Critical Values in the Coagulation Laboratory: Results of a Survey of the North American Specialized Coagulation Laboratory Association.

Critical laboratory values (CVs) are those that indicate the patient is in danger of death unless corrective action is initiated immediately. CVs are an important feature of laboratory practice parameters, standards of regulatory agencies (including the Joint Commission's National Patient Safety Goals), and national and institutional quality improvement studies. However, there has been no research into CVs in coagulation laboratories. Our objectives were to determine: 1) The current policies on CVs in specialized coagulation laboratories 2) Current patterns of practice for reporting CVs for coagulation parameters; and 3) If there is any consensus, based on practice, on CVs for coagulation tests.

A web-based survey on CVs was distributed to members of the North American Specialized Coagulation Laboratory Association in February 2009.

38 laboratories participated. 97% had CVs for coagulation tests in place. 85% of laboratories used local opinion or consensus to set their CV policies, likely reflecting a lack of published data. 9% of laboratories were unsure where their CVs came from. CV reporting practices were fairly uniform. 97% of surveyed laboratories authorized technologists to report CVs, and only a minority (<40%) involved senior technologists or laboratory physicians in reporting. CV policies at almost all sites (97%) authorized the patient's nurse or MD, or the ordering MD to receive CV results. Medical students, clerical staff, or uninvolved staff nurses were rarely authorized to receive CVs (3%, 13%, and 37%, respectively).

Policies in all participating laboratories required documentation of CV communication. Telephone was the primary method of communication, with 39% of sites used electronic broadcast or forced print as an adjunct. Inconsistency was noted in strategies to handle repeat CVs on the same patient, ranging from reporting all CVs, to reporting worsening CVs, to not reporting CVs on certain patient populations (e.g. critical FVIII:C levels in known hemophiliacs). After-hours communication of CVs on outpatients and referred clients was identified as challenging. All sites first attempted to telephone the patient's on-call MD, and if unsuccessful, sent a report by facsimile, contacted the Laboratory Chief of Service, or delayed reporting until the next day.

When laboratories were asked about their CV values, over 80% had CVs for the INR (mean > 5, range > 2 - 6), aPTT (mean > 100 sec, range > 45 - 150 sec) and fibrinogen level (mean < 90 mg/dL, range < 50 - 100 mg/dL). Fewer laboratories (< 25%) had CVs for less commonly performed coagulation tests, including anti-Xa levels, factor and inhibitor assays, and thrombophilia testing. These CVs were more heterogeneous.

This survey identified several potential areas for improvement in the way specialized coagulation laboratories handle CVs. Consensus data would assist laboratories in standardizing their policies, and establishing benchmarks for CV reporting and policy review. It would also ensure that a laboratory's CVs are in line with those of its peers, and are clinically relevant. The workload associated with CVs for coagulation assays is unknown, and it is possible that some of the current reporting strategies lead to inefficiencies and delays (e.g. reporting CVs for tests that are not truly life threatening; lack of established policies for after-hours handling of CVs when an on-call physician cannot be reached). Our study identifies an important need for further evaluation and standardization of CVs for coagulation tests.

No relevant conflicts of interest to declare.