title: Rotating night shift work and disparate hypertension risk in African-Americans.
abstract: OBJECTIVE
  Hypertension disproportionally affects black compared with white Americans, even after accounting for known risk factors. Circadian disruption as encountered by rotating night shift workers has been associated with an increased risk for hypertension. Because blood pressure responds differently to sleep alterations in blacks compared with whites, we hypothesized that rotating night shift work may be a stronger risk factor for hypertension among blacks.
  
  
  METHODS
  We prospectively examined the association between rotating night shift work and the risk of hypertension in 1510 black and 94 142 white female participants of the Nurses' Health Study II who were nonhypertensive at baseline in 1991. We used Cox proportional hazards models to control for potential confounders.
  
  
  RESULTS
  During 16 years of follow-up (1991-2007), we identified 580 incident cases of hypertension in blacks and 23 360 cases in whites. In blacks, the multivariable hazard ratio for incident hypertension among women who worked rotating night shift for more than 12 months in the previous 2 years was 1.81 [95% confidence interval (CI) 1.14-2.87], compared with those working none. By contrast, in whites, we observed no increase in risk (hazard ratio 0.99, 95% CI 0.93-1.06). The association between shift work and hypertension varied significantly by race (P interaction = 0.01). In secondary analyses, the multivariable hazard ratio for incident hypertension in black women who ever performed rotating night shift work was 1.46 (95% CI 1.07-1.99), compared with those never working rotating night shifts. In whites, there was no increase in risk (hazard ratio 0.97, 95% CI 0.93-1.01) (P interaction < 0.01).
  
  
  CONCLUSIONS
  Rotating night shift work is independently associated with an increased risk of hypertension in blacks but not in whites.
authors: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA. slieu@partners.org
authors: Sung J
authors: SJ
authors: Lieu
authors: Gary C
authors: GC
authors: Curhan
authors: Eva S
authors: ES
authors: Schernhammer
authors: John P
authors: JP
authors: Forman
mesh_terms: D000328:Adult; D044383:Black People; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors; D014940:Work Schedule Tolerance; D001741:Black or African American