Perhaps the greatest challenge that will face health systems around the world this century will be how to develop effective responses to the growing burden of chronic diseases. Several interlinked factors come together to create this challenge. Many chronic diseases are a consequence, albeit not always inevitable, of the ageing process. However, unlike in past generations, for whom the onset of a disease such as diabetes could mean a rapid death, we now have the means to keep people alive but on treatment for their diseases.
In a world where fertility rates are declining, this means that there is now a much higher proportion of the population living with chronic diseases and, in many cases, multiple diseases. Many older people will be receiving treatment for a combination of conditions that will often include some degree of hypertension, heart failure, angina, obstructive airways disease, or arthritis. And the list of complex chronic diseases is constantly growing. In many industrialized countries there is an ageing cohort of individuals living with HIV infection who will have to add a complex mix of life-sustaining treatments for non-communicable diseases to their already complex combination of anti-retroviral therapy. AIDS, once considered a rapidly progressive fatal condition, with treatment, has become yet another chronic disease.