Appropriateness of Thrombophilia Testing in Tertiary Care Centers in Edmonton
Authors: Zainab Alabdurubalnabi , Shivji Salma , Wu Cynthia 
Published: October 2019

INTRODUCTION

Thrombophilia is associated with an increased risk of venous thromboembolism (VTE). Despite this link, determining the presence or absence of such conditions has no role in VTE management including determining the choice or duration of anticoagulant therapy. Testing can be potentially harmful when results are misinterpreted or impact patient anxiety and insurance eligibility.

METHODS

We performed a retrospective chart review of adult patients presenting to the emergency department (ED) or were admitted to the University of Alberta Hospital (UAH), Royal Alexandra Hospital (RAH) and Grey Nuns Hospital (GNH) and underwent any number of thrombophilia tests (including factor V Leiden [FVL], prothrombin gene mutation [PT20210], protein C [PC], protein S [PS], antithrombin [AT] and antiphospholipid antibody testing). To assess for appropriateness of testing, categories of data were collected including presence of other strong risk factors obviating the need to look for other causes, indicators for higher yield (age of patient, presence of family history of VTE, idiopathic nature of VTE), presence of factors that confound testing (such as therapeutic anticoagulation) and relevant follow up (appropriate repeat testing when necessary). We also collected basic patient demographics, VTE details and ordering physician/service details to evaluate under what circumstances testing may be ordered more frequently.

RESULTS

134 charts of patients tested for thrombophilia were reviewed between 2007-2013 at UAH and RAH Hospitals. A total of 965 thrombophilia tests were done (see analysis table). 13.4% of the testing was ordered by hematologists, 23.1% by neurologists, 52.2% by other internists. Overall, all patients had tests performed inappropriately, lacked appropriate follow up or had uninterpretable results and none had documented counseling prior to thrombophilia testing.

CONCLUSIONS

Thrombophilia testing is frequently ordered inappropriately and not adequately followed up. Strategies to educate physicians on indications and limitations of testing are warranted. These strategies can help decrease over/under/misinterpretation of thrombophilia testing as well as result in significant savings to the health care system if testing can be reduced.

Table 1. Demographics Sample Size Males Females Total 74 (55.22%) 60 (44.78%) 134 (100%) Age at time of testing (Yrs) Range 19-88 Average 48.7 Patients' Test Results Test Times Performed Abnormal Results APCR 134 (100%) 32 (23.8%) FVL genetic test 58 (43%) 21 (39%) PT20210 105 (77%) 4 (3.8%) Protein C 100 (74.1%) 8 (8%) Protein S 99 (73.3%) 16 (16.2%) AT levels 99 (73.3%) 19 (19.2%) Anticardiolipin Ab 117 (86.7%) 4 (3.4%) Lupus Anticoagulant 109 (81.3%) 10 (10.2%) Provoking Factors Patients with One or More Provoking Factors Major 10 7.4% Moderate 74 56% Minor 29 21.8% No Provoking Factors 49 36.8% Family History of VTE 12 8.9% Protein C and Protein S Testing Done During Acute VTE 64 64% Patient was on Warfarin 25 25% Number of Abnormal Test Results 24 16% Number of Repeated Abnormal Tests 0 0% AT Testing Total Tests Performed 99 73.3% Done During Acute VTE 62 63% Patient was on Therap. Heparin or LMWH 62 62.6% Number of Abnormal Test Results 19 19.2% Abnormal Tests Repeated? 7 37% Repeat Tests Showing Normal Results 3 57% APA Testing Tests were Repeated After 12 Weeks for Confirmation 11%

Disclosures

Wu: Leo Pharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.