Assessing Clinical Laboratory Quality A College of American Pathologists Q-Probes Study of Prothrombin Time INR Structures, Processes, and Outcomes in 98 Laboratories Peter J. Howanitz, MD; Theresa P. Darcy, MD; Frederick A. Meier, MD; Christine P. Bashleben, MT(ASCP)  Context.—The anticoagulant warfarin has been identi- ers, 12 different timeliness goals for reporting critical fied as the second most frequent drug responsible for values, and 18 unique critical value limits were used by serious, disabling, and fatal adverse drug events in the participants. All required documentation elements were United States, and its effect on blood coagulation is present in 94.8% of 192 reviewed INR validation reports.
monitored by the laboratory test called international Critical value INR results were reported within the time normalized ratio (INR).
frame established by the laboratory for 93.4% of 2604 Objective.—To determine the presence of INR policies results, but 1.0% of results were not reported. Although and procedures, INR practices, and completeness and the median laboratories successfully communicated all timeliness of reporting critical INR results in participants' critical results within their established time frames and had all the required validation elements based in their 2 most Design.—Participants reviewed their INR policies and recent INR calculations, those participants at the lowest procedure requirements, identified their practices by using 10th percentile were successful in 80.0% and 85.7% of a questionnaire, and studied completeness of documenta- these requirements, respectively.
tion and timeliness of reporting critical value INR results Conclusions.—Significant opportunities exist for adher- for outpatients and emergency department patients.
ence to INR procedural requirements and for practice Results.—In 98 participating institutions, the 5 required patterns and timeliness goals for INR critical results' policies and procedures were in place in 93% to 99% of clinical laboratories. Fifteen options for the allowable (Arch Pathol Lab Med. 2015;139:1108–1114; doi: variations among duplicate results from different analyz- In 2011, two million patients were injured seriously in the anticoagulation effect is not monitored routinely by clinical United States by prescription drug therapy, ultimately laboratory testing.
resulting in 128 000 patient deaths.1 A 2013 report The laboratory test used to guide warfarin therapy was the summarizing patient drug safety issues found that the prothrombin time (PT). Blood was collected in a tube anticoagulation drugs dabigatran and warfarin were the 2 containing liquid sodium citrate, which acts as an antico- drugs most frequently reported to the US Food and Drug agulant by binding calcium in the specimen. After centri- Administration (FDA) as causing serious, disabling, or fatal fugation, plasma was analyzed by adding excess calcium, adverse events.2 Warfarin (Coumadin), first introduced in tissue factor, and phospholipids, followed by measurement 1954, has been the mainstay of anticoagulation treatment of the clotting time. The prothrombin time will vary with the for the past 60 years and requires laboratory testing to guide different lots of tissue factor and phospholipids used in the dosing for subtherapeutic, therapeutic, and toxic effects. In prothrombin reagent. More recently, the reactivity of these contrast, dabigatran, the leading cause of patient injury different lots of tissue factor reagents was calibrated against reports to the FDA, was approved for use in 2010 and its the international reference tissue factor and assigned aninternational sensitivity index (ISI). When the PT is Accepted for publication December 11, 2014.
controlled for the effects of various ISIs, the measurement From the Department of Pathology, State University of New York, is called the international normalized ratio (INR) and is Downstate Medical Center, Brooklyn (Dr Howanitz); the Department calculated from the quotient of the patient's PT divided by of Pathology, University of Wisconsin School of Medicine and Public the geometric mean of the control population raised to the Health, Madison, (Dr Darcy); the Department of Pathology, Henry power of the ISI. The INR reference range for healthy Ford Health System, Detroit, Michigan (Dr Meier), and the SurveysDepartment, College of American Pathologists, Northfield, Illinois patients not using warfarin is 0.8 to 1.2, and for a variety of (Ms. Bashleben).
diseases, 2 general ranges are widely accepted. An INR The authors have no relevant financial interest in the products or range of 2.0 to 3.0 is required for such diseases as pulmonary companies described in this article.
embolism or atrial fibrillation, whereas a range of 2.5 to 3.5 Reprints: Peter J. Howanitz, MD, Department of Pathology, SUNY Downstate, Medical Center, Mail Stop 25, 450 Clarkson Ave, is used for patients with mechanical aortic or mitral valves or Brooklyn, NY, 10013 (e-mail: Peter.Howanitz@downstate.edu).
