BACKGROUND: Rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and 
psoriasis are immune-mediated inflammatory diseases with similarities in 
pathophysiology, and all can be treated with similar biological agents. Previous 
studies have shown that there are gender differences with regard to disease 
characteristics in RA and IBD, with women generally having worse scores on pain 
and quality of life measurements. The relationship is less clear for psoriasis. 
Because treatment differences between men and women could explain the 
dissimilarities, we investigated gender differences in the disease 
characteristics before treatment initiation and in the biologic treatment 
prescribed.
METHODS: Data on patients with RA or IBD were collected from two registries in 
which patients treated with biologic medication were enrolled. Basic demographic 
data and disease activity parameters were collected from a time point just 
before the initiation of the biologic treatment. For patients with psoriasis, 
the data were taken from the 2010 annual report of the Swedish Psoriasis 
Register for systemic treatment, which included also non-biologic treatment. For 
all three diseases, the prescribed treatment and disease characteristics were 
compared between men and women.
RESULTS: In total, 4493 adult patients were included in the study (1912 with RA, 
131 with IBD, and 2450 with psoriasis). Most of the treated patients with RA 
were women, whereas most of the patients with IBD or psoriasis were men. There 
were no significant differences between men and women in the choice of 
biologics. At treatment start, significant gender differences were seen in the 
subjective disease measurements for both RA and psoriasis, with women having 
higher (that is, worse) scores than men. No differences in objective 
measurements were found for RA, but for psoriasis men had higher (that is, 
worse) scores for objective disease activity measures. A similar trend to RA was 
seen in IBD.
CONCLUSIONS: Women with RA or psoriasis scored significantly higher on 
subjective, but not on objective, disease activity measures than men, and the 
same trend was seen in IBD. This indicates that at the same level of treatment, 
the disease has a greater effect in women. These findings might suggest that in 
all three diseases, subjective measures are discounted to some extent in the 
therapeutic decision-making process, which could indicate undertreatment in 
female patients.