Epidemiology Of Obesity And Its Relation To Non-communicable Chronic Diseases In Adults Living In The Rural Areas Of Gansu

BackgroundObesity is not only an important risk factor for a variety of non-communicable chronic diseases (NCDs), but also is important diseases resulted in premature death, disability, and affected the living quality. Obesity is a worldwide problem with a globally increasing prevalence. The prevalence of obesity has reached epidemic proportions and is expected to rise further in the developing countries, especially in those emerging developing countries with rapid economic development and significant transition in the dietary patterns. Because risk factors of obesity could vary due to time, place, personal behavior, genetic factors and the others, and now we can not have effective prevention and intervention measures to curb the rapid growth of obesity so that this disease is still an ancient and young research topic. Therefore, to analyze the epidemic trend and strengthen the study on the etiology of obesity become a particularly important to prevent and control obesity.ObjectiveBy investigated the distribution characteristics and changed trend of indicators related to adult’s obesity in the rural areas, we can know the epidemic characteristics and changing trend of different types of obesity to provide the basic evidence for establishing obesity-related intervention strategies.Through the qualitative and quantitative analysis of the major risk factors for the different types of obesity, we can determine the risk factors and protective factors related to different types of obesity during quick transiting period of the dietary pattern which could provide scientific evidence for the development of obesity prevention and control strategies.By analyzing the relationship between general obesity and central obesity measures and their association with NCDs, we can evaluate which measure related to obesity would be a better predictor of NCD risk which would be a very useful scientific basis used for the long-term plan to develop obesity prevention and control.MethodsData were from a cross-sectional study involving 3000 adults living in rural areas of Gansu Province from "The Chinese Non-Communicable Chronic Disease and Risk Factor Surveillance project". Using the multi-stage sampling and cluster randomly sampling methods, the representative samples over the age of 18 were sampled as an subject from the National surveillance points of NCDs in Gansu Province. The survey includes questionnaires, physical examination, laboratory tests (blood lipids profiles, blood glucose, glucose tolerance test, etc.) and dietary surveys. According to the cut-off point on overweight and obesity definition of the Chinese Working Group on Obesity for adults and the definition of World Health Organization, the prevalence of overweight and obesity and central obesity was estimated. Descriptive epidemiological methods were used to analyze the epidemiological characteristics and trends of of general and central obesity; the cross-section and case-control studies were used to evaluate the association of the major risk factors of the general obesity and central obesity with related NCDs and the clustering of major risk factors of NCDs in adults.Results1. The basic characteristics on the surveyed samples:A total of 3,000 adults (1355 male and 1645 female) with aged 18 and over living in the sampling sites over 6 months were surveyed. The averaged age were 46.3 ± 14.2 year. Energy intake in men and women achieved the recommended intake and protein intake accounted for 90% of the recommended intake, the proportion of energy provided by protein, fat and carbohydrates were 10.3%,28.1%, and 61.6%, respectively, and there was no significant difference between men and women. Calcium deficiency was serous problem and the intake met 43.3% of the recommended intake. Vitamin A and vitamin B1 intakes were in slightly inadequate status.2. The epidemic characteristics of obesity:The average body mass indexes (BMI) in total population, men and women were 23.91 ± 3.39 kg/m2,23.97 ± 3.41 kg/m2 and 23.86 ± 3.38 kg/m2; respectively; and mean waist circumference (WC) was 80.49 ± 9.53 cm,82.59 ± 9.52 cm, and 78.76 ± 9.20 cm, respectively.According to the cut-off points on BMI of China and WHO classification criteria, the standardized overweight and obesity rates were respectively 33.1% vs 29.8% and 11.0% vs 4.4%; and central obesity prevalence were 40.6% and 28.2%, respectively.Based on the China’s classification criteria on BMI, the prevalence of overweight or obesity and central obesity between men and women was no significant difference (P> 0.05). However, the overweight rate in men trended higher than that of women (P > 0.05), and central obesity prevalence in women was significantly higher than that of men (P< 0.001) according to