Error identification in a high-volume clinical chemistry laboratory: Five-year experience

Total Clinical Chemistry Laboratory Errors and Evaluation of the Analytical Quality Control Using Sigma Metric for Routine Clinical Chemistry Tests

BACKGROUND

Currently, the use of clinical laboratory tests is growing at a promising rate and about 80% of the clinical decisions made are based on the laboratory test results. Therefore, it is a major task to achieve quality service. This study was conducted to assess the magnitude of errors in the total testing process of Clinical Chemistry Laboratory and to evaluate analytical quality control using sigma metrics.

METHODS

A cross-sectional study was conducted at Dessie Comprehensive Specialized Hospital Clinical Chemistry Laboratory, Northeast Ethiopia, from 10 February 2020 to 10 June 2020. All Clinical Chemistry Laboratory test requests with their respective samples, external quality control and all daily internal quality control data during the study period were included in the study. Data were collected using a prepared checklist and analyzed using SPSS version 21.

RESULTS

A total of 4719 blood samples with their test requests were included in the study. Out of 145,383 quality indicators, an error rate of 22,301 (15.3%) was identified in the total testing process. Of the total errors, 76.3% were pre-analytical, 2.1% were analytical and 21.6% were post-analytical errors (p<0.0001). Of the total 14 analytes in the sigma metric evaluation, except ALP, all routine clinical chemistry tests were below the standard (<3). In multivariate logistic regression, the location of patients in the inpatient department was significantly associated with the specimen rejection ((AOR=1.837, 95% CI (1.288-2.618), p=0.001).

CONCLUSION

The study found a higher frequency of errors in the total testing process in the Clinical Chemistry Laboratory and almost all test parameters had an unsatisfactory sigma metric value.

Heparin and citrate additive carryover during blood collection

Background Published evidence on the risk of additive carryover during phlebotomy remains elusive. We aimed to assess potential carryover of citrated and heparinized blood and the relative volume needed to bias clinical chemistry and coagulation tests. Methods We simulated standardized phlebotomies to quantify the risk of carryover of citrate and heparin additives in distilled water, using sodium and lithium as surrogates. We also investigated the effects of contamination of heparinized blood samples with increasing volumes of citrated blood and pure citrate on measurements of sodium, potassium, chloride, magnesium, total and ionized calcium and phosphate. Likewise, we studied the effects of contamination of citrated blood samples with increasing volumes of heparinized blood on heparin (anti-Xa) activity, lithium, activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT). We interpreted these results based on measurement deviations beyond analytical, biological and clinical significance. Results Standardized phlebotomy simulations revealed no significant differences in concentration of surrogate markers. Clinically significant alterations were observed after contamination of heparinized blood samples with volumes of citrated blood beyond 5-50 μL for ionized calcium and beyond 100-1000 μL for sodium, chloride and total calcium. Investigations of pure citrate carryover revealed similar results at somewhat lower volumes. Heparinized blood carryover showed clinically significant interference of coagulation testing at volumes beyond 5-100 μL. Conclusions Our results suggest that during a standardized phlebotomy, heparin or citrate contamination is highly unlikely. However, smaller volumes are sufficient to severely alter test results when deviating from phlebotomy guidelines.

European survey on preanalytical sample handling - Part 2: Practices of European laboratories on monitoring and processing haemolytic, icteric and lipemic samples. On behalf of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group for the Preanalytical Phase (WG-PRE)

Introduction

No guideline currently exists on how to detect or document haemolysis, icterus or lipemia (HIL) in blood samples, nor on subsequent use of this information. The EFLM WG-PRE has performed a survey for assessing current practices of European laboratories in HIL monitoring. This second part of two coherent articles is focused on HIL.

Materials and methods

An online survey, containing 39 questions on preanalytical issues, was disseminated among EFLM member countries. Seventeen questions exclusively focused on assessment, management and follow-up actions of HIL in routine blood samples.

Results

Overall, 1405 valid responses from 37 countries were received. A total of 1160 (86%) of all responders stating to analyse blood samples - monitored HIL. HIL was mostly checked in clinical chemistry samples and less frequently in those received for coagulation, therapeutic drug monitoring and serology/infectious disease testing. HIL detection by automatic HIL indices or visual inspection, along with haemolysis cut-offs definition, varied widely among responders. A quarter of responders performing automated HIL checks used internal quality controls. In haemolytic/icteric/lipemic samples, most responders (70%) only rejected HIL-sensitive parameters, whilst about 20% released all test results with general comments. Other responders did not analysed but rejected the entire sample, while some released all tests, without comments. Overall, 26% responders who monitored HIL were using this information for monitoring phlebotomy or sample transport quality.

Conclusion

Strategies for monitoring and treating haemolytic, icteric or lipemic samples are quite heterogeneous in Europe. The WG-PRE will use these insights for developing and providing recommendations aimed at harmonizing strategies across Europe.

