To assess the mechanism responsible for the improvement in life expectancy in Hong Kong over the past several decades, Arriaga's decomposition method was applied to quantify the influence of the age structure and the leading causes of death on the increase in life expectancy in Hong Kong from 1986 to 2015. Our results showed that, during the observed period, the major contribution to the improvement in life expectancy in Hong Kong was attributable to the older population for both males and females. Contributions of malignant neoplasms in the period of 1986-1995, 1996-2005 and 2006-2015 were 0.613, 0.279 and 0.887 years in males and 0.391, 0.312 and 0.226 years in females, respectively. For circulatory diseases, the corresponding figures were 1.452, 0.202 and 0.832 years in males and 0.675, 0.192 and 1.069 years in females, with the largest contribution also shifting to older ages. However, these positive contributions were partly offset by the negative contribution of pneumonia, especially among those at advanced ages. Furthermore, although the impact was limited, attention should also be paid to the prevalence of some chronic diseases among the younger age groups in recent years.
Keywords: life expectancy; mortality; public health policy.