title: [Risk factors of hypertension and its interaction in population in Liuyang, Hunan Province--a case-control study].
abstract: OBJECTIVE
  To explore the risk factors of hypertension in a rural area in Hunan Province.
  
  
  METHODS
  A population-based case-control study was used. In the first step, three villages in Liuyang were selected by stratified cluster random sampling method and all local residents were investigated by face-to-face interview. Then some patients with hypertension found in the first step were randomly sampled to case group, while healthy adults with no hypertension and in similar compositions of gender and age with the case group were selected to control group. Independent effects of risk factors were analyzed by Logistic regression, and the interaction among risk factors was analyzed by using an additive effects model.
  
  
  RESULTS
  Effective investigation data for 218 patients in the case group and 182 healthy people in the control group were used. The main risk factors of hypertension in rural areas of Liuyang, Hunan province were overweight (OR = 4.048), obesity (OR = 6.476), central obesity (OR = 2.632), and family history of hypertension (OR = 2.527). After adjusting some confounding factors, significant positive interaction were observed between family history, overweight/obesity and central obesity; the relative excess risk of interaction (RERI), attributable proportion of interaction (API), and the interaction index (S) were 3.268 vs 0.569, 48.365% vs 14.880%, and 2.313 vs 1.249, respectively.
  
  
  CONCLUSIONS
  The cause of hypertension in rural areas of Liuyang, Hunan province was closely related with overweight, obesity, central obesity and family hypertension history. There were positive interactions between family history and overweight/obesity and central obesity in the causes of hypertension.
authors.affiliation: Department of Epidemiology, School of Public Health, Central South University, Changsha 410008, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Hongzhuan
authors.initials: H
authors.lastname: Tan
authors.forename: Peng
authors.initials: P
authors.lastname: Huang
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.forename: Siyu
authors.initials: S
authors.lastname: Zhang
authors.forename: Ting
authors.initials: T
authors.lastname: Chen
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D005192:Family Health; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology* / Q000517:prevention & control; D016015:Logistic Models; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D015995:Prevalence; D012307:Risk Factors; D012424:Rural Population; D012494:Sampling Studies