The Economic Burden of Inflammatory Arthritis: A Systematic Review.

Background and objective: Inflammatory arthritis is a common condition treated in rheumatology clinics, contributing significantly to healthcare costs and societal burden. Understanding the economic impact of inflammatory arthritis requires a comprehensive analysis through cost-of-illness studies. This systematic review aims to gather up-to-date cost-of-illness data on inflammatory arthritis from various countries, identify the primary cost drivers, describe shifts in cost components and appraise the quality of cost-of-illness study reporting in this field.

Methods: An electronic search was performed across four databases, including MEDLINE, Embase, the Cochrane Database of Systematic Reviews and the Health Management Information Consortium, to identify cost-of-illness studies on inflammatory arthritis published over the past two decades. The primary outcome was the annual cost per patient with inflammatory arthritis, categorised by cost components. All costs were standardised to 2024 US dollar values. The quality of the included studies was evaluated using the Larg and Moss checklist and the modified Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist.

Results: From an initial 12,264 publications, 82 studies were included in this review, covering axial spondyloarthritis (n = 49), psoriatic arthritis (n = 30), reactive arthritis (n = 2), rheumatoid arthritis (n = 13; 2019 onwards) and seronegative/seropositive rheumatoid arthritis (n = 8). Annual total societal costs varied considerably across inflammatory arthritis subtypes and countries. Medication expenditures consistently emerged as the primary direct healthcare cost driver, while productivity losses due to morbidity constituted the major component of indirect costs. Carer productivity loss represented a substantial proportion of indirect costs (up to 60.9%), yet was infrequently reported. Over time, we observed an increasing proportion of medication-related costs and a decreasing proportion of productivity losses for axial spondyloarthritis, alongside a reduction in inpatient care costs for psoriatic arthritis. These evolving cost distributions mirror patterns previously reported in rheumatoid arthritis. Methodological gaps were evident, with most studies lacking sensitivity analyses and comprehensive cost perspectives.

Conclusions: A substantial economic impact of inflammatory arthritis across different regions and subtypes was identified. This review emphasises the importance of including comprehensive cost components to fully assess the economic burden of inflammatory arthritis and provides methodological recommendations for future studies.