Denmark: When the severity of psoriasis worsens, the chance of serious and uncommon infections increases proportionally, says an article published in the British Journal of Dermatology. Clinicians should, therefore, be aware of the increased risk of severe and rare infections in patients with severe psoriasis so that early investigation and treatment can be initiated early.
Psoriasis patients are at a greater risk of developing several comorbid diseases. However, only a few studies have looked into the link between psoriasis and severe and uncommon illnesses. This study compares the prevalence of severe and unusual infections (considered rare in Denmark) among Danish psoriasis patients to the general population. Nikolai Loft and colleagues conducted this study with the goals of assessing the incidence and risk of severe and unusual infections in Danish psoriasis patients and the matched general population, as well as comparing this risk among patients with severe or mild psoriasis and the general public.

For this study data from the Danish National Patient Register were obtained from persons aged 18 and living in the source population between January 1st, 1997, and December 31st, 2018. Individuals who had any of the chronic infections studied previously to inclusion were excluded. Psoriasis patients were matched 1:6 for age and gender to general population controls. Infections classified as severe required hospital care, whereas infections classified as uncommon included HIV, hepatitis B and C, and TB infections. Incidence rates (IR) per 100,000 person-years of exposure were reported. Severe psoriasis was defined by the use of systemic or biologic therapy in the past or present. Patients with mild psoriasis who had never had biologic or systemic therapy were classified as such.
The key findings of this study were as follows:
1. A total of 94,450 affected patients and 566,700 healthy controls were matched.
2. Patients with any psoriasis had higher IRs than controls: 3104.9 and 2381.1 for any infection, 3080.6 and 2364.4 for severe infections, and 42.9 and 31.8 for uncommon infections, respectively.
3. When compared to patients with mild psoriasis and controls, those with severe psoriasis had higher IRs of serious or unusual illnesses.
In conclusion, professionals should be aware of the increased risk of serious and unusual infections in patients with severe psoriasis so that early assessment and treatment can begin.
Reference:
Loft, N., Skov, L., Richardson, C., Trivedi, V., Alarcon, I. and Egeberg, A. (2022), A nationwide population-based cohort study of the incidence of severe and rare infections among adults with psoriasis in Denmark. Br J Dermatol. Accepted Author Manuscript. https://doi.org/10.1111/bjd.21595