children on ventricular assist devices whose condition is 1108 Arch Pathol Lab Med—Vol 139, September 2015 Q-Probes INR—Howanitz et al stable.3 In addition, there are a few circumstances when Table 1. Clinical Laboratory Policies/Procedures of other INRs are desired.3 INR Testing and Reporting in 98 Institutions Warfarin has a narrow therapeutic window with multiple drug and food interactions and genetic metabolic variabil- ities, making management difficult, so that bleeding fromovercoagulation, or thrombus growth from undercoagula- Laboratory has a policy/procedure with the tion, are major risks. In addition, the clinical laboratory following stipulations: requirements for the accurate measurement and reporting of Requires collection of all PT/INR specimens in 3.2% buffered sodium results are complex and require meticulous attention to detail. Results also are influenced by the quality and the type Specifies use of the geometric mean of of the specimen required for testing. To aid in these efforts, reference interval in INR calculationa the College of American Pathologists (CAP) Laboratory Specifies adjustment of INR calculations for Accreditation Program (LAP) has developed several specific every new lot or change in type of PTreagenta requirements that must be fulfilled when collecting speci- Specifies type of documentation required to mens, testing, and reporting INR results.4 Adherence to verify the ISI is appropriate to the these strict CAP requirements is essential for accurate INR particular PT reagent and instrumentation results. This study was developed to assess the quality of clinical laboratory practices associated with the structures Requires checks of patient reports for correct INR (policies and procedures), processes (practices), and out- calculations for the following circumstancesa: comes (data of INR validation documentation as well as Change in lot or type of PT reagenta completeness and timeliness of result reporting) for the INR Change in instrumenta in clinical laboratories.
Establishment of new PT reference rangea Change in INR calculationa MATERIALS AND METHODS Requires verification of INR calculation under the following Participants enrolled in the CAP Q-Probes program collected data during July and August of 2010 as previously described.5 The After instrument repair study included 10 multiple choice questions on patient safety After upgrades to the instrument, interface/ practices for monitoring the INR (Input Form 1) and reviewed the 2 most recent INR calculation verifications, by having participants fill in specific information about those procedures on a preprinted Specifies equation used to calculate the INR form (Input Form 2). Participants used preprinted Input Form 3 to Specifies where INR calculation is performed collect results prospectively from 30 consecutive INR critical Where INR calculation is performed: results. At the conclusion of the data collection, participants sent the required data to the CAP for data analysis. If they were unable to collect results from 30 consecutive results during the study dates, participants were to return the data that were collected to Abbreviations: INR, international normalized ratio; ISI, international the CAP for data analysis. Characteristics about the test systems sensitivity index; LIS, laboratory information system; PT, prothrombin used in the central laboratory and throughout the organization were collected by using 28 multiple choice questions contained in a Required by College of American Pathologists Laboratory Accredita- Input Form 4.
tion Program Checklist.4 The required validation components listed in the CAP LAP Hematology Checklists for clinical laboratories included thefollowing4: from the database for only the question they did not answer. A P .05 was considered significant.
HEM 22748: All coagulation specimens should be collectedinto 3.2% buffered sodium citrate (phase II).
HEM 23360: The appropriate geometric mean of the PTreference interval is used in the INR (phase II).
Ninety-one participants (93%) were from the United HEM 23290: The calculation of the INR is appropriately States, their hospital type was voluntary, nonprofit in 51 adjusted for every new lot of PT reagents, changes in types of (60%), and nongovernmental in 66 (77.6%) cases; 44 reagent, or change in instrumentation (phase II).
(53.7%) had an occupied bed size of up to 150 beds, and HEM 23220: For PT there is documentation that the ISI is 53 (62.3%) were located in a city or suburb.
appropriate to the particular PT reagent and instrumentation Table 1 describes the policies and procedures used in the used (phase II).
