Conceptual Model of Stage-Dependent Transition in Rheumatoid Arthritis: A Threshold Framework for Ultra-Early Intervention

Rheumatoid arthritis (RA) is traditionally diagnosed once clinical joint swelling becomes apparent. However, many patients report non-localized stiffness in very early stage then preceding overt synovitis. The transitional processes linking systemic autoimmunity to localized joint inflammation remain incompletely conceptualized. This study proposed a conceptual stage-dependent transition model distinguishing a reversible inflammatory phase from a structurally consolidated phase. Tenosynovitis and joint ultrasound gray scale (GS)-negative/Power Doppler (PD)-positive synovitis were conceptualized as reversible states, whereas GS synovial hypertrophy was hypothesized to represent local immune consolidation. In this framework, “threshold” denoted a conceptual transition point rather than a fixed numerical value, at which gradual inflammatory amplification results in qualitative transition from reversible immune activation to structurally stabilized inflammation (Figure 1). A minimal dynamic representation was introduced to illustrate the theoretical plausibility of threshold-like behavior (Figure 2). Based on this model, we proposed a conceptual algorithm for ultra-early, time-limited intervention prior to structural consolidation (Figure 3). This study was hypothesis-generating and aims to provide a theoretical basis for reconsidering intervention timing in RA.