Association between psoriasis and alopecia areata: A systematic review and meta‐analysis

The association between psoriasis and alopecia areata has not been thoroughly investigated. The objective of this study is to investigate the association of psoriasis with alopecia areata. An electronic search was conducted in August 2021. The analysis included studies that reported sufficient data on the prevalence, odds, or hazard of alopecia areata in patients with psoriasis or that of psoriasis in patients with alopecia areata. Meta‐analysis using an inverse variance method was performed with a random‐effects model, assuming inherent heterogeneity between the included studies. The subgroup analyses were performed according to the age group and study quality. A total of 27 studies were included. The pooled prevalence of alopecia areata among patients with psoriasis was 0.5% (95% confidence interval [CI], 0.3–0.7%). The pooled odds ratio of alopecia areata among patients with psoriasis was 2.71 (95% CI, 2.29–3.21), whereas the pooled prevalence of psoriasis among patients with alopecia areata was 2.5% (95% CI, 2.0–3.0%). Moreover, the pooled odds ratio of psoriasis among patients with alopecia areata was 3.52 (95% CI, 1.27–9.74). The association of psoriasis and alopecia areata remained in the subgroup analyses according to the age group and study quality. In conclusion, this study suggests a bidirectional association between psoriasis and alopecia areata. Clinical examinations may be necessary to determine the presence of comorbid alopecia areata in patients with psoriasis and vice versa.