Regional and local burden of psoriasis in China, 1990–2021: Findings from the Global Burden of Disease Study 2021

To the Editor: Psoriasis is a chronic inflammatory disease associated with high morbidity and poor quality of life, especially in China.^[1,2] However, the full picture of spatial variability and temporal trends in the disease burden of psoriasis in China remains unclear. This lack is detrimental to the prevention and control of the disease and medical equity and poses a public health challenge.

The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 is a systematic analysis of health loss due to 371 diseases, injuries, risk factors, impairments, and causes of death. Its measurement framework and estimates, covering 204 countries and territories from 1990 to 2021, are described in the GBD 2021 capstone publication.^[3–5]

In this context, we used data from the GBD 2021 to analyze the overall and age/sex-specific number of cases, incidence rates, prevalence rates, and associated disability-adjusted life years (DALYs) of psoriasis in 2021 and investigated the regional and local burdens of the disease based on spatial variability. We further estimated the average annual percent change (AAPC) in the three indicators above to explore temporal trends in China from 1990 to 2021, and analyzed the correlation between disease burden and provincial gross domestic product (GDP) per capita or urbanization rates. All statistical analyses were conducted using the Joinpoint Regression Program (Version: 5.1.0, https://www.surveillance.cancer.gov/joinpoint/) and R (Version: 4.3.3, https://www.r-project.org/).

According to GBD 2021, China had a total of 8453.04 (95% uncertainty interval [UI]: 8161.39–8743.68) thousand patients with psoriasis, with 1012.64 (979.13–1044.62) thousand incident cases and 728.55 (528.47–971.58) thousand DALYs caused [Supplementary Table 1, http://links.lww.com/CM9/C456]. The incidence and prevalence rates of psoriasis were 71.17 per 100,000 population (95% UI: 68.82–73.42) and 594.14 per 100,000 population (573.64–614.56), respectively. In addition, the DALY rate for psoriasis was 51.21 DALYs per 100,000 population (37.14–68.29) [Supplementary Table 1, http://links.lww.com/CM9/C456].

Overall, our model estimated 4669.81 (95% UI: 4492.00–4840.65) thousand prevalent cases of psoriasis in males and 3783.23 (3661.64–3903.61) thousand in females in China, with 551.27 (532.30–570.22) thousand and 461.36 (446.39–476.27) thousand new cases, respectively [Supplementary Table 1, http://links.lww.com/CM9/C456]. Significant sex differences were demonstrated in the age-standardized incidence and prevalence rates, with higher rates in males than in females, which were not seen in the DALYs and age-standardized DALY rate [Supplementary Figure 1, Supplementary Table 1, http://links.lww.com/CM9/C456]. The age-standardized male-to-female incidence prevalence ratios were 1.08 and 1.10, respectively. Among all age groups, males aged 55–59 years (132.12 [95% UI: 116.52–150.16]) and females aged 70–74 years (135.77 [119.97–150.67]) had the highest incidence rate [Supplementary Figure 1, http://links.lww.com/CM9/C456]. The age-specific prevalence and DALY rates exhibited a left-skewed distribution, with a peak in the 60–64 and the 75–79 year age groups for males and females, respectively [Supplementary Figure 1, http://links.lww.com/CM9/C456].

At the provincial level, we found a North–South trend and a West–East trend in the age-standardized incidence rate at the regional and provincial levels. Provinces with a high age-standardized incidence rate of psoriasis were clustered in Eastern and Southern China [Supplementary Table 1, http://links.lww.com/CM9/C456]. Specifically, the highest age-standardized incidence rate was predicted in Chongqing (94.73 new-onset psoriasis per 100,000 population [95% UI: 91.43–97.90]), followed by Shanxi (65.88 per 100,000 population [63.67–68.19]) and Macao (63.77 per 100,000 population [61.62–66.05]). In contrast, provinces with low age-standardized incidence rates were clustered in Western and Northern China, mostly rural regions with low socioeconomic status. This included Inner Mongolia (50.10 per 100,000 population [48.34–52.06]) and Tibet (53.15 per 100,000 population [51.41–55.00]) [Supplementary Table 1, http://links.lww.com/CM9/C456]. Among all provinces, Beijing was a spatial outlier because it had a low age-standardized incidence rate (51.56 per 100,000 population [49.56–53.74]) but was surrounded by areas with high age-standardized incidence rates.

