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 to 0.948; Visual Analogue Scale [VAS] = 0-100) measured HRQoL. The Work Productivity and Activity Impairment: Specific Health Problem (WPAI: SHP) evaluated productivity. Differences across disability levels were analysed 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: One thousand one hundred seventy-seven (1177) 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 with 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.