Highlights
- The UPsA activity (inflammation) and damage (structural) ultrasound composite scores were derived and internally validated in 312 patients with psoriatic arthritis (PsA) from 19 Italian centres.
- Both scores range 0–10; the activity score correlated moderately with composite clinical disease activity and joint counts (Spearman rs 0.31–0.45) and demonstrated responsiveness to change (overall SRM 0.63; SRM 1.03 in patients achieving minimal disease activity).
- A simplified UPsA (sUPsA) preserved ~90% of the information of the full score while improving feasibility for routine use.
Background
Psoriatic arthritis (PsA) is a heterogeneous inflammatory musculoskeletal disorder characterized by peripheral arthritis, enthesitis, dactylitis, and axial disease, frequently accompanied by cutaneous psoriasis. Accurate measurement of both active inflammation and irreversible structural damage is central for patient management, treat-to-target strategies, treatment-effect appraisal in clinical trials, and longitudinal prognostication. Clinical indices capture symptoms and exam findings but can miss subclinical synovitis or tenosynovitis; conventional radiography detects damage but detects erosions relatively late. Musculoskeletal ultrasound (US) offers a bedside, non-ionizing modality that detects synovitis, power Doppler (PD) signal, tenosynovitis, enthesitis, and erosions with high sensitivity and in multiple anatomic sites. However, standardized, validated, feasible composite US scores tailored to PsA that quantify both activity and damage have been limited.
Study design and methods
The UPsA study (Ultrasound in Psoriatic Arthritis Treatment — NCT03330769) is a multicentre effort coordinated by the Italian Society of Rheumatology. Baseline and 6-month data from 312 patients with PsA were used to develop and internally validate ultrasound composite scores. Investigators performed comprehensive US scans using trained sonographers across 42 joints, 36 tendons, 12 entheses and 2 bursae per patient, and captured both inflammatory (e.g., synovial hypertrophy, PD signal, tenosynovitis) and structural lesions (erosions, enthesophytes) according to predefined scoring definitions.
Factor analysis (presumably exploratory) informed variable reduction and weighting to assemble two composite scores: the UPsA activity score (targeting inflammatory burden) and the UPsA damage score (targeting structural change). Both were normalized to a 0–10 scale to facilitate interpretation. A simplified UPsA (sUPsA) was derived to reduce the number of sites assessed while retaining maximal informational content for routine feasibility.
Construct validity was evaluated by Spearman rank correlations (rs) with clinical measures including Disease Activity for Psoriatic Arthritis (DAPSA), 68-tender and 66-swollen joint counts, patient-reported outcomes, and the modified Sharp–van der Heijde radiographic score (for damage). Responsiveness to change was quantified using the standardised response mean (SRM) at 6 months overall and in subgroups (notably patients achieving minimal disease activity, MDA).
Key findings
Population and baseline scores: 312 patients with PsA were enrolled across 19 centres. The mean UPsA activity score at baseline was 3.7 (SD 1.86) on a 0–10 scale; the mean UPsA damage score was 4.1 (SD 2.26).
Construct validity: The UPsA activity score demonstrated moderate correlations with established clinical disease measures: DAPSA (rs = 0.42), 68-tender joint count (rs = 0.31), and 66-swollen joint count (rs = 0.45); all correlations were statistically significant (P < .001). The UPsA damage score correlated with radiographic damage as measured by the modified Sharp–van der Heijde score (rs = 0.36, P < .001).
Responsiveness: The UPsA activity score showed moderate sensitivity to change at 6 months with an overall SRM of 0.63. Notably, in patients who achieved minimal disease activity (MDA), the activity score was highly responsive (SRM = 1.03), supporting its utility to detect clinically meaningful improvements. The study reports that the sUPsA retained approximately 90% of the information content of the full activity score while markedly improving feasibility.
Feasibility and simplification: The sUPsA was created to enhance uptake in routine practice by reducing scan time and the number of assessment sites. Retaining 90% of the variance of the full score suggests efficient dimensionality reduction and potential for broader real-world application.
Interpretation of effect sizes and correlations
The magnitude of correlations between ultrasound activity and clinical indices is consistent with prior observations that imaging and clinical measures capture overlapping but non-identical constructs. Moderate correlations (rs ~0.3–0.45) indicate that UPsA activity reflects clinical disease burden while also detecting subclinical inflammation that may not be captured by joint counts or patient-reported measures. The SRM values indicate moderate overall responsiveness and excellent responsiveness in patients with meaningful clinical improvement.
