Investigating the Relationship Between CT-Derived Sarcopenia Index and Patient Acceptable Symptom State (PASS) in Psoriatic Arthritis: A Preliminary Analysis.

Background

This proof-of-concept study examined the association between CT-derived sarcopenia indices and achievement of Patient Acceptable Symptom State (PASS) in a metabolically homogeneous subgroup of patients with psoriatic arthritis (PsA) receiving biologic therapy.

Methods

We retrospectively analyzed 26 PsA patients without diabetes, hypertension, or thyroid disorders who were treated with TNF or IL-17 inhibitors and underwent opportunistic CT imaging at the L2 vertebral level. Body composition parameters included total abdominal muscle area (TAMA), subcutaneous adipose tissue (SAT), and sarcopenia index (SI = TAMA/height2). PASS achievement at 12 weeks was assessed retrospectively. Receiver operating characteristic (ROC) analysis was performed.

Results

Fourteen patients achieved PASS. Compared with non-achievers, these patients had significantly higher TAMA, SAT, and SI values (all p < 0.05). ROC analysis identified an SI threshold of 4657.5 cm2/m2 (sensitivity 78.6%, specificity 83.3%, p = 0.003).

Conclusions

In this metabolically homogeneous PsA subgroup, higher CT-derived muscle mass measures were associated with PASS achievement at 12 weeks. These findings are hypothesis-generating and require validation in larger prospective cohorts.