Critical analysis of economic tools and economic measurement applied to rheumatoid arthritis.

Rheumatoid arthritis (RA) is chronic, progressive systemic inflammatory disease that if uncontrolled may lead to significant joint damage, dysfunction, work disability and other sequelae that result in large economic losses. A rich literature estimating the economic burden of RA, has been intensified recently, driven by costly biologic agents that have had a notable effect improving the outcomes of patients with RA. In order to optimally assess the value of therapies, it is best to take a comprehensive approach, considering all related costs of illness. This includes direct costs (e.g. the costs of the medications themselves and the monitoring required), indirect costs (e.g. loss of productivity, such as employment due to uncontrolled disease) and intangible cost (e.g. effects on pain and quality of life). Indirect costs constitute a substantial part of total cost in the patient with RA. In order to help assess the impact of RA on productivity, various tools for measuring productive loss like absenteeism and presenteeism have been introduced. No single tool reflects the entire spectrum of the productive loss clearly, as other factors such as use of a human capital approach or friction cost approach affect the valuation of productive loss monetarily. Although favourable outcomes are achieved with the use of biologic agents, their higher acquisition costs, as compared to traditional disease-modifying anti-rheumatic drugs (DMARDs) remain a barrier to their use. Assessments of the cost effectiveness of novel therapies are critically important, but published results have been contradictory, in some measure due to the heterogeneity of instruments utilised. While the various instruments appear to be valid and reliable, correlations between instruments has been modest, driven by factors such as differences in recall times, attribution and other confounders.