Lack of association of biologic therapy for psoriasis with psychiatric illness: An electronic medical records cohort study

Background: Psoriasis and biologic therapies have been associated with psychiatric illnesses. Objective: To determine if persons with psoriasis or those exposed to biologics are more likely to develop a psychiatric illness. Methods: Retrospective electronic medical records cohort study. Results: Individuals with psoriasis were significantly more likely to have a history of several medical (eg, cardiovascular illnesses) and psychiatric (eg, depression, suicide) illnesses than those without psoriasis. Those with psoriasis who were prescribed a biologic therapy were significantly less likely than those with psoriasis not prescribed a biologic agent to receive a psychiatric illness diagnosis (hazard ratio for any psychiatric illness 0.52, 95% confidence interval 0.51-0.53, P < .0001). With respect to any psychiatric illness, this finding was confirmed when comparing biologic therapy versus methotrexate treatment (0.80, 95% confidence interval 0.76-0.84, P < .0001). Limitations: These findings were likely attributable to treatment selection bias. Conclusion: Individuals with psoriasis have an increased risk of several medical and psychiatric illnesses. Individuals with psoriasis prescribed biologic agents are less likely than those not prescribed biologic agents to develop psychiatric illnesses. Most likely because of treatment selection, individuals with psoriasis prescribed biologic therapy are not currently at increased risk of a psychiatric outcome.