Association of 25-hydroxyvitamin D serum levels and metabolic parameters in psoriatic patients with and without arthritis

Background: Psoriasis has been related to a higher prevalence of cardiovascular risk factors. Vitamin-D deficiency has been associated with metabolic syndrome, cardiovascular disease, and psoriasis. However, there has been no comparative study on the effects of vitamin-D status between patients with and without psoriatic arthritis. Objective: The objective was to assess the relationship of 25-hydroxyvitamin D [25-(OH)D] levels with lipid and glucose metabolism parameters in psoriatic patients with and without arthritis. Methods: We studied 122 patients with psoriasis (61 without arthritis and 61 with arthritis) from the psoriasis unit (dermatology department) and rheumatology department of our hospital, analyzing lipid and glucose metabolism variables and serum 25-(OH)D concentrations. Measurements were conducted within a 2-month period to minimize seasonal bias in 25-(OH)D levels. Results: In the psoriatic patients without arthritis, serum 25-(OH)D levels were inversely correlated with fasting glucose (r = -0.285; P = .026), total cholesterol (r = -0.440; P = .000), low-density lipoprotein (r = -0.415; P = .001), total cholesterol/high-density lipoprotein (r = -0.303; P = .01), and triglyceride (r = -0.280; P = .029) values. This association remained statistically significant for glucose, total cholesterol, and low-density lipoprotein after controlling for confounding factors in multivariate analysis. No association was found between serum 25-(OH)D levels and any metabolic parameter in the patients with psoriatic arthritis. Limitations: This is a cross-sectional study that supports the hypothesis of an association between vitamin D and metabolic parameters but does not establish a causal relationship. Conclusions: Serum 25-(OH)D was inversely related to lipid and glucose metabolism parameters in psoriatic patients without arthritis, whereas no such association was observed in psoriatic patients with arthritis. Interventional studies are warranted to assess the effects of vitamin-D supplements on the metabolic profile of psoriatic patients without arthritis.