|
|
 |
|
|
|
Prothrombin Time Testing Practices in the U.S. Pacific Northwest, 2004
Topic: Hematology/Coagulation
S. Shahangian1, K. LaBeau2. 1CDC, Atlanta, GA,
2Washington State Department of Health, Shoreline, WA
Presentation Number: D-9
Keyword: Prothrombin time, Laboratory practice, Quality assurance
Context: Coagulation and bleeding problems are associated with
substantial morbidity and mortality; and certain inappropriate prothrombin time (PT)
testing practices may lead to such complications.
Objective: To evaluate reported PT testing practices in the U.S. Pacific
Northwest and compliance with practice standards.
Methods: Laboratory sites in the U.S. Pacific Northwest performing PT
test were targeted to receive a questionnaire enquiring if they followed specific
testing practices. We used Washington Medical Test Site database and licensure
application forms for laboratories in Washington, and CLIA (OSCAR) database of
laboratories performing proficiency testing for the laboratories located in Alaska,
Idaho and Oregon. The questionnaire was mailed to all the 591 laboratories on
January 27, 2004. By March 19, 2004, 297 completed questionnaires were returned
(response rate, 50%). There were 152 point-of-care respondents (response rate, 46%),
117 hospital respondents (response rate, 59%), and 28 independent laboratory
respondents (response rate, 47%). Inconsistent responses were excluded from data
analysis.
Results: Of the 297 respondents, PT testing was performed for the
following purposes: monitoring of oral anticoagulant therapy, 90%; evaluation of
bleeding, 76%; assessment of liver disease, 68%; and detection of factor deficiency,
60%.
Heparin sensitivity. Of 248 respondents, 29 (12%) reported determining
sensitivity of their PT assay to heparin. Of 223 respondents, 94 (42%) reported
selecting a reagent that is insensitive to heparin in the heparin therapeutic range.
Sodium citrate concentration. Of 206 respondents, 192 (93%) used 109 mmol/L
(3.2%) sodium citrate as anticoagulant, 10 (5%) used 129 mmol/L (3.8%) sodium citrate;
2 (1%) used both.
Specimen acceptability policy. Of 230 respondents, 209 (91%) reported having a
written policy addressing specimen acceptability. The following items among 18 listed
options were noted: properly anticoagulated specimen, 97%; adequate labeling of
specimen, 96%; information on requisition and specimen label matching, 90%; drawing
specimens from patient lines, 73%; and heparinized specimens, 60%.
Practices followed with new thromboplastin lots. The following practices among
8 listed options were followed: verifying reference range, 84%; establishing patient
mean of normal, 80%; and confirming calculation of international normalized ratio
(INR), 75%.
Patient test report. Of those responding, 99.6% reported PT results as INR,
89% in seconds, and 7% as the PT ratio. The following information items were provided
on test reports: reference range, 84%; specimen comment, 79%; therapeutic range, 74%;
and result interpretation, 30%.
Reasons for repeating a test. Among 7 listed options, the following prompted
repeating a test: instrument failure or flag, 99%; quality control values outside of
acceptable limits, 97%; critical value, 95%; and abnormal value, 59%.
Quality assurance (QA) procedures. Among 10 listed options, the following QA
practices were followed: immediately alerting clinicians about critical test results,
100%; verifying performance of new analytical test systems, 95%; assuring clinicians'
receipt of test results, 91%; and periodically verifying calibration of all instruments,
86%.
Conclusion: We observed substantial variability in certain PT testing practices. Some of these practices are not consistent with current laboratory practice guidelines, and may impact patient outcome. Interventions should address awareness of existing practice guidelines among laboratory professionals.
|
This page last reviewed: 8/8/2005
|
|