Cost effectiveness of strategies to combat cardiovascular disease, diabetes, and tobacco use in sub-Saharan Africa and South East Asia: mathematical modelling study

Dear Editor,

In their paper on the cost effectiveness of strategies to reduce non-communicable diseases in low and middle income countries (1), Ortegon and colleagues use epidemiological figures for risk factor and disease which are estimated at the level of macro-regions (Sub-Saharan Africa, South-East Asia). As pointed out in an accompanying editorial (2), this approach ignores between-country variations. It would be therefore useful to compare these modelled data for macro regions with actual data at the population level in single countries.

In the Seychelles, population-wide information is available for both the causes of death and the prevalence of cardiovascular risk factors. When compared to estimates for Sub-Saharan Africa in Table 2 of Ortegon’s paper, data from the Seychelles show an age-adjusted stroke mortality (2000-2004) 20% higher in men and 40% lower in women (data available from authors, paper submitted). With regards to cardiovascular risk factors, the age-adjusted prevalence (2004) of smoking was 4 times higher in Seychelles than in the estimates for Sub-Saharan Africa in Ortegon’s paper (Table 2). Further, mean BMI and mean cholesterol were 20% higher in Seychelles, while mean systolic blood pressure was similar (3). Admittedly, Seychelles is a middle-income country with a relatively high GDP compared to other Sub-Saharan African countries, and life expectancy is fairly high, as in most small island states throughout the world. However, the existence of large variations in cardiovascular risk factor prevalence between countries in the African region is well known (4).

Cost effectiveness studies are attractive for advocacy purposes, and the use of simplified unique estimates may be an inevitable contingency in absence of reliable data at the country level. However, these estimates are likely to be more meaningful if related to stages of demographic or epidemiological transition (e.g., GDP, life expectancy, or birth rate) rather than according to geographical regions. If only a few stages were considered (typically three or four categories of countries), the number of different scenarios would be kept low and the advantage of parsimonious models would be maintained. Single-country policy makers could rely on information that better fits a country’s specific situation.

References

1) Ortegón M, Lim S, Chisholm D, Mendis S. Cost effectiveness of strategies to combat cardiovascular disease, diabetes, and tobacco use in sub-Saharan Africa and South East Asia: mathematical modelling study. BMJ 2012;344.
2) Revill P, Sculpher M. Cost effectiveness of interventions to tackle non-communicable diseases. BMJ 2012;344.
3) Bovet P, Romain S, Shamlaye C, Mendis S, Darioli R, Riesen W, et al. Divergent fifteen-year trends in traditional and cardiometabolic risk factors of cardiovascular diseases in the Seychelles. Cardiovasc Diabetol 2009;8:34.
4) World Health Organisation. Global status report on noncommunicable diseases 2010. Geneva, Switzerland: WHO; 2010.