98 participating clinical laboratories for the collection of HEM 23430: There are checks of patient reports for correct specimens for INR testing, the parameters of INR testing, INR calculations, patient values, and reference ranges under and when the INR was evaluated for correctness in patient the following circumstances: (1) change in lot or type of PT reports. In 90 participants' laboratories (92%), policies and reagent, (2) change in instrument, (3) establishment of newPT reference ranges, and (4) change in INR calculation procedures existed for all 5 CAP-required INR parameters.
Some laboratories had more detailed procedures than whatwas required by the CAP LAP and included recalculation of The percentage of checklist-required components was calculated the INR after instrument repair, upgrades to the INR as the number that was completed/verified divided by the total instrument, equation used to calculate the INR, and site of number of validation components. The successfully communicated electronic software where the INR was recalculated.
INR critical results to the responsible caregivers were calculated asthe number successfully communicated within the clinical labo- Table 2 describes practices in 98 clinical laboratories for ratory's established time frame over the total number identified. If measurement of the INR. On patient reports, participants in participants neglected to answer a question, they were excluded 94 clinical laboratories included an INR reference range Arch Pathol Lab Med—Vol 139, September 2015 Q-Probes INR—Howanitz et al 1109 Table 2. Laboratory Practices Used for Measurement Table 3. Practices at 33 Institutions With Multiple INR Testing Sitesa PT reference range and geometric mean No. of INR testing sites other than main laboratory (N ¼ 33) reviewed with each change in PT reagent Patient report includes a reference range for the INR (N ¼ 94) Patient report includes a target range of other interpretive information for the INR (N ¼ Location of additional testing sites (N ¼ 33)b Anticoagulation clinic No. of laboratory instruments used for reporting INR in Satellite laboratory central laboratory (N ¼ 96) Physician office laboratory Home health agency ISI value for additional test systemsb Same lot of reagents used for multiple instruments reporting central laboratory Patient specimens used for comparisons between multiple INR instruments (N ¼ 76) Frequency of performing comparisons between multiple INR instruments (N ¼ 70) Patient comparisons run with central laboratory Monthly or quarterly Frequency of patient comparisons with main laboratory Acceptable INR magnitude of difference (N ¼ 69) 0–0.4 absolute units ,1.0 absolute units 1–2 absolute units Abbreviations: INR, international normalized ratio; ISI, international sensitivity index.
a N ¼ 33 clinical laboratories.
b Indicates multiple responses allowed.
Assigned ISI of PT reagents in use on primary instrument semiannually in 68 of 70 laboratories (97%). The ISIs varied widely between 0.91 and 1.97, with 6 of the participants (6%) using ISIs that exceeded 1.7 (1.73, 1.78, 1.81, 1.95, 1.95, and 1.97). In 92 of 97 clinical laboratories (94.8%) patient results were not run in duplicate, and in 43 of 96 laboratories(44.4%) delta checks for the INR were not run. In all, 86 of Patient results run in duplicate (N ¼ 97) Delta check used on INR (N ¼ 96) 97 laboratories ran 2 levels of controls every 8 hours (86%),and 11 remaining clinical laboratories (11.3%) ran 3 or more No. of quality control levels run every 8 hours (N ¼ 97) levels of controls every 8 hours.
In Table 3 are the practices in 33 institutions where INR determinations are performed at more than 1 location. Thenumber of additional INR sites varied from 1 to 4, with 15 Abbreviations: INR, international normalized ratio; ISI, internationalsensitivity index; PT, prothrombin time.
institutions having 1 additional site and 6 institutions having 4 or more additional testing sites. The additional sites N, number of institutions responding to question.
included anticoagulation clinics, satellite laboratories, phy-sician office laboratories, and home health agencies.
(98.9%), in 82 clinical laboratories they incorporated an INR Table 4 provides information on the documentation target range or other interpretive information (87.0%), and quality of the 2 most recent INR calculation verifications in 94 (98.9%) clinical laboratories they reviewed the PT in each laboratory. The 3 most common reasons for reference range and geometric mean with each change in PT calculation verifications were a change in reagent lot or reagent lots. In 75 of 96 clinical laboratories (78.1%), 2 or type of reagent, required annual check, and regularly more instruments were used in the main laboratory to scheduled nonannual checks in 99, 37, and 31 verifications perform INR measurements and in these circumstances (51.6%, 19.3%, and 16.1%), respectively. In 110 of 195 almost all participants (98.7%) used the same lot of reagents verifications (56.4%), a change in the ISI occurred. There for their instruments. Fifteen different cutoffs were used to was documentation that the ISI was verified as appropriate describe the magnitude of the allowable result difference for the instrument/reagent combination in 187 of 192 between analyzers performing the same INR measurement.
