title: A New Zealand linkage study examining the associations between A1C concentration and mortality.
abstract: OBJECTIVE
  To examine associations between A1C concentration and mortality in a New Zealand population.
  
  
  METHODS
  During a Hepatitis Foundation screening campaign for hepatitis B (1999-2001), participants were offered A1C testing. The participants were anonymously linked to the national mortality collection to 31 December 2004. Hazard ratios (HRs) and 95% CIs adjusted for age, ethnicity, smoking, and sex were estimated using Cox regression.
  
  
  RESULTS
  There were 47,904 participants (71% Mâori, 12% Pacific, 5% Asian, and 12% other). A1C measurements were categorized as <4.0% (n = 142), 4.0 to <5.0% (reference category; n = 12,867), 5.0 to <6.0% (n = 30,222), 6.0 to <7.0% (n = 2,669), and >or=7.0% (n = 1,596); there were also 408 participants with a previous diabetes diagnosis. During the follow-up period, 815 individuals died. In those without a prior diabetes diagnosis, there were steadily increasing HRs from the A1C reference category to the highest category (>or=7.0%; HR 2.36 [95% CI 1.72-3.25]). As well as all-cause mortality, A1C was associated with mortality from diseases of the circulatory system; endocrine, nutritional, metabolic, and immunity disorders; and other and unknown causes. Mortality was also elevated in those with a prior diabetes diagnosis (5.19 [3.67-7.35]), but this was only partially explained by their elevated A1C levels.
  
  
  CONCLUSIONS
  This is the largest study to date of A1C levels and subsequent mortality risk. It confirms previous findings that A1C levels are strongly associated with subsequent mortality in both men and women without a prior diabetes diagnosis.
authors.affiliation: Centre for Public Health Research, Massey University, Wellington, New Zealand. n.brewer@massey.ac.nz
authors.forename: Naomi
authors.initials: N
authors.lastname: Brewer
authors.forename: Craig S
authors.initials: CS
authors.lastname: Wright
authors.forename: Noémie
authors.initials: N
authors.lastname: Travier
authors.forename: Chris W
authors.initials: CW
authors.lastname: Cunningham
authors.forename: John
authors.initials: J
authors.lastname: Hornell
authors.forename: Neil
authors.initials: N
authors.lastname: Pearce
authors.forename: Mona
authors.initials: M
authors.lastname: Jeffreys
mesh_terms: D002423:Cause of Death; D003920:Diabetes Mellitus / Q000401:mortality; D005006:Ethnicity; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006306:Health Surveys; D006801:Humans; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D015203:Reproducibility of Results; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology
chemical_list: D006442:Glycated Hemoglobin