F8 and Venous thrombosis: In the case-control Age and Thrombosis, Acquired and Genetic risk Factors in the Elderly Study (AT-AGE) study, a subgroup of 312 outpatients aged ≥70 years with a first episode of VTE showed an association between high levels of coagulation factors VIII (FVIII) and XI (FXI) and the occurrence of VTE, and another subgroup of 163 patients showed an association between a high level of factor IX (FIX) with first VTE; the associations were calculated by comparing the highest and lowest quartiles (odds ratios of 4.5, 1.7, and 2.4 for FVIII, FXI, and FIX, respectively).