verifications (97.4%), that the ISI used was the proper ISI Patient specimens were used for comparisons among for the INR in 193 of 195 verifications (99.0%), and that multiple instruments in 69 of 73 clinical laboratories patient reports were reviewed for correct INR calculations in (94.5%) and these comparisons were conducted at least 185 of 195 verifications (94.9%). Overall there were 17 1110 Arch Pathol Lab Med—Vol 139, September 2015 Q-Probes INR—Howanitz et al Table 4. Practice Patterns During Last 2 INR Table 5. Laboratory Policies and Procedures for Reporting INR Critical Values Reason INR calculation was High critical value limit used in participants' laboratories (N ¼ 96) Change in lot or type of INR Other scheduled check (eg, monthly, 6 months) Change in instrumentation Critical value results rerun before result CAP proficiency testing reported (N ¼ 96) Repair or maintenance of Time frame required to report critical INR result, min (N ¼ 93) Two instrument calibrations The INR verification included a Laboratory requirements for reporting critical Appropriateness of the ISI for INR result (N ¼ 97) Date and time of notification Identity of person calling result Laboratory verified that ISI used First name of person receiving result for the INR calculation was Two patient identifiers Last name of person receiving result Patient reports were reviewed Title of person receiving result for correct INR calculations ID number of person receiving result How the INR calculation was Manually (hand calculated or Personnel authorized to receive outpatient and ED critical INR results (N ¼ 97) By INR instrument CAP proficiency testing Mid-level providers Other clinical staff Nonclinical staff Abbreviations: CAP, College of American Pathologists; INR, interna- Laboratory participated in INR performance tional normalized ratio; ISI, international sensitivity index; LIS, improvement project in previous 2 years laboratory information system.
a Data Innovations, South Burlington, Vermont.
Abbreviations: ED, emergency department; INR, international normal-ized ratio.
documentation verification errors. Ten errors consisted ofpatient reports that were not reviewed for the correct INR Improvement Program in the previous 2 years for INR calculation, followed by 5 errors in not documenting that the ISI was appropriate for the instrument reagent combination.
Table 6 shows reporting data from 2604 critical INR In 140 of 191 verifications (73.3%), the INR verification was patient specimen results from 97 institutions. Of the a manual, hand calculation, although in 27 laboratories reported results studied, 2431 (93.4%) were received within (14.1%) the instrument performing the INR measurement, the time frame specified by the institution, with 12 different or laboratory information system in 8 laboratories (4.2%), timeliness goals ranging from 0 to 120 minutes. Of the 173 was used for calculation verifications.
attempts (6.7%) that failed, 148 (5.7%) were not reportedwithin the time frame and 25 (1.0%) of all critical value Shown in Table 5 are surveys of the policies and results were not reported. In these 25 instances where the procedures used by participants to report INR critical values.
INR critical result was not reported, the reasons for failure There were 18 high critical value limits ranging from 2.6 to included the fact that the laboratory staff did not follow the 10.0, with 23 (24%) choosing 5.0; 22 (23%) choosing 4.0; critical value procedure (12 times, 52.2%) or did not and 10 (10%) choosing either 4.5 or 6.0. Eighty of 96 recognize the result as a critical value (2 times, 8.7%).
participants (83%) remeasured specimens with critical Complete reports containing all documentation elements as values before reporting them. The time required to report required in policies or procedures of the participating results was variable, with 34 (37%), 26 (28%), and 10 (14%) laboratories were present in 2386 reporting events participants allowing 60, 30, and 15 minutes, respectively.