the WHO standard.There was different in changed trend on BMI and WC with age in men and woman.. BMI and WC were relatively higher in men over the aged 18 years and did not changed significantly with age, and became to decline after the age of 50 years; but BMI and WC were increased with age in women, and the increasing trend was slow down after the age of 50 years.The positive correlation was observed between BMI and WC in men with education and income levels (P< 0.001), the higher family income and education levels, the higher prevalence of obesity.. In women, the risk of obesity and central obesity trended to slightly lower in the group with higher education level than in the group with lower education level, but there was not statistically significant (P> 0.05).3. Major risk factor for obesity:Present study analyzed the relationship of demographic characteristics, smoking, alcohol consumption, physical activity, and dietary habits and other aspects with risk of obesity, and a variety of possible confounding factors were adjusted at the same time.Demographic characteristics:Older age, married and had a history of marriage were the risk factors for obesity and central obesity in women. With the increase in BMI and WC, obesity risk was also increased. The group aged 45-59 years and the group aged 60 years and over had 1.7 and 2.4 time higher risk suffered from obesity than that of the group aged 28-44 years. Compared to the unmarried group, the married group and the group how had married experience respectively had 3.8 times and 3.6 time risk suffered from obesity.Smoking:the younger beginning to daily smoking age, the larger daily smoking, the longer smoking lasted, and the more to smoking, the lower for general obesity and central obesity. Starting daily smokers age under 30 years, more than 20 cigarettes per day, and more than 90 pack per year would have a lower risk for obesity (general obesity and central obesity), and OR values were 0.66～0.69,0.72～0.72,0.49～ 0.65,0.76～0.78 respectively. Drinking:drinking, especially heavy drinking with high frequency was independent risk factors for obesity in men. Drinking three times or more per week, or heavy drinking once a week or more, would have 1.8 and 2.1 time,2.15 and 2.20 time risk suffered from general obesity and central obesity.Physical activity:The more occupational physical activity intensity and the longer duration would be a protective factor for obesity, especially for central obesity. Occupational daily physical activity with 84.39 MET-h/dk/yr or more had a lower risk of overweight and obesity with 0.82 time (95% CI:0.63～1.03) and 0.79 time (95%CI: 0.63～1.00) compared with the other two groups with occupational physical activity less than 18.86 MET-h/dk/yr. Stationary state behavior with long duration could significantly increase the risk of central obesity in male. The group who had stationary state behavior more than 6 hours per day should had 1.76 (95%CI: 1.02-3.02) time risk suffered from central obesity compared with the group who had stationary state behavior less than 2 hours per day.Plant foods:cereals and tuber crops were independent protective factor for obesity. The groups eaten>450 g/d cereals and>100g/d tuber crops could decrease the risk suffered from obesity and central obesity, the OR values were respectively 0.76 and 0.67,0.66 and 0.72. Vegetable, fruit, soy product intakes was an independent risk factor for general obesity, large amounts of vegetable, fruit, and soy product intakes might increase the risk of central obesity which would be related to the use of a large number of animal and vegetable oils in the cooking process. The correlation analysis showed that the vegetable intakes were significantly positively correlated with pork, poultry, vegetable oils and animal fat, total fat and total energy intakes (P< 0.001). Taking more than 150g/d vegetables,28.57g/d fruits or 3.33g/d soybean products significantly increased the risk of obesity, OR values were respectively 1.44, 1.80 and 1.76; after adjusted the other confounding factors, the OR value only slightly decreased to 1.29,1.70 and 1.57. After adjusted the confounding factors, the intake of vegetables more than 450g/d increased the risk of central obesity (OR= 1.24,95% CI = 0.98-1.57); intake of soy products more than 3.33g/d or more increased 1.33 time risk of central obesity.Animal foods:Red meats and poultry were the risk factors of obesity, however, milk and its products had a trend to reduce risk of obesity in women. The group with intake of red meat 100g/d or more had higher risk (1.37 times 1.48 times) suffered from obesity and central obesity compared with the lowest intake group; the intake of poultry 14.29g/d or more would have 1.32 and 1.69 time risk suffered from obesity and central obesity respectively.4. Obesity indicators and related NCDsFirst, the association