Clinical Features and Disease Activity in Psoriatic Arthritis: A Sex-Related Perspective on Leptin and Comorbidity

Background/Objectives: Many studies have addressed the sex differences in patients with psoriatic arthritis, although these are aimed more at describing the phenotype than at investigating the causes underlying these differences. The aims of our study were to assess the presence of clinical features in relation to sex, and to measure the effect on disease activity of different comorbidities in each sex. Methods: This was a cross-sectional study in which the following factors were measured: the clinical features of the disease, disease activity, the physical function and the disease impact. We measured serum leptin levels, to eliminate the effect of obesity on leptin levels, and a leptin/BMI ratio was calculated. The comorbid conditions evaluated included anxiety and depression, and sleep quality. Results: A total of 203 patients participated in this study. The mean age was 54.6 ± 11.3, and 46.8% of the patients were women. Women less frequently presented axial involvement (8% vs. 28%; p < 0.001) and more commonly had enthesitis (2 vs. 0.3; p < 0.001). They also had higher DAPSA (16.4 vs. 13.4; p < 0.001) and PsAID12 scores (4.1 vs. 2.9; p < 0.001), worse HAQ results (0.8 vs. 0.5; p < 0.001), and greater FACIT-F scores (32.7 vs. 38.1; p < 0.001). As for the comorbid conditions, women presented a higher leptin/BMI ratio (0.8 vs. 0.2; p < 0.001), higher levels of HADS-A (6.9 vs. 4.7; p < 0.001) and HADS-D (4.9 vs. 3.4; p < 0.001), and poorer ISI (9.3 vs. 7.0; p < 0.001). By sex, pain affecting women was associated with the leptin/BMI ratio (β: 0.29; p < 0.004; 95%CI: 0.3–1.6) and sleep quality (β: 0.31; p < 0.004; 95%CI: 0.04–0.25; R2: 0.26). The leptin/BMI ratio was not associated with pain in men (p = 0.46). Conclusions: Sex was associated with several clinical manifestations. Leptin/BMI ratio levels were associated with pain in women, but not in men.