title: Hemoglobin A1clevels and risk of sudden cardiac death: A nested case-control study.
abstract: Sudden cardiac death (SCD) is often the first manifestation of cardiovascular disease (CVD), and preventive strategies within this broad population are lacking. Patients with diabetes represent a high-risk subgroup, but few data exist regarding whether measures of glycemia mediate risk and/or add to SCD risk stratification.
  
  
  
  The purpose of this study was to examine the association between hemoglobin A1c(HbA1c) and SCD.
  
  
  
  We performed a case-control analysis among individuals enrolled in 6 prospective cohort studies. HbA1clevels were determined for 482 cases of SCD and 914 matched controls. Conditional logistic regression with fixed effects meta-analysis was used for analysis.
  
  
  
  In multivariable models, HbA1clevels were linearly associated with SCD risk over follow-up of 11.3 years (P <.001). Each 1% increment in HbA1cwas associated with a hazard ratio (HR) of 1.32 (95% confidence interval [CI] 1.16-1.50). The magnitude of the association was greater in subjects without vs those with known CVD [HR per 1% increment 1.64 (95% CI 1.31-2.06) vs 1.15 (95% CI 0.99-1.33), P interaction = .009]. In models simultaneously controlling for diabetes status and HbA1c, the association between HbA1cand SCD remained significant (HR 1.29, 95% CI 1.07-1.55, P = .01), whereas the association between diabetes and SCD was attenuated (relative risk 1.21, 95% CI 0.64-2.27, P = .56).
  
  
  
  In these prospective cohorts, HbA1clevels associated with SCD risk, particularly among those without known CVD, even after controlling for diabetes status. These data support the hypothesis that hyperglycemia mediates SCD risk among patients with diabetes.
authors: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Ravi B
authors: RB
authors: Patel
authors: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Center for Arrhythmia Prevention, Brigham and Women's Hospital, Boston, Massachusetts; Division of Preventive Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
authors: M V
authors: MV
authors: Moorthy
authors: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Division of Preventive Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
authors: Stephanie E
authors: SE
authors: Chiuve
authors: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Division of Preventive Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
authors: Aruna D
authors: AD
authors: Pradhan
authors: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Division of Preventive Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
authors: Nancy R
authors: NR
authors: Cook
authors: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Center for Arrhythmia Prevention, Brigham and Women's Hospital, Boston, Massachusetts; Division of Preventive Medicine, Brigham and Women's Hospital, Boston, Massachusetts; Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts. Electronic address: calbert@partners.org.
authors: Christine M
authors: CM
authors: Albert
mesh_terms: D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000032:analysis*; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000503:physiopathology; D016022:Case-Control Studies; D015331:Cohort Studies; D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D003920:Diabetes Mellitus / Q000097:blood* / Q000453:epidemiology / Q000503:physiopathology; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D014481:United States / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D006442:Glycated Hemoglobin
keywords: Diabetes; Epidemiology; Hemoglobin A(1c); Risk factor; Sudden cardiac death