Supplementary Material for: Epidemiological Risk Factors Associated with Acne Vulgaris Presentation, Severity, and Scarring in a Singapore Chinese Population: A Cross-Sectional Study

Background: Acne vulgaris is classified based on the severity of skin lesions and post-healing scar types of these lesions. Numerous epidemiology studies have investigated the risk factors associated with acne presentation and severity, but studies for acne scarring are lacking. Objective: To investigate the prevalence of acne, severity, and scarring grades and their associated risk factors among Singapore Chinese. Methods: A total of 3,888 subjects (2,090 cases/1,798 controls; median age = 21 ± 4.589; range 17–71) completed an investigator-administered questionnaire as part of a cross-sectional study, which included sociodemographics, familial medical history, lifestyle factors, dietary habits, and acne history. Acne cases were further evaluated for their severity (n = 991) and scarring (n = 988) grades by a trained personnel. Results: The majority of the acne cases had mild acne/grade 1 scarring, while less than 1% had severe acne/grade 4 scarring. Parental acne was significantly associated with acne presentation and moderate/severe acne, while sibling acne was significantly associated with grade 3/4 scarring. Gender and age affected acne severity and scarring but not acne presentation, while tertiary maternal education level and the possession of ≥3 siblings were particularly associated with acne scarring. Underweight BMI was protective against acne presentation, while atopic diseases (asthma, allergic rhinitis, eczema) were its predisposing factors. Of the evaluated lifestyle factors, computer/TV usage had significant association with acne presentation, while alcohol consumption was significantly associated with acne severity. Frequent milk consumption was associated with a protective effect for moderate-severe acne, while frequent butter consumption had a detrimental effect on acne scarring extent. Conclusion: Positive familial history is a strong predisposing factor in determining acne presentation, severity, and scarring. Demographic factors (gender, age) and sedentary lifestyle (increased computer/TV usage) influence acne presentation, while dietary habits (milk and butter consumption) influence acne severity and scarring. The predisposing factors revealed in this study could help us to gain insights into acne pathophysiology and hence develop interventions especially targeting modifiable risk factors.背景：寻常痤疮（Acne vulgaris）依据皮损严重程度及愈后瘢痕类型进行分级分类。现有大量流行病学研究探讨了痤疮发病与严重程度相关的危险因素，但针对痤疮瘢痕的相关研究仍较为匮乏。 目的：本研究旨在探究新加坡华裔人群中痤疮、痤疮严重程度及瘢痕分级的患病情况，并分析其相关危险因素。 方法：本研究为横断面研究，共纳入3888名受试者（病例组2090例，对照组1798例；中位年龄21±4.589岁，年龄范围17~71岁），所有受试者均填写由研究人员发放的调查问卷，问卷内容涵盖社会人口学特征、家族病史、生活方式因素、饮食习惯及痤疮患病史。其中991例痤疮病例由经过培训的专业人员评估痤疮严重程度，988例接受了瘢痕分级评估。 结果：大部分痤疮病例表现为轻度痤疮伴Ⅰ级瘢痕，仅不足1%的病例为重度痤疮伴Ⅳ级瘢痕。父母痤疮病史与痤疮发病及中重度痤疮显著相关，而兄弟姐妹痤疮病史则与Ⅲ/Ⅳ级瘢痕显著相关。性别与年龄可影响痤疮严重程度及瘢痕分级，但对痤疮发病无明显影响；而母亲高等教育程度及拥有≥3名兄弟姐妹则与痤疮瘢痕显著相关。体重指数（BMI）偏低可降低痤疮发病风险，而特应性疾病（哮喘、过敏性鼻炎、湿疹）则为痤疮发病的易感因素。在所评估的生活方式因素中，电脑/电视使用时长与痤疮发病显著相关，而饮酒与痤疮严重程度显著相关。频繁饮用牛奶可降低中重度痤疮的发生风险，而频繁食用黄油则会加重痤疮瘢痕程度。 结论：阳性家族史是影响痤疮发病、严重程度及瘢痕形成的重要易感因素。人口统计学因素（性别、年龄）及久坐生活方式（增加的电脑/电视使用时长）可影响痤疮发病，而饮食习惯（牛奶及黄油摄入）则可影响痤疮严重程度与瘢痕形成。本研究揭示的易感因素有助于深入理解痤疮的病理生理机制，进而开发针对可改变危险因素的干预手段。