Current and future worldwide prevalence of dependency, its relationship to total population, and dependency ratios.

OBJECTIVE To estimate the number of people worldwide requiring daily assistance from another person in carrying out health, domestic or personal tasks. METHODS Data from the Global Burden of Disease Study were used to calculate the prevalence of severe levels of disability, and consequently, to estimate dependency. Population projections were used to forecast changes over the next 50 years. FINDINGS The greatest burden of dependency currently falls in sub-Saharan Africa, where the "dependency ratio" (ratio of dependent people to the population of working age) is about 10%, compared with 7-8% elsewhere. Large increases in prevalence are predicted in sub-Saharan Africa, the Middle East, Asia and Latin America of up to 5-fold or 6-fold in some cases. These increases will occur in the context of generally increasing populations, and dependency ratios will increase modestly to about 10%. The dependency ratio will increase more in China (14%) and India (12%) than in other areas with large prevalence increases. Established market economies, especially Europe and Japan, will experience modest increases in the prevalence of dependency (30%), and in the dependency ratio (up to 10%). Former Socialist economies of Europe will have static or declining numbers of dependent people, but will have large increases in the dependency ratio (up to 13%). CONCLUSION Many countries will be greatly affected by the increasing number of dependent people and will need to identify the human and financial resources to support them. Much improved collection of data on disability and on the needs of caregivers is required. The prevention of disability and provision of support for caregivers needs greater priority.