sex-stratified projections showed that females had higher incidence, prevalence, and DALY rates than males, and this difference is projected to persist throughout the forecast period (Figure 6).

Figure 6.

Projected case numbers of alopecia areata in China, Japan, South Korea, and globally from 2024 to 2046, by sex.(A) Incidence; (B) prevalence; (C) DALYs.DALY disability-adjusted life-year.

Discussion

Based on the GBD 2023 dataset, this study provides the first comparative assessment of the burden of AA in China, Japan, and South Korea over the period from 1990 to 2023. By further applying projection models to estimate disease trends through 2046, our analysis extends beyond a purely retrospective description and provides forward-looking insights for regional health planning. The findings identify both shared and distinct epidemiological patterns of AA across these three neighboring East Asian countries, highlighting that, despite their geographic proximity and common regional characteristics, country-specific strategies tailored to local epidemiological and demographic contexts remain necessary.

In 2023, Japan and South Korea had substantially higher ASIRs, ASPRs, and ASR of DALYs than China and the global average. Although China had relatively low age-standardized rates, its large population resulted in a considerable absolute number of cases. From 1990 to 2023, the global burden of AA generally declined slowly, and similar downward or stable trends were observed in Japan and South Korea. In contrast, ASIR and ASPR remained largely stable in China. Previous studies have also reported gradual declines in the age-standardized burden of AA.²³ The reasons underlying these trends remain uncertain. Possible explanations include improvements in healthcare access and disease management, increased public health awareness, changes in environmental and nutritional exposures, and greater availability of psychological support. These interpretations, however, remain speculative and require confirmation in future studies.

Despite the slowing rate of increase, the absolute numbers of incident and prevalent AA cases continued to rise, particularly at the global level, likely reflecting the combined effects of population growth, population ageing, and changes in population structure. Sex-specific analyses revealed substantially higher ASPRs in females than in males in Japan, South Korea, and globally, consistent with previous reports.¹⁵ This female predominance has been linked, at least in part, to sex-specific differences in immune regulation.²⁴ Fluctuations in sex hormone levels have also been proposed to influence susceptibility to autoimmune diseases, with potentially greater effects in females.²⁵ In China, however, the sex difference in ASPR was minimal. This contrast suggests that sex disparities in AA may not represent a universal epidemiological pattern, but rather may arise from complex interactions among geographic, ethnic, socioeconomic, and healthcare-related factors, including diagnostic and healthcare-seeking practices. Population-specific differences in genetic susceptibility²⁶ may further modify the contribution of sex to AA risk. In addition, as Japan and South Korea are high-income countries, women in these populations may have greater health awareness and more convenient access to dermatological care than women in China, potentially increasing the likelihood of diagnosis and case ascertainment and thereby influencing the observed magnitude of sex differences. Overall, the greater burden of AA among females highlights the need for future management strategies to place greater emphasis on women, particularly with regard to early disease recognition, psychological support, and improvement in quality of life.

Age-specific incidence patterns were broadly similar across the four locations, with the primary incidence peak occurring in the 30–34-year age group, consistent with previously reported patterns of AA onset in young adults.²⁷ Individuals aged 30–34 years are often at a critical stage of life characterized by career development, family formation, and childbearing, and may therefore be exposed simultaneously to occupational, familial, and social stressors. Previous research has suggested that such cumulative multidomain stress may be associated with an allostatic load approximately 34% higher than that observed in younger individuals.²⁷ Prolonged psychological stress and emotional strain have also been considered important potential triggers or exacerbating factors for AA.²⁸ Notably, females exhibited a bimodal age-specific incidence pattern, with peaks at 30–34 and 65–69 years, whereas this pattern was not apparent in males. These two peaks broadly coincide with reproductive and menopausal stages, respectively, both of which are characterized by substantial changes in the reproductive endocrine environment. It has therefore been hypothesized that, in females, fluctuations in sex hormone levels may affect immune homeostasis and potentially increase susceptibility to AA during these periods.^29,30 Nevertheless, these mechanistic interpretations remain speculative, and the ecological nature of the present analysis precludes inference of individual-level or causal relationships.