A critical review of laboratory performance indicators

Healthcare budgets worldwide are under constant pressure to reduce costs while improving efficiency and quality. This phenomenon is also visible in clinical laboratories. Efficiency gains can be achieved by reducing the error rate and by improving the laboratory's layout and logistics. Performance indicators (PIs) play a crucial role in this process as they allow for performance assessment. This review aids in the process for selecting laboratory PIs-which is not trivial-by providing an overview of frequently used PIs in the literature that can also be used in clinical laboratories. We conducted a systematic review of the laboratory medicine literature on PIs. As the testing process in clinical laboratories can be viewed as a production process, we also reviewed the production processes literature on PIs. The reviewed literature relates to the design, optimization or performance assessment of such processes. The most frequently cited PIs relate to pre-analytical errors, timeliness, resource utilization, cost, and the amount of congestion. Their citation frequency in the literature is used as a proxy for their importance. PIs are discussed in terms of their definition, measurability and impact. The use of suitable PIs is crucial in production processes, including clinical laboratories. By also reviewing the production processes literature, additional relevant PIs for clinical laboratories were found. The PIs in the laboratory medicine literature mostly relate to laboratory errors, while the PIs in the production processes literature relate to the amount of congestion in the process.

Optimisation of perioperative investigations among elective orthopaedic patients in a Dublin-based teaching hospital

Background

The current National Institute for Health and Care Excellence guidelines, in accordance with the Association of Anaesthetists of Great Britain and Ireland guidelines, recommend the following haematological investigations for all patients undergoing major elective surgery: full blood count, renal profile and coagulation screen if clinically indicated. However, the guidelines fail to specify a time-interval for which normal blood results remain valid. Currently all patients in Ireland undergoing substantial elective surgery requiring general or regional anaesthetic have a preoperative assessment prior to the surgery. Patients have phlebotomy performed as part of this assessment. Patients admitted for elective surgery often have these bloods repeated on the morning of surgery.

Objectives

To determine if blood investigations taken over a one-year period prior to surgery can be used as a baseline for clinically stable patients undergoing elective surgery.

Study design and methods

All consecutive day of surgery admission patients >18 years of age undergoing elective orthopaedic surgery in Tallaght Hospital between 1 December 2014 and 1 December 2015 were identified using hospital records. Their blood results in the one-year period prior to surgery were compared to the blood results on the morning of surgery, using a McNemar’s test. A further clinical analysis was performed.

Results

There was no statistically significant change between blood results from three months prior to the surgery and the morning of surgery (P < 0.05). Furthermore, the blood results remained largely unchanged in the one year prior to surgery. No patient had the operation deferred due to aberrant blood results, following previously normal results prior to surgery. The potential cost-saving of omitting bloods is enormous.

Conclusions

There appears to be neither a statistical nor clinical benefit to repeating blood tests on the morning of surgery, following normal bloods <3 months in a clinically stable individual.

Performance evaluation of a coagulation laboratory using Sigma metrics

Purpose Two-thirds of medical decisions are based on laboratory test results. Therefore, laboratories should practice strict quality control (QC) measures. Traditional QC processes may not accurately reflect the magnitude of errors in clinical laboratories. Six Sigma is a statistical tool which provides opportunity to assess performance at the highest level of excellence. The purpose of this paper is to evaluate performance of the coagulation laboratory utilizing Sigma metrics as the highest level of quality. Design/methodology/approach Quality indicators of the coagulation laboratory from January 1, 2009, to December 31, 2015, were evaluated. These QIs were categorized into pre-analytical, analytical and post-analytical. Relative frequencies of errors were calculated and converted to Sigma scale to determine the extent of control over each process. The Sigma level of 4 was considered optimal performance. Findings During the study period, a total of 474,655 specimens were received and 890,535 analyses were performed. These include 831,760 (93.4 percent) routine and 58,775 (6.6 percent) special tests. Stat reporting was requested for 166,921 (18.7 percent). Of 7,535,146 total opportunities (sum of the total opportunities for all indicators), a total of 4,005 errors were detected. There were 2,350 (58.7 percent) pre-analytical, 11 (0.3 percent) analytical and 1,644 (41 percent) post-analytical errors. Average Sigma value obtained was 4.8 with 12 (80 percent) indicators achieving a Sigma value of 4. Three (20 percent) low-performance indicators were: unacceptable proficiency testing (3.8), failure to inform critical results (3.6) and delays in stat reporting (3.9). Practical implications This study shows that a small number of errors can decrease Sigma value to below acceptability limits. If clinical laboratories start using Sigma metrics for monitoring their performance, they can identify gaps in their performance more readily and hence can improve their performance and patient safety. Social implications This study provides an opportunity for the laboratorians to choose and set world-class goals while assessing their performance. Originality/value To the best of the authors' knowledge and belief, this study is the first of its kind that has utilized Sigma metrics as a QC tool for monitoring performance of a coagulation laboratory.