Patients as their own controls: use of the computer to identify "laboratory error".

I describe a system of quality control based on computer detection of changes in individual patient test results. This system, called "delta check," was used to follow all the tests performed by the clinical chemistry laboratory in a 1200-bed hospital. Analysis of 22 months' experience indicates that specimen misidentification is a serious problem in the clinical chemistry laboratory. Over a nine-month period, errors were most frequent in the results for total thyroxine, total calcium, and total protein. Instances of laboratory error detectable by the delta check system are not detected by other currently used methods of quality control. This system therefore appears to be a valuable asset to the clinical laboratory.     

Determining the utility of creatinine delta checks: A large retrospective analysis

IntroductionDelta checks are a long-standing practice for identifying errors in the laboratory. However, with the decrease in errors due to laboratory automation, their utility is unclear. The objective of this retrospective analysis was to determine whether establishment of a creatinine delta check would be an effective means for capturing true laboratory error.MethodsAll patients with a minimum of two creatinine results during March of 2015 were selected for review (n = 23,410 creatinine results). The lowest % change for a previously confirmed creatinine error in our laboratory was approximately 60%; therefore only results that changed by at least ±60% (n = 254) were reviewed. The etiology of creatinine value change was categorized as laboratory error, pathologic change, or non-pathologic change, based upon chart review.Results: 1.2% (3/254) of reviewed delta checks were determined to reflect 2 instances of true laboratory error that went unrecognized by laboratory staff. 91.3% (232/254) of the delta checks were determined to reflect a pathologic or dialysis-related change in creatinine levels. The remaining 7.5% of delta checks (19/234) were deemed to be non-pathologic changes in creatinine.DiscussionThis study identified two instances of laboratory error reflected by 3 delta checks (1.2%); the vast majority (91.3%) of creatinine results that changed by ±60% were pathologic or dialysis-related. Thus, establishment of a ±60% delta check for creatinine would overwhelmingly flag true biological change and would not be an efficient means for identifying rare laboratory errors. Clinical laboratories should perform similar retrospective analyses prior to enacting delta checks to determine whether they will effectively capture laboratory error.     

General prescribing principles. Supplementary prescribing: an overview

The independent prescriber (doctor) is responsible for the diagnosis and setting the parameters of the clinical management plan. The supplementary prescriber decides on the product, dosage, frequency, and other variables within the confines of the management plan. The patient's progress must be regularly reviewed by the independent prescriber. The independent prescriber may at any time review the patient's treatment and/or resume full responsibility for the patient's care. The independent and supplementary prescriber must share a common patient record. There must be a good working relationship between the prescribers. Nurse prescribers need to be clear at all times which prescribing regime they are working under--district nurse/health visitor prescriber, extended formulary nurse prescriber or supplementary prescriber.     

Assessing the effectiveness of critical pathways on reducing resource utilization in the surgical intensive care unit

OBJECTIVES: To evaluate the effectiveness of procedure-specific surgical critical pathways on reducing resource utilization in a university surgical intensive care unit (ICU). DESIGN AND SETTING: Prospective cohort study in a university surgical ICU. PATIENTS: 194 patients, accounting for 255 patient days, sampled on randomly selected days over a 12-month period of time. MEASUREMENTS AND RESULTS: The primary outcomes of this study were pathway eligibility and laboratory utilization. Patients were eligible for a procedure-specific pathway in 34% of patient days identified, and the patient's clinical course was "on" pathway in 22% of patient days. Of those "on" the pathway, 54% had a pathway present in the chart and 32% of these included documentation of the patient's clinical course. Thus in 78% of the patient days the patient was either not eligible for a critical pathway or the patient's clinical course was "off" pathway. In those patients "on" the pathway 46 % did not have a pathway present in the chart. Being on a critical pathway did not reduce laboratory utilization. Laboratory utilization did not vary between patients "on" and "off" the pathway (19.1 +/- 11.3 laboratory tests/patient day versus 20.4 +/- 5.7 laboratory tests/patient day). Predicted laboratory utilization by the pathway was 5.6 laboratory tests/patient day. By reducing actual laboratory utilization to that predicted by the critical pathway we would reduce laboratory utilization at our institution by $1.2 million per year. CONCLUSIONS: Procedure-specific surgical critical pathways are not an effective tool for reducing resource utilization in our ICU. Most of our patients were not eligible for an available pathway, and those who were eligible and were "on" the pathway did not appear to have laboratory utilization guided by the pathway. Future initiatives need to explore other means such as ICU-specific care processes to reduce resource utilization in the ICU.     

