Why does US lag behind in life expectancy?

Higher mortality rates among Americans younger than 50 are responsible for much of why life expectancy is lower in the United States than most of the world's most developed nations.

The research, published in Health Affairs, found that excess mortality among Americans younger than 50 accounted for two-thirds of the gap in life expectancy at birth between American males and their counterparts and two-fifths between females and their counterparts in the comparison countries.

Most of the excess mortality of those younger than 50 was caused by noncommunicable diseases, including perinatal conditions, such as pregnancy complications and birth trauma, and homicide and unintentional injuries including drug overdose, a fact that she said constitutes a striking finding of the study.

"These deaths have flown under the radar until recently," Ho said. "This study shows that they are an important factor in our life expectancy shortfall relative to other countries."

The author stated that the majority of the drug overdose deaths stemmed from prescription drug use.