Hypercoaguable Work up : Are We Overtesting ?

BACKGROUND : Hypercoaguable states are defined as a group of inherited or acquired conditions associated with predisposition to venous thromboembolism(VTE) , arterial thrombosis or both . Of the inherited thrombophilias , Factor V Leiden mutation(FVL) is the most common, with Prothrombin mutation G20210(PT) being the second most common cause, both being inherited as autosomal dominant.

FVL is a single point mutation in the gene that codes for coagulation factor V. It renders factor V resistant to inactivation by activated protein C. Heterozygosity for Factor V Leiden occurs in 3-8% of the general US and European populations, homozygosity being very rare. Approximately 10% of FVL heterozygotes develop VTE over their lifetime. The relative risk for VTE is increased three to six fold in Factor V Leiden heterozygotes. PT is a single point mutation (G to A substitution at nucleotide 20210) in the prothrombin gene. This mutation appears to result in elevated concentration of plasma prothrombin. The overall prevalence is approximately 2%. Risk of VTE in individuals who are heterozygous for PT has been estimated to be increased approximately three- to fourfold. However , the relative risk of having one of these mutations in patients presenting with a first time VTE is 15-20% and 6% for FVL and PT respectively .

Although these mutations increases the chances of VTE, its association with arterial thrombosis and obstetric complications( recurrent miscarriages , still birth, Intraueterine fetal demise) are not clear. Therefore testing for these mutations is appropriate only in patients with idiopathic VTE, younger patients and or those with family history , recurrent thrombosis , thrombosis in unusual vascular bed. In our institution ,there was a concern that appropriate selections of patients to test for these mutations was not occurring and the cost of inappropriate testing may be adding to the healthcare costs. We performed a retrospective review of indications for thrombophilia testing and its costs over a period of one year at our tertiary medical center.

METHODS : All patients who had testing for FVL and PT from June 2015-June 2016 were identified by screening ordered tests done in the special coagulation laboratory. Inpatients and outpatients were included .

The clinical data reviewed included age, sex and indication for the tests ordered.

Overall cost was calculated for each group.

RESULTS : We evaluated 144 patients . The mean age of patients was 51 years (range :7 Weeks - 88 years)

Males constituted 51%(74/144), females were 49%(70/144) of the cohort.

Both FVL and PT tests were ordered on all the patients.

Of 144 patients , only 3 patients tested positive and were heterozygous for FVL and, 1 positive patient was heterozygous for PT.

The cost of the test for FVL was $348 and for PT $267 in a standard laboratory.

The following table lists the common indications for the tests ordered :

*Other included Lung transplant workup 10%, heart transplant work up9% , VAD thrombosis 1%, MI (0.9%) miscarriage 5% and other -10%

The number of tests that did not meet the standard criteria for testing were: 103

Only 28 % of testing was done for an appropriate indication (Unprovoked VTE , Recurrent VTE , VTE at an unusal site)

Cost associated of unnecessary testing :$63,345

CONCLUSION : Testing for inherited risk factors for VTE when not indicated by standard criteria leads to excess costs for patients and healthcare systems .Education of healthcare providers may limit unnecessary testing and ultimately reduce healthcare costs .

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