title: Is weak association between cigarette smoking and cardiovascular disease mortality observed in Japan explained by low total cholesterol? NIPPON DATA80.
abstract: BACKGROUND
  An international comparison has indicated that the association between smoking and cardiovascular disease (CVD) differs according to total cholesterol (TC) levels. However, little has been published about the relationship between smoking and CVD mortality among populations with various cholesterol levels.
  
  
  METHODS
  We calculated the adjusted relative hazard (RH) of smoking for CVD mortality among 8912 Japanese individuals without a history of stroke or heart disease, who were separated according to TC levels of >or=5.40, 4.81-5.39, 4.26-4.80 and <4.25 mmol/l into groups Q4, Q3, Q2 and Q1, respectively. The P-values for multiple interactions between TC and smoking status for CVD mortality were calculated using TC as a continuous variable, dichotomized smoking status (never vs current), and by including cross-product terms in the regression models.
  
  
  RESULTS
  After 19 years of follow-up, 313 men and 291 women died of CVD. The RH of CVD mortality among men who currently smoked compared with those who never smoked was increased with higher TC (RH = 2.36 in Q4) and decreased in those with lower TC (RH = 0.85 in Q1) (interaction, P < 0.01). The profiles for coronary heart disease (CHD) mortality and ischaemic CVD (composite endpoint of CHD and ischaemic stroke) in men and for ischaemic CVD mortality in women were identical. The interaction might be explained by a biological mechanism and by frailty of those who have never smoked with lower TC.
  
  
  CONCLUSIONS
  Counteractive measures should be implemented against smoking targeted towards Japanese with elevated TC levels.
authors.affiliation: Department of Health Science, Shiga University of Medical Science, Shiga, Japan. ahozawa@belle.shiga-med.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hozawa
authors.forename: Tomonori
authors.initials: T
authors.lastname: Okamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Kadowaki
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Murakami
authors.forename: Koshi
authors.initials: K
authors.lastname: Nakamura
authors.forename: Takehito
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Kita
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Akira
authors.initials: A
authors.lastname: Okayama
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology* / Q000401:mortality; D002423:Cause of Death; D002784:Cholesterol / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects* / Q000097:blood; D016540:Smoking Cessation
chemical_list: D002784:Cholesterol