Quality control in the Netherlands; todays practices and starting points for guidance and future research.

OBJECTIVES: Adequate analytical quality of reported results is primarily ensured by performing internal quality control (iQC). Currently, several different iQC practices are in use. As a prelude to the revision of a Dutch guidance document on analytical QC, a questionnaire was sent out to gain insights in the applied practices and the need for guidance. METHODS: A questionnaire, containing 20 multiple-choice questions with possibilities for explanation and comment on iQC practices and aspects was distributed to all clinical chemistry laboratories within the Netherlands. Results were reported descriptively. RESULTS: Responses were received from 27 clinical laboratories (response 43 %). In 30 % the iQC was based on the analytical characteristics only, while 30 % used a 6-Sigma method, 19 % risk-based beyond 6-Sigma and 22 % used an alternative approach. 89 % of laboratories used a virtual analyzer model for iQC setup within one or more laboratory sites. Practices for determining standard deviation (SD) values included determining SD for each new iQC material (35 %), using historical SD values for new materials (35 %), and incorporating clinical tolerances into the SD value (31 %). Furthermore, 44 % of laboratories used patient moving averages for one or more tests. Daily iQC management was based on either "traffic lights" indicating in or out of control status, and review of all QC charts, often using multiple software systems. CONCLUSIONS: A large heterogeneity of iQC practices in clinical laboratories was observed in the Netherlands. Several starting points for further research and/or guidance were identified, particularly in relation to the determination of SD values, the virtual analyzer model and methods to ensure analyzer equivalence.

An LC-MS/MS-based method for the simultaneous quantification of melatonin, cortisol and cortisone in saliva.

Disturbances in the diurnal pattern are associated with several clinical and psychological conditions, including depression and fatigue. Salivary sampling for melatonin, cortisol and cortisone provides a non-invasive method for frequent sampling and obtaining biochemical insight into the diurnal pattern of individuals. Therefore, a new liquid chromatography-tandem mass spectrometry-based method for the measurement of salivary melatonin, cortisol and cortisone was developed and validated. The method required 250 µl saliva, used isotope dilution methodology and was based on a liquid-liquid extraction for sample preparation, reversed-phase chromatography and multiple reaction monitoring on a mass spectrometer for quantitation. The lower limits of quantification obtained were 0.010 nmol/L for melatonin, 0.5 nmol/L for cortisol and 1.00 nmol/L for cortisone and the limits of detection were 0.003 nmol/L, 0.15 nmol/L and 0.1 nmol/L respectively. The method imprecision was ≤14% for all measurands, and the method comparison showed highly comparable results with high correlation coefficients (all ≥0.964). Potential interference of cortisol and cortisone by prednisolone was observed and could be detected by chromatogram review. Typical diurnal patterns for melatonin, cortisol and cortisone were observed in the saliva of 20 cancer survivors who collected saliva throughout the day.

Lung cancer tumor marker analysis: A clinical laboratory perspective.

 Clinical laboratories are responsible for performing lung cancer tumor marker testing as part of routine clinical care. It is their responsibility to guarantee that the reported tumor marker results are reliable and meet the necessary quality standards for proper clinical use. During the different laboratory phases, pre-analytical, analytical and post-analytical, specific steps and processes can introduce errors and generate incorrect clinical interpretation. This editorial briefly outlines critical laboratory issues related to lung cancer tumor markers, specific for each of these three laboratory phases.

Lung cancer biomarkers: Raising the clinical value of the classical and the new ones.

Blood-based diagnostics for lung cancer support the diagnosis, estimation of prognosis, prediction, and monitoring of therapy response in lung cancer patients. The clinical utility of serum tumor markers has considerably increased due to developments in serum protein tumor markers analytics and clinical biomarker studies, the exploration of preanalytical and influencing conditions, the interpretation of biomarker combinations and individual biomarker kinetics, as well as the implementation of biostatistical models. In addition, circulating tumor DNA (ctDNA) and other liquid biopsy markers are playing an increasingly prominent role in the molecular tumor characterization and the monitoring of tumor evolution over time. Thus, modern lung cancer biomarkers may considerably contribute to an individualized companion diagnostics and provide a sensitive guidance for patients throughout the course of their disease. In this special edition on Tumor Markers in Lung Cancer, experts summarize recent developments in clinical laboratory diagnostics of lung cancer and give an outlook on future challenges and opportunities.

