Monday, October 19, 2015: 2:00 PM
Grand Ballroom C (Hyatt Regency St. Louis at the Arch)

David van Klaveren, MSc1, John B. Wong, MD2, David M. Kent, MD, MSc2 and Ewout W. Steyerberg, PhD1, (1)Erasmus MC, University Medical Center, Department of Public Health, Rotterdam, Netherlands, (2)Tufts Medical Center, Boston, MA

Purpose: Stratified medicine may improve the cost-effectiveness of medical interventions by targeting the right patients. Long-term survival benefit of a one-time treatment may be estimated by multiplying a trial-based short-term mortality risk reduction with the life expectancy after short-term survival. We aimed to study the influence of different modelling choices for the within-trial mortality risk reduction and post-trial life expectancy on estimates of cost-effectiveness for individual patients.

Method: We analyzed 30,510 patients with an acute myocardial infarction who were included in the GUSTO-I trial and treated with different forms of thrombolysis. Estimates of short-term mortality risk reduction were obtained from a logistic regression model with treatment (aggressive vs standard thrombolysis), sex and age as predictor variables. Life expectancy estimates were derived from sex and age-specific US life tables with an additional 2% yearly excess hazard to capture the increased mortality risk of cardiovascular patients. Aggressive thrombolysis was considered cost-effective when incremental costs per life year gained fell below $50,000.

Result: Based on sex and age-specific risk reductions but average population life expectancy, there was a substantial difference in expected life years gained between the lowest and highest quintile of short-term mortality risk (0.04 in first quintile vs 0.43 in fifth quintile; Figure 1). On individual patient level these assumptions imply aggressive thrombolysis to be cost-effective for men above the age of 48 and women above the age of 44 (83% of the population). When both mortality risk reduction and life expectancy were sex and age-specific, the difference in life years gained between the lowest and highest risk quintile was substantially attenuated (0.06 in first quintile vs 0.24 in fifth quintile; Figure 1). Individual cost-effectiveness of aggressive thrombolysis was extended to men above 43 and women above 37 of age (92% of the population).

Conclusion: This case-study illustrates how failure to model short-term risk reduction and life expectancy at a congruent level of detail may mislead our estimates of individualized cost-effectiveness and misallocate resources.


Figure 1   Life years gained from aggressive thrombolysis per 100 patients with an acute MI by sex and age specific short-term mortality risk quintile. Based on average population life expectancy (white bars) and on sex and age specific life expectancy (grey bars).