title: Elevated hemoglobin A1c is associated with readmission but not complications.
abstract: BACKGROUND
  studies have shown that elevated hemoglobin A1c levels are associated with worse short-term outcomes after cardiac surgery. However, the effect on readmission has not been studied. The primary purpose of this study was to determine the independent effect of hemoglobin A1c level on the readmission rate after cardiac surgery. The secondary purpose was assess its effect on complications and mortality.
  
  
  METHODS
  consecutive patients undergoing coronary artery bypass surgery between April 2007 and August 2010 were divided into 3 groups based on preoperative hemoglobin A1c levels. Outcomes were controlled for demographics, comorbidities, and surgery.
  
  
  RESULTS
  300 (34%) patients had normal hemoglobin A1c levels (<6.0%), 305 (35%) had mildly elevated levels (6.0%-6.9%), and 275 (31%) had markedly elevated levels (≥ 7.0%). Postoperative glucose levels were similar among all 3 hemoglobin A1c groups. Compared to patients with normal hemoglobin A1c levels, those with higher levels were more likely to be readmitted: adjusted odds ratio 2.091 (95% confidence interval: 1.074-4.069, p = 0.036) for hemoglobin A1c 6.1%-6.9%; and adjusted odds ratio 2.089 (95% confidence interval: 1.050-4.155, p = 0.036) for hemoglobin A1c ≥ 7.0. Overall, 381 (43%) patients suffered complications, and hemoglobin A1c levels were similar in those with and without complications (6.8% ± 1.6% vs. 6.9% ± 1.7%, p = 0.837). Mortality was equivalent in all 3 hemoglobin A1c groups.
  
  
  CONCLUSIONS
  elevated preoperative hemoglobin A1c levels are associated with an increased risk of readmission but not complications.
authors.affiliation: Department of Anesthesiology, Mercy St. Vincent Medical Center, Toledo, OH, USA Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA engoren@pol.net.
authors.forename: Milo
authors.initials: M
authors.lastname: Engoren
authors.affiliation: Division of Cardiothoracic Surgery, University of Toledo College of Medicine Toledo, OH, USA Department of Cardiac and Thoracic Surgery, Mercy St. Vincent Medical Center, Toledo, OH, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Schwann
authors.affiliation: Outcomes Research Unit, Department of Internal Medicine, American University of Beirut, Beirut, Lebanon.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Habib
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D015897:Comorbidity; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000401:mortality; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010359:Patient Readmission; D011183:Postoperative Complications / Q000097:blood* / Q000401:mortality; D057234:Preoperative Period; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human
keywords: Coronary artery bypass; Diabetes mellitu; Hemoglobin A; Patient readmission; Postoperative complications; glycosylated