Prevalence of inflammatory bowel disease in Japanese psoriatic patients

<jats:title>Abstract</jats:title><jats:p>Psoriatic patients reportedly have a higher prevalence of inflammatory bowel disease (<jats:styled-content style="fixed-case">IBD</jats:styled-content>); however, there have been few research studies of Japanese psoriatic patients. To elucidate the prevalence of <jats:styled-content style="fixed-case">IBD</jats:styled-content> in Japanese psoriatic patients, a cross‐sectional study was performed. Information was collected regarding psoriatic patients with current or prior history of Crohn's disease (<jats:styled-content style="fixed-case">CD</jats:styled-content>) or ulcerative colitis (<jats:styled-content style="fixed-case">UC</jats:styled-content>) who were treated at Fukuoka University Hospital from 2010 to 2018. Among 681 psoriatic patients (449 men and 232 women), eight (1.2%, six men, two women) had <jats:styled-content style="fixed-case">UC</jats:styled-content> and two (0.3%, one man, one woman) had <jats:styled-content style="fixed-case">CD</jats:styled-content>. Diagnosis of <jats:styled-content style="fixed-case">IBD</jats:styled-content> preceded psoriasis in five patients, while diagnosis of psoriasis preceded <jats:styled-content style="fixed-case">IBD</jats:styled-content> in two; the remaining patients’ records did not have sufficient information. Seven of 10 <jats:styled-content style="fixed-case">UC</jats:styled-content>‐positive patients had mild psoriasis, two had moderate psoriasis and one had severe psoriasis. When <jats:styled-content style="fixed-case">UC</jats:styled-content>‐positive psoriatic patients were compared with <jats:styled-content style="fixed-case">IBD</jats:styled-content>‐negative psoriatic patients, there were no differences in age at onset of psoriasis, age at first visit or complications (e.g. psoriatic arthritis, hypertension, hyperlipidemia, hyperuricemia and diabetes). However, <jats:styled-content style="fixed-case">UC</jats:styled-content>‐positive patients had significantly higher body mass index (<jats:styled-content style="fixed-case">BMI</jats:styled-content>) (26.7 vs 23.7; <jats:italic>P</jats:italic> = 0.021), compared with patients without <jats:styled-content style="fixed-case">IBD</jats:styled-content>. The <jats:styled-content style="fixed-case">CD</jats:styled-content>/<jats:styled-content style="fixed-case">UC</jats:styled-content> ratio in this cohort was 0.25, while the prevalence of <jats:styled-content style="fixed-case">IBD</jats:styled-content> was 1.2%; these values were both lower than those in previous reports involving Caucasian patients. Patients with psoriasis and <jats:styled-content style="fixed-case">UC</jats:styled-content> may have higher <jats:styled-content style="fixed-case">BMI</jats:styled-content> and milder skin symptoms than those with psoriasis alone. These observations must be further confirmed by controlled domestic studies with larger samples.</jats:p>