Rosacea is a facial inflammatory dermatosis that is linked with various systemic illnesses. With regards to the eye, rosacea patients have been described to manifest ocular surface changes, such as blepharitis and conjunctivitis. However, studies that examine the association of rosacea with a wider array of ocular diseases are limited. Thus, our aim was to identify the range of ocular comorbidities in the Korean patient population and create a reference data set. A multi-institutional, case-control study was conducted, where 12,936 rosacea patients and an equal number of sex- and age-matched control subjects were extracted over a 12-year period. We were able to discover a notable association between rosacea and blepharitis (adjusted odds ratio (aOR) 3.44; 95% confidence interval, 2.71–4.36, p < 0.001), conjunctivitis (aOR 1.65; 95% CI, 1.50–1.82, p < 0.001), glaucoma (aOR 1.93; 95% CI, 1.70–2.20, p < 0.001), dry eye syndrome (aOR 1.89; 95% CI, 1.70–2.09, p < 0.001), and chalazion (aOR 3.26; 95% CI, 1.41–7.57, p = 0.006) from logistic regression analysis. Female subjects and individuals younger than 50 exclusively showed higher odds for chalazion. Our study suggests that ocular comorbidities (i.e., glaucoma, dry eye syndrome, and chalazion as well as blepharitis and conjunctivitis) are more prevalent among Koreans with rosacea. Clinicians should proactively check ocular symptoms in rosacea and employ joint care with an ophthalmologist in cases of need.

Introduction: Seasonal variations of allergic diseases have been of great interest in clinical practice, but large‐scale epidemiological data in the real world is lacking.Methods: We conducted a nationwide, population‐based, cross‐sectional study using the Korean National Health Insurance claims database to examine the seasonalities of allergic rhinitis (AR), asthma, allergic conjunctivitis (AC), and atopic dermatitis (AD). In addition, we investigated the correlations between the monthly patient numbers of each disease and climate factors such as daytime length, temperature, daily temperature range, humidity, solar radiation, rainfall, UVA dose, UVB dose, and PM10.Results: The highest seasonal variation was identified in AC, followed by AR, asthma, and AD. AR was most prevalent in September and least prevalent in July and was positively correlated with a daily temperature range. Asthma had peaked in the winter and spring and was negatively correlated with both temperature and humidity. AC had dual peaks in May and September and the valley in winter. AD was prevalent between May and August with the lowest visits in winter and positively correlated with temperature.Conclusions: We demonstrated a clear seasonality of four allergic diseases. Korea is located in a temperate region with four distinct seasons, with 50 million people all having a single health insurance system. Therefore, our data reflects all hospital visits in Korea with the least chance for selection bias.

Recent evidence links rosacea to systemic disease, but there are not enough methodologic studies addressing this association in Asians. Our aim was to identify rosacea comorbidities in Koreans and establish a reference database. A multi-center, case-control study was performed where a total of 12,936 rosacea patients and 12,936 age- and sex-matched control subjects were identified from 2007 to 2018. Logistic regression was performed to find significant association between rosacea and Sjögren syndrome (odds ratio [OR] 2.05; 95% confidence interval, 1.40–3.00), systemic sclerosis (OR 6.56; 95% CI, 1.50–28.7), rheumatoid arthritis (OR 1.72; 95% CI, 1.50–1.98), ankylosing spondylitis (OR 2.32; 95% CI, 1.42–3.84), autoimmune thyroiditis (OR 1.96; 95% CI, 1.40–2.73), alopecia areata (OR 1.77; 95% CI, 1.27–2.45), vitiligo (OR 1.90; 95% CI, 1.30–2.77), lung cancer (OR 1.54; 95% CI, 1.06–2.21), hepatobiliary cancer (OR 1.38; 95% CI, 1.06–1.77), alcohol abuse (OR 1.59; 95% CI, 1.05–2.39), diabetes mellitus (OR 1.11; 95% 1.02–1.19), obesity (OR 1.72; 95% CI, 1.22–2.41), allergic rhinitis (OR 1.65; 95% CI, 1.54–1.76), allergic conjunctivitis (OR 1.57; 95% CI, 1.27–1.94), chronic rhinosinusitis (OR 1.28; 95% CI, 1.14–1.42), herpes infection (OR 1.69; 95% CI, 1.53–1.86), and human papillomavirus infection (OR 2.50; 95% CI, 2.06–3.02). Higher odds for Sjogren syndrome, systemic sclerosis, ankylosing spondylitis, thyroiditis, vitiligo, hepatobiliary cancer, and obesity was exclusive in female subjects with rosacea, whereas increased prevalence of alopecia areata and alcohol abuse was confined to men. Only those who were 50 years and older exhibited higher odds for vitiligo, lung cancer, and gastroesophageal reflux disease while individuals younger than 50 were exclusively associated with hepatobiliary cancer, allergic conjunctivitis, and irritable bowel syndrome. Our study suggests that Koreans with rosacea are more likely to experience systemic comorbidity. Clinicians should acknowledge these interrelations and employ comprehensive care with an individual-based approach.

Imbalances in gut microbiota reportedly contribute to the development of autoimmune diseases, but the association between the etiopathogenesis of alopecia areata (AA) and gut microbial dysbiosis remains unclear. This cross-sectional study was conducted to identify and compare the composition of the gut microbiome in patients affected by AA and those in a healthy control (HC) group, and to investigate possible bacterial biomarkers for the disease. Fecal samples were collected from 19 AA patients and 20 HCs to analyze the relationship with fecal bacteria. The three major genera constituting the gut microbiome of AA patients were Bacteroides, Blautia, and Faecalibacterium. The alpha diversity of the AA group was not statistically significant different from that of the HC group. However, bacterial community composition in the AA group was significantly different from that of HC group according to Jensen–Shannon dissimilarities. In patients with AA, we found an enriched presence of the genera Blautia and Eubacterium_g5 compared to the HC group (p < 0.05), whereas Bacteroides were less prevalent (p < 0.05). The gut microbiota of AA patients was distinct from those of the HC group. Our findings suggest a possible involvement of gut microbiota in in the as-yet-undefined pathogenesis of AA.