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Letter to the editor submitted in response to ‘Should the presence of psoriatic arthritis change how we manage psoriasis?’

We read with great interest the article published by Chan et al. “Should the presence of psoriatic arthritis change how we manage psoriasis?” investigating the impact of psoriatic arthritis (PsA) on the psoriasis management (1). In their editorial, the authors recommended that clinicians should select the best biologic treatment for patients with both psoriasis and PsA considering the clinical evidence and not respecting the Food and Drug Administration (FDA) approval. We agree with their conclusion, highlighting that the goal is to choose the right treatment for the right patient at the right time. Indeed, existing biologics for psoriasis act on cytokines that are highly involved in PsA pathogenesis so that Chan et al. do not believe that the presence of PsA should change what treatment we initiate for psoriasis. However, in this scenario, it is also very important to consider the increasing concern of new onset PsA despite biologic treatment (2). Indeed, literature is enriching of studies showing that from 1.9% to 9.4% of psoriasis patients under biologic may develop new onset PsA (3–5). We recently showed that new onset PsA may develop among psoriasis subjects without PsA signs under each different existing biologic class (antiTNF, anti-IL12/23, anti-IL17 and anti-IL23) over time (3). Even if the incidence of PsA is significantly reduced in patients undergoing biologic treatment for psoriasis, biologic drug does not seem to completely protect against the possibility of a future development of PsA (3). Thus, dermatologist should continue PsA screening also in patients undergoing biologics and their therapeutic choice should also follow and consider the possibility of new onset PsA risk. However, no definitive new onset PsA predictive factors can be highlighted with statistically significative association. Contrasting data are available regarding if female sex, higher body mass index, and psoriasis severity could be risk factors for new onset PsA (3–5). Thus, further studies are needed to understand new onset PsA pathogenesis and possible correlations with biologic use in order to find out risk factors and, on consequence, “at-risk” patients as well as to select the best treatment considering these factors. At the moment, the use of ultrasound examination during routine dermatologic clinical practice may represent the best solution to better diagnose early PsA, screening selected sites as recently reported (6). Moreover, there is no guideline which may help clinicians in choosing how modify the treatment for psoriasis patients on biologics who develop new-onset PsA. In our experience (3), we mainly observed mild-to-moderate forms of new-onset PsA, requiring biologic switch only in 30% with the majority of the cases being treated with the addition of cDMARDs. In conclusion, we agree with Chan et al. about choosing the best available biologic treatments for patients with psoriasis and PsA considering the available pathogenetic and clinical data, not considering FDA approval. However, clinicians should keep in mind the possibility of new-onset PsA onset also in patients undergoing biologic treatment, continuing PsA screening in each follow-up visit. Hence for the reasons above reported, the open actualized question would be: “Should the presence of new onset psoriatic arthritis change how we manage psoriasis?” It is possible to prevent or minimize its development?