1 International normalized ratio (INR) and activated partial thromboplastin time (aPTT) have limited clinical utility
The INR and aPTT should be used only for specific clinical indications (see Appendix 1, available at www.cmaj.ca/lookup/doi/10.1503/cmaj.220629/ tab-related-content). (1)
2 Bleeding history is the most important predictor of an inherited bleeding disorder
The INR and aPTT have poor sensitivity (1.0%-2.1%) for bleeding disorders. (1) Clinicians considering an inherited bleeding disorder should first use a Bleeding Assessment Tool (BAT). (2) A negative BAT score has a sensitivity approaching 100% to rule out von Willebrand disease (the most common inherited bleeding disorder). (2) A positive BAT score should prompt referral to a hematologist for consideration of specialized coagulation testing. (1)
3 International normalized ratio and aPTT testing are not indicated before low-risk surgery or interventional radiology
Abnormal INR or aPTT results are not associated with an increased bleeding risk in the setting of low-risk procedures. (3,4) An abnormal result with no bleeding...