INTRODUCTION

We are reporting the results of a survey of the U.S. hospital coagulation laboratory practices conducted in 2001. The Centers for Disease Control and Prevention (CDC) contracted with Research Triangle Institute (RTI), Durham, NC to conduct this survey. RTI subcontracted with Analytical Sciences, Inc. (ASI), Durham, NC to assist the CDC in the development and administration of this survey to a sample of the U.S. hospital laboratories.

Hospital clinical laboratories play an important role in the health of Americans; and as documented in this survey, virtually all hospital laboratories performed some coagulation tests. Coagulation laboratory testing is vital to the diagnosis, treatment and management of bleeding and hypercoagulability disorders affecting millions of patients in the U.S. For example, the most commonly performed coagulation test, prothrombin time (PT) assay, is currently performed over 40 million times annually. The majority of coagulation laboratory tests are performed as screening tests for coagulation disorders or to monitor therapeutic anticoagulant therapy; these assays are also used in conjunction with other tests to increase overall diagnostic accuracy. Although variation in coagulation testing practices within individual laboratories has been documented, little is known about the extent or nature of variation across hospital laboratories. Variability in some testing processes can affect test result accuracy and result interpretation, potentially impacting patient outcomes (e.g., complications of bleeding or thrombosis). Given that the diagnosis and treatment of many patients depend, in part, on coagulation testing, such variation could have serious consequences for patient and population health care and assessment.

In response to the uncertainty surrounding coagulation testing practices, we conducted this national survey of hospital coagulation laboratories. This survey focused on testing practices involving 3 coagulation disorders potentially impacting patient outcomes. These disorders were (1) hypercoagulability or thrombophilia, (2) von Willebrand disease (vWD), and (3) heparin induced thrombocytopenia (HIT)/heparin-induced thrombocytopenia thrombotic syndrome (HITTS). We chose these disorders because, in our judgment along with that of a panel of coagulation laboratory experts,^* (1) they had serious health consequences affecting a large number of people and (2) valid test results were critical for their diagnosis and treatment.

Our purpose here was to assess variation of coagulation laboratory practices in the U.S. hospitals by assessing

• availability of specific tests for diagnosing and treating hypercoagulability or thrombophilia, vWD and HIT/HITTS,
• pre-analytical issues such as collection methods, information provided with specimens, and processing of specimens,
• analytical issues such as instrumentation, quality control (QC), and qualifications of testing personnel,
• post-analytical issues such as result reporting, interpretations, and recommendations, and
• use of selected laboratory practices specific to each test that are subject to variation (such as availability, methodology and sensitivity) and that are critical to the diagnostic or therapeutic use of the test.

^*The members of this panel were Michael Laposata, M.D., Ph.D. of Harvard Medical School, Boston, MA, Connie Miller, Ph.D. of the CDC, Atlanta, GA, Stephan Moll, M.D. of the University of North Carolina, Chapel Hill, NC, and John Olson, M.D., Ph.D. of the University of Texas Health Science Center, San Antonio, TX.