Direct Oral Anticoagulants (DOACs) in the Laboratory: 2015 Review

- APTT, PT and thrombin time are not reliable measures of DOAC anticoagulant effect
- DOAC plasma concentration can be accurately measured with calibrated assays
- DOACs can interfere with special coagulation assays causing spurious results

Direct oral anticoagulant therapies, including direct anti-Xa and thrombin inhibitors have recently been introduced and may have advantages over vitamin K antagonists such as warfarin. This review describes briefly the clinical utility and mechanism of action of these agents. Detailed information is provided on effect of these agents on routine assays including the APTT and PT as well as their impact on specialty laboratory assays. Also included are the use of drug specific assays and a discussion of alternative methods to determine relative drug concentration, such as evaluating drug calibrators in APTT and PT assays and using heparin calibrated anti-Xa assays to measure direct Xa inhibitors.