Scholze et al. BMC Public Health 2010, 10:529 http://www.biomedcentral.com/1471-2458/10/529 Page 6 of 12 Table 1 Annual number and event rate per 1,000 hypertensive patients of incident cases of cardiovascular disease, mortality and prevalent cases of type 2 diabetes; 2008 and 2020 Germany Spain Italy No. events Event rate* No. events Event rate* No. events Event rate* Annual incidence of cardiovascular events 2008 2020 2008 2020 2008 2020 MetS† No MetS‡ MetS† No MetS‡ MetS† No MetS‡ MetS† No MetS‡ MetS† No MetS‡ MetS† No MetS‡ Annual incidence of mortality Annual prevalence of type 2 diabetes 583,500 188,500 889,500 124,400 64,000 20,600 97,800 13,600 5,287,600 627,300 8,676,100 510,300 27 14 29 14 3.00 1.49 3.17 1.52 248 45 281 57 74,600 134,000 208,300 132,200 14,800 8,200 22,800 14,500 834,500 515,100 2,364,500 703,400 25 13 27 14 2.74 1.45 2.90 1.50 281 51 301 73 103,300 202,500 267,800 189,900 11,300 22,400 29,300 20,800 1,313,300 823,700 3,390,200 1,021,600 24 13 25 13 2.64 1.40 2.78 1.50 308 52 322 71 * Event rate per 1000, † hypertension patients with MetS, ‡ hypertension patients without MetS. diabetes costs were varied by plus or minus 20% than when drug costs and continuation rates were varied. We also assessed the impact of applying a discount rate of 3% to future costs. This would reduce the total annual cost of hypertension in 2020 from €42,769 million to €29,997 million in Germany; from €8,180 million to €5,737 million in Spain; and from €18,710 million to €13,123 million in Italy. Discussion The results of this modelling study suggest that the pre- sence of MetS in patients with hypertension significantly inflates the cost of illness due to the increase in cardio- vascular events and cases of type 2 diabetes. These costs rise incrementally with the additional number of MetS components present. In Germany hypertensive patients with MetS account for over 60% of all hypertensive patients and contribute to 80% of the costs. In Spain and Italy they account for nearly a quarter of the hyper- tensive population and contribute to nearly half of the costs. The much higher prevalence in Germany can be explained by the country having one of the highest rates of abdominal obesity in Europe [47]. Mean annual costs per patient for those with MetS are two to three times higher than for those without. Antihypertensive drug costs make up less than 10% of overall costs of care in this high risk patient group with the management and treatment of cardiovascular events and type 2 diabetes accounting for the majority of costs. These costs are set to rise in the future as the propor- tion of the population over the age of 50 years grows and the prevalence of the components of MetS increases. The most prevalent component of MetS in patients with hypertension is abdominal obesity which has reached epidemic proportions in Europe and cur- rently shows no sign of slowing down [48]. This study used a prevalence-based modelling approach to estimate cost-of-illness and therefore is sub- ject to a number of assumptions. Although efforts were made to ensure the best sources of data available to date were used in the model, as the published literature in this area is still relatively limited and national data- bases do not provide all appropriate data required to estimate epidemiological burden [49], there were a num- ber of data gaps. As with all models that require some assumptions to be made an element of caution is required when interpreting the results. The assumptions used in this model are described in detail elsewhere [28]. For example we used a United States database to develop our conditional probability matrix which pro- vided data on the probability of hypertensive subjects having no other MetS components, one, two, three or