title: Relationship of predominantly mild current smoking to out-of-office blood pressure in a community sample in Africa.
abstract: OBJECTIVE
  As the impact of mild smoking on blood pressure (BP) is uncertain, we assessed the relationship between predominantly mild current smoking and out-of-office BP and the effect of angiotensin-converting enzyme (ACE) genotype on this relationship in a community sample of black African ancestry.
  
  
  METHODS
  In 689 participants randomly recruited from an urban, developing community of black African descent, we assessed smoking habits, out-of-office (24-h), and in-office conventional and central (applanation tonometry) BP, and ACE insertion (I)/deletion (D) variant genotype.
  
  
  RESULTS
  A total of 14.5% (n=100) were current smokers, the majority being mild (72%, 7.4 ± 4.6 cigarettes/day). Despite current smokers having only modest increases in in-office (P<0.05) and similar central aortic BP values as nonsmokers, current smokers had higher unadjusted (P<0.005-P<0.0005) and multivariate adjusted 24-h SBP/DBP (mmHg; smokers=123 ± 15/76 ± 10; nonsmokers=118 ± 14/72 ± 9; P<0.005-P<0.0005) than nonsmokers, effects that were DD genotype-dependent (P<0.005 for interaction) and replicated in sex-specific groups, nondrinkers, and in overweight and obese. Current smoking was second only to age in the quantitative impact on 24-h DBP. Smoking 4.6 cigarettes per day (one standard deviation) translated into increases in 24-h SBP (mmHg) of 2.12 [confidence interval (CI)=1.77-2.47] in all participants and 3.62 (CI=3.13-4.12) in participants with the DD genotype. The risk of uncontrolled 24-h BP was increased in smokers as compared to nonsmokers (adjusted odds ratio=1.87, CI=1.02-3.41, P<0.05), an effect that was enhanced in participants with the DD genotype (adjusted odds ratio=4.01, CI=1.59-10.09, P<0.005).
  
  
  CONCLUSIONS
  Mild current smoking is independently associated with an appreciable proportion of out-of-office BP in a black African community, an effect that is ACE genotype-dependent.
authors.affiliation: Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Angela J
authors.initials: AJ
authors.lastname: Woodiwiss
authors.forename: Leon
authors.initials: L
authors.lastname: Scott
authors.forename: Muzi J
authors.initials: MJ
authors.lastname: Maseko
authors.forename: Olebogeng H I
authors.initials: OH
authors.lastname: Majane
authors.forename: Leanda
authors.initials: L
authors.lastname: Vengethasamy
authors.forename: Michelle
authors.initials: M
authors.lastname: Redelinghuys
authors.forename: Pinhas
authors.initials: P
authors.lastname: Sareli
authors.forename: Gavin R
authors.initials: GR
authors.lastname: Norton
mesh_terms: D000328:Adult; D000349:Africa; D001794:Blood Pressure; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D007703:Peptidyl-Dipeptidase A / Q000235:genetics; D012907:Smoking / Q000009:adverse effects*
chemical_list: D007703:Peptidyl-Dipeptidase A