Bidirectional Associations Between Substance Abuse and Psoriasis: A Prospective Cohort Study

Background: Psoriasis and substance abuse remains a serious healthcare burden. However, associations between substance abuse and psoriasis have not been elucidated. Objective: To evaluate the bidirectional associations between substance abuse and psoriasis. Methods and Subjects: Based on the UK Biobank data, we conducted two prospective cohort studies to compare the risk of incident psoriasis in participants with versus without substance abuse (Cohort 1) and the risk of incident substance abuse in participants with versus without psoriasis (Cohort 2). Incident substance abuse (ICD: F10-F19) and psoriasis (ICD: L40) were primarily determined from hospital and primary care data, death registries and self-assessments. Results: In Cohort 1, 4,097 of 454,245 developed psoriasis during follow-up. Baseline substance abuse was linked to an increased psoriasis risk (hazard ratio [HR]: 2.31, P< 0.001), notably in alcohol and tobacco users (HRs: 2.29 and 2.33, P < 0.001). Those with high genetic risk and substance abuse had the greatest psoriasis risk (HR: 5.19, P < 0.001). In Cohort 2, 25,176 out of 451,547 were diagnosed with substance abuse during follow-up. A notable association between baseline psoriasis and subsequent substance abuse (HR: 1.28, P < 0.001) was observed, slightly mediated by depression, anxiety, and sleep quality (1.7% to 3.4%; all P < 0.001). Sensitivity analyses showed consistent results. Conclusion: Our findings identify bidirectional positive associations of substance abuse with psoriasis. This association is especially pronounced in those with both high genetic risk and alcohol or tobacco abuse. It is suggested that clinicians should consider alcohol or tobacco abuse among psoriasis patients to improve their life quality. Plain Language Summary: What is already known about this topic? Individual factors, like alcohol or tobacco consumption, have been reported to be associated with psoriasis risk. The bidirectional associations between the incidence of substance abuse and psoriasis remain unclear. What does this article add to our knowledge? Our findings emphasize a bidirectional positive relationship between substance abuse incidents and psoriasis. This association is especially pronounced in psoriasis patients with high genetic risk and in those who abuse alcohol and tobacco. How does this study impact current management guidelines? Our findings underscore the imperative of proactive measures against both psoriasis and substance abuse, especially concerning alcohol and tobacco. Keywords: substance abuse, psoriasis, UK Biobank, bidirectional cohorts