(94.8%). In the 132 reports, 175 defective elements were Physicians and nurses were the personnel categories that found; the most common missing elements were read back, were authorized most frequently to receive results, and a which did not occur in 49 reports (37% of the time). The minority of participants participated in a Performance other frequent missing piece of documentation was the Arch Pathol Lab Med—Vol 139, September 2015 Q-Probes INR—Howanitz et al 1111 Table 6. Data From Participants' Review of Patient Table 8. Relationship Between Successful Critical International Normalized Ratio Results Communication of INR Critical Results and Resident Training Programs (P ¼ .03) Percentile Rate of Successful Result reported within the time frame Communication of INR Laboratory Trains established by laboratory (N ¼ 2604) Critical Resultsa Pathology Residents Result not reported Person accepting result was authorized by Abbreviation: INR, international normalized ratio.
policy to accept result (N ¼ 2599) a Higher percentiles indicate better relative performance.
Reason result not reported to, or accepted by, A landmark article by Olson and colleagues6 described caregiver (N ¼ 23) progress and problems associated with laboratory reporting Laboratory staff did not follow policy/ of the INR and also provided recommendations for changes Caregiver not reachable in INR laboratory practices to improve patient safety. To Laboratory staff did not recognize result as help improve patient safety and the precision and accuracy of the INR, the CAP LAP Checklist encompasses many of the suggestions made by Olson and colleagues6 on how INR All documentation elements required by measurements must occur. These requirements include the laboratory are present (N ¼ 2518) tube used for specimen collection, the use of geometric mean for INR calculations, the readjustment of the INR with every new lot of PT reagents, documentation that the ISI is Reports missing documentation elementsa (N appropriate for the PT reagent in use, and reviews of the patient reports for correct INR calculations when there is a change in the lot of PT reagents, instruments, a new Name of person receiving result reference range, or a change in the INR reagents.4 When our Missing result elements Title of person receiving result participants reviewed their INR policies or procedures for ID of person calling result these 5 specifics, they found them present in 90 to 97 of the Patient identifier 98 clinical laboratories (93% to 97%) sampled for each of ID of person receiving result these characteristics. Many institutions had even more detailed procedures such as the specific equation used to a Multiple elements missing on some reports.
calculate the INR and a required reverification of the INRafter an instrument repair or upgrades to the instrument.
name of the person receiving 38 reports (28.8%), followed Because PT INR is a test that has profound influence on closely by 37 failures (21.2%) to document the receiving patient care, 75 of 96 clinical laboratories (78%) had more person's title such as RN or MD.
than 1 instrument to perform these tests, assuring that the Percentile distributions seen in Table 7 for 2 quality laboratories would make important INR measurements for indicators were based upon requirements established by the patient care without delay. To make it easier to maintain CAP's LAP Hematology Checklist. Participants from 98 their instruments, almost all participants used the same lot institutions submitted 2604 INR critical results with 93% of of reagents on their primary and secondary instruments.
results reported within the time frame established by the Having additional instruments complicates testing, as laboratory. The rate of required INR validation elements instrument results must be compared at regular time ranged from 42.9% to 100.0% with a median rate of 100.0%.
intervals to assure that they are equivalent. Although there Table 8 indicates the statistical relationship between are no CAP LAP requirements for the frequency of INR successful communication of an INR critical result and the comparisons,4 routine laboratory practices for other labora- absence of a pathology residents or fellows training program tory tests require that comparisons of results among instruments occur every 6 months. Almost all laboratories Table 7. Percentile Distributions for 2 Quality Indicators All Institution Percentilesa Percentage of successfully communicated INR critical results to the responsible caregiver within the time frameestablished by the laboratory Percentage of required validation elements based on 2 most recent INR calculation events and laboratory policy/procedure review against required checklist elements Abbreviation: INR, international normalized ratio.
a Higher percentiles indicate better relative performance.
1112 Arch Pathol Lab Med—Vol 139, September 2015 Q-Probes INR—Howanitz et al compared results semiannually or more frequently. When unfortunate situation in a clinical laboratory in Philadelphia, results were compared among instruments in the same Pennsylvania, whereby 2146 patients' INR results were laboratory, there was little intralaboratory agreement of released when an incorrect ISI was used during a 7-week what precision specification was acceptable. In a minority of period for the INR reagents, causing the death of clinical laboratories the absolute difference in INR values patients.12,13 Other reports of patient injuries or deaths have was used, with most of these choosing up to 0.4 absolute resulted in recalls of INR reagents because of errors in units as acceptable. In contrast, in most clinical laboratories calculations of the ISI, the INR, or manufacturer errors.14–17 a percentage difference was used with the largest group Such reports support the meticulous performance of the INR choosing values within 10%.
and the need to follow CAP LAP guidelines.
