The 2019 GBD Study data in 2019 reflects the significant impact of skin diseases on the GBD. Dermatitis, especially atopic dermatitis and scabies had the largest skin disease burden in China in 2019 among all skin and subcutaneous diseases, followed by viral skin diseases and acne vulgaris.
Atopic dermatitis ranks 15th among all non-fatal diseases globally [10]. Some studies have reported a moderate positive association between the national GDP and the burden of atopic dermatitis [11]. The prevalence of dermatitis continues to increase in low-and middle-income countries [12]. A longitudinal birth cohort study showed that the prevalence of atopic dermatitis is similar in early adulthood and childhood [13]. Atopic dermatitis can have adverse physical and mental effects, such as psychological stress and low self-esteem due to the social stigma and unbearable itching. Scabies is a skin infection caused by scabies mites and is characterized by intense skin itching with varying degrees of skin lesions. The transmission of scabies is mainly through skin contact; the risk of transmission reflects the number of scabies mites on the skin and the duration and frequency of contact with infected individuals. When defense mechanisms are compromised, crusted scabies occurs, which can be transmitted through contact with mite-containing objects and dandruff. The most common complication of scabies is a bacterial infection caused by Streptococcus pyogenes and Staphylococcus aureus, which cause impetigo and erysipelas, respectively [14]. In addition, immunodeficiency, malnutrition, disability, and the elderly population are often prone to scab scabies, which contains a large number of infectious mites that may be life-threatening and spread through clothing, bedding, or other pollutants [15]. With the aging of the population, scabies outbreaks have become more common in nursing homes. One study found that 51% of residents in nursing homes with confirmed symptoms and elderly patients with cognitive impairment, such as dementia, had a reduced ability to kill mites by scratching, resulting in delayed diagnosis of scabies and large-scale outbreaks [16], which is an important reason for the peak incidence of scabies in older people. The survey showed a global decline in the prevalence of scabies between 1990 and 2017, which is consistent with our findings and interventions for large-scale drug management may be an effective strategy [17]. Moreover, we observed that the burden of bedsores also increased substantially between 1990 and 2019, which was mainly due to the increase in the elderly population accompanied by the increased burden of bedsores [6].
The number of new leprosy cases worldwide has decreased from 750,000 in 2000 to approximately 200,000 in 2019 [18], which suggests a significant improvement in the control of leprosy cases due to comprehensive measures, such as the introduction of multi-medications worldwide in the 1980s, case-finding exercises, and national health education [19]. Another measure of the disease burden of leprosy is the number of new cases with grade 2 disability (G2D) [20]. The number of new cases with G2D worldwide decreased by 16% from 13,275 in 2010 to 10,813 in 2019 [19]. This finding is due to the implementation of various early detection measures. The reported incidence and prevalence of leprosy in China has steadily decreased year-after-year from 2016–2020, and leprosy continues to maintain an overall low prevalence [21]. Therefore, it is necessary to train dermatologists and leprosy control workers to improve their awareness and skills in the early diagnosis of leprosy and actively refer suspected leprosy cases for monitoring of leprosy symptoms to reduce the disease burden due to a delay in leprosy diagnosis [22].
Despite the decline in age-standardized YLD of sexually transmitted infections (excluding HIV) from 1990–2019, the YLD increased. Therefore, sexual transmission of infections remains a huge public health challenge at the global level. China had a higher age-standardized incidence per 100,000 (10462.50, 95% UI: 8843.39-12385.92) of sexually transmitted infections (except HIV) in 2019 than the global incidence (9535.71, 95% UI: 8169·73–11054·76) [23], which may be attributed to the expansion of routine sexually transmitted infection testing in asymptomatic and high-risk individuals in China [24]. The age-standardized YLD rates per 100,000 of sexually transmitted infections (except HIV) in China (10.49, 95%UI: 5.99–17.76) was significantly lower than the global age-standardized YLD (22.74, 95% UI: 14.37–37.11) in 2019. Moreover, the age-standardized YLD rates for syphilis, gonococcal infections, and chlamydia infections showed a downward trend between 1990 and 2019, which is consistent with the global change [23].This finding may be attributed to advances in various highly sensitive and specific early detection techniques over the past 20 years, which facilitates early treatment and improved the quality of life [25]. Sexually transmitted infections that fail to attract attention not only affect the quality of life of individuals and threaten reproductive and newborn health, but also bring financial stress to families and countries [26]. Thus, the WHO Sexual Transmission Infection Global Health Department strategy sets out guidelines and priorities for the end of sexually transmitted infections as a public health issue by 2030 [27].
Skin malignancies can be divided into malignant skin melanoma and non-melanoma skin cancer (NMSC). NMSC represents approximately one-third of all malignancies diagnosed worldwide each year [28] and includes squamous cell carcinoma (SCC) and basal cell carcinoma (BCC).The age-standardized DALY per 100,000 for global NMSC increased significantly from 14.44 (95% UI: 13.31–15.42) in 1990 to 14.67 (95% UI: 13.45–15.67) in 2019 [29]. Some of the disease burden indicators of SCCs and BCCs, such as the YLD and the number of new cases, increased over the same period, which is consistent with the development trend in YLD for NMSC in China. Therefore, NMSC causes a very serious disease burden and poses a serious threat to global human health. Although the age-standardized incidence of BCC was higher than SCC in 2019, the YLD and age-standardized YLD rates for SCC in 2019 were higher than BCC, which may be related to the following factors: SCC has the strongest association with ultraviolet irradiation and is more prone to metastasis than BCC [30]; and studies suggest that the incidence of BCC is expected to increase continuously to at least 2040 [31], which may be due to the development of an aging population, as the elderly are a key population with NMSC [32]. Considering the spread of these factors and the fact that the disease burden caused by NMSC remains high or continues to grow, more prevention and control policies should be developed for high-risk individuals and risk factors to help reduce the adverse effects associated with NMSC [29].