The age-standardized prevalence and DALY rates shared similar geographical patterns with the incidence. The lowest age-standardized prevalence and DALY rates were in Inner Mongolia (356.78 cases per 100,000 population [95% UI: 342.14–372.02]; 31.14 DALYs per 100,000 population [22.51–41.72]) and the highest estimates were in Chongqing (951.17 cases per 100,000 population [918.49–983.01]; 82.51 DALYs per 100,000 population [59.65–110.82]) [Supplementary Table 1, http://links.lww.com/CM9/C456].

Based on the Joinpoint regression analysis, the age-standardized incidence, prevalence, and DALY rates of psoriasis gradually increased in China between 1990 and 2021, with AAPCs of 0.74 (95% CI: 0.72–0.76), 0.88 (95% CI: 0.85–0.90), and 0.88 (95% CI: 0.86–0.91), respectively [Supplementary Figure 2, Supplementary Table 2, http://links.lww.com/CM9/C456]. The national-level age-standardized rate of the three indicators increased in both males and females, with females showing a higher trend in the incidence than males (AAPC of 0.75 [95% CI: 0.74–0.77] in males, 0.78 [95% CI: 0.77–0.79] in females) [Supplementary Table 2, http://links.lww.com/CM9/C456].

Across all provinces, the age-standardized incidence, prevalence, and DALY rates of psoriasis significantly increased over the 30 years. However, increases in the burden of psoriasis were higher in Western China than in provinces in other regions. Specifically, Shaanxi had the highest increase in age-standardized incidence rates of psoriasis (0.92 [95% CI: 0.91–0.94]) [Supplementary Table 2, http://links.lww.com/CM9/C456]. Guizhou and Ningxia also had notable increases in age-standardized incidence rates (Guizhou 0.91 [95% CI: 0.88–0.94], Yunnan: 0.86 [95% CI: 0.85–0.88]) [Supplementary Table 2, http://links.lww.com/CM9/C456].

A positive and moderate correlation between incidence rate and GDP per capita was observed (rho = 0.37, P <0.001) [Supplementary Figure 3, http://links.lww.com/CM9/C456]. Similar positive correlations were also observed between prevalence and DALY rates and GDP per capita (prevalence rho = 0.35, P <0.001; DALY rho = 0.35, P <0.001) [Supplementary Figure 3, http://links.lww.com/CM9/C456]. The incidence, prevalence, and DALY rates of psoriasis showed consistent and positive correlations with urbanization rates in 33 provinces (incidence rho = 0.55, P <0.001; prevalence rho = 0.54, P <0.001; DALY rho = 0.54, P <0.001) [Supplementary Figure 3, http://links.lww.com/CM9/C456].

Our study revealed that in 2021, the incidence, prevalence, and DALYs of psoriasis in China were substantial, particularly in older adults and males. The age-standardized incidence, prevalence, and DALY rates of psoriasis increased from East to West and from North to South across China, with the highest disease burden recorded in Chongqing and the lowest in Inner Mongolia. In addition, there has been a rapid increase in the disease burden of psoriasis both nationally and regionally over the past 30 years, with the most significant rise seen in Western China, specifically in Shaanxi, Guizhou, and Ningxia provinces. Furthermore, the incidence, prevalence, and DALY rates of psoriasis showed consistent positive correlations with GDP per capita and urbanization rates in China. However, several limitations should be noted. As part of the GBD 2021 study, we acknowledge common limitations such as data source heterogeneity, potential differences between the actual situation and the collected data, and a limited range of risk factors.^[2–4] Moreover, GBD 2021 mainly estimated the disease burden of psoriasis from existing available provincial data and previous literature in China. Unfortunately, high-quality epidemiological studies on psoriasis in China were very limited, especially in some provinces with a lack of relevant data, which induced some local detection bias.

In conclusion, China has a large and increasing disease burden of psoriasis in aged individuals and males. North–South and West–East trends imply potential impacts of urbanization. These findings highlight the urgent need for innovative and specific prevention strategies for different regions in China.

Funding

This study was supported by a grant from the National Natural Science Foundation of China (No. 72304129).

Conflicts of interest

None.

Supplementary Material

cm9-139-314-s001.docx ^{(933KB, docx)}