of BMI with obesity-related NCD indicators and their prevalence was analyzed. When BMI level were within 20 to 21kg/m2, the related NCD indicators and their prevalence was in the lowest. When the BMI level was in excess of this range, SBP, DBP, serum glucose, TG levels were elevated with BMI increase in men and women. But HDL-C level was decreased with BMI increase. Hypertension, diabetes, low high-density lipoprotein hyperlipidemia and hypertriglyceridemia prevalence had a same trend.Then, the association of obesity populations with NCD risk was analyzed. Based on Normal BMI and WC as the reference group, BMI and WC levels had positive correlation with obesity-related NCD indicators and their prevalence except HDL-C. Regardless of whether at the same level of BMI or different BMI level, the group with higher WC had higher rick suffered from NCDs than that of the lower WC group; within the same or different levels of WC, the higher BMI group had higher rick suffered from NCDs than that of the lower BMI group. When the obesity combined with central obesity, the risk suffered from a variety of obesity-related NCDs was increased significantly. When obesity combined with higher waist II, the risk suffered from hypertension, diabetes, low HDL-C and high TG was respectively increased to 9.27,3.41,2.76 and 8.99 times.Final, the association of clustering risk of obesity-related NCDs with different measures of obesity was compared using two ways. BMI and WC were independently positively correlated with the clustering risk of obesity-related NCDs, and the clustering risk of obesity-related NCDs was sharply increased with the rise of BMI and waist circumference. The correlation on clustering risk of BMI and NCDs was higher in men than in women, but the impact of WC was larger than that of BMI in women.If only a simple obesity, the clustering rates of NCDs were respectively 71.4% and 37.7% in men and women, the clustering risk of NCDs increased 2.64 times compared with the normal weight group; when suffered from central obesity, the clustering rates of NCDs were respectively 33.3% and 30.0% in men and women, the clustering risk of NCDs increased 2.38 times compared with the normal weight group; when obesity combined with severe central obesity, the clustering rates of NCDs were respectively 84.7% and 71.9% in men and women, the clustering risk of NCDs increased 15.26 times. When using BMI, WC, BMI combined WC predicted ROC curve of obesity-related NCD clustering risk, the areas under ROC curve, sensitivity and specificity using BMI combined WC were all greater than that of using single BMI or WC.Conclusions1. The prevalence of overweight and obesity in adults living in rural areas of Gansu, especially the abdominal obesity situation, is very serious problem and has an increasing tendency in the younger age group. The effective intervention measures at population or community-based levels need to be urgently implemented to curb the severe trends in obese prevalence.2. Education, socio-economic factors could have significant impact on the prevalence of overweight and obesity in adults. The higher level of education and the better income were the important risk factors for overweight and obesity in male living in the economically backward rural areas. The general populations should be Propagandized and guided to have an idea on reasonable consumption in such areas..3. At the present study, smoking was related to the lower risk for obesity in male, however, smoking could not be taken as a way to control body weight. It should be more alert that male smokers would be the target population for NCD intervention if they had obesity.4. Univariate analysis showed that the eaten more tuber crops and cereals could reduce overweight and obesity risk, but higher intake of vegetables was important risk factors for obesity in local areas, even though the obesity risk was decreased slightly after adjusted energy intake and other confounding factors, the effect was still very significant, which would be related to the use of a large number of animal and vegetable oils in the cooking process. The present study indicated that practice on vegetable cooking fried with a plenty of animal and vegetable oils at home should be changed and the intake of tuber crops should be increased which would be useful for prevent and control obesity.5. Significantly independently associations were observed between BMI and WC indicators with obesity-related NCDs. Different combinations of BMI and WC would be better to predict NCD risk. We recommended to simultaneously use both BMI and WC to assess obesity-related NCD risk; because general obesity consolidated central obesity significantly increased the clustering risk on NCDs, BMI combined WC were recommended to better evaluate the clustering risk on related NCDs compared with the single BMI or WC.