Over the past decades, studies have confirmed that obesity is related to higher mortality. Moreover, obesity is also a major risk factor for a variety of chronic diseases, such as cardiovascular and heart diseases that are among the top leading causes of death in Taiwan. At the same time, there are also debates arguing that the effect of BMI status on mortality would be weaker among older populations. In this study, we examined the effect of BMI status on both the all-cause mortality and death causes related to cardiovascular and heart diseases.
Data were taken from the Survey of Health and Living Status of the Middle Aged and Elderly in Taiwan, which followed a representative sample of elders (N=2185), aged 60 and over in1989, until 2003. Cox regressions were used to investigate the relationship between their BMI status and survival over the 15-year period.
Results showed that obesity might not be a serious problem among this cohort of elders in Taiwan. Only 11.5% of the elders were considered as overweight (BMI≧27). Plus, a somewhat surprised finding was revealed from our uni-variate analysis. That is, instead of being overweight, being underweight (BMI≦18.5) was associated with higher mortality over the study period. However, when gender, age, and socioeconomic status measures were controlled for, those overweight (BMI≧27) were more likely to died and this effect of overweight on mortality could be explained away by the fact that those overweight elders were also more likely to have chronic diseases. A similar pattern was observed from our Cox models analyzing the effect of BMI status on cardiovascular-and-heart-diseases-related causes of deaths. However, we did find a stronger association between BMI status and the causes of deaths related to cardiovascular and heart diseases.
