Surprise figures indicate a fall in life expectancy in the US for the first time in decades

Life expectancy figures released this week in the USA have shown that Americans were not living as long in 2015 as they were in 2014. This fall, for the first time since the 1980s has surprised demographers and got them scratching their heads about possible causes.

Many geography students confuse Death Rates with Life Expectancy. The Death Rate is measured per 1000 people and follows a non-uniform trend as countries develop. Initial advances in medical care, diet, living and working conditions and improved hygiene tend to see death rates fall as countries develop. But then as countries go through the demographic transition, the proportion of elderly people within a country increases while the share of younger population declines, and death rates begin to increase again. This simply reflects a more elderly population structure with a larger ratio of people entering the phase when their life comes to a natural end. So, wealthy Finland has a death rate of 9.9/1000 compared with Bangladesh at 5.3/1000 (2016 est. World Factbook CIA)

Life Expectancy is different, though. It is the number of years (and months) the average person can be expected to live from birth. Again, it is generally assumed to increase with development and improvements in diet, medicine etc. Some countries see their life expectancy deteriorate, but that may be due to prolonged economic decline. Russia experienced a significant fall from 63.8 years to 57.7 (NCBI report) for men between 1990-1994 as the Soviet Union (USSR) disintegrated and institutions fragmented.

Last year's decline in the US affected both men (76.5 to 76.3 years) and women (81.3 to 81.2) according to this BBC News report. It has occurred before, but not for a number of decades and not with such lack of clarity over the cause. There can be a number of factors affecting life expectancy that may be classified as:

• Economic factors: ability to purchase good quality food, medicine and care
• Structural factors: provision and accessibility of health care and quality of medical staff
• Political factors: proportion of national expenditure devoted to health care in both preventative and responsive medical support systems
• Social factors: diet, alcohol-use, rates of exercise, drug-use
• Socio-psychological factors: stress, suicide rates, anxiety
• Environmental factors: pollution, quality of water, physical dangers

There has been considerable focus on affluence-related illness as it is clear that too-much of certain indulgences can be harmful to health. Smoking, drug-use, over-consumption of alcohol, red meat, high-saturated-fat foods etc. can all combine to reduce life-span.

In this report on the issue, by the New York Times, it is suggested that stress and anxiety brought on by post-2008 economic issues along with greater use of high-risk drugs (opiates) may be behind the shortening of life in 2015, but the jury is still out.

The other main question other than the cause(s) is whether the statistics are a single-year blip or the beginning of substantial decline in life expectancy across the USA. It shows the importance of considering long-term trends over single-point data.