Association of serum vitamin D concentrations with inflammatory cytokines and quality of life in patients with psoriasis: A cross-sectional observational study

Background & Objectives Psoriasis is a chronic inflammatory skin disease with systemic repercussions that is associated with low levels of vitamin D, a nutrient capable of modulating immune responses. The aim of this study was to determine the prevalence of hypovitaminosis D and to investigate the relationship between serum concentrations of 25-hidroxivitamin D (25(OH)D) and inflammatory markers and a quality of life index in patients with psoriasis. Methods This cross-sectional study was conducted with 146 patients from a statewide referral center for the treatment of psoriasis, located in João Pessoa, Paraíba, Brazil. Clinical, anthropometric, and food consumption data were collected, the Dermatology Life Quality Index (DLQI) was applied, and serum concentrations of 25(OH)D, parathyroid hormone, total calcium and inflammatory markers were analyzed. Results Among the participants, 56.8% had sufficient serum concentrations and 43.1% had insufficient or deficient concentrations of 25(OH)D. Interleukin-2 (IL-2) and interleukin-6 (IL-6) and the DLQI score were significantly higher in the insufficiency/deficiency group (p=0.015, p=0.017 and p=0.014, respectively). In addition, significant inverse correlations were observed between 25(OH)D and IL-2 (ρ= -0.223, p=0.027), IL-6 (ρ= -0.255, p=0.007), and DLQI (ρ = -0.200, p=0.016). In linear regression, body mass index (β= -0.383, p=0.003, CI=-0.631 to -0.134), waist circumference (β= -0.158, p=0.003, CI=-0.260 to -0.056), and IL-6 (β= -0.477, p=0.009, CI=-0.831 to -0.123) were predictors of 25(OH)D, after adjusting for confounding factors. Conclusions These findings suggest that low vitamin D levels are associated with more pronounced inflammation and a reduced quality of life in this population.