Economic consequences of rheumatoid arthritis and ankylosing spondylitis: a literature review

Background: Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) are characterised by chronic impairments that result in various socio-economic consequences for patients, their environment and society, such as an increased healthcare utilisation, a need for formal and informal care, and a reduced productivity or ability to work.
Objectives: To review and summarise the cost of illness studies with a societal perspective for rheumatoid arthritis (RA) and ankylosing spondylitis (AS).
Methods: Medline, Embase and Econlit (EBSCO) were searched up to April 2007 for original bottom-up studies reporting detailed costs of RA or AS. Both cost-of-illness studies and economic evaluations of treatments were included. Studies from non-western countries were excluded, as the organisation of the healthcare system and costs of services in non-western countries are difficult to compare and aggregated with those of western countries. Studies were appraised for patient and study characteristics, type of costs and actual costs. Reported costs were aggregated by various cost categories and overall mean costs were summarised by cost domain (healthcare, patient & family, and productivity costs).
Results: The meta-search retrieved 603 titles with abstracts of which 89 studies on RA and 11 studies on AS, fulfilled the abstract inclusion criteria. The assessment of full transcripts of the selected studies resulted in 25 papers on RA and 7 papers on AS suitable for inclusion in this review. Most were COI studies; 7 studies on RA and one study on AS were economic evaluations within an RCT setting.While the overall mean costs of RA (€14,961/pt/yr) were slightly above that of AS (€9,475/pt/yr), the relative distribution of costs over the cost domains was approximately similar for both diseases. When excluding those studies of RA that also included patients treated with TNF inhibitors (three COI studies and one trial based cost-effectiveness study), the mean medication costs decreased (from €1567 to €895/pt/yr). For both diseases, mean productivity costs based on the human cost approach were 3 to 10 times higher than the friction costs. Productivity costs (human capital approach) accounted for more than half the total costs of both diseases. Productivity costs because of at-work production loss (presenteeism) have not formally been assessed in these patient groups.
Conclusion: Productivity costs constitute the largest part of the total cost-off-illness of RA and AS, reflecting the high burden of the disease on work participation. Although the total and direct costs of illness in RA were higher than for AS, the average age of AS patients was 10 years lower and therefore, the lifetime costs associated with AS may actually be equal or higher.