Symptomatic venous thromboembolism in elderly patients following major orthopedic surgery of the lower limb is associated with elevated vitamin B12 serum levels

Background: Elevated vitamin B12 serum levels are associated with systemic inflammation and mortality. Since venous thromboembolism (VTE) is associated with systemic inflammation and mortality as well, we have hypothesized that it is also associated with elevated vitamin B12 serum levels in elderly patients following major orthopedic surgery of the lower limb. Methods: This is a retrospective study. Medical charts of consecutive elderly (≥65. years) patients admitted for rehabilitation following major orthopedic surgery of the lower limb during 2007-2009 were reviewed. The study group included symptomatic VTE patients. The control group included patients in whom VTE was excluded. Demographics, co-morbidities, VTE risk factors, vitamin B12 serum levels, and 1-year mortality were studied. Results: The cohort included 197 elderly patients (median age: 82. years): 140 (71.1%) women and 57 (28.9%) men. Overall, 20 (10.2%) patients had VTE (study group) and in 177 (89.8%) patients VTE was excluded (control group). Vitamin B12 serum levels were higher in the study group compared with the control group (median: 634 vs. 409. pg/dL, p. =0.024). The incidence of elevated vitamin B12 serum levels (≥500. pg/dL) was higher in the study group compared with the control group (odds ratio 3.1, p. =0.031). Elevated vitamin B12 serum levels were associated with VTE (odds ratio 5.3, p. =0.011) and with 1-year mortality (odds ratio 6.6, p. =0.015) independent of demographics, co-morbidities, and VTE risk factors. Conclusions: Symptomatic VTE is associated with elevated vitamin B12 serum levels in elderly patients following major orthopedic surgery of the lower limb.