To map sex-stratified clinical phenotypes and high-resolution musculoskeletal ultrasound (MSUS) findings in a prospective Chinese psoriatic arthritis (PsA) cohort.  

Consecutive PsA patients enrolled in the Peking University PsA prospective cohort (PKUPsA-PC, January 2016–July 2025) were analysed. Demographics, disease duration, DAPSA, C-reactive protein (CRP), patient-reported outcomes (pain-VAS, HAQ-DI, GAD-7 and PHQ-9) and treatment were collected. A standardised 60-joint/8-enthesis MSUS protocol was applied; grey-scale (GS 0-3) and power-Doppler (PD 0-3) synovitis scores were summed. Tenosynovitis, erosions and enthesophytes were recorded. Sex-stratified comparisons used non-parametric or χ² tests, multivariable logistic regression identified associated factors of DAPSA remission.  

Of 584 patients (median age 47 years, 59 % male), Females had lower BMI (25.8 [23.2-27.8] vs 23.4 [21.5-25.4] kg/m², P<0.001) and waist circumference (90 [85-98] vs 80 [74-85] cm, P<0.001), and smoked less (6.3 % vs 53.3 %, P<0.001) . Despite lower PASI (3.1 [0.7-8.2] vs 2.4 [0-6.0], P=0.022) and hs-CRP (3.3 [1.3-9.7] vs 2.6 [1.0-8.1] mg/ L, P=0.027), females reported higher pain-VAS (30 [10-50] vs 20 [10-40] mm, P=0.032), HAQ-DI (1 [0-3] vs 0, P=0.004), GAD-7 (3 [0-7] vs 0, P<0.001) and PHQ-9 (3 [0-6] vs 1, P=0.012). Female PsA patients had less axial disease (5 % vs 15 %, P<0.001) but more peripheral arthritis (77 % vs 67 %,  P=0.013).   Multivariable analysis showed remission in female PsA was associated with lower pain-VAS, PASI, HAQ-DI and GAD-7; while male remission was only associated with lower pain-VAS and axial involvement.  

MSUS revealed significantly greater inflammation in men: total synovitis score (GS: 4 vs 1, P<0.001). GS synovitis was more frequent in men at PIP1 (10.9 % vs 4.6 %), DIP2 (5.6 % vs 1.7 %), DIP4 (3.7 % vs 0.8 %), MTP1 (32.0 % vs 13.4 %) and MTP2 (23.7 % vs 10.9 %); PD positivity was higher at DIP3 (2.2 % vs 0.5 %), DIP4 (7.1 % vs 0 %) and MTP1 (6.5 % vs 1.4 %) (all P<0.05). Erosions were more common in male feet (PIP 6.9 % vs 5.5 %; and DIP5 3.1 % vs 0.9 %, P<0.05). Enthesitis showed male predominance at olecranon (chronic 15.5 % vs 9.2 %) and patellar apex (acute 3.3 % vs 0 %; chronic 43.9 % vs 28.4 %, P<0.05), whereas females had more chronic lateral humeral epicondylitis (31.4 % vs 21.9 %, P=0.016). No sex difference was observed for tenosynovitis. 

Chinese PsA displays a pronounced sex-specific inflammation-pain mismatch. Males carry a heavier ultrasound-detected inflammatory load yet report less disability, whereas females experience worse patient-reported outcomes despite lower objective inflammation. Integrating comprehensive MSUS with multidimensional clinical data provides an objective blueprint for sex-tailored treat-to-target strategies.