Adapting a Markov simulation model for forecasting the requirements of CARPs and assessing scenarios for implications of drug eluting stents and changes in trends for CHD incidence

![CDATA[Background: Treatments for CHD have evolved rapidly over the last 15 years with considerable change in the number and effectiveness of both medical and surgical treatments such as coronary artery revascularization procedures (CARPs). Also, CHD incidence has been declining in the population mainly due to reduced overall levels of CHD risk factors and/or improved medical care for those at higher risk of heart attack. However, the ‘obesity epidemic’ may have slowed down this decline. Methods: In this article, we expand on the use of a well validated Markov Monte Carlo simulation model for forecasting CARPs in Western Australian population during the mid-1990s (when actual numbers of CARPs are known) when there were considerable changes to CARP technology and implementation policy. Also, we develop scenarios to explore a range of reasonable forecasts for CARPs for 2001–2010 (when actual numbers of CARPs are not known) in the same population, by varying transition probabilities which may be influenced by induction of drug eluting stent (DES) and changes in trends of CHD incidence as might be caused by the ‘obesity epidemic’. These objectives are obtained by examining trends in key CARP/CHD model probabilities over the 1990s, considering the improved effectiveness of CARPs from clinical trial evidence, an awareness of trends in policy and practice of CARPs and modifying the projected model probabilities of key CARP events accordingly. These model probabilities and the ones obtained by standard extrapolation methods are used as simulation inputs.]]