The influence of the ISI on participant results was great, as The frequency and consequences of critical INR values there was more than a 2-fold difference in the activity of this make the critical values system a very important quality material among some of our participants. In 1998, Fair- attribute for clinical laboratories, their physicians, and weather and colleagues7 recommended that ISIs be between patients.18–20 We found clinical laboratory policies and 0.9 and 1.7, and between 1997 and 2003, the percentage of procedures of reporting critical value results highly variable.
users who had ISIs greater than 1.7 dropped from more than For example, the INR critical limit used ranged from 2.6 to 60% to 22%.6 Our data indicating that 6% of users have ISIs 10.0 with a median of 4.5, and there were 18 different limits, greater than 1.7 demonstrate that this percentage has with the most common limits being 5.0 (24%), 4.0 (23%), continued to decrease and manufacturers are close to 4.5 (10%), and 6.0 (10%). These results were similar to those achieving the 1998 recommendation.7 In addition, all ISIs found by Pai et al21 in a small sample of 21 specialized in our participants' INR test systems outside of the clinical hematology laboratories where the median INR limit was laboratory were below 1.7.
5.0 with a range of 2.0 to 6.0. Although the high critical In almost one-third of laboratories, INR testing was value limit varied from 2.6 to 10.0 in our study, it is unlikely performed in close proximity to patients in locations such as that the patient populations had a major influence on the anticoagulation clinics, satellite laboratories, physician office choice of the critical value limit because for most patient laboratories, and home health agencies; it is common conditions the INR target is 2.0 to 3.0. Exceptions include practice to use point-of-care testing with instruments that children with central venous access devices, with a require whole blood specimens rather than plasma speci- suggested INR target of 1.5 to 1.9; patients with acute deep mens for these types of testing locations. Karon and vein thrombosis, with a recommended target of 2.0 or colleagues,8 as well as others,9,10 have demonstrated that higher; and patients with mechanical aortic, mitral, or both marked differences in INR results occur between central aortic and mitral values, with a recommended INR target of laboratory and point-of-care instruments, and these biases among locations change over time, complicating physician The time required by participants for reporting of the INR interpretation of results.8 Hence, it is likely that the INR for critical values varied from 0 to 120 minutes. The employees most testing performed outside the clinical laboratory was receiving the results were almost always physicians, nurses, different from that of the clinical laboratory, requiring and mid-level providers such as nurse practitioners and additional education of physicians using this type of testing in addition to the INR testing performed in the central Despite The Joint Commission's National Patient Safety laboratory. A CAP LAP procedure for point-of-care devices Goals,22 and the CAP's Laboratory Patient Safety Goals,23 requires that when 2 or more devices are used for the same only 93.4% of the critical values were reported within the test, they must be checked against each other at least twice a clinical laboratories' required time, and 1.0% of the results year for correlation of results.11 were not delivered to the appropriate caregivers. Of the 25 Guyatt and colleagues3 have reviewed the INR therapeutic results that were not delivered, most were because of errors range and found that the same range may not be optimal for by laboratory staff in either failure to recognize the critical all indications. They also point out that an equally important result or failures to follow established polices for critical goal is that the INR targeted range be achieved promptly value notification. These easily can be improved, as and maintained. Key to maintaining accurate INR results knowledge of the clinical laboratory policies and the critical over time is that appropriate practices be applied when value limit can be achieved by persistent reinforcement and introducing new lots of reagents when current lots are thorough education of the clinical laboratory staff. Fully replaced. Review of the practices indicated that the change automated systems for notification of critical results can in reagent lots or types was the overwhelming reason why reduce the number of times physicians are unable to receive the INR calculation verifications were again performed, with results and are now being used in a few institutions.24,25 the routine check at a specific time interval the second most Documentation was defective in 6.7% of critical value calls common reason. Almost all calculation verifications (97%– with read back, the name of the person receiving the results, 99%) included an appropriateness check for the ISI, a the result elements, and the title of the person receiving the verification that the INR calculation was the ISI assigned, results not being recorded. These errors also can be reduced and a review of patient reports for correct INR calculations.
