AB0924 Individual Digit Level Nail Involvement and Joint Assessment in Patients with Nail Psoriasis

Abstract

BackgroundThe relationship between the evolution of nail disease and the articular features of Psoriatic Arthritis (PsA) is poorly understood. There is a lack of data on the relationship between nail and joint disease, important clinical parameters of disease activity, specifically at the individual digit level.ObjectivesTo evaluate the level of association, at digit level, between nail involvement and joint disease at baseline, with a special focus on distal interphalangeal joint (DIP) assessment.MethodsSPIRIT-H2H (NCT03151551) was a 52 week, multicenter, randomised, open-label, parallel-group, assessor-blinded study evaluating the efficacy and safety of IXE vs ADA in PsA.1 Nail psoriasis was measured using Nail Psoriasis Severity Index (NAPSI). Joint involvement was measured by tender/swollen joint count (TJC/SJC) scores. Here we examine both baseline tenderness and swollenness at the DIP joint, proximal interphalangeal (PIP) joint and metacarpophalangeal (MCP) joint level for each digit and evaluate the level of association between nail involvement (NAPSI>0 vs NAPSI=0) and joint assessment using Chi-square tests and/or Fisher’s exact test where relevant.ResultsOverall, 368 patients (IXE N=191, ADA N=177) out of 566 had a baseline NAPSI >0. The overall level of nail involvement ranged from 52.7% (n=194) (right 5th finger) to 67.9% (n=250) (right 1st finger). When considering a digit-wide assessment of joints (DIP, PIP, and MCP), in general, no clear association was found between NAPSI >0 and joint involvement. However, there was more frequent DIP joint involvement in patients with nail involvement compared to patients without nail involvement. When taking only the DIP joint into account, nail involvement was found to be statistically associated with tenderness and/or swelling at the DIP level (Figure 1), with differences between patients with nail involvement vs. without nail involvement ranging from 7.9% (p=0.023) (right 5th finger) to 19.4% (p<0.001) (left 3rd finger). These differences are mostly driven by tenderness rather than swelling, irrespective of digit. For tenderness, differences (with vs. without nail involvement) ranged from 7.0% (right 2nd finger) to 18.0% (left 3rd finger). Differences due to swelling ranged from 5.0% (left 1st finger) to 12.2% (left 3rd finger).Figure 1.Digit level association between nail assessment and DIP joint.Significant difference between nail involvement and no nail involvement denotated by * (p≤0.05), ** (p≤0.01), *** (p≤0.001). Abbreviation: DIP= Distal interphalangeal joint.ConclusionIn SPIRIT-H2H, tenderness and/or swelling at the DIP joint was significantly associated with nail involvement in individual digits.