Severity of psoriasis increases risk for rare infections, hospital treatment

As severity of psoriasis increases, so does the risk of severe and rare infections, according to a population-based cohort study.

“Patients with psoriasis are known to be at higher risk for multiple comorbid conditions,” Nikolai D. Loft, MD, PhD, fellow in the department of dermatology and allergy at Copenhagen University Hospital Gentofte in Denmark, and colleagues wrote. “There is currently limited real-world evidence regarding the occurrence and risk of severe and rare infections among patients with psoriasis.”

In this Danish study, researchers compared the risk of infection among those with psoriasis with the general population.

Descriptive data were obtained from Danish administrative registries for individuals aged at least 18 years who were diagnosed with psoriasis, and each of these patients was matched for age and sex with general population controls 1:6. The researchers defined severe infections as those requiring hospital treatment. Rare infections in Denmark included tuberculosis, HIV, hepatitis B virus and hepatitis C virus.

The study included 94,450 patients with psoriasis who were matched with 566,700 individuals in the general population. Among patients with any type of psoriasis, the incidence rate of any infection per 100,000 person-years was higher at 3,104.9 (95% CI, 3,066.6-3,143.7) compared with 2,381.1 (95% CI, 2,367.6-2,394.6) for the control group. Additionally, the incidence rate of severe or rare infections for patients with severe psoriasis (3,847.7; 95% CI, 3,754.3-3,943.4) was higher than the incidence rate in both those with mild psoriasis (3,003.5; 95% CI, 2,964.1-3,043.4) and the general population (2,351.9; 95% CI, 2,322.9-2,381.2).

Although patients with all types of psoriasis incurred higher incidence rates than the general population, those with severe psoriasis showed greater risk. The increased risk of infection may be due to the altered immune environment as a result of treatment, not due to the psoriasis itself, according to the researchers.

“If clinicians are aware of the increased risk of severe infection in patients with severe psoriasis who are being treated with a systemic agent,” Loft and colleagues wrote, “the surveillance of these patients could be increased for signs of infection.”