title: Body mass index, blood pressure, and mortality from stroke: a nationally representative prospective study of 212,000 Chinese men.
abstract: OBJECTIVE
  Despite previous investigations, substantial uncertainty remains about the relation between body mass index (BMI) and stroke, especially in populations with a relatively low BMI but a high stroke rate.
  
  
  METHODS
  A nationally representative prospective study of mortality included 212,000 Chinese men 40 to 79 years old without known cardiovascular disease in 1990 to 1991 who were followed up for 10 years. Standardized hazard ratios were calculated for stroke mortality by baseline systolic blood pressure (SBP) and BMI.
  
  
  RESULTS
  Mean SBP and BMI were 124 mm Hg and 21.7 kg/m(2), respectively. During 10 years of follow-up, 5766 stroke deaths were recorded. There were strong, positive relations between BMI and SBP and between SBP and stroke mortality, with a 3-mm Hg higher baseline SBP associated with a 5.6% (95% CI, 5.3% to 6.0%; P<0.00001) higher stroke mortality. The association between BMI and stroke mortality was, however, not linear, with the hazard increasing substantially only for BMI >25 kg/m(2) (P<0.001 for nonlinearity). Approximately 90% of men had a baseline BMI <25 kg/m(2), and among them, BMI was not associated with stroke mortality despite its strong association with BP (which continued to a BMI <18 kg/m(2)). The relation with BMI was similar for ischemic and hemorrhagic stroke but appeared to be steeper among lifelong nonsmokers than among current smokers (P=0.01 for difference between slopes) despite similarly positive relations between BMI and SBP and between SBP and stroke risk in both smoking categories.
  
  
  CONCLUSIONS
  High BMI was strongly associated with increased stroke mortality only among men who were overweight or obese.
authors.affiliation: Disease Surveillance Points Central Office, Chinese Center for Disease Control, Beijing, People's Republic of China.
authors.forename: Maigeng
authors.initials: M
authors.lastname: Zhou
authors.forename: Alison
authors.initials: A
authors.lastname: Offer
authors.forename: Gonghuan
authors.initials: G
authors.lastname: Yang
authors.forename: Margaret
authors.initials: M
authors.lastname: Smith
authors.forename: Gei
authors.initials: G
authors.lastname: Hui
authors.forename: Gary
authors.initials: G
authors.lastname: Whitlock
authors.forename: Rory
authors.initials: R
authors.lastname: Collins
authors.forename: Zhengjing
authors.initials: Z
authors.lastname: Huang
authors.forename: Richard
authors.initials: R
authors.lastname: Peto
authors.forename: Zhengming
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D015992:Body Mass Index; D002681:China / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D050177:Overweight / Q000150:complications; D011446:Prospective Studies; D020521:Stroke / Q000150:complications / Q000401:mortality* / Q000503:physiopathology*; D011795:Surveys and Questionnaires