Low vitamin B6, and not plasma homocysteine concentration, as risk factor for abdominal aortic aneurysm: A retrospective case–control study
Received 16 October 2006; accepted 8 December 2006.
Background
Hyperhomocysteinemia has been associated with vascular disease in many epidemiologic studies, but only a few have reported on the relation between hyperhomocysteinemia and aneurysms of the abdominal aorta (AAAs). Although these studies showed higher homocysteine concentrations in patients with AAA than in controls, little attention had been given to possible confounding factors. Most patients with AAA are of older age, have an impaired renal function, and have other risk factors for cardiovascular disease. This matched case–control study investigated the relation between homocysteine concentration (before and after methionine loading) and AAA, taking into account possible confounders such as age, sex, and concentrations of creatinine and B vitamins.
Methods
Patients with a history of AAA were recruited from the outpatient clinic; 60% had already undergone surgery for their AAA. They were asked to invite a friend or neighbor to participate as a control subject (age-matched and sex-matched). Concentrations of homocysteine, vitamin B6, vitamin B12, folate, and creatinine were determined in the fasting state, and blood was taken for methylenetetrahydrofolate reductase (MTHFR) mutation analysis. Six hours after oral methionine loading, the postmethionine load homocysteine concentration was determined.
Results
Univariate analysis showed an odds ratio (OR) of 2.2 (95% confidence interval (CI), 0.9 to 5.5) for the risk of AAA for the highest quartile of homocysteine concentration. After adjustment for creatinine, the OR was markedly reduced to 1.24 (95% CI, 0.42 to 3.66), and this risk further attenuated in the multivariate analysis. Univariate analysis of the B vitamins showed an increased risk of AAA for the bottom quartile of vitamin B6 (OR, 3.75; 95% CI, 1.22 to 11.54), which even increased after adjustments. The relative risk associated with the MTHFR 677TT polymorphism was 2.1 (95% CI, 0.9 to 5.3).
Conclusion
Vitamin B6, but not homocysteine, is an independent risk factor for AAA. The role of vitamin B6 in the pathogenesis of AAA needs to be further elucidated.
aDepartment of Endocrinology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
bDepartment of Epidemiology and Biostatistics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
cDepartment of Paediatrics, Laboratory of Paediatrics and Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
dDepartment of Clinical Chemistry and Haematology, St. Elisabeth Hospital, Tilburg, The Netherlands
eDepartment of Internal Medicine, TweeSteden Hospital, Tilburg, The Netherlands
fDepartment of Surgery, TweeSteden Hospital, Tilburg, The Netherlands.
Reprint requests: Martin den Heijer, MD, PhD, Department of Endocrinology (471), Radboud University Nijmegen Medical Centre, PO-Box 9101, 6500 HB Nijmegen, The Netherlands.
This work was supported by the “Stichting Voorziening voor Wetenschappelijk onderzoek,” Tilburg, The Netherlands.
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