0443: Association Between Pan-immune-inflammation and Synovitis as Assessed by Ultrasound in Rheumatoid Arthritis

Background/Purpose: The pan-immune-inflammation value (PIV) is a novel composite biomarker derived from blood count parameters, reflecting the systemic balance of immune-inflammatory activity. Although it has been explored in various inflammatory conditions, its association with ultrasound-detected synovitis in rheumatoid arthritis (RA) remains uncharacterized. Musculoskeletal ultrasound provides a sensitive modality for detecting synovitis through semiquantitative grading of gray scale (GS) and power Doppler (PD) signals on a 0–3 scale for each joint.
To evaluate the association between PIV and synovitis, as assessed by GS and PD scores, and to compare these correlations with clinical disease activity (DAS28) and functional disability (HAQ-DI) in patients with RA.

Methods: RA patients were prospectively recruited from a single-center cohort. Bilateral wrists and the second and third metacarpophalangeal (MCP) joints were assessed using the EULAR-OMERACT semiquantitative scoring system. PIV was calculated as: (neutrophils × monocytes × platelets) / lymphocytes). Spearman’s ρ coefficients with 95% confidence intervals (CIs) were used to assess relationships between PIV, DAS28, HAQ-DI, and ultrasound scores. Multivariable linear regression models were developed using GS and PD scores as dependent variables. PIV values were also compared against a reference population of healthy adults from Mexico City.

Results: Seventy patients with RA were recruited and compared with 2,170 healthy adults. GS scores were significantly correlated with PIV (ρ = 0.356; 95% CI: 0.155–0.529) and DAS28 (ρ = 0.411; 95% CI: 0.217–0.574), but not with HAQ-DI (ρ = 0.027; 95% CI: −0.180 to 0.239). Similarly, PD scores correlated with both PIV (ρ = 0.344; 95% CI: 0.141–0.519) and DAS28 (ρ = 0.459; 95% CI: 0.273–0.612), but not with HAQ-DI (ρ = 0.069; 95% CI: −0.145 to 0.279). In multivariable models, PIV (β = 0.0061, p = 0.001) and DAS28 (β = 1.120, p = 0.014) were independently associated with GS scores; both PIV (β = 0.0043, p = 0.004) and DAS28 (β = 0.960, p = 0.007) also emerged as independent predictors of PD scores. Notably, 42% of RA patients had PIV values exceeding the 75th percentile (285.3) of the healthy reference population.

Conclusion: Ultrasound-detected synovitis is independently associated with systemic inflammatory activity as measured by the PIV and with clinical disease activity assessed by DAS28, but not with patient-reported functional disability. These findings suggest that PIV may represent a useful, non-invasive biomarker for quantifying inflammatory burden in RA.