Supplementary Material for: Hidradenitis Suppurativa in Sweden: A Registry-Based Cross-Sectional Study of 13,538 Patients

<b><i>Background:</i></b> Hidradenitis suppurativa (HS) is a chronic, inflammatory skin condition with nodules and fistula formation and scarring. It is a debilitating disease with a severe negative impact on quality of life. There is a need for increased knowledge about the social and lifestyle characteristics of patients with HS in general, and pregnant women in particular. <b><i>Objectives:</i></b> The aims of this study were to investigate and describe social characteristics and comorbidity in all HS patients in Sweden as well as to study the prevalence of lifestyle factors associated with negative impact on health and pregnancy in Swedish pregnant women with HS. <b><i>Methods:</i></b> A registry-based cross-sectional study was performed by record linkage between Swedish registers covering the entire population. A cohort of 13,538 HS patients diagnosed with HS in specialised care during the years 2001–2014 and a subgroup of 1,368 HS patients who had undergone pregnancy during 2010–2015 were defined and described. Aggregated public data on the entire Swedish population and all pregnancies in 2014 were described for reference. <b><i>Results:</i></b> The HS population had an average age of 44 years on December 31, 2014. The prevalence of HS was 0.14%. In comparison to the Swedish reference population the HS patients were more often women, unmarried (36 vs. 44% married), and had lower education (68 vs. 82% with an upper-secondary school degree or higher) and lower income (39 vs. 16% made SEK &lt;100,000 a year). Comorbidity was 3% for inflammatory bowel disease and 8% for type 2 diabetes. The subgroup analysis showed high prevalence of overweight, obesity, and smoking in pregnant women with HS. <b><i>Conclusions:</i></b> The results from this comprehensive characterisation of Swedish HS patients may be used to improve preventive measures, information, and care for this vulnerable group.

**背景**：化脓性汗腺炎（Hidradenitis suppurativa, HS）是一种慢性炎症性皮肤疾病，以结节、瘘管形成及瘢痕形成为主要特征，属于致残性疾病，会对患者的生活质量造成严重负面影响。目前学界亟需进一步了解HS患者的社会与生活方式特征，尤其是合并妊娠的HS女性患者。
**研究目的**：本研究旨在调查并描述瑞典全部HS患者的社会特征与共病情况，并分析瑞典境内合并妊娠的HS女性群体中，与健康及妊娠不良结局相关的生活方式因素的患病率。
**研究方法**：本研究采用基于登记系统的横断面研究设计，通过覆盖瑞典全人群的多登记系统开展记录关联数据收集。研究纳入2001-2014年间在专科诊疗机构确诊的13538名HS患者队列，以及2010-2015年间发生妊娠的1368名HS患者亚组，并对其进行描述性分析。同时纳入2014年瑞典全人群及所有妊娠事件的汇总公开数据作为参照基准。
**研究结果**：截至2014年12月31日，HS患者队列的平均年龄为44岁，HS的人群患病率为0.14%。与瑞典参照人群相比，HS患者中女性占比更高、未婚比例更高（HS患者已婚占比36%，参照人群已婚占比44%）、受教育水平更低（拥有高中及以上学历者占比：68% vs 参照人群82%）、年收入更低（年收入低于10万瑞典克朗者占比：39% vs 参照人群16%）。共病情况方面，炎性肠病患病率为3%，2型糖尿病患病率为8%。亚组分析显示，合并妊娠的HS女性群体中，超重、肥胖及吸烟的患病率显著升高。
**研究结论**：本研究对瑞典HS患者群体的全面特征表征结果，可用于优化这一脆弱患者群体的预防措施、健康宣教与诊疗服务。