The chronic disease explosion: artificial bang or empirical whimper?

The World Health Organization defines health as the complete state of physical, mental, and social wellbeing. A recent paper from the Global Burden of Disease study suggests only 4% of the world’s population is now free of disease.1 If true, health is not the norm but an anomalous state, and only a tiny fraction of the world’s population could meet the WHO’s exacting standard. The main culprit, chronic disease, is now so common that healthcare systems are increasingly focused on people with more than one condition. Multimorbidity, recently described as the “most common chronic condition,”2 affects at least half of the population over age 65.3

The effect of chronic conditions, and particularly multimorbidity, on healthcare expenditures is striking. Patients with chronic conditions now account for most consultations in primary care4 and an estimated 84% of total spending in the US.5 Not surprisingly, costs are related to the number of chronic conditions. Compared with people with no chronic conditions, costs are nearly three times greater for people with one condition, five times greater for those with two, and eight times greater for those with three.5

Moreover, recent reports suggest that the number of people with chronic disease is rising faster than previously projected.5 The combination of increasing prevalence and the cost of treatment has led to widespread consensus that dealing with and managing chronic conditions is the single largest challenge facing healthcare systems in the developed world.4

This is a gloomy scenario, but only if reported increases reflect real health problems that can benefit from enhanced diagnosis and treatment. There has been little or no critical assessment of the pace of epidemiological change, the plausibility of proposed explanations …