Associations between psoriatic arthritis and mental health among patients with psoriasis: A replication and extension study using the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR).

Background:Despite some evidence that psoriatic arthritis (PsA) may increase psychological burden in psoriasis, the mental health of this subpopulation is under-investigated. Objectives:To investigate whether PsA is associated with higher depression and anxiety in moderate-to-severe psoriasis; explore whether pain mediates these associations; and estimate the prevalence of undiagnosed and untreated depression. Methods:Baseline data from British Association of Dermatologists Biologic and Immunomodulators Register (BADBIR) participants completing the Hospital Anxiety and Depression Scale (HADS) were analysed. Results:707 patients (n = 540 with psoriasis only; n = 167 with PsA) were included. Depression prevalence was higher in patients with than without PsA, when a HADS-depression subscale cut-off ≥8 was used (33% vs. 23%, adjusted Odds Ratio [OR] (95% Confidence Intervals [CI]) = 1.64 (1.09-2.45)), but did not differ using the HADS cut-off ≥ 11. Anxiety prevalence was higher among PsA patients, regardless of HADS cut-off (cut-off ≥11: adjusted OR (95% CI) = 1.62 (1.07-2.45)). Pain fully mediated the effect of PsA on depression and anxiety in psoriasis. 53.6% of participants identified as depressed did not have a known psychiatric disorder; two thirds of depressed participants were not treated. Conclusions:PsA comorbidity in psoriasis is associated with higher anxiety; its association with depression appears to be robust when milder depressive syndromes are included, but less consistent for higher-threshold depression definitions. Depression remains unrecognized and untreated in over half of moderately-to-severe psoriasis patients. Routine depression and anxiety screening is recommended in psoriasis and PsA. PsA comorbidity may increase depression and anxiety in psoriasis through pain experience.