[Study on the risk factors of hypertension among rural residents in mid-west areas of Shandong province, using the classification tree analysis methodology].

OBJECTIVE: To explore the risk factors of hypertension and risk population for adults aged > or = 25 in the mid-western rural areas of Shandong province and to provide evidence for development of intervention measure. METHODS: Subjects aged > or = 25 were selected by multi-stage stratified random sampling method. All participants were interviewed with a standard questionnaire and physically examined on height, weight, waist circumference, blood pressure and fasting plasma glucose (FPG). Classification tree analysis was employed to determine the risk factors of hypertension and high risk populations related to it. RESULTS: The major risk factors of hypertension would include age, abdominal obesity, overweight or obesity, family history and high blood sugar. The major populations at high risk would include populations as: a) being elderly, b) at middle-age but with: high blood sugar or with abdominal obesity/overweight, or with family history, c) people at middle-age but with family history and abdominal obesity. Through classification tree analysis, sensitivity, specificity and overall correct rates were 71.87%, 66.38% and 68.79%, respectively on 'learning sample' while 70.70%, 65.84% and 67.97% respectively on 'testing sample'. CONCLUSION: Efforts on both weight and blood sugar reduction were common prevention measures for general population. Different kinds of prevention and control measures should be taken according to different risk factors existed in the targeted high-risk population of hypertension. Community-based prevention and control for hypertension measures should be integrated when targeting the population at high risk.

[Application of 'waist circumference cutoff point' in screening diabetes mellitus among rural residents in mid-western area of Shandong Province, China].

OBJECTIVE: To determine the value and the optimal cutoff point of waist circumference (WC) in screening diabetes mellitus (DM) and to provide evidence for DM prevention and identifying population at risk in mid-western rural areas of Shandong province. METHODS: A sample consisting 16 341 rural residents was selected and studied. All participants were physically examined on height, weight, WC and fasting plasma glucose (FPG). Oral glucose tolerance test (OGTT) was performed for subjects with FPG valued from 6.1 to 7.0 mmol/L. DM was defined according to the criteria set by WHO in 1999. Area under the curve (AUC), sensitivity, specificity and Youden index were computed based on the receiver operating characteristic (ROC) curve analysis. Optimal cutoff point was determined by the maximum of Youden index. RESULTS: The prevalence rates of DM for males and females increased along with the rise of WC (trend test chi2 = 72.01, 122.65, P < 0.01). It appeared significantly higher in those with WC > or = 85 cm in females and > or = 80 cm in males, with those WC < 85 cm for females and < 80 cm for males, in particular. AUCs were 0.639 and 0.655 for males and females respectively and both had significant differences (t = 7.22, 11.07, P < 0.01). However, the AUCs did not show significant difference (t = 0.70, P > 0.05) between males and females. The Youden index reached maximum when WC approached 85 cm for females (24.90%) and 80 cm for males (24.39%). The sensitivity and specificity were 58.04% and 66.86% for males, and 67.08% and 57.31% for females. CONCLUSION: WC seemed to be an effective indicator for screening the DM. The optimal cutoff point of WC would be 85 cm for females and 80 cm for males in screening DM and defining the population at risk in this area.