Obesity and mortality among older Thais
Reported, January 6, 2012
Obesity has become a global public health concern. The World Health Organization (WHO) estimated that there were 400 million obese adults (as measured by body mass index, BMI) worldwide in 2005 and expected to be 700 million in 2025 . The major health consequences associated with obesity include diabetes mellitus (DM), hypertension (HT), dyslipidemia and cardiovascular diseases (CVDs) . As a result, the global burden of disease attributable to obesity amounted to 2.6 million deaths of which ranked the 7th of mortality and the 10th in term of burden of disease due to leading global risk factors . In Thailand, the burden of disease attributable to obesity was 359114 Disability Adjusted Life Years (DALYs) loss in 2000 .
In the past two decades, Thailand, a rapidly economic growth country with the advent of an ageing population, the predominant cause of deaths is now changing from infectious diseases to chronic non-communicable diseases including chronic diseases and cancer . Such changes are likely to be attributable to urbanization and changes in lifestyle leading to the increases in cardiovascular risk factors such as hypertension, diabetes and obesity .
For obesity in Thailand, recent data from a series of Thai National Health Examination Survey (NHES) I-III, 1991-2004 showed that the prevalence of obesity had been increasing in all age groups. In older people, about one-third of Thai adults age =60 years were obese (using Asian criteria of BMI = 25 kg/m2). A reverse association between obesity and mortality among older persons had been reported from several studies in the western countries and China . The risk of all-cause mortality increased in the low BMI group and decreased in the middle BMI group and increased again in the obesity group especially for BMI = 35 kg/m2; however, such relationship had never been investigated in Thai population. To address the question, using mortality data from a national representative population-based data, this study aimed to examine the relationship of body mass index with all-cause mortality in older persons.
The present study focused on older persons; subjects aged 60 years and older were included in the analysis (n = 19372). The records of the interviewed individuals had been linked using a unique personal identifier (not all records had personal identifiers) to 2004-2007 death records from vital registration, which had per cent completeness greater than 90 [26,27]. According to the personal identifier completion rate, only 17504 from the total number of older persons (90.4%) could be used to link to vital registration. From this linkage, older persons who died from all causes, except accidents and assault (57 cases), and those without information on health risk behaviours were included. The final number of subjects left in this analysis was 15997 or 82.6% of the total number of older persons.
Among 15997 older persons, 7742 (48.4%) were male and 8255 (51.6%) were female. According to BMI, 16.3% of male and 13.6% of female had BMI less than 18.5 kg/m2, 43.8% of male and 34.0% of female had BMI between 18.5 to 22.9 kg/m2, 17.5% of both male and female had BMI between 23.0 to 24.9 kg/m2, 13.8% of male and 17.0% of female had BMI between 25.0 to 27.4 kg/m2, 5.8% of male and 9.5% of female had BMI between 27.5 to 29.9 kg/m2, 2.6% of male and 7.0% of female had BMI between 30.0 to 34.9 kg/m2. There were only 0.3% of older men and 1.3% of older women whose BMI were 35.0 kg/m2 or more. Distributions of several factors including demo-social and health risk factors . Older people, both male and female, in the higher BMI categories were likely to have younger age, more co-morbidity of diabetes, hypertension, hypercholesterolemia, less smokers, more physically inactive. Those with higher BMI were also had higher education level and resided in urban area.
Age-adjusted all-cause mortality rate by BMI and other potential health risks
During the mean follow-up time of 3.8 years (60545.7 person-years), 1575 subjects (936 men and 639 women) died (9.9%). Median survival time among those who died was 2.25 years (95% confidence interval [CI], 2.12-2.37) and 2.31 years (95% CI, 2.14-2.43) for men and women respectively.
There was evidence of the association between BMI and all-cause mortality. A flat U-shaped associations with the highest risk of death in the lowest and the highest categories of BMI (<18.5 kg/m2 and = 35.0 kg/m2, respectively) was observed in older men.
This is the first population-based and prospective study on BMI and survival among the older people in Thailand. This study takes an advantage of the linkages between two potential sources of data, NHES III and vital registration. The results show evidences of higher mortality rates in people who are underweight, compared to normal weight persons with a higher magnitude in men compared to women. Being overweight or obese appears to have different effects by gender as lower risk of mortality were observed in women but not in men.
The results of this study support the obesity paradox phenomenon in older Thai people, especially in women. It shows that being underweight is a strong predictor of mortality in both men and women, while being obese is a protective factor of mortality in the older women. Improvement in quality of mortality data and further investigation to confirm such association are needed in this population.
Credits: Patama Vapattanawong,Wichai Aekplakorn,Uthaithip Rakchanyaban,Pramote Prasartkul, and Yawarat Porapakkham.
More Information:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2964629/?tool=pubmed