HHE Rheumatology and musculoskeletal supplement 2018 | Page 5

rheumatology and musculoskeletal Challenges in the management of psoriatic arthritis The ability to understand and manage psoriatic arthritis has progressed enormously over the past few years and we are thus approaching a more personalised approach Elena Generali MD Carlo Selmi MD PhD Division of Rheumatology and Clinical Immunology, Humanitas Research Hospital, Milan, Italy; BIOMETRA Department, University of Milan, Italy Psoriatic disease is a chronic inflammatory systemic condition affecting up to 3% of the general population, characterised by skin psoriasis, and in about 20–40% of patients, characterised by psoriatic arthritis (PsA), which may also be diagnosed in the absence of a personal history of psoriasis. 1 PsA, different from rheumatoid arthritis, affects both sexes with equal frequency, albeit with differences in clinical manifestations. 2 The incidence of PsA is of approximately 6 per 100,000 per year and the prevalence is approximately 6–25 per 10,000 in the general population. 3 The peak of incidence is around 30–50 years, with skin psoriasis in the majority of cases preceding the arthritis by an average of five years; although in 15% of cases, psoriasis and PsA occur simultaneously, or PsA PsA is often undiagnosed/ misdiagnosed and likely undertreated PsA is burdened by significant metabolic comorbidities Unmet needs in PsA Treatments must aim to prevent the long-term outcomes of PsA PsA must be treated to the target of remission or low disease activity precedes the skin manifestation, while, more importantly, psoriasis is diagnosed simultaneously with PsA in over 25% of patients. 4 While the diagnosis and management of other forms of arthritis, particularly rheumatoid arthritis, are well characterised, taking care of patients with psoriatic disease in general, and PsA in particular, manifests numerous challenges and the major ones are discussed here. Diagnostic delay Due to variable manifestations, suspecting and timely diagnosis of PsA is a major issue in daily 5 HHE 2018 | hospitalhealthcare.com practice. In fact, the diverse clinical features of PsA often result in delayed diagnosis and treatment, ultimately leading to reduced quality of life and elevated risk of cardiovascular disease, and depression. 5 The major clinical manifestations can be separated into different phenotypes: distal arthritis; asymmetric arthritis; symmetric polyarthritis; dactylitis; enthesitis; and arthritis mutilans and axial involvement, which can coexist in the same patient along with skin and nail psoriasis. 6 PsA can lead to bone erosions in up to 45% of patients within the first two years. Spontaneous remission of PsA is extremely rare, and relapse rates are high when treatment is discontinued. The diagnosis of PsA can be only supported by the CASPAR classification criteria, 7 and is based on clinical and imaging features that reflect a later stage of the disease. Unlike rheumatoid arthritis, there are no known autoantibodies. 8 Thus, a significant diagnostic delay in PsA can be observed, 9 which can lead to irreversible damage and permanent disability; therefore establishing an early diagnosis as one of the key challenges in the management of PsA. Unfortunately, only human leukocyte antigen (HLA)-B27 and and HLA-Cw6 are important markers to identify patients at higher risk of PsA. 8 However, HLA-B27 is positive in 25% of PsA cases, and increases in levels of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) can be observed in 40% of patients. By contrast, several studies are investigating PsA biomarkers, and the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) has launched a biomarker initiative. 10 Recently, serum proteins (CD5L, ITGB5, M2BP, MPO, MMP3 and CRP) have been found to differentiate PsA from controls, whereas CD5L, M2BP and MPO were independently associated with psoriasis only. 11 To increase the detection of PsA, ideally every psoriasis case complaining of musculoskeletal pain should undergo a rheumatological evaluation; however, this approach is not feasible in every setting. Therefore, in the past years, a number of screening tools have been developed to improve PsA early diagnosis among dermatologists and primary care physicians. 12 These screening tools are questionnaires that are feasible in daily practice and include, among others, the Psoriatic Arthritis Screening and Evaluation (PASE), the Psoriasis Epidemiology Screening Tool (PEST), and the Toronto Psoriatic Arthritis Screening