Impact of intervention targeting risk factors on chronic disease burden.

The aging of the population is accompanied by a sharp rise of chronic disease prevalences, such as dementia. These diseases generally cannot be prevented or cured and persist over time, with a progressive deterioration of health, requiring specific care. To reduce the burden of these diseases, it is appropriate to propose interventions targeting disease risk factors, but the association between most of these risk factors and mortality makes it difficult to anticipate the potential impact of such interventions. A method was previously proposed to estimate changes in disease prevalence following an intervention targeting subjects at a given age where the incidence of the disease is supposed to be null. Here, we propose a general framework to make projections for life expectancies with and without the disease, the age at onset, and the lifelong probability of the disease, and to evaluate the consequences of preventive interventions targeting risk factors on these various measures of disease burden. The methodology takes into account the mortality trend over calendar time and age in both healthy and diseased subjects, and the change in mortality due to the intervention. The method is applied to make projections for dementia in 2030 according to several scenarios of public health interventions.