The role of C-reactive protein and genetic predisposition in the risk of psoriasis: results from a national prospective cohort.

Background: Psoriasis is an immune-mediated chronic inflammatory disease associated with multiple factors. To evaluate the extent to which C-reactive protein (CRP) and genetic predisposition affect the incidence of psoriasis.

Methods: The cohort study retrieved 420,040 participants without psoriasis at baseline from the UK Biobank. Serum CRP was categorized into two levels: < 2 mg/L (normal) and ≥ 2 mg/L (elevated). The polygenic risk score (PRS) was used to estimate genetic predisposition, and was characterized as low, moderate and high PRS. The possible interaction and joint associations between CRP and PRS were assessed using Cox proportional hazards models.

Results: Participants with high CRP levels had an increased risk of incident psoriasis compared to those with low CRP levels (HR: 1.26, 95% CI: 1.18-1.34). Participants with high CRP levels and high PRS had the highest risk of incident psoriasis [2.24 (95% CI: 2.01, 2.49)], compared with those had low CRP levels and low PRS. Significant additive and multiplicative interaction were found between CRP and PRS in relation to the incidence of psoriasis.

Conclusions: Our results suggest that higher CRP concentration may be associated with higher psoriasis incidence, with a more pronounced association observed in individuals with high PRS for psoriasis. So, clinicians should be aware that the risk of incident psoriasis may increase in general population with high CRP levels and high PRS, so that early investigation and intervention can be initiated.