Expert commentary and clinical implications
Strengths: This is a large, multicentre study with standardized scanning across many anatomic sites, reflecting real-world heterogeneity of PsA manifestations. The derivation of both activity and damage composites addresses the dual needs of monitoring reversible inflammation and irreversible structural progression. The use of factor analysis to summarize high-dimensional ultrasound data and provision of a simplified score are pragmatic steps toward implementation.
Clinical applications: UPsA activity and damage scores offer several potential roles: 1) objective adjuncts to clinical assessment in routine rheumatology clinics, 2) endpoints or exploratory imaging biomarkers in clinical trials, 3) tools to monitor subclinical inflammation in treat-to-target strategies, and 4) instruments to stratify patients at higher risk of progression for early aggressive therapy.
Limitations and considerations: The study reports internal validation only. Key issues that remain to be addressed include inter- and intra-observer reliability across sonographers, time and resource requirements in routine practice, reproducibility across different ultrasound machines and settings, and external validation in other cohorts and ethnic populations. The absence of reported minimal clinically important difference (MCID) thresholds for UPsA limits interpretation of what constitutes a clinically meaningful change in individual patients. Comparisons with other imaging modalities (MRI) or focused US scores used in clinical trials were not reported in detail; such comparisons would help position UPsA relative to existing tools.
Operational considerations: Widespread adoption will depend on training, sonographer availability, and scan time. The sUPsA appears promising to reduce burden, but prospective implementation studies are needed to document scan duration, clinician acceptance, and impact on decision-making and outcomes.
Research agenda and next steps
- External validation in independent cohorts, including different practice settings and countries.
- Formal reliability testing (inter- and intra-reader) and assessment of equipment-related variability.
- Establishing MCID and response cutoffs linked to patient-important outcomes and decision thresholds (e.g., when to escalate or de-escalate therapy).
- Comparative studies versus MRI and focused US scores to define relative strengths, costs, and roles in trials and clinics.
- Implementation research to measure feasibility, time per scan, required training, and effect on patient management and outcomes.
Conclusion
The UPsA ultrasound activity and damage scores are rigorously derived composite tools from a large multicentre PsA cohort that quantify inflammatory burden and structural damage on a 0–10 scale. Their moderate correlations with clinical measures and responsiveness to change—especially in patients achieving MDA—support construct validity and potential utility for both clinical practice and research. The sUPsA offers a pragmatic, lower-burden option that retains much of the full score’s information and may facilitate adoption. Before widespread implementation, external validation, reproducibility testing, and definition of clinically meaningful thresholds are essential.
Funding and clinicaltrials.gov
The UPsA development was conducted within the Ultrasound in Psoriatic Arthritis Treatment study (NCT03330769). Funding sources and conflicts of interest are reported in the primary publication; readers should consult the original article for detailed disclosures.
References
1) Zabotti A, Piga M, Canzoni M, Nicola CD, Rozza D, Carrara G, Boffini N, Picerno V, Giovannini I, Floris A, Cabas N, Farina N, Sakellariou G, Leccese P, Zanframundo G, Bortoluzzi A, Silvagni E, Raffeiner B, Zanoni S, Parisi S, Ditto MC, De Lucia O, Zandonella Callegher S, Idolazzi L, Figus F, Dagna L, Ramonda R, D’Angelo S, Cauli A, Quartuccio L, Scirè CA, Iagnocco A; Collaborators:; Guiotto A, Rossi S, Trebo P, Piccione F, Maioli G, Lorenzin M, Gabrielli B. Ultrasound for assessing disease activity and structural damage in psoriatic arthritis: the UPsA scores from a multicentre study by the Italian Society of Rheumatology. Ann Rheum Dis. 2025 Nov 28:S0003-4967(25)04524-8. doi: 10.1016/j.ard.2025.10.032. Epub ahead of print. PMID: 41314909.
For clinicians seeking immediate practical guidance, consider the UPsA as a promising standardized ultrasound instrument that requires further external testing before routine adoption. Its availability may meaningfully enhance objective assessment in PsA management and research.
