Evolution of psoriatic arthritis study patient population characteristics in the era of biological treatments.

Objectives: Psoriatic arthritis is a chronic inflammatory disease that affects the musculoskeletal system. It can include arthritis, spondylitis, dactylitis and enthesitis, and is strongly associated with the presence of psoriasis. The introduction of biological therapies as a treatment option has brought a significant improvement in disease control for patients with psoriatic arthritis. Here, we aimed to detect emerging differences in demographic and clinical characteristics of the psoriatic arthritis patient study population since the introduction of biologicals. We hypothesised that evolving views on control of disease activity and increased experience in the management of psoriatic arthritis have affected the patient population considered for clinical trials and that this may serve as a proxy for changes in clinical practice. Methods: We systematically searched for and selected 12 phase II and phase III trials and divided them into three treatment periods based on different time periods and working mechanisms of the particular biologicals. We made a selection of patient and disease parameters for which data were available in all three periods, calculated those data per period and looked for statistically significant differences between the treatment periods. Results: Statistical analysis showed significant differences in patient characteristics, disease characteristics, disease activity, disease effects and use of prior treatments between the patient populations of the three periods. Conclusion: This study shows a clear evolution of the patient population considered for clinical trials since the introduction of biologicals. Further research is needed to see if those changes can be detected in the daily clinical practice.