Vitamin D in psoriatic arthritis - A systematic review and meta-analysis

This systematic review and meta-analysis aimed to summarize current evidence on vitamin D status in patients with psoriatic arthritis (PsA) with a particular focus on disease activity.

PubMed, Web of Science, Scopus and Cochrane Library databases were searched for studies that investigated vitamin D levels in PsA. The search was conducted on 12^th October 2022. Included studies were cohorts, RCTs or observational studies, those assessing the level of 25(OH)D₃ with control group consisting of healthy or psoriasis (Pso) patients. Nottingham-Ottawa Quality Scale was used to assess methodological quality. Random effects meta-analysis model was applied with inverse variance weighting and mean difference with 95% CI was calculated.

Of 356 retrieved studies, 76 duplicates and 270 studies were excluded according to the exclusion criteria with one study unavailable. Four studies including 264 PsA patients and 287 healthy controls and five studies including 225 PsA patients and 391 Pso patients assessing vitamin D levels were eligible for meta-analysis. Vitamin D levels were lower in PsA patients compared to the healthy group (MD = -6.42; 95 % CI -8.31, -4.53; P < 0.01), while higher compared to Pso patients (MD = 2.37; 95 % CI 0.97, 3.78; P < 0.01). Included studies had moderate to low risk of bias.

In conclusion, PsA patients have lower vitamin D levels than the general population. However, further studies are essential to understand the role of vitamin D in the development and treatment of PsA and the differences in vitamin D metabolism in PsA and Pso.