Exploring the likely effect of the introduction of drug eluting stents on requirements for coronary artery revascularisation procedures in Western Australia : a use of the CHD/CARP Markov simulation model

Background: Coronary artery revascularisation procedures (CARPs) include coronary artery bypass graft procedures (CABGs) and the less invasive percutaneous coronary interventions (PCIs) and they are common surgical interventions for coronary heart disease (CHD). The effectiveness of PCIs increased when stents were introduced and there was also a shift towards doing more PCIs and less CABGs, especially in older patients. More recently, PCIs have been further improved by the use of drug-eluting-stents (DES). In this study we used a recently developed CHD/CARP Markov model to explore the likely effect on CARP requirements due to the introduction of DES. Methods: This is achieved by considering the population of Western Australia aged 35 to 79 years at the beginning of 2001 (grouped according to history of CHD and CARPs) as the cohort, calculating the mean population risks for CHD/CARP events over three years 1998 to 2000, and using these population risks and certain modifications of them that incorporate the likely effect of the introduction of DES (in 2002) in the CHD/CARP Markov model to explore difference in total requirements for CABGs and PCIs over the period 2001 to 2010. The anticipated likely effect of DES on probabilities of CARP procedures was based on results of meta-analysis of randomized controlled trials comparing DES stents to ordinary stents and an anticipated further reduction in CABGs and increase in PCIs as was observed when (ordinary) stents were introduced. Results: The simulation results suggest that, over the period 2001 to 2010, the total number of CABGs will decline by up to 19% and the total number of PCIs will increase by up to 6%.Conclusion: The introduction of DES will have greater effect on the requirement of CABGs as compared to that on PCIs.