Investigating the Current Harmonization Status of Tumor Markers Using Global External Quality Assessment Programs: A Feasibility Study.

BACKGROUND: The harmonization status of most tumor markers (TMs) is unknown. We report a feasibility study performed to determine whether external quality assessment (EQA) programs can be used to obtain insights into the current harmonization status of the tumor markers α-fetoprotein (AFP), prostate specific antigen (PSA), carcinoembryonic antigen (CEA), cancer antigen (CA)125, CA15-3 and CA19-9. METHODS: EQA sample results provided by 6 EQA providers (INSTAND [Germany], Korean Association of External Quality Assessment Service [KEQAS, South Korea], National Center for Clinical Laboratories [NCCL, China], United Kingdom National External Quality Assessment Service [UK NEQAS, United Kingdom], Stichting Kwaliteitsbewaking Medische Laboratoriumdiagnostiek [SKML, the Netherlands], and the Royal College of Pathologists of Australasia Quality Assurance Programs [RCPAQAP, Australia]) between 2020 and 2021 were used. The consensus means, calculated from the measurement procedures present in all EQA programs (Abbott Alinity, Beckman Coulter DxI, Roche Cobas, and Siemens Atellica), was used as reference values. Per measurement procedure, the relative difference between consensus mean for each EQA sample and the mean of all patient-pool-based EQA samples were calculated and compared to minimum, desirable, and optimal allowable bias criteria based on biological variation. RESULTS: Between 19040 (CA15-3) and 25398 (PSA) individual results and 56 (PSA) to 76 (AFP) unique EQA samples were included in the final analysis. The mean differences with the consensus mean of patient-pool-based EQA samples for all measurement procedures were within the optimum bias criterion for AFP, the desirable bias for PSA, and the minimum bias criterion for CEA. However, CEA results <8 µg/L exceeded the minimum bias criterion. For CA125, CA15-3, and CA19-9, the harmonization status was outside the minimum bias criterion, with systematic differences identified. CONCLUSIONS: This study provides relevant information about the current harmonization status of 6 tumor markers. A pilot harmonization investigation for CEA, CA125, CA15-3, and CA19-9 would be desirable.

Clinical perspectives on serum tumor marker use in predicting prognosis and treatment response in advanced non-small cell lung cancer.

The optimal positioning and usage of serum tumor markers (STMs) in advanced non-small cell lung cancer (NSCLC) care is still unclear. This review aimed to provide an overview of the potential use and value of STMs in routine advanced NSCLC care for the prediction of prognosis and treatment response. Radiological imaging and clinical symptoms have shown not to capture a patient's entire disease status in daily clinical practice. Since STM measurements allow for a rapid, minimally invasive, and safe evaluation of the patient's tumor status in real time, STMs can be used as companion decision-making support tools before start and during treatment. To overcome the limited sensitivity and specificity associated with the use of STMs, tests should only be applied in specific subgroups of patients and different test characteristics should be defined per clinical context in order to answer different clinical questions. The same approach can similarly be relevant when developing clinical applications for other (circulating) biomarkers. Future research should focus on the approaches described in this review to achieve STM test implementation in advanced NSCLC care.

Pre-analytical stability of the CEA, CYFRA 21.1, NSE, CA125 and HE4 tumor markers.

BACKGROUND: For lung cancer, circulating tumor markers (TM) are available to guide clinical treatment decisions. To ensure adequate accuracy, pre-analytical instabilities need to be known and addressed in the pre-analytical laboratory protocols. OBJECTIVE: This study investigates the pre-analytical stability of CA125, CEA, CYFRA 21.1, HE4 and NSE for the following pre-analytical variables and procedures; i) whole blood stability, ii) serum freeze-thaw cycles, iii) electric vibration mixing and iv) serum storage at different temperatures. METHODS: Left-over patient samples were used and for every investigated variable six patient samples were used and analysed in duplicate. Acceptance criteria were based on analytical performance specifications based on biological variation and significant differences with baseline. RESULTS: Whole blood was stable for at least 6 hours for all TM except for NSE. Two freeze-thaw cycles were acceptable for all TM except CYFRA 21.1. Electric vibration mixing was allowed for all TM except for CYFRA 21.1. Serum stability at 4°C was 7 days for CEA, CA125, CYFRA 21.1 and HE4 and 4 hours for NSE. CONCLUSIONS: Critical pre-analytical processing step conditions were identified that, if not taken into account, will result in reporting of erroneous TM results.

