Patient-reported quality of life and working status outcomes in ambulatory patients with idiopathic inflammatory myopathy.

OBJECTIVE: To investigate the health-related quality of life (HR-QoL), work productivity and activity impairment, and associated factors among patients with idiopathic inflammatory myopathy (IIM).

METHODS: This was an observational, cross-sectional study. The 189 ambulatory patients with IIM were recruited from May 2019 to May 2022. HR-QoL was measured by the European Quality of Life 5-Dimension (EQ-5D). The work productivity and activity impairment (WPAI) questionnaire was used to evaluate work productivity and activity impairment. The IIM-related parameters were assessed by the Manual Muscle Testing-8 (MMT-8), Myositis Disease Activity Assessment Visual Analogue Scale (MYOACT), Myositis Damage Index (MDI), Disease Activity Score (DAS), and Physician/Patient Global Assessment (PGA/PtGA). Quantile regression and ordinal logistic regression were performed to identify the factors, considering EQ-5D or WPAI scores as dependent variables, respectively.

RESULTS: Of the 189 IIM patients enrolled, 60% had dermatomyositis, 13% had polymyositis, and 27% had clinical amyopathic dermatomyositis. The median EQ-5D score was 1.00 (0.73, 1.00), 28% were employed, and 45% of overall work was impaired due to health problems. EQ-5D values were positively associated with MMT-8, and negatively with MYOACT, DAS, MDI-global, and PGA/PtGA. For the WPAI, activity impairment was associated with lower MMT-8, older onset age, and higher PGA only in 25th-75th percentile. Increased PtGA was associated with increased activity and overall working productivity impairment in most quantiles (P < 0.05).

CONCLUSION: Multiple disease characteristics were associated with reduced HR-QoL or working productivity impairment in patients with IIM, especially for PtGA.