Hypovitaminosis D, or vitamin D deficiency, affects many people, particularly during the winter. Vitamin D deficiency has been established as a risk factor for osteoporosis and has also been associated with other autoimmune diseases, including rheumatoid arthritis, Crohn’s disease, systemic lupus erythematosus, and multiple sclerosis. Previous reports have also observed a link between hypovitaminosis D and autoimmune skin conditions, including pemphigus vulgaris, bullous pemphigus, alopecia areata, and vitiligo.
More evidence is beginning to suggest that psoriasis, which affects about 3.2% of the U.S. population, is a systemic disorder. Some reports have observed improved clinical outcomes associated with sun exposure. In this systematic review and meta-analysis, researchers sought to determine whether a link exists between psoriasis and hypovitaminosis D.
The researchers performed a comprehensive search of the Medline, Embase, and Cochrane Central Register databases through July 2018 for relevant cohort studies and to evaluate serum 25-hydroxyvitamin D (25[OH]D) levels among adults with psoriasis. The main outcome was the mean difference in serum 25(OH)D levels between patients with psoriasis and non-psoriatic controls.
A total of 107 articles were identified, of which 10 prospective cohort studies encompassing 6,217 controls and 693 cases met the criteria. The researchers calculated a pooled mean difference in serum 25(OH)D level between cases and controls of −6.13 ng/mL (95% confidence interval, –10.93 to –1.32; P=0.01) and a between-study heterogeneity of 98% (P<0.00001).