University of Virginia case conference. Macroamylase, macro creatine kinase, and other macroenzymes

The importance of macroenzymes has become increasingly apparent in recent years (1,2). Macroamylase (EC 3.2.1.1) and macro CK (EC 2.7.3.2) are the macroenzymes most commonly noted in the clinical laboratory, and they are frequently responsible for diagnostic confusion. Several methods are available for the confirmation and analysis of macroenzymes, many of which require expensive equipment or complicated techniques. In this report we summarize two cases of macro creatine kinase and two cases of macroamylase that illustrate the clinical importance of recognizing these macroenzymes. We review the features of these macroenzymes, discuss their laboratory evaluation, and describe a simple method that we have used to detect the macroenzymes in these (and other) patients at our institution. Finally, we review the literature on other, less commonly observed macroenzymes in human blood. We stress (a) the impact of methodology on clinical impressions and (b) the importance of discussing laboratory observations with the patient's physician and communicating them to the patient's medical record in writing.     

Autoverification of test results in the core clinical laboratory

Verification of laboratory test results represents the last opportunity to identify errors before they become part of the electronic medical record. Manual verification of test results places significant reliance on the experience and attentiveness of individual observers to identify errors and is vulnerable to errors through omission and neglect. Peer-reviewed publications have documented gains in process efficiency and quality improvement by use of middleware or laboratory information systems to autoverify test results based on pre-defined acceptability criteria. This review evaluates the acceptability of autoverification (AV) as a safe and reliable alternative to total manual review of laboratory test results. AV schemes developed in accordance with international guidelines and standards are applied throughout the laboratory. Careful design of AV systems involves using multidisciplinary teams to develop test-specific decision algorithms, to assist with programming, to verify programming, and validate programmed algorithms prior to use in evaluation of patient test result profiles. Development of test specific decision algorithms makes use of criteria based on instrument messages and flags, quality control status, result limit checks, delta checks, critical values, consistency checks, and patient-related clinical information. Monitoring of the performance of AV parameters, and regular audits of the AV system integrity is recommended in both the literature and guidelines. The potential for gains to process efficiency, error detection and patient safety, through adoption of AV as part of a laboratories quality assurance tool-case, is well supported in published literature.     

Simulations of delta check rule performance to detect specimen mislabeling using historical laboratory data

BackgroundDespite their widespread use, the performance of delta check rules is rarely evaluated because errors are rare and lack a gold standard for detection. In this study we used a simulation-based approach to compare strategies for empirically defining criteria for univariate delta checks, and assessed the performance of these rules for detecting mislabeled specimens in 2 inpatient populations.MethodsWe performed simulations using historical laboratory test results by randomly sampling pairs of specimens successively drawn from the same patient or two different patients. We evaluated the performance of delta check rules using a variety of thresholds, including those currently in use in our laboratory.ResultMean corpuscular volume had the highest positive predictive value for specimen mislabeling, and produced the fewest false positives. Conversely, rules using other laboratory tests had considerably poorer performance. Several of the “best guess” thresholds historically used in our laboratory, notably those for potassium and anion gap, were predicted to have extremely low yields. In addition, rule performance was not consistent between the two patient populations.ConclusionsThe low yield of delta checks based on any single analyte should prompt careful evaluation of their practical utility. Furthermore, our results indicate that it may not be possible to generalize delta rules across institutions.     

Documenting patients' end-of-life decisions

The anguish families experience when they are asked to make health care decisions for incompetent members has stimulated the search for an adequate procedure to document patients' end-of-life decisions. This study explores a method of recording competent patients' wishes via a "value history," a questionnaire that can guide families and the health care team during an incompetent person's terminal illness. Questions addressed were these: Can a primary care physician gather information from competent patients about their care before they become incompetent? Can a nurse practitioner gather the information as efficiently as a physician? Do patients want this information recorded in their charts? and, Is the primary care office as well as the patient's home an appropriate location to obtain a value history? Four hundred patients were invited to record their wishes for future care. Patients expressed that they wanted to be told the truth about their health and their health care, and they wanted to participate in decision-making, even while dying. The majority did not want to be maintained indefinitely on life-support systems. Patient responses were similar regardless of whether the NP or physician conducted the interview. A primary care office or patient's home are both suitable for filling out the value history. Because of the enthusiastic patient responses, the authors recommend that value histories become a routine part of a patient's medical record.     