Comparing modeling strategies combining changes in multiple serum tumor biomarkers for early prediction of immunotherapy non-response in non-small cell lung cancer.

BACKGROUND: Patients treated with immune checkpoint inhibitors (ICI) are at risk of adverse events (AEs) even though not all patients will benefit. Serum tumor markers (STMs) are known to reflect tumor activity and might therefore be useful to predict response, guide treatment decisions and thereby prevent AEs. OBJECTIVE: This study aims to compare a range of prediction methods to predict non-response using multiple sequentially measured STMs. METHODS: Nine prediction models were compared to predict treatment non-response at 6-months (n = 412) using bi-weekly CYFRA, CEA, CA-125, NSE, and SCC measurements determined in the first 6-weeks of therapy. All methods were applied to six different biomarker combinations including two to five STMs. Model performance was assessed based on sensitivity, while model training aimed at 95% specificity to ensure a low false-positive rate. RESULTS: In the validation cohort, boosting provided the highest sensitivity at a fixed specificity across most STM combinations (12.9% -59.4%). Boosting applied to CYFRA and CEA achieved the highest sensitivity on the validation data while maintaining a specificity >95%. CONCLUSIONS: Non-response in NSCLC patients treated with ICIs can be predicted with a specificity >95% by combining multiple sequentially measured STMs in a prediction model. Clinical use is subject to further external validation.

Advances in clinical chemistry patient-based real-time quality control (PBRTQC).

Patient-Based Real-Time Quality Control involves monitoring an assay using patient samples rather than external material. If the patient population does not change, then a shift in the long-term assay population results represents the introduction of a change in the assay. The advantages of this approach are that the sample(s) are commutable, it is inexpensive, the rules are simple to interpret and there is virtually continuous monitoring of the assay. The disadvantages are that the laboratory needs to understand their patient population and how they may change during the day, week or year and the initial change of mindset required to adopt the system. The concept is not new, having been used since the 1960s and widely adopted on hematology analyzers in the mid-1970s. It was not widely used in clinical chemistry as there were other stable quality control materials available. However, the limitations of conventional quality control approaches have become more evident. There is a greater understanding of how to collect and use patient data in real time and a range of powerful algorithms which can identify changes in assays. There are more assays on more samples being run. There is also a greater interest in providing a theoretical basis for the validation and integration of these techniques into routine practice.

Self-sampling of blood using a topper and pediatric tubes; a prospective feasibility study for PSA analysis using 120 prostate cancer patients.

OBJECTIVES: Self-collection of blood for diagnostic purposes by blood collection assist devices (BCAD) has gained a lot of momentum. Nonetheless, there are a lack of studies demonstrating the feasibility and reliability of self-collecting capillary blood for routine (immuno)chemistry testing. In this study we describe the topper technology together with pediatric tubes to enable self-collection of blood and investigated its feasibility for PSA testing by prostate cancer patients. METHODS: A total of 120 prostate cancer patients for which a routine follow-up PSA test was requested, were included in this study. Patients received instruction materials and the blood-collection device consisting of a topper, pediatric tube and base-part, and performed the blood collection procedure themselves. Afterwards a questionnaire was filled-in. Finally, PSA was measured on a Roche Cobas Pro. RESULTS: The overall self-sampling success rate was 86.7 %. Furthermore, when specified per age category, a 94.7 % success rate for patients under 70 years and a 25 % success rate for patients of 80 years and older was observed. Venous and self-collected PSA were highly comparable when analyzed by Passing-Bablok regression with a slope of 0.99 and intercept of 0.00011, Spearmans correlation coefficient (0.998) and average self-collected PSA recovery of 99.8 %. CONCLUSIONS: Evidence is presented that self-collected capillary blood by topper and pediatric tube from the finger is feasible, particularly for patients under 70 years. Furthermore, capillary blood self-sampling did not compromise any of the PSA test results. Future validation in a real-world setting, without supervision and including sample stability and logistics, is required.

Clinical value of preoperative serum tumor markers CEA, CA19-9, CA125, and CA15-3 in surgically treated urachal cancer.