We identified substantially lower absolute age-standardized estimates in GBD 2023 than in previously published GBD 2021 analyses. Through additional validation, we confirmed that these differences were not attributable to errors in data filtering, measure selection, or statistical analysis. They more likely reflect changes in input data sources, disease definitions, data mapping, and modeling strategies between GBD iterations. Despite these cross-version differences, the internally consistent GBD 2023 framework remains suitable for comparing relative patterns across locations, sexes, age groups, and years. Moreover, the direction of temporal trends, the generally higher female burden, and the age-specific peaks observed in our study were broadly consistent with previous epidemiological evidence. Nevertheless, absolute estimates from different GBD rounds should not be treated as directly interchangeable.

Joinpoint regression showed that ASIR, ASPR, and the age-standardized rate of DALYs declined gradually from 1990 to 2023 globally and in Japan. South Korea also showed declining or relatively stable trends, although the reduction in the age-standardized rate of DALYs was not statistically significant. In China, ASIR and ASPR remained largely stable, with AAPCs close to zero, whereas the age-standardized rate of DALYs increased slightly. This finding suggests that the health loss associated with AA has not decreased substantially in China over the past three decades and may even have increased modestly. The increase in DALY burden may reflect the persistent effects of AA on long-term psychological well-being, social functioning, and quality of life. However, the underlying reasons cannot be determined from aggregated GBD data.

AA may occur as an isolated disorder or coexist with a range of comorbid conditions, including thyroid diseases, iron deficiency anemia, atopic dermatitis, anxiety disorders, and depressive disorders.^20–22 Characterizing these comorbidity patterns may provide valuable insights into the mechanistic heterogeneity of AA and help stimulate further research in this field.³¹ In our ecological analysis, AA showed strong positive temporal correlations with atopic dermatitis and iron deficiency anemia in Japan, and with atopic dermatitis, iron deficiency anemia, and thyroid disorders in South Korea. By contrast, strong negative correlations were observed with anxiety and depressive disorders in Japan and with anxiety disorders in South Korea, whereas AA showed a moderate positive correlation with anxiety disorders in China. These findings suggest that AA, atopic dermatitis, iron deficiency anemia, and thyroid disorders may share similar temporal epidemiological patterns in Japan and South Korea, potentially reflecting common background changes in disease susceptibility, healthcare utilization, diagnostic practices, or other population-level determinants. In contrast, the divergent correlations between AA and psychiatric disorders across the three East Asian countries may largely reflect differences in the direction and magnitude of secular trends during the study period.

A study based on a Japanese claims database reported that allergic diseases, including allergic rhinitis, conjunctivitis, and asthma, were among the most common comorbidities in patients with AA.³² Atopic dermatitis is predominantly characterized by type 2 immune activation, while elevated levels of type 2-related cytokines, including interleukin-4, interleukin-5, and interleukin-6, as well as increased eosinophil levels, have also been reported in patients with AA.³³ These observations have led to the hypothesis that, in some Japanese and South Korean populations, AA and allergic diseases may share common genetic or immunological backgrounds. Similarly, a Korean study reported significantly increased risks of Graves’ disease and Hashimoto’s thyroiditis in patients with AA, with stronger associations among those with more severe disease.³⁴ This finding further raises the possibility that, in certain Korean populations, the genetic and immunological basis of AA may overlap with that of other autoimmune disorders.

Taken together, the heterogeneity of comorbidity patterns across populations may reflect population-specific differences in AA susceptibility genes and the immune dysregulation pathways to which they contribute, which in turn may influence the spectrum of associated diseases. Nevertheless, our analysis was based on region-level temporal correlations and therefore falls within the scope of ecological research. The observed associations represent population-level statistical concordance and should not be interpreted as evidence of individual-level comorbidity or causality. Future studies using individual-level clinical, genetic, and longitudinal data are needed to further clarify the potential relationships between AA and immune, endocrine, nutritional, and psychiatric disorders.

