Copyright ? 2020 Hospital for Skin Diseases (Institute of Dermatology), Chinese Academy of Medical Sciences, and Chinese Medical Association, published by Wolters Kluwer, Inc.

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International Journal of Dermatology and Venereology (2020) 3:4

Received: 26 April 2020, Revised: 8 June 2020, Accepted: 2 July 2020

doi: 10.1097/JD9.0000000000000118

Dear Editor:

Rosacea is a disease characterized by erythema,flushing,telangiectasia, papules, pustules, and possible ocular or phymatous changes.1The difficulties in defining rosacea and explaining its pathogenesis have received much attention from dermatologists. The level of interest in rosacea among the general public is unknown. Hancox et al.2reported no significant seasonal variations in rosacea;however,a recent study showed that rosacea was more common in hotter periods.3Annual and seasonal trends in Internet searches have been evaluated for skin cancer,4tanning,5and psoriasis.6This study was performed to evaluate the annual and seasonal trends in Internet searches of rosacea based on Google Trends and the Baidu Index, and to assess the general interest in rosacea in the United States and China.

In Google Trends, the search index value (SIV) for rosacea increased over time (P＜0.001). Overall, the United States showed periodicity in the general interest in rosacea (Fig. 1A). The highest SVI appeared in March(mean,79.56),and the lowest SVI appeared in September(mean,55.69).The SVI in March was significantly higher than that from June to December(all P＜0.001).In Google Trends, the top five related queries were “rosacea skin,”“rosacea face,” “rosacea acne,” “acne,” and “rosacea cream,” while the top five rising related queries were“cream for rosacea,” “rosacea eyes,” “moisturizer for rosacea,”“remedies for rosacea,”and“red cheeks.”In the Baidu Index, an increasing trend (P＜0.001) and periodicity were also observed (Fig. 1B). The two highest SIVs appeared in July (mean, 2,405.56) and August (mean,2,409.89). The SIV was ＞2,200 from April to August and ＜2,100 from November to February. The SIV was significantly higher in July and August than from November to February (all P＜0.001).

This preliminary study used infodemiology methods to assess the general interest in rosacea. The results showed that the general interest in rosacea increased over time and changed seasonally in a calendar year in both the United States and China. The top and top rising related queries were also identified,which could provide new insights into the behaviors and demands of the general public. Online users were concerned about rosacea creams, ocular rosacea, moisturizers, and the relationship between acne and rosacea. Rosacea creams and moisturizers are associated with the skincare of patients with rosacea,which might not be fully emphasized in dermatology clinics. Treatment of ocular rosacea requires cooperation between dermatologists and ophthalmologists,1with which the public might not be familiar. Experience in the differential diagnoses of rosacea in adolescent patients(eg, acne vulgaris, perioral dermatitis, and seborrheic dermatitis) is also important. Dermatologists can more effectively identify the needs of patients in this way and provide more helpful health-related information for patients thanks to the popularity of smartphones and the Internet. Seasonality was observed in both countries;the interval between the highest and lowest search index was about 6 months. However, the peak occurred in March in the United States but in July and August in China,which might have been due to the different climate characteristics or skincare habits between the two countries.Rosacea can be triggered by heat,sun exposure,and ultraviolet radiation,which can explain its periodicity.The roles of these factors in its pathogenesis require more exploration and elaboration.

This study has several limitations. The data from these two search engines cannot represent all online users, let alone the general public. Additionally, how these search index data were generated is unknown. More efforts are needed to elucidate the changes in the incidence and prevalence rate of rosacea, the relationship between seasonality and rosacea, the pathogenic factors of rosacea and their roles in the disease, and the popularization of hot topics among patients with rosacea and the general public.

Han-Lin Zhang1,2, Ke-Yun Tang1,2, Yu-Chen Wang2,Rou-Yu Fang1, Qiu-Ning Sun1,?1Department of Dermatology, Peking Union Medical College Hospital,Beijing 100730,China;2Eight-year MD Program,Peking Union Medical College,Beijing 100730,China.

?Corresponding author:E-mail:doctorjenny1@163.com.

Figure 1. Search index value of rosacea in the United States and China.(A)Search volume index of rosacea in the United States from 2004 to 2019. (B) Search index value of rosacea in China from 2011 to 2019.