Psoriatic arthritis (PsA) is a chronic, inflammatory and complex disease characterized by skin and joint involvement, frequently associated with extra-musculoskeletal manifestations and comorbidities [1,2]. PsA exhibits diverse phenotypes and a highly variable course, with recognized sex-related differences in both clinical presentation and disease perception [3]. During the last twenty years, the management of PsA has radically changed since the introduction of effective treatment strategies aimed at achieving remission or low disease activity [4]. Despite this, a subset of patients may still develop significant joint damage, functional impairment, and reduced quality of life, ultimately leading to a more “severe” disease [5]. Although the terms severity and disease activity are often used interchangeably in PsA, they might capture different yet complementary aspects of PsA. High disease activity often manifests as a transient flare in a specific domain, reflecting current inflammation that is generally reversible with appropriate treatment, allowing the patient to recover without long-term consequences. Conversely, a patient with “severe” PsA may experience irreversible damage, persistent functional impairment, low quality of life and chronic pain despite low measurable disease activity with currently used tools and beyond the progression of radiographic damage, underscoring the need to distinguish these concepts in clinical evaluation. In fact, identifying patients with severe PsA may lead to different clinical management strategies and more personalized treatment approaches. Several studies have focused on the identification of prognostic risk factors which, when present, may indicate a higher likelihood of structural damage progression, functional decline, or reduced quality of life, thereby justifying a more aggressive therapeutic approach [6], but these predictive factors might not be confused with severity itself.

Therefore, in light of the aforementioned considerations and the lack of a current consensus, the aim of this scoping review of the literature is to explore the various definitions of severity in PsA, outlined to date, and based on these, we eventually tried to propose a model for this intriguing concept.