1. Psoriatic Arthritis: Creating a Model for Cost- Effectiveness Analysis GRAPPA meeting San Antonio, TX October 15, 2004 Supported by Schering Participants: D. Gladman, P. Mease, C. Antoni, A. Kavanaugh, V. Farewell, A. Maetzel, C. Marra, J. Wong, J. Pew

2. Introduction Anti-TNF’s provide substantial clinical benefit for patients with psoriatic arthritis but are relatively expensive National Institutes for Clinical Effectiveness (UK) request: –Cost-effectiveness of etanercept and infliximab for patients with inadequate response to standard DMARD therapy

3. What are the Requirements to Determine Cost-effectiveness? Impact of intervention on natural history and costs –IMPACT I –Supplemented by Toronto Psoriatic Arthritis Research Program Natural history of the disease –Mortality: Toronto Psoriatic Arthritis Research Program –Morbidity or quality of life: EQ-5D in Toronto PsA Program patients Lifetime cost: –Utilization and drug costs in Toronto Cohort

4. Cost-Effectiveness Ratio Compares a specific (new) intervention to a stated alternative (old) intervention (Cost new – Cost old )/ (Benefit new – Benefit old ) Incremental resources required by the intervention Incremental health effects gained by using the intervention

5. Markov Cohort Simulation Model Cycle 1 2 3 Well Sick Well Dead

6. Attributes Used to Define Markov States Determine health states by ability to predict death, disability or functional status or costs Determine likelihood of moving from one health state to the others for each treatment (transition probabilities) in a period of time Associate with each health state, chance for 1) death, 2) change in health status, 3) quality of life, 4) costs

7. Potential Heath States for PsA HAQ categories –May not capture full disease burden –Values lower than for RA Active joints –0, 1-4, 5-9, 10+ Deformed joints –0, 1-4, 5-9, 10+

8. Markov Model

9. Choosing Heath States for PsA Active joint model –Good gradient with EQ-5D for health related quality of life (poorer QOL with more active joints) –Good gradient for cost (higher costs with more active joints) –IMPACT I patients easily mapped onto health states Deformed joint model –Gradient for QOL not as good –Gradient for costs better –Mapping of IMPACT I patients problematic

10. Issues Patients from IMPACT I appear to have a poorer prognosis than those from the Canadian database For some patients, we had to use the Toronto database to estimate prognosis (underestimate disease progression) PASI only has mild EQ-5D impact

11. Economic Project and GRAPPA What should the role of GRAPPA be? –Endorsement of work already done –Level of involvement –Other companies doing similar assessments