Factor V Leiden Testing and Its Effects on Decision-Making: An Institutional Survey
Authors: Pawar Tushar , Garrahy Ian , Donato Anthony , Stevenson Amber , Forman Daniel 
Published: November 2019

Introduction: The incidence of factor V Leiden is documented to be around 5% in Caucasian population and is a known risk factor for venous thromboembolism (VTE). However, the incidence of recurrent VTE for heterozygous factor V Leiden mutation (FVL) is not significantly different from non-carriers. As per established guidelines, 3 months of anticoagulant treatment is enough in cases of provoked VTE, and does not require a hypercoagulability panel. Guidelines also dictate that in case of heterozygous factor V Leiden, there should be no change in duration of treatment for provoked VTE.
Methods: We studied answers acquired through a survey questionnaire administered to healthcare providers at Reading Hospital, Tower Health System. An anonymous online survey was used for acquiring this data, which included specialty, practice setting, degree (physician's vs non-physician practitioners) and years of experience (0-3, 4-10, 11-20, >20). As part of a larger survey, practitioners were asked anticoagulation duration for two patients with provoked VTE, one of which was noted to be heterozygous for FVL mutation, and answers were compared. he data was then filtered for incomplete responses and de-identified. SPSS software was then used for further descriptive analysis. One-way ANOVA and t-tests were used to analyze differences between various groups.
Results: A total of 404 responders provided answers to all the questions. For provoked DVT with no mention of FVL testing , 372 (92%) providers used anticoagulants for duration of 3 months, and 32 (8%) continued anticoagulants for excessive duration (28 for 12 months, 4 chose indefinite therapy). For question 2, which included heterozygous factor V mutation; 257 (63.6%) used anticoagulants for 3 months, whereas 147 (36.4%) continued anticoagulants for excessive duration (29 for 12 months, 118 chose indefinite therapy). Independent sample t-test was performed to analyze difference between the duration of anti-coagulant prescribed by physicians versus non-physician practitioners (NPP). Physicians (mean 79.70) did significantly better compared to NPP (mean 58.40), with P-value<0.001. In case of practice setting, there was no significant difference between in-patient versus out-patient providers, with P-value of 0.26. One-way ANOVA results used to analyze difference between 4 groups for years of experience was non-significant (p=0.18).
Conclusion: It was observed in our study that FVL testing may incorrectly influence decision-making in anticoagulation duration. This could be attributed to several factors, such as lack of knowledge of current guidelines, incorrect estimation of the risk of recurrent VTE, and poor understanding of the indications for indefinite treatment. It is also important acknowledge the variation in the use of anti-coagulation between physicians and NPP. A wide multi-institutional survey analysis in the future can help acknowledge these factors to prevent excessive use of anticoagulants and reduce risk of bleeding. Furthermore, given the potential harm associated with excessive anticoagulation, testing for FVL should be judiciously monitored and limited to more skilled practitioners.

Disclosures
No relevant conflicts of interest to declare.