with re-education of both the laboratory staff and those Also, in more than half of the verifications, a change was approved to receive results about how important it is to required in the INR. The percentage of INRs that required a follow policies.
change in ISI appears low; however, approximately 45% of The one policy that was in need of improvement in many the INR calculations were performed because of routine laboratories was the use of 2 patient identifiers, used in only procedures, such as annual or scheduled checks, software 70% of laboratories. Safe laboratory practices require upgrades, or proficiency testing survey challenges, and these accurate patient identification; adverse events may occur most likely did not involve changes to the reagents or the when a patient has identifiers similar or identical to those of instrument performing the INR measurement. We suspect another patient (a ‘‘doppelg ¨anger''), when a patient is that many laboratorians remembered a well-publicized and doubly registered (a ‘‘duplicate registration''), or when Arch Pathol Lab Med—Vol 139, September 2015 Q-Probes INR—Howanitz et al 1113 registration details are derived from 2 or more separate sources (a ‘‘hybrid'' registration).26 Such errors, once Accessed May 24, 2014.
3. Guyatt GH, Akl EA, Crowther M, Gutterman DD, Sch¨unemann HJ.
thought of as coincidences, are in fact not extraordinary, Antithrombotic therapy and prevention of thrombosis 9th ed: American College but ordinary; 2 identifiers are required to reduce the chance of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(2)(suppl):7S–47S.
of an action occurring with an incorrect patient. We 4. College of American Pathologists. Hematology and Coagulation Checklist: recommend that similarly to phlebotomy practices, 2 patient College of American Pathologist Accreditation Program. Northfield, IL: College of identifiers be used to report critical values.
American Pathologists; 2013.
5. Howanitz PJ. Quality assurance measurements in the department of It is common for physicians in general practice to admit pathology and laboratory medicine. Arch Pathol Lab Med. 1990;114(11):1131– their patients to more than 1 hospital; for example, if physicians practice in hospitals that use the critical value 6. Olson JD, Brandt JT, Chandler WL, et al. Laboratory reporting of the international normalized ratio: progress and problems. Arch Path Lab Med. 2007; limit of 2.6 or 10.0, the physicians may quickly become confused by their expectation of when they will be called for 7. Fairweather RB, Ansell J, Anton MHP, et al. College of American a critical INR result. Efforts aimed at harmonizing results Pathologist Conference XXXI on laboratory monitoring of anticoagulant therapy.
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such as the critical value limits for the INR should be 8. Karon BS, McBane RD, Chaudhry R, Beyer LK, Santrach, PJ. Accuracy of encouraged, as it will lead to less confusion for busy capillary whole blood international normalized ratio on the CoaguChek S,CoaguChek XS, and i-STAT 1 point-of-care analyzers. Am J Clin Pathol. 2008; physicians treating patients at multiple institutions, all with different critical value limits. Such discussions have started 9. Sunderji R, Gin K, Shalansky K, et al. Clinical impact of point-of-care vs worldwide27 with recommendations by Kost and Hale28 laboratory measurement of anticoagulation. Am J Clin Pathol. 2005;123(2):184–188.
widely circulated. As a first step, we would recommend that 10. Shermock KM, Streiff MB, Pinto BL, Kraus P, Pronovost PJ. Novel analysis those with critical INR limits far from the median reconsider of clinically relevant diagnosis errors in point-of-care devices. J Thromb their limits and chose a limit closer to our median or to the 11. College of American Pathologists. Point of Care Checklist: A College of median described by Pai et al.21 American Pathologist Accreditation Program. Northfield, IL: College of American International normalized ratio is one of the most Pathologists; 2013.
important laboratory tests, as the reproducibility of the 12. Office of the Director, Division of Healthcare Quality Promotion, National Center for Infectious Diseases, CDC. Adverse events and deaths associated with result is one of the most important quality attributes of a laboratory errors at a hospital—Pennsylvania 2001. MMWR Morb Mortal Wkly clinical laboratory. Not only the usage is complex, but also the establishment and management of the test are unusual 13. Laboratory errors suspected as cause of two deaths: Warfarin is commonly associated with medication errors, and its appropriate use is an important for the clinical laboratory. The CAP requirements have been indicator of patient safety. Emerg Med News. 2002;24(6):58–59.
valuable in providing the best practices for the laboratories 14. Inside story. Indian Head Union Hospital coagulation testing error: update.