Application and optimization of reference change values for Delta Checks in clinical laboratory

BackgroundDelta check is a patient‐based QC tool for detecting errors by comparing current and previous test results of patient. Reference change value (RCV) is adopted in guidelines as method for delta check, but the performance is not verified. We applied RCV‐based delta check method to patients'' data and modified for application.Materials and methodsReference change value were calculated using results of internal QC materials and biological variation data. Test results of 17 analytes in inpatients, outpatients, and health examination recipients were collected. The detection rates of currently used delta check method and those of RCV‐based method were compared, and the methods were modified.ResultsReference change value‐based method had higher detection rates compared to conventional method. Applied modifications reduced detection rates. Removing the pairs of results within reference interval reduced detection rates (0.42% ~ 10.92%). When RCV was divided by time interval, the detection rates were similar to prior rates in outpatients (0.19% ~ 1.34%). Using RCV multiplied by twice the upper limit of reference value as cutoff reduced the detection rate (0.07% ~ 1.58%).ConclusionsReference change value is a robust criterion for delta check and included in clinical laboratory practice guideline. However, RCV‐based method generates high detection rates which increase workload. It needs modification for use in clinical laboratories.     

Intraoperative thyroid storm: a case report

An 18-year-old woman being treated for Graves disease underwent elective thyroidectomy. Tachycardia was noted before surgery. The patient's heart rate and temperature started to rise 30 minutes into surgery. Malignant hyperthermia was excluded on clinical grounds, and treatment with beta blockers was started. The patient's conditions stabilized, and surgery was completed. A review of the patient's laboratory test results revealed a high free thyroxine level before surgery. Diagnosis and management of thyroid storm are discussed.     

Discussion between reviewers does not improve reliability of peer review of hospital quality

OBJECTIVES: Peer review is used to make final judgments about quality of care in many quality assurance activities. To overcome the low reliability of peer review, discussion between several reviewers is often recommended to point out overlooked information or allow for reconsideration of opinions and thus improve reliability. The authors assessed the impact of discussion between 2 reviewers on the reliability of peer review. METHODS: A group of 13 board-certified physicians completed a total of 741 structured implicit record reviews of 95 records for patients who experienced severe adverse events related to laboratory abnormalities while in the hospital (hypokalemia, hyperkalemia, renal failure, hyponatremia, and digoxin toxicity). They independently assessed the degree to which each adverse event was caused by medical care and the quality of the care leading up to the adverse event. Working in pairs, they then discussed differences of opinion, clarified factual discrepancies, and rerated the record. The authors compared the reliability of each measure before and after discussion, and between and within pairs of reviewers, using the intraclass correlation coefficient for continuous ratings and the kappa statistic for a dichotomized rating. RESULTS: The assessment of whether the laboratory abnormality was iatrogenic had a reliability of 0.46 before discussion and 0.71 after discussion between paired reviewers, indicating considerably improved agreement between the members of a pair. However, across reviewer pairs, the reviewer reliability was 0.36 before discussion and 0.40 after discussion. Similarly, for the rating of overall quality of care, reliability of physician review went from 0.35 before discussion to 0.58 after discussion as assessed by pair. However, across pairs the reliability increased only from 0.14 to 0.17. Even for prediscussion ratings, reliability was substantially higher between 2 members of a pair than across pairs, suggesting that reviewers who work in pairs learn to be more consistent with each other even before discussion, but this consistency also did not improve overall reliability across pairs. CONCLUSIONS: When 2 physicians discuss a record that they are reviewing, it substantially improves the agreement between those 2 physicians. However, this improvement is illusory, as discussion does not improve the overall reliability as assessed by examining the reliability between physicians who were part of different discussions. This finding may also have implications with regard to how disagreements are resolved on consensus panels, guideline committees, and reviews of literature quality for meta-analyses.     

