Understanding the rapid increase in life expectancy in shanghai, China: a population-based retrospective analysis

Background: Life expectancy at birth (LE) is a comprehensive measure that accounts for age-specific death rates in a population. Shanghai has ranked first in LE in China mainland for decades. Understanding the reasons behind its sustained gain in LE provides a good reflection of many other cities in China. The aim of this study is intended to explore temporal trend in age-and cause-specific gains in LE in Shanghai and the probable reasons lay behind. Methods: Joinpoint regression was applied to evaluate temporal trend in LE and the long time span was then divided accordingly. Contributions to change in LE (1973-2015) were decomposed by age and cause at corresponding periods. Results: LE in Shanghai could be divided into four phases ie., descent (1973-1976), recovery (1976-1998), rapid rise (1998-2004) and slow rise (2004-2015). The growing LE was mainly attributed to reductions in mortality from the elderly populations and chronic diseases such as cerebrovascular disease, chronic lower respiratory disease, and gastrointestinal cancers (stomach, liver and esophageal cancer). Conclusions: The four-decade sustained gain in LE in Shanghai is due to the reductions in mortality from the elderly and chronic diseases such as cerebrovascular disease, chronic lower respiratory disease, and gastrointestinal cancers. Further growth momentum still comes from the elderly population.