FACTOR-V-LEIDEN AND FATAL PULMONARY-EMBOLISM

To investigate whether the factor V Leiden mutation increases the risk of fatal pulmonary emboli, we determined the presence of the factor V Leiden mutation in pathology material from two series of autopsies of patients from the Leiden University Hospital, The Netherlands. The fi rst series consisted of consecutive autopsies in which pulmonary embol i were mentioned in the autopsy report; most patients of this series h ad major underlying disease. The second series consisted of autopsies in patients younger than age 70 in which pulmonary emboli were the sol e cause of death and no major acquired risk factor for venous thrombos is was present. Extraction of DNA was done on newly prepared tissue fr om archival paraffin blocks. In the first series, the presence of fact or V Leiden was determined in 44 patients, 1 of whom carried the mutat ion (2.3 percent; 95% confidence interval 0.06 to 12.0 percent). This prevalence is not different from the general population prevalence in The Netherlands. In the second series, factor V Leiden could be determ ined in 30 patients of whom 3 carried the mutation (10 percent; 95% co nfidence interval 2.1 to 26.5 percent), which would lead to a threefol d relative risk. A large number of patients with diverse psychiatric d iagnoses was present in the second series (eleven). We conclude that i n the presence of severe illness, the factor V Leiden mutation plays n o additional role in the development of pulmonary emboli. The relative risk of the very rare fatal pulmonary embolus that is the sole cause of death might also be less than the relative risk for deep-vein throm bosis in carriers of the factor V Leiden mutation.