Improvement of Joint and Skin Symptoms and Their Contribution to Improving the Quality of Life in Patients with Psoriatic Arthritis
The cause of reduced quality of life in patients with psoriatic arthritis is the involvement of both skin and joints. Commonly used therapy certainly improves symptoms of both systems to some extent, but to what extent does this improvement correlate with a higher health-related quality of life? This question was addressed by analyzing two randomized studies.
Introduction
Psoriatic arthritis (PsA) is a chronic immune-mediated inflammatory disease that includes both joint and extra-articular symptoms, notably psoriasis (PsO). The deterioration in health-related quality of life (HRQoL) associated with psoriatic arthritis is similar to that of rheumatoid arthritis (RA). Although PsA typically affects fewer joints than RA, it additionally damages other organ systems including the skin. Currently used disease-modifying antirheumatic drugs (DMARDs) may have varying efficacy in treating PsA manifestations; however, it is unclear to what extent the treatment of joint and extra-articular symptoms will improve the patient's HRQoL.
Methodology of Analysis
The presented post-hoc analysis includes data from 2 double-blind, placebo-controlled phase III studies evaluating the efficacy of ixekizumab, an interleukin-17A antagonist. The analysis included patients with active PsO (n = 402) covering ≥ 3% of body surface area, who had never been treated with biological DMARDs, or who did not tolerate tumor necrosis factor (TNF) inhibitors or had an inadequate response to them. Patients received either placebo (until the end of week 24) or ixekizumab 80 mg every 2 or 4 weeks. At week 16 of the study, treatment was added or changed for patients with an inadequate response.
Improvement of both joint and extra-articular symptoms was measured as a percentage improvement from baseline of the PsA activity index (DAPSA score − Disease Activity Index for Psoriatic Arthritis) and the PASI score (Psoriasis Area and Severity Index). DAPSA is a composite assessment including swollen and tender joints, function, pain, and disease activity, but it does not directly measure psoriasis skin symptoms. Improvement in HRQoL was measured as a change from baseline in questionnaires assessing health status and quality of life: the visual analog scale of the European Quality of Life − Five Dimensions (EQ-5D VAS), the domain assessing activity limitations from the Work Productivity and Activity Impairment Questionnaire (WPAI), and the 36-Item Short-Form Health Survey (SF-36) questionnaire.
Results
Correlations between DAPSA, PASI, and HRQoL improvement were monitored at week 24. The greatest improvement in HRQoL, measured by the EQ-5D VAS, was achieved when patients achieved a 100% improvement in both DAPSA and PASI scores (improvement was about 30%). In cases of improvement in joint symptoms only, HRQoL increased by 17.7%, while improvement in skin symptoms only resulted in a decrease in HRQoL by 1.2%. For patients with ≥ 10% body surface area affected by psoriasis, greater improvement in skin symptoms was required to achieve higher HRQoL. Similar results were obtained using the WPAI and SF-36 questionnaires.
Conclusion
The study measured the impact of improvement in joint and skin symptoms on health-related quality of life in patients. The greatest benefit in terms of quality of life was observed with simultaneous improvement in both. Therefore, for optimal effect on a patient's quality of life, therapy should target both joint and skin symptoms.
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Source: Kavanaugh A., Gottlieb A., Morita A. et al. The contribution of joint and skin improvements to the health-related quality of life of patients with psoriatic arthritis: a post hoc analysis of two randomised controlled studies. Ann Rheum Dis 2019; 78 (9): 1215−1219, doi: 10.1136/annrheumdis-2018-215003.
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