Background: Subclinical psoriatic arthritis (PsA) represents a critical window for early intervention, yet its defining clinical and ultrasonographic features remain poorly characterized. Family history of psoriatic disease is a well-established risk factor, but its association with subclinical phenotypes remains underexplored.

Purpose: This cross-sectional study aims to systematically characterize the clinical and ultrasonographic features of subclinical psoriatic arthritis (PsA) patients and analyze the similarities and differences across various dimensions among patients with different levels of familial risk (quantified by FRS).

Methods: This cross-sectional study comprehensively evaluated clinical characteristics and ultrasonographic features of subclinical PsA patients. All participants underwent standardized assessments, including clinical evaluation and musculoskeletal ultrasound. We developed a Family Risk Score (FRS) based on weighted family history from the prospective subclinical PsA database at West China Hospital (enrolling patients since March 4, 2024). Eligible participants were diagnosed with subclinical PsA during dermatology outpatient visits and provided informed consent. An FRS was constructed by assigning weights to 1^st-, 2^nd-, and 3^rd-degree relatives (2, 1, and 0.5 points, respectively) with PsA, psoriasis (PsO), or other immune diseases (2, 1.5, and 1 points, respectively). Note: The FRS reflects aggregated familial risk but does not incorporate genetic variants.

Results: A total of 310 participants were stratified into high-FRS (≥3 points, n=47) and low-FRS (<3 points, n=270) groups. The demographic, clinical, and sonographic characteristics of all patients have been presented in Figures 1 and 2, and the details are summarized in Table 1. Patients in the high-FRS group demonstrated a significantly longer duration of psoriasis (19.64 ± 11.98 vs. 14.07 ± 10.86 years, P=0.01) and a trend towards an earlier onset of psoriasis (24.63 ± 14.2 vs. 14.07 ± 10.86 years, P=0.06). Furthermore, the high-FRS group exhibited an elevated prevalence of hyperlipidemia (29.8% vs. 17.9%, P=0.09). There were no significant differences found in peripheral joint involvement, psoriasis severity, and ultrasound-detected features, etc. (Table 1)

Conclusion: This study provides insights into the clinical and ultrasound characteristics of patients with subclinical arthritis. An elevated familial risk, quantified by FRS, is specifically associated with prolonged psoriasis duration and metabolic comorbidity trends, but not inflammatory severity in subclinical PsA. Future studies may combine FRS with genetic data to further stratify PsA progression risk.