Vinod Chandran, MBBS, MD, DM, PhD
Research on psoriatic arthritis (PsA) published over the past month has highlighted the effect of disease on patients and provided insights into clinical management. Because of the heterogeneous nature of PsA, assessing disease activity is difficult. A blood biomarker for disease activity would be useful. C-reactive protein (CRP) is a commonly used and well-established marker of inflammation in general. However, CRP does not reflect PsA disease activity itself. In a cross-sectional study, Gialouri and colleagues evaluated the association between CRP and PsA disease activity. CRP status (CRP ≤ 0.5 mg/dL [normal] and CRP > 0.5 mg/dL [increased]) was not associated with any of the clinical disease activity (clinical Disease Activity Index for Psoriatic Arthritis [cDAPSA] or minimal disease activity [MDA]) or patient-reported outcomes measures (Patient Global, Patient Pain, Health Assessment Questionnaire-Disability Index [HAQ-DI] or EuroQol [EQ-5D]). Among patients with normal CRP levels, a substantial proportion (45.9%) were not in MDA (thus, an indicator of active disease) while 76.7% of patients with elevated CRP were not in MDA. Therefore, an elevated CRP may indicate active PsA, but a normal CRP is not a reliable indicator of disease state in PsA.
Gender differences in PsA are increasingly being recognized as important. In a real-world survey of 2270 PsA patients (1047 women) from Europe and the United States, Gossec and colleagues demonstrated that, despite similar disease duration, disease presentation, and biologic use, women had worse quality-of-life, disability, and physical functioning scores, a greater degree of work activity impairment, and higher pain and fatigue scores compared with men. Thus, it is increasingly clear that PsA affects women differently from men. Interventions for the holistic management of PsA should be tailored according to the patient's gender for optimal outcomes.
Despite major advances in the treatment of adult PsA, the treatment options for children with PsA (juvenile PsA [JPsA]) are limited. Anti–tumor necrosis factor (TNF) agents are the only currently approved advanced therapy. Brunner and colleagues conducted a treatment-withdrawal, phase 3 study including 86 biologic-naive patients with active enthesitis-related arthritis (n = 52) or JPsA (n = 34) who were randomly assigned to receive secukinumab or placebo.
This study demonstrated that, compared with placebo, secukinumab was associated with a significant delay in disease flare and a higher proportion of patients achieving juvenile idiopathic arthritis American College of Rheumatology 30 response at week 104. This study provides evidence that secukinumab, a safe and effective therapy used in adult psoriatic disease, may provide similar benefits in JPsA, especially in patients who either have not responded to or have contraindications to treatment with anti-TNF agents.
Finally, because skin disease predates joint disease in almost 90% of PsA patients, identifying predictors for the development of joint disease is of considerable interest. It is hoped that identifying such predictors will help dermatologists and primary care physicians stratify management such that those at higher risk are carefully followed up for early diagnosis or even preventive therapy.
To identify such predictors, Ogdie and colleagues conducted a prospective study of 1489 patients with psoriasis and no prior diagnosis of PsA from the CorEvitas Psoriasis registry. They demonstrated that 10% of patients with psoriasis developed PsA after 2 years. Psoriasis Epidemiology Screening Tool (PEST, a brief screening questionnaire for PsA) and body mass index (BMI) were important factors predicting the development of PsA. Although the incidence of PsA in this cohort is higher than that reported from other studies, the study indicates that PEST and BMI should be important factors that predict PsA and should be variables in any prediction model.