A multicenter cross-sectional study in RMD Open reported that musculoskeletal ultrasound distinguished inflammatory and non-inflammatory phenotypes in patients with difficult-to-treat psoriatic arthritis (D2T-PsA).

Among 517 patients receiving biologic or targeted synthetic therapies, 53 met the definition of D2T-PsA. Of these, 30 were classified as persistent inflammatory psoriatic arthritis and 23 as non-inflammatory.

Persistent inflammatory PsA (PIPsA) was associated with more swollen joints, dactylitis,  nail psoriasis and higher physician global assessments. 

Non-inflammatory PsA (NIPsA) was characterized by more tender points, higher SPARCC enthesitis index, and greater discordance between patient and physician assessments. Fibromyalgia was significantly more common in NIPsA (43% vs 13%).

Disease activity scores were similar between groups, but ultrasound showed PIPsA patients had more synovitis, paratenonitis, and tenosynovitis, as well as greater structural damage. Some NIPsA patients had swollen joints without evidence of inflammation, underscoring the gap between symptoms and imaging.

The D2T-PsA cohort had a median age of 59 years and disease duration of 11 years; 64% were women. Most had peripheral joint involvement (94%) and had failed tumor necrosis factor inhibitors (91%) or interleukin-17 in  hibitors (72%).

Study limitations included the cross-sectional design, lack of standardized definitions for D2T-PsA, small subgroup sizes, and reliance on ultrasound rather than MRI to detect osteitis.

Researchers concluded that ultrasound differentiated inflammatory from non-inflammatory mechanisms in patients with D2T-PsA, which may support more targeted treatment approaches and avoiding unnecessary escalation of immunosuppressive therapy in non-inflammatory cases.

The authors reported no conflicts of interest.

Source: RMD Open