Proton Pump Inhibitors Are Associated with Increased Risk of Psoriasis: A Nationwide Nested Case-Control Study

<b><i>Background:</i></b> Proton pump inhibitors (PPIs) are among the most widely used drugs. Little is known about the association between PPI use and risk of psoriasis. <b><i>Objective:</i></b> To investigate the association between PPI use and subsequent psoriasis risk. <b><i>Methods:</i></b> We included participants from the Taiwan National Health Insurance Research Database. Patients with PPI use and an incidence of psoriasis (<i>n</i> = 5,756) were assigned to the case cohort and 1:1 matched to controls. PPI use was defined as &#x3e;30 cumulative defined daily doses (cDDDs); PPI nonuse was defined as ≤30 cDDDs. Logistic regression was used for the analyses. <b><i>Results:</i></b> There was a significant association between PPI use and psoriasis risk. The confounder-adjusted odd ratios (95% confidence interval [CI]) were 1.52 (1.31–1.76) and 1.54 (1.22–1.93) for patients with 120–365 cDDDs and &#x3e;365 cDDDs, respectively, compared with PPI nonusers. Stratified analyses based on PPI type showed that exposure to lansoprazole (OR, 1.25; 95% CI, 1.11–1.41) was associated with subsequent psoriasis risk. <b><i>Conclusions:</i></b> PPI use might be associated with an increased risk of developing psoriasis or as an epiphenomenon. Further prospective studies are needed to elucidate the association and underlying mechanisms.