A MARKOV MODEL OF LONG-TERM COST EFFECTIVENESS OF ADALIMUMAB IN JUVENILE IDIOPATHIC ARTHRITIS IN CANADA

Background: There are currently no published economic models that evaluate the impact of treatment on the course of juvenile idiopathic arthritis (JIA) beyond the time horizon of 1 year. There is evidence from long-term controlled studies that adalimumab is an effective therapy for children with JIA. However, longer-term economic and quality-of-life consequences of adalimumab treatment for children with JIA are still unknown. Objectives: To determine the longer-term cost-effectiveness of adalimumab for the treatment of children with JIA from a Canadian healthcare system and societal perspective. Methods: We used factor and cluster analysis of data from the DE038 clinical trial of adalimumab in JIA (patients aged 4-17) to assist us in structuring the model. The resulting Markov structure had 5 health states consisting of mild, moderate, and severe active symptoms and remission with and without joint limitations. Quality-of-life weights for each health state were estimated using the Health Utilities Index Mark 2 quality-of-life instrument to structure trial Childhood Health Assessment Questionnaire and symptom responses. Model cost weights were developed from reports of medical care costs (in Canadian dollars) for patients with JIA receiving biological therapy. The time horizon for the base model was 7 years (ages 11 through 17 years). Lifetime costs and consequences were also explored to assess the residual effects of joint replacements required for patients with JIA in adulthood. A 2010 Canadian healthcare system and societal perspective were used. Future cost and quality-adjusted life years (QALYs) were discounted at 5% per year. Results: The model was consistent with findings of the clinical trial in terms of disease remission rates (5-year remission rate of 53.1% in the model, 55.0% in the clinical trial), indicating a high degree of predictive validity. The incremental cost-effectiveness ratios (ICERs) for the base model with a 7-year time horizon were $58,392 and $46,199 per QALY gained from a Canadian healthcare system and societal perspective, respectively. The lifetime analysis, which included the expected costs for joint replacement procedures required in adulthood, improved the ICERS to $24,931 and $18,872 respectively. We examined the sensitivity of the model to changes in the mean age of the children, and found that the base model estimate improved from $58,392 to $41,104 when the mean age was changed to 7 years and these children were observed until age 18 years (an 11-year time horizon). Similar improvements were noted for the societal perspective and for the estimates that were generated by the adulthood model. Conclusions: Adalimumab appears to be cost-effective for the treatment of JIA even over a relatively short time horizon. Using the lifetime analysis that accounts for joint replacement significantly improves the ICERs, indicating that treatment benefits persist over a lifetime. References: 1. Ungar WJ, et al. Arthritis Care Res. 2011;63:111–9. doi: 10.1002/acr.20337. Disclosure of Interest: K. Simpson Employee of: Medical U. of S. Carolina, S. Kirbach Shareholder of: Abbott, Employee of: Abbott, P. On Shareholder of: Abbott, Employee of: Abbott, M. Cifaldi Shareholder of: Abbott, Employee of: AbbottCitation: Annals of the Rheumatic Diseases, volume 70, supplement 3, year 2011, page 205Session: Epidemiology, health services and outcome research (Poster Presentations )