Infections in psoriatic arthritis: association with treatment.

Serious infections (SIs) remain one of the most significant comorbidities in patients with inflammatory arthritides including psoriatic arthritis (PsA). Apart from methotrexate (MTX) and biologics such as tumor necrosis factor (TNFi), interleukin-12/23 (IL-12/23i), and IL-17 inhibitors (IL-17i), traditionally used for the treatment of PsA, recently biologics such as IL-23i and targeted synthetic agents like JAK inhibitors (JAKi) have been introduced in the daily clinical practice for the treatment of this disease. Although overall the incidence of SIs in patients with PsA treated with these agents is lower compared to patients with rheumatoid arthritis, still a number of unresolved issues regarding their safety remain. Current evidence is reassuring regarding the safety profile of conventional synthetic disease-modifying anti-rheumatic drugs, such as MTX. The increased risk for reactivation of latent infections, such as tuberculosis and hepatitis B virus (HBV) with the use of TNFi, is well described; nevertheless, it is significantly ameliorated with the appropriate screening and prophylaxis. Regarding IL-12/23i and IL-17i, there are no significant safety signals, except from an increased incidence of usually mild Candida infections with the latter class. Newer biologics such as IL-23i and targeted synthetic agents like JAKi have been recently introduced in the daily clinical practice for the treatment of this disease. While IL-23i has not been shown to increase the risk for common or opportunistic infections, a well-established association of JAKi with herpes zoster warrants the attention of rheumatologists. In this narrative review, we summarize the infectious complications of available treatment options by drug class in patients with PsA.