Key points

• Adults aged 15 to 64 years account for a sizeable proportion of the population (over 60%) both worldwide and within the UK.

• Non-communicable diseases are the leading causes of death in developed countries whereas in developing countries, communicable diseases, maternal, perinatal and nutritional conditions and injuries are the leading causes of death.

• Within the UK, cancers, cardiovascular diseases, diabetes mellitus, mental illness and obesity are significant public health problems in this age group.

• Although national policies are already in place to tackle these conditions, concerted health-improvement efforts with engagement of local populations are required to make a significant impact on the burden of ill health.

Introduction

Approximately 66% of the world’s population in 2010 was estimated to be aged between 15 and 64 years, with a male:female ratio of 1.02. In less-developed regions of the world, this age group comprises 65% of the total population whereas in the more developed regions it comprises about 68% [1].

In 2009, 65% of the UK population were aged between 15 and 64 years. Although the total UK population increased by 10% between 1984 and 2009, the proportion of the population aged 15–64 years increased only by 1% [2]. The old-age dependency ratio (number of people aged 65 or more for every 100 people aged 15–64) in the UK was 24 in 2009; this is close to the EU average but is projected to rise to 39 by 2035 as the population ages (see Chapter 14).