title: B-Vitamin Serum Concentrations Predicting Long-Term Overall and Stroke-Free Survival after Carotid Endarterectomy.
abstract: BACKGROUND
  Both deficiency and, according to recent reports, excess of vitamin B12 (B12) are associated with increased mortality. Thus, it is difficult to estimate the effect of B12 on overall survival, which also depends on folate (FA) in homocysteine lowering. This study aimed to assess FA and B12 serum concentrations associated with long-term survival of vascular surgery patients by means of a prognostic index (PI).
  
  
  METHODS
  This single-center, prospective cohort study comprised 485 consecutive carotid surgery patients. B-vitamin baseline concentrations of B12 and FA were used to compute a PI for postoperative overall survival from January 2003 to January 2012 (mean observation period 102.3 months).
  
  
  RESULTS
  Increasing B12 serum concentrations showed a nonlinear association with overall survival (P = .033). A B vitamin-based PI significantly predicted overall (hazard ratio [HR] per standard deviation = 1.97, confidence interval [CI] 1.37-2.82; P < .001), cardiovascular (HR = 3.03, CI 1.78-5.14; P < .001), and stroke-free survival (HR = 2.20, CI 1.22-3.98; P = .009), and revealed that the highest adverse event-free survival was predicted by high FA (16.3 ± 12.9 ng/mL) but only moderate B12 (360.3 ± 156.0 pmol/L) baseline concentrations.
  
  
  CONCLUSIONS
  Prediction of increased long-term overall, cardiovascular, and stroke-free survival is based on high FA but only moderate B12 serum concentrations. Excessive B12 concentrations might harbor a potential harm and are no requisite for low homocysteine concentrations. The association between B vitamins and survival might serve either as a tool for risk stratification or, if causative, as effective therapy, if optimal dosing of B vitamins is provided and on-treatment concentrations, including homocysteine and renal functions, are closely monitored.
authors.affiliation: Department of Vascular and Endovascular Surgery, Wilhelminenspital, Vienna, Austria. Electronic address: nduschek@me.com.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Duschek
authors.affiliation: Department of Vascular and Endovascular Surgery, Wilhelminenspital, Vienna, Austria.
authors.forename: Jelena
authors.initials: J
authors.lastname: Basic
authors.affiliation: Department of Vascular and Endovascular Surgery, Wilhelminenspital, Vienna, Austria.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Falkensammer
authors.affiliation: Department of Vascular and Endovascular Surgery, Wilhelminenspital, Vienna, Austria.
authors.forename: Fadi
authors.initials: F
authors.lastname: Taher
authors.affiliation: Department of Vascular and Endovascular Surgery, Wilhelminenspital, Vienna, Austria.
authors.forename: Afshin
authors.initials: A
authors.lastname: Assadian
mesh_terms: D000368:Aged; D001317:Austria; D015415:Biomarkers / Q000097:blood; D016893:Carotid Stenosis / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000601:surgery*; D018572:Disease-Free Survival; D016894:Endarterectomy, Carotid / Q000009:adverse effects / Q000401:mortality; D005260:Female; D005492:Folic Acid / Q000009:adverse effects / Q000097:blood*; D005494:Folic Acid Deficiency / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000401:mortality; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017711:Nonlinear Dynamics; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis / Q000209:etiology / Q000401:mortality / Q000517:prevention & control*; D013997:Time Factors; D016896:Treatment Outcome; D014805:Vitamin B 12 / Q000009:adverse effects / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000401:mortality
chemical_list: D015415:Biomarkers; D005492:Folic Acid; D014805:Vitamin B 12
keywords: Vitamin B12; carotid surgery; folate; homocysteine; risk factor