Trauma care documentation: a comprehensive guide

The medical record serves numerous functions. It provides chronologic evidence of patient evaluation, treatment, and response to therapy, and a means to review the quality of the care. Communication among members of the health care team regarding the patient's status and plan of care also occurs by means of the medical record. The medical and legal importance of a comprehensive, accurate trauma resuscitation record cannot be overemphasized. The success of this type of documentation will depend on the design of the record and the understanding of the personnel involved. In addition, nursing managers responsible for the fiscal accountability of their departments understand the value of accurate documentation. The trauma resuscitation record can be used to demonstrate to insurance companies the reason for charging trauma patients additional fees. Inadequate documentation can cause charges to be disallowed by the third-party payors. Perhaps one of the most important functions of the medical record is to assist in protecting the legal interest of the patient and the health care provider. Minimum documentation for care provided in the emergency department must include patient identification, how the patient arrived, care that was rendered before arrival, pertinent history, chronologic notation of results of physical examination including vital signs, and the results of diagnostic and therapeutic procedures and tests. The physician's orders and diagnostic impression should be recorded. It is important that the patient's response to the interventions, not just the intervention itself, be described. The patient's disposition and condition on discharge from the emergency department must be documented. For the trauma patient, mechanisms of injury, GCS, trauma score (or essential components), spinal immobilization, and the status of airway, breathing, and circulatory systems also must be recorded. The importance of accurate and comprehensive documentation on every medical record should not be underestimated. (National Standards of Emergency Nursing Practice dictate that nurses are responsible for the accurate documentation of patient care.) The medical record provides both important information about the patient's clinical condition and the corner-stone for lawsuits in alleged medical negligence. It is the legal documentation of ongoing patient care delivery and the chronicle of the patient's responses to therapeutic interventions.     

The degree of abdominal imaging (AI) subspecialization of the reviewing radiologist significantly impacts the number of clinically relevant and incidental discrepancies identified during peer review of emergency after-hours body CT studies

Purpose

To evaluate if and to what extent the degree of subspecialization in abdominal imaging (AI) affects rates of discrepancies identified on review of body CT studies initially interpreted by board-certified radiologists not specialized in AI.

Method and Materials

AI division radiologists at one academic medical center were classified as primary or secondary members of the division based on whether they perform more or less than 50% of their clinical duties in AI. Primary AI division radiologists were further subdivided based on whether or not they focus their clinical duties almost exclusively in AI. All AI radiologists performed subspecialty review of all after-hours body CT studies initially interpreted by any non-division radiologist. The discrepancies identified in the subspecialty review of consecutive after-hours body CT scans performed between 7/1/10 and 12/31/10 were analyzed and placed into one of three categories: (1) discrepancies that potentially affect patient care (“clinically relevant discrepancies”, or CRD); (2) discrepancies that would not affect patient care (“incidental discrepancies”, or ID); and (3) other types of comments. Rates of CRD and ID detection were compared between subgroups of Abdominal Imaging Division radiologists divided by the degree of subspecialization.

Results

1303 studies met the inclusion criteria. Of 742 cases reviewed by primary members of the AI division, 33 (4.4%) had CRD and 78 (10.5%) had ID. Of 561 cases reviewed by secondary members of the AI division, 11 (2.0%) had CRD and 36 (6.5%) had ID. The differences between the groups for both types of discrepancies were statistically significant (p = 0.01). When primary members of the AI division were further subdivided based on extent of clinical focus on abdominal imaging, rates of CRD and ID detection were higher for the subgroup with more clinical focus on abdominal imaging.

Conclusion

The degree of AI subspecialization affects the rate of clinically relevant and ID identified in body CT interpretations initially rendered by board certified but non-abdominal imaging subspecialized radiologists.     

Computerized clinical decision-support in respiratory care

Computers were initially used in health care for billing and administrative functions. More recently computers have been used to present clinical information such as laboratory results and pharmacy orders. Many medical informatics researchers believe that the ultimate goal of the "electronic health record" should be to advance computerized clinical decision-support. This report considers the challenges of developing electronic-health-record systems and integrating them into useful computerized decision-support systems and presents a "pyramid of progress" concept that involves 5 steps: (1) to gather electronic health data into a standardized and coded format, (2) to validate the quality of that electronic health data, (3) to optimize presentation of electronic health data and explore computerized decision-support, (4) to develop and share computerized knowledge bases that are based on clinical evidence as well as consensus, and (5) to tailor and to implement the computerized strategies so that they fit into the workflow process of patient care. This report discusses 3 examples of successful computerized clinical decision-support (use of antibiotics, laboratory alerting, and ventilator management) and discusses strategies essential to making computerized clinical decision-support more widely available and useful.     

Problems in interpreting laboratory tests. What do unexpected results mean?