From 1990 to 2023, Japan, South Korea, and the global population showed a pattern of increasing SDI accompanied by declining ASIRs, whereas China experienced a substantial increase in SDI while its ASIR remained largely stable Japan and South Korea remained high-SDI settings throughout the study period. Further socioeconomic development in these countries, together with improvements in public health measures, health education, healthcare accessibility, and medical resource availability, may have contributed to the gradual reduction in age-standardized AA burden over time. A broadly similar pattern was observed globally. This may partly reflect the substantial contribution of high-SDI regions to the observed global epidemiological pattern, as previous studies have reported that high AA burden is concentrated in high-income regions such as North America, East Asia, and Western Europe, and that AA burden is closely associated with SDI.³⁵ The pattern observed in China was distinct. The rapid rise in SDI reflects broad improvements in economic development, education, and healthcare accessibility, yet ASIR remained essentially unchanged. One possible explanation is that factors potentially reducing disease burden, such as improved healthcare services and public health interventions, may have been counterbalanced by factors increasing disease detection or measured burden, including population ageing, greater disease awareness, and enhanced diagnostic capacity. China may therefore be undergoing a different stage of epidemiological transition in AA compared with Japan and South Korea. More broadly, these findings suggest that the relationship between socioeconomic development and AA burden may not be linear or uniform across populations. However, because the SDI–ASIR associations identified in this study are ecological, they should not be interpreted as direct causal effects of socioeconomic development on AA incidence.

Our projection analysis revealed marked geographic heterogeneity in the future burden of alopecia areata from 2024 to 2046. Globally, although the ASIR, ASPR, and age-standardized rate of DALYs were projected to continue declining, the absolute numbers of incident cases, prevalent cases, and DALYs were expected to increase further, suggesting that population growth and changes in age structure may partly offset reductions in the age-standardized disease burden. In contrast, the absolute burden in China, Japan, and South Korea was generally projected to decline. Among the three East Asian countries, China was projected to maintain the lowest and relatively stable age-standardized rates; however, owing to its substantially larger population, the absolute numbers of incident cases, prevalent cases, and DALYs were expected to remain the highest in 2046. Japan and South Korea were projected to retain comparatively high ASIRs, ASPRs, and age-standardized DALY rates despite gradual reductions in absolute burden associated with demographic changes. Sex-stratified projections further indicated that the future burden of AA would remain higher among females than males in most regions, particularly in Japan and South Korea, whereas sex differences were relatively limited in China. These findings highlight the importance of considering both age-standardized rates and absolute burden when evaluating future AA trends, as changes in population size and age structure may lead to divergent temporal patterns between these two measures.

Several limitations should be noted in this study. First, it relied on estimates from the GBD, and the availability and quality of primary data vary across countries and regions. The burden of AA may be underestimated in low-SDI settings where disease awareness, healthcare access, and diagnostic coverage are limited. Second, the GBD estimates are model-based and rely heavily on the quality, representativeness, and availability of the input data.³⁶ Third, patients were not stratified according to AA severity, limiting our ability to assess differences between localized disease, alopecia totalis, and alopecia universalis. Fourth, the associated disease and SDI analyses were ecological and cannot establish individual-level associations or causal relationships. Finally, the future projections were based on a linear extrapolation of historical trends and did not consider potential future changes in treatment accessibility, diagnostic criteria, environmental exposures, healthcare policies, or disease awareness. Therefore, the projected results should therefore be interpreted as trend-based scenarios rather than deterministic forecasts.

Conclusions

From 1990 to 2023, the burden of AA showed marked regional, sex-specific, and age-specific heterogeneity globally and across China, Japan, and South Korea. Japan and South Korea consistently had higher age-standardized burdens than China and the global average, and females generally experienced a greater burden than males. Although global age-standardized rates declined overall, the absolute number of AA cases is projected to remain substantial.

The associated disease profile and SDI analyses suggest that immune, nutritional, endocrine, psychological, and socioeconomic factors may be associated with the complex epidemiological background of AA. In clinical practice, surveillance of AA should be strengthened in East Asia, with particular attention to female patients and high‑burden countries. Individual‑level studies are needed to validate these findings and guide targeted prevention and precision therapy.

Data Sharing Statement

The data that support the findings of this study are openly available in the Global Burden of Disease (GBD) Study 2023 through the Institute for Health Metrics and Evaluation (IHME) website (http://ghdx.healthdata.org/gbd-results-tool).

Ethics Statement

The data in this work is from publicly available datasets from the Global Burden of Disease Study 2023 without ethical approval.Approval of the research protocol by an Institutional Review Board:Medical Ethics Committee of the First Affiliated Hospital of Guangxi Medical University (ethics number:2026-E0657).

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors declare no conflicts of interest.