Validating the Rosner Index

From “Maria:” Hello, I am looking into using the Rosner Index to assess mixing studies correction or not. Literature states that the Rosner Index must be validated with each new lot # of partial thromboplastin time (PTT) or prothrombin time (PT) reagent. Do we also need to validate each new lot of CaCl2? Also, what would be the way to validate the Rosner Index? do you have a method or recommendations?
Hello, Maria, and thank you for your question. The Rosner index is described in our audio module #25, and is recommended as a consistent approach to defining PT and PTT mixing study correction. I know of no direct method for validating the Rosner index or any parallel means for establishing correction, instead, you need simply validate the underlying PT and PTT methods. The North American Specialized Coagulation Testing Association (NASCOLA), provides a proficiency testing module, and mixing study guidelines are available from the International Society on Thrombosis and Haemostasis Subcommittee on Lupus Anticoagulant and Phospholipid-Dependent Antibodies, chaired by Thomas Ortel, MD, of Duke University Medical Center. These may help you to develop your mixing study protocols.