Karolinska Institutet Studies Sweden’s Hidradenitis Suppurativa Population

Karolinska Institutet Studies Sweden's Hidradenitis Suppurativa Population

Swedish researchers from Karolinska Institute and Lund University conducted a registry-based, cross-sectional study targeting Hidradenitis suppurativa (HS) patients in Sweden. The team sought to better understand the 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. The investigators found that HS patients were more frequently women, unmarried and had lower education and lower-income levels as when compared with the Swedish reference population. There were associations with inflammatory bowel disease and type 2 diabetes.   Additionally, pregnant women in Sweden exhibited higher prevalence of weight issues, including obesity and smoking.  Overall, the findings indicate that HS patients represent a vulnerable population that should be understood so that medical professionals can enhance preventive measures, improve care coordination, etc.

The Study

The Swedish team employed a registry-based cross-sectional study linking Swedish registers covering the entire population.  A cohort of 13,538 HS patients diagnosed with HS in specialized care during the period 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.


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 <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. 


The research team’s findings verify what many studies are revealing in other countries including America. HS represents a challenging and potentially debilitating condition that hasn’t seen enough research and investment for improved treatment. There appear to be socioeconomic factors such as income, education and lifestyle that may play a role but genetics, environmental factors and the like are also relevant. Regardless this population is in dire need of better care—including potential preventative measures should they be relevant and feasible—and the Swedish research shines some light on the importance of this population and their health and well-being.

Lead Research/Investigator

Hassan Killasli, Dermatology and Infectious Diseases, Department of Medicine, Karolinska Institutet

Karin Sartorius, Department of Clinical Science and Education, Karolinska Institutet

Lennart Emtestam, Dermatology and Infectious Diseases, Department of Medicine, Karolinska Institutet

Åke Svensson, Department of Dermatology and Venerology, Lund University, Skåne University Hospital