It is always important that physicians not overreact to apparently abnormal laboratory values by undertaking inappropriate further investigations or clinical treatments. When confronted with unexpected differing test results from repeat testing in the same individual, physicians should be aware of explanations other than laboratory error and change in the patient's clinical status. While test-related variables may be factors, intraindividual biologic variation is much more common and may be the explanation for discrepant results. For this reason, physicians need to know which laboratory tests are associated with significant intraindividual biologic variation as well as the magnitude of possible changes. Age-associated physiologic changes may significantly alter certain laboratory values in the elderly without constituting a pathologic process. Laboratory values that may appear abnormal in 10% or more of the healthy elderly without necessarily representing a pathologic process include serum alkaline phosphatase, fasting blood glucose, 2-hour postprandial glucose, erythrocyte sedimentation rate, hemoglobin, and a normal serum creatinine level in the face of a markedly decreased creatinine clearance. To ensure proper assessment of the geriatic patient, the clinician needs to be aware of these age-related changes and possible effects on laboratory values. More clinical research is needed to establish appropriate reference ranges, especially for those over the age of 75 years.     

A model to establish autoverification in the clinical laboratory

ObjectivesAutoverification is the process of evaluating and validating laboratory results using predefined computer-based algorithms without human interaction. By using autoverification, all reports are validated according to the standard evaluation criteria with predefined rules, and the number of reports per laboratory specialist is reduced. However, creating and validating these rules are the most demanding steps for setting up an autoverification system. In this study, we aimed to develop a model for helping users establish autoverification rules and evaluate their validity and performance.Design & methodsThe proposed model was established by analyzing white papers, previous study results, and national/international guidelines. An autoverification software (myODS) was developed to create rules according to the model and to evaluate the rules and autoverification rates. The simulation results that were produced by the software were used to demonstrate that the determined framework works as expected. Both autoverification rates and step-based evaluations were performed using actual patient results. Two algorithms defined according to delta check usage (Algorithm A and B) and three review limits were used for the evaluation.ResultsSix hundred seventeen rules were created according to the proposed model. 1,976 simulation results were created for validation. Our results showed that manual review limits are the most critical step in determining the autoverification rate, and delta check evaluation is especially important for evaluating inpatients. Algorithm B, which includes consecutive delta check evaluation, had higher AV rates.ConclusionsSystemic rule formation is a critical factor for successful AV. Our proposed model can help laboratories establish and evaluate autoverification systems. Rules created according to this model could be used as a starting point for different test groups.     

Rate and delta checks compared for selected chemistry tests

We compared delta and "rate" check methods for 12 selected chemistry tests. Rate checks were determined by dividing delta checks by inter-specimen interval time. The delta and rate check methods were based on differences and percent change of untransformed and absolute value-transformed values. The distribution of delta differences was not symmetrical for calcium, alkaline phosphatase, aspartate aminotransferase, or phosphorus, which led to different check limits between untransformed and absolute value-transformed methods. The dispersion of rate checks was large. The interval time between two consecutive tests was multimodal, which probably reflected adherence to fixed testing protocols.     

Thymic origin of embryonic intestinal gamma/delta T cells

Current evidence suggests both thymic and extrathymic origins for T cells. Studies in mice favor an in situ origin for a prominent population of intestinal intraepithelial lymphocytes that express gamma/delta T cell receptor (TCR). This developmental issue is explored in an avian model in which the gamma/delta lymphocytes constitute a major T cell subpopulation that is accessible for study during the earliest stages of lymphocyte development. In the chick embryo, cells bearing the gamma/delta TCR appear first in the thymus where they reach peak levels on days 14-15 of embryogenesis, just 2 d before gamma/delta T cells appear in the intestine. Using two congenic chick strains, one of which expresses the ov antigen, we studied the origin and kinetics of intestinal colonization by gamma/delta T cells. The embryonic gamma/delta+ thymocytes homed to the intestine where they survived for months, whereas an embryonic gamma/delta- thymocyte population enriched in thymocyte precursors failed to give rise to intestinal gamma/delta+ T cells. Embryonic hemopoietic tissues, bone marrow, and spleen, were also ineffective sources for intestinal gamma/delta+ T cells. Intestinal colonization by gamma/delta+ thymocytes occurred in two discrete waves in embryos and newly hatched birds. The data indicate that intestinal gamma/delta T cells in the chicken are primarily thymic migrants that are relatively long-lived.     

Retrograde transvenous perfusion

Serious consequences of stroke dictate that new approaches to the treatment of stroke be investigated. We have developed a method for perfusing the patient's own arterial blood retrograde through the venous system to ischemic brain tissue. This treatment has proven beneficial in preventing and reversing serious injury in the laboratory and in a small clinical trial. The laboratory investigation has also demonstrated that this therapy, retrograde transvenous neuroperfusion, can be coupled with hypothermia to potentially increase its benefit. History, experimental development, and the clinical trial are reviewed in this article.