Modifiable factors of mortality in older people : what can we learn from Hong Kong?

Abstract

Background: With increasing life expectancy, population aging is becoming a global public health issue. Most evidence concerning modifiable factors for mortality in older people is derived from observational studies in long-term developed Western settings and they usually find moderate drinking associated with a lower risk of death whilst diabetes, for which obesity is a substantial risk factor, associated with a higher risk of death from cancer, especially for cancers related to obesity, such as colon and pancreatic cancer. However, older people in Hong Kong have different lifetime experiences. They have experienced macro-environmental transition from pre- to post-industrial living conditions in their own lifetime, as well as considerable social re-assortment. Results of the association of modifiable factors for mortality in this setting may act as a sentinel for mainland China and other similar settings where economic transitions are currently underway.

Objectives: This study took advantage of a large (n=66,820) prospective elderly cohort (65+ years) from Hong Kong, a developed non-Western setting where patterns of lifestyle, chronic conditions, and socioeconomic position (SEP) differ from those in the West, to examine the association of alcohol use with death from cancer and respiratory disease, and to examine the association of self-reported diabetes, SEP and physical activity with death from all- and specific causes.

Methods: All participants were enrolled from July 1998 to December 2001 at all the 18 Elderly Health Centers in Hong Kong, and followed until May 31, 2012. Multivariable Cox regression was used to analyze the association of alcohol use categories (never, social, moderate, excessive and ex-drinking) with death from cancer and respiratory disease, and to analyze the association of self-reported diabetes, SEP across the life course (education, housing type and monthly expenditure) and different types of physical activity (aerobic exercise, traditional Chinese exercise (TCE), stretching exercise and slow walking) with death from all- and specific causes.

Results: Social drinking rather than moderate drinking was associated with a lower risk of death from non-esophageal cancer. Moderate drinking was associated with a higher risk of death from esophageal cancer. Both social drinking and moderate drinking were associated with a lower risk of death from respiratory disease with similar patterns of association. Self-reported diabetes was associated with a higher risk of death from all-causes, cardiovascular disease and respiratory disease, but was weakly associated with death from all-cancer, and only clearly associated with death from liver and stomach cancer. Socioeconomic disadvantages at different life stages contributed to death from all- and specific causes independently and sometimes interactively, often with a larger contribution from early life. TCE was inversely associated with death from all- and specific causes with similar estimates to aerobic exercise.

Conclusion: This large prospective elderly cohort study from an understudied population found different associations of several modifiable factors including alcohol use, diabetes, SEP and physical activity, with mortality from those in the West. More effective and possibly contextually-specific public health strategies are needed.