The overall estimated prevalence of immune-mediated inflammatory diseases in western societies is 5-7%. Interestingly, the European Working Group on Immune-Mediated Inflammatory Diseases has initiated a forum to foster collaborations in this important clinical field which includes diseases such as rheumatoid arthritis (RA), inflammatory bowel disease (IBD) and psoriasis. All three diseases have similar pathophysiology and are treated by common biological therapies including tumor necrosis factor (TNF) inhibitors.
Gender differences are observed for RA and IBD with female: male incidence ratios of 3:1 and 1:1.5, respectively. These differences have been suggested to be caused by differences in treatment administered to men and women.This plausible explanation has been investigated by Prof van Vollenhoven and colleagues in an observational study recently published in BMC Medicine.
The data used in the study were on patients with RA (N = 1912), IBD (N = 131) and psoriasis (N = 2450) collected from the Stockholm TNF follow-Up (STURE), the Remicade (infliximab) and PsoReg registries, respectively. The results show gender differences at the start of treatment, with men having a higher incidence of IBD and psoriasis than women whereas most of the patients with RA were women. However, at this level of treatment and in all diseases overall worse symptoms and quality of life were found in women. These data can partially explain the under-treatment of their more severe outcomes particularly for RA, as previously reported. The authors recommend these data are taken into consideration during the clinical decision making process, which will ensure appropriate treatment for female patients with inflammatory diseases.