From disability to daily life: functional status, quality of life, and work productivity in real-world inflammatory arthritis

Objective Inflammatory arthritis (IA) can impair physical function, health-related quality of life (HRQoL), and productivity. Associations among these domains are recognized; however, evidence quantifying them across clearly defined disability levels remains limited. This study aimed to evaluate HRQoL and productivity across functional disability levels in IA using standardized patient-reported outcome measures (PROMs). Methods This cross-sectional analysis included consecutive IA patients attending rheumatology clinics in Calgary/Canada, enrolled in the Rheum4U Precision Health Registry (2018–2026). The Health Assessment Questionnaire Disability Index (HAQ-DI=0–3) assessed functional disability, categorized as no (0), mild-to-moderate (>0–1), moderate-to-severe (1–2), or severe-to-very-severe disability (2–3). EuroQol 5-Dimension 5-Level (EQ-5D-5L; utility= -0.148 – 0.948; Visual Analog Scale- VAS=0–100) measured HRQoL. The Work Productivity and Activity Impairment: Specific Health Problem (WPAI:SHP) evaluated productivity. Differences across disability levels were analyzed using Kruskal-Wallis tests with Dunn’s post-hoc comparisons and effect sizes. Minimum important difference (MID) thresholds supported the interpretation (EQ-5D-5L utility=0·20; VAS=9·3; productivity=20%). Results 1,177 IA patients were included. Worsening functional disability was associated with progressively lower HRQoL and productivity (p < 0.001). Deterioration was evident starting at mild-to-moderate disability, with the moderate-to-severe disability representing a critical threshold for impairment compared to no disability (difference utility=0·223; VAS=25; productivity=40%). Conclusion In this robust real-world study using standardized PROMs, functional decline was associated with progressively worse HRQoL and productivity, with differences statistically significant and clinically meaningful. Moderate-to-severe disability appeared to mark a critical threshold. These findings underscore the importance of early identification and management of disability to prevent clinically meaningful impairments in quality of life and productivity.