Development of an IMPACT model for assessing the relative contribution of risk factors and treatment coverage to trends in mortality from Ischaemic Heart Disease

GA-CDRC Investigators:

T. Alafia Samuels, Nigel Unwin, Ian R. Hambleton

Other UWI Investigators:

Natasha Sobers-Grannum (Principal Investigator), Faculty of Medical Sciences, Cave Hill campus

External Investigators:

Julia Critchley, St Georges, London University.

Funding Obtained:

Supported by small grants from the University of the West Indies, Cave Hill Campus

Start Date:

June 2012

End Date:

June 2016



IMPACT is an epidemiological model that was developed originally to understand why mortality from ischaemic heart disease (IHD) was falling in the countries of Western Europe and North America, and in particular the relative contribution of changes in risk factors and the coverage of medical and surgical interventions. It has also been used in settings in which IHD mortality is increasing. Once developed for a specific population it can be used for ‘what if’ analyses, examining the potential impact of different interventions and thus assist in policy decision making. The aim of this work is to develop an IMPACT model initially for Barbados, followed by use in the wider Caribbean.


Data are being identified, appraised for quality and collated on trends in the major cardiovascular risk factors in Barbados, and on trends in the coverage of effective medical and surgical interventions. Data collection involves detailed review of the published and grey literature, identification and new analyses of existing data sets, key informant interviews, accessing data on drug procurement, and medical record review. These data will be used to adapt the model to the situation in Barbados, and determine its ability to account for observed trends in IHD mortality. Multi-way sensitivity analyses will be conducted, and the model used to assess the potential impact on IHD mortality of a range of potential interventions.

Main Results:

Data collection and model development are largely complete, with multi-way sensitivity analyses still to be conducted. It is anticipated that model development and testing will be complete by the end of 2015 and that the model will be used to assess different policy options for IHD prevention and control in the first half of 2016.


Expected Impact:

It will provide for the first time in the Caribbean realistic estimates of the relative contribution trends in risk factors and treatment coverage to trends in IHD mortality, and
estimates of the most effective approaches to reducing mortality in the future.

Next Steps / Future Plans:

Two main developments are planned for this work. The first is to undertake costed ‘what if’ analyses with the model for Barbados, and thus provide estimates of
cost-effectiveness for different policy interventions. This requires working with a health economist, and it hoped that such an individual will be in post at CDRC from September 2015.The second development is to expand the model to include stroke, and thus be able to examine drivers of trends in cardiovascular disease mortality as a whole. This expansion will be conducted in collaboration with modellers in the United Kingdom, including with Julia Critchley at St Georges, London University. One of the initial uses of this expanded model in the Caribbean will be to investigate the determinants of disparities between countries in trends in CVD mortality,
as described under the theme of disparities.

Back to top