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2004 PT Survey Report - Background
Prothrombin Time Testing Practices in the Pacific Northwest:
A Model for Monitoring Voluntary Practice Guidelines

Survey Home
Medical mistakes and errors are unacceptably high, despite a longstanding focus on activities carried out in the name of total quality management, quality assurance (QA), and quality assessment. In 1999, a report by the Institute of Medicine (IOM) revealed the magnitude of medical errors and concluded that most were the result of systematic failures and were preventable (1). Therefore, the right changes in systems should result in the reduction of errors. Approaches to reducing medical errors include
  • tracking errors and determining their causes,
  • monitoring indicators of quality, and
  • overcoming barriers to adhere to accepted standards of laboratory practice.
In clinical laboratory medicine, practice standards and guidelines are not new. Federal regulatory standards addressing laboratory QA programs have been in existence for hospitals and independent laboratories since 1967 [Clinical Laboratory Improvement Act of 1967 (CLIA '67)] and for all other testing facilities since 1992 [Clinical Laboratory Improvement Amendments of 1988 (CLIA '88)]. While government standards set the tone for laboratory testing quality, they represent minimal requirements and allow individual testing sites much latitude in their implementation.

More rigorous voluntary practice standards exist for laboratories that wish to be accredited by a private accrediting organization, in lieu of being directly certified by the Government. While the College of American Pathologists (CAP), the Joint Commission on Accreditation of Healthcare Organizations (JCAHO), the American Association of Blood Banks (AABB), COLA and other accrediting organizations offer excellent standards of practice, the majority of laboratories are not accredited.

Studies have shown that despite required and voluntary standards of practice, many laboratorians fail to use them (2). Although quality laboratory work may be their aim, many personnel lack the resources to adhere to the "state of the art" voluntary protocols or recommendations. In addition, many facilities use only CLIA-waived test systems, which are not subject to regulation other than the requirement to follow current manufacturer's instructions.

One common laboratory test that is vulnerable to errors and adverse patient outcomes is the prothrombin time (PT) test. Nearly all hospitals perform the PT test, but it is also performed in many non-hospital settings as well. Systematic changes in test results that are not due to biological reasons can occur when patients move from one setting to another due to a lack of correlation between methods and a lack of communication between sites. A patient may be tested while an inpatient in the hospital (by the traditional laboratory and/or at the nursing station). They may then visit an anticoagulation center as an outpatient or be tested in their physician's office. In some cases, patients may perform PT testing at home, using one of the prescription home use devices now available. How does the patient's physician make sense of the PT values when test results come from all these different settings, with different reference ranges, reporting formats, reagent systems, etc?

Errors may also occur when a testing site changes to a new lot of testing reagents. Testing personnel may not recognize that their reagent sensitivity has changed and may not do studies to verify their test results are consistent and calculations are accurate.

Prothrombin time testing is now commonly done by non-traditional test methods [point-of-care (POC) and CLIA-waived test devices]. These devices differ from traditional laboratory methodologies by using capillary whole blood samples, unitized reagent strips or cartridges, electronic quality control (QC), pre-set values for the international sensitivity index (ISI), "mean of normal," reference ("normal") ranges, and the automatic calculation of the international normalized ratio (INR). Prothrombin time testing using these devices is common in non-traditional settings (POC and waived test sites) where there is the advantage of the patients being present along with their medical records at the time of testing. However, these sites often have minimal requirements for QC, QA, and testing personnel qualifications. Many current practice standards and guidelines for PT testing were not written with these non-traditional test methods or settings in mind.
Purpose of the project
In October 2003, the Washington State Office of Laboratory Quality Assurance (LQA) and the Centers for Disease Control and Prevention (CDC) entered into a cooperative agreement to study laboratory testing practices in the Pacific Northwest. Using PT testing as a model, the purpose of this project was to
  • evaluate current laboratory testing practices,
  • determine which practice standards and guidelines laboratories use,
  • assess the reasons testing sites do not adhere to accepted standards of practice,
  • compare practices in different settings and by different test methods, and
  • educate laboratory personnel about the commonly accepted standards of practice.

To gather information about current laboratory testing practices, a questionnaire was developed in October-December 2003 by the LQA and CDC, and was pilot-tested in 5 laboratories in Washington State in December 2003.

Using the Washington Medical Test Site (MTS) database and licensure application forms, testing sites performing PT by either CLIA-waived or non-waived methods were identified and targeted to receive the questionnaire. Laboratories located in Alaska, Idaho and Oregon performing proficiency testing for PT were identified using the CLIA (OSCAR) database. Questionnaires were mailed to the 591 such laboratories in the Pacific Northwest region on January 27, 2004. Two hundred ninety-seven completed questionnaires were returned by March 19, 2004, resulting in an overall response rate of 50.3% (Tables 1 and 2).
Table 1 - Questionnaire respondents
  Site Type Laboratory Classification Location
  Total Point of Care 1 Hospital IL2 Waived/ PPMP3 Moderate/ High4 Accredited Urban Rural
Targeted 42 18 21 3 2 14 26 7 35
Respondent 17 7 9 1 0 7 10 4 13
Response Rate(%) 40 39 43 33 0 50 38 57 37
Targeted 91 43 40 8 8 61 22 20 71
Respondent 46 15 27 4 3 33 10 7 39
Response Rate(%) 51 35 68 50 38 54 45 35 55
Targeted 187 103 59 25 25 61 101 110 77
Respondent 81 44 28 9 9 27 45 48 33
Response Rate(%) 43 43 47 36 36 44 45 44 43
Targeted 271 169 78 24 84 111 76 187 84
Respondent 153 86 53 14 33 73 47 100 53
Response Rate(%) 56 51 68 58 39 66 62 53 63
Targeted 591 333 198 60 119 247 225 324 267
Respondent 297 152 117 28 45 140 112 159 138
Response Rate(%) 50 46 59 47 38 57 50 49 52
1Point of care includes the following types of sites: POLs, clinics, community health clinics, home health agencies, health maintenance organizations (HMOs), and ambulatory surgical centers.
2IL = independent laboratory
3PPMP = provider performed microscopy procedure
4Moderate/High = moderate or high test complexity, but not accredited
Table 2 - Comparison of respondent demographics
N = 2971
All labs targeted
N = 5911
All Pacific NW labs N = 6072
  Percent of laboratories
Alaska 6 7 7 (N = 436)
Idaho 15 15 12 (N = 724)
Oregon 27 32 34 (N = 2069)
Washington 52 46 47 (N = 2843)
Urban/Rural 54/46 55/45 67/33
Point of care site2/Hospital/IL3 51/39/9 56/34/10 92/5/3
Waived & PPMP/
Moderate/High4 & Accredited
15/85 20/80 75/25
1Numerator data are not included since they can be obtained from Table 1.
2Point of care site includes the following types: POLs, clinics, community health clinics, home health agencies, health maintenance organizations (HMOs), and ambulatory surgical centers.
3IL = independent laboratory
4PPMP = provider performed microscopy procedure; Moderate/High = moderate or high test complexity, but not accredited
In an instruction sheet that was provided with the questionnaires, we clarified the phrase "voluntary practice standard" as documents published by professional organizations [such as the CLSI, World Health Organization (WHO), CAP and others] whose use is voluntary, as opposed to regulatory or accreditation requirements that must be followed for certification or accreditation.

This page last reviewed: 3/7/2005
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