Regina Qu'Appelle Health Region. http://www.rqhealth.ca/inside/district_news/ they inspect, and the activities listed in the checklists are news_indianheadhospital_testingupdate.shtml. Accessed November 18, 2014.
implemented almost entirely within clinical laboratories.
15. Kocis PT, Liu G, Stipe TW, Zhu J, Reichwein RK. Comparison of the Abbott However, like all issues, there are some that must be i-STAT POC INR result with a corresponding venous INR result (12 monthsbefore/12 months after): the March 2012 Clew B23 software upgrade improved. Greater than 50% of participants were able to implementation. Thrombosis and Hemostasis Societies of North America.
communicate all their critical INR values within their timeliness goals, and more than 75% of laboratories had window¼yes&abstractno¼110. Accessed November 18, 2014.
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were not able to communicate all their critical INR values 19. Wagar EA, Stankovic AK, Wilkinson DS, Walsh M, Souers RJ. Assessment monitoring of laboratory critical values: a College of American Pathologists within their own timelines, and those laboratories that did Q-Tracks study of 180 institutions. Arch Pathol Lab Med. 2007;131(1):44–49.
not have the required checklist elements within their most 20. Lehman CM, Howanitz PJ, Souers R, Karcher DS. Utility of repeat testing of recent INR calculation verifications, although in the critical values: a Q-Probes analysis of 86 clinical laboratories. Arch Pathol LabMed. 2014;138(5):788–793.
minority, must improve their performance.
21. Pai M, Moffat KA, Plumhoff E, Hayward CPM. Critical values in the Although errors in the structure, process, and outcomes of coagulation laboratory: results of a survey of the North American Specialized INR results appeared to be fewer than for most laboratory Coagulation Laboratory Association. Am J Clin Pathol. 2011;136(6):836–841.
22. The Joint Commission. Preventing Errors Relating to Commonly Used tests, because of the criticality of the INR results, goals for all Anticoagulant: Sentinel Event Alert No. 41. Oakbrook Terrace, IL: The Joint aspects of this test must be at complete compliance; indeed, Commission; September 24, 2008.
23. College of American Pathologists. Patient safety. http://www.cap.org/apps// experience has shown that an error, such as not using the correct ISI, has resulted in the death of patients. Hence, until the INR is performed in an error-free environment, improvement must continue. To reach this goal, we suggest 24. Parl FF, O'Leary MF, Kaiser AB, Paulett JM, Statnikova K, Shultz EK.
that the clinical laboratory improvement programs include Implementation of a closed-loop reporting system for critical values and clinical evaluations of the INR performance so that INR results can communication in compliance with goals of The Joint Commission. Clin Chem.
be available error-free.
25. Piva E, Pelloso M, Penello L, Plebani M. Laboratory critical values: automated notification supports effective clinical decision making. Clin Biochem.
1. Moore TJ, Cohen MR, Furberg CD. Anticoagulants: the leading reported 26. Cummins D. Patient identification: hybrids and doppelg¨angers. Ann Clin drug risk in 2011. QuarterWatch 2012. Quarters 3–4: Institute for Safe Biochem. 2007;44(pt 2):106–110.
27. Campbell CA, Horvath AR. Harmonization of critical result management in cessed May 24, 2014.
laboratory medicine. Clin Chim Acta. 2014;432:135–147.
2. Moore TJ, Cohen MR, Furberg CD. Leading drug safety issues of 2012.
28. Kost G, Hale KN. Global trends in critical values practices and their QuarterWatch 2013. Data from 2012 Quarter 4 and Annual Report. Institute for harmonization. Clin Chem Lab Med. 2011;49(2):167–176.
1114 Arch Pathol Lab Med—Vol 139, September 2015 Q-Probes INR—Howanitz et al

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