INTRODUCTION: Urachal adenocarcinoma (UrAC) is a very rare malignancy with a poor prognosis. The role of preoperative serum tumor markers (STMs) in UrAC is unknown. The aim of this study was to assess the clinical value of elevated STMs including carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), cancer antigen 125 (CA125), and cancer antigen 15-3 (CA15-3) in surgically treated UrAC, and to evaluate their prognostic significance. METHODS: This was a retrospective study of consecutive patients with histopathologically confirmed UrAC who underwent surgical treatment at a single tertiary hospital. Blood levels of CEA, CA19-9, CA125, and CA15-3 were determined before surgery. The proportion of patients with elevated STMs was calculated, as well as the association between elevated STMs and clinicopathological characteristics, recurrence-free survival and disease-specific survival. RESULTS: Of the 50 patients included; CEA, CA 19-9, CA125, and CA15-3 were elevated in 40%, 25%, 26%, and 6% respectively. Elevated CEA was associated with higher pT-stage (odds ratio [OR] 3.3 [95% confidence interval 1.0-11.1], P = 0.003), higher Sheldon stage (OR 6.9 [95% CI 0.8-60.4], P = 0.01), male sex (OR 4.7 [95% CI 1.2-18.3], P = 0.01), and the presence of peritoneal metastases at the time of diagnosis (OR 3.5 [95% CI 0.9-14.2], P = 0.04). Elevated CA19-9 was associated with signet-cell component (OR 1.7 [95% CI 0.9-3.3], P = 0.03) and elevated CA125 was associated with peritoneal metastases at the time of diagnosis (OR 6.0 [95% CI 1.2-30.6], P = 0.04). Elevated STMs before surgery were not associated with recurrence-free survival and/or disease-specific survival. CONCLUSION: A subset of patients with surgically treated UrAC has elevated STMs preoperatively. CEA was most frequently (40%) elevated and correlated with unfavorable tumor characteristics. However, STM levels did not correlate with prognostic outcomes.

Current Routine Testosterone Immunoassays Are Unsuitable for Lowering the General Castration Cutoff Recommendation to <0.7 nmol/l (20 ng/dl).

Testosterone measurements are essential in the management of patients with prostate cancer undergoing castration and androgen deprivation therapy. There has been an ongoing discussion on the testosterone castration cutoff (TCC), with the primary focus on large cohort studies in which the testosterone measurement system was not specified or studies that used individual testosterone measurement systems. Here we present a post hoc analysis of a study comparing testosterone measurement systems in a cohort of 120 castrated patients with prostate cancer. We investigated the suitability of general, measurement system-independent, TCC values recommended in all clinical guidelines. We show that the four testosterone immunoassays commonly used are unsuitable to support lowering of TCC to 0.7 nmol/l (20 ng/dl) testosterone, since testosterone levels are falsely quantified as higher than this cutoff in 4.2-29.2% of the castrated cohort, depending on the testosterone immunoassay used. When using 1.0 nmol/l (30 ng/dl) as the TCC for the Beckman immunoassay, 13.3% of the results were falsely quantified as being higher than this value. The results suggest that the measurement systems used in current practice do not support lowering the TCC to 0.7 nmol/l. Furthermore, a more local, immunoassay-dependent TCC should be considered. Patient summary: Patients with advanced prostate cancer who are treated to reduce their testosterone to a castration level are monitored using testosterone measurements. The testing systems currently used for measurement do not support lowering of the testosterone cutoff value to 0.7 nmol/l. Testosterone cutoff values to define castration status should preferably be based on the measurement system in local use.

Predictive value of low testosterone concentrations during and prior to enzalutamide treatment in metastatic castration-resistant prostate cancer.

BACKGROUND: Enzalutamide is an effective treatment for metastatic castration-resistant prostate cancer (mCRPC) patients. However, variances in responses are observed and there is a need for biomarkers predicting treatment outcome and selection. In this study, we aimed to explore the predictive value of testosterone for first-line enzalutamide treatment of mCRPC. METHODS: A retrospective analysis of 72 mCRPC patients with no prior abiraterone or docetaxel treatment was performed. Serum testosterone was measured using a liquid chromatography tandem-mass spectrometry method. Association of pre- and during-enzalutimide treatment testosterone levels with progression-free survival (PFS) and failure-free survival (FFS) was investigated using univariate and multivariate Cox models. Testosterone levels were dichotomized into a low (Q1) and high (interquartile range-Q4) group. RESULTS: Median PFS (7.4 v. 20.8 months, P<0.0001) and FFS (6.6 v. 17.7 months, P<0.0001) were shorter for patients with low testosterone levels (<0.217 nmol/L) during enzalutamide treatment. Furthermore, univariate Cox proportional hazards models revealed that low testosterone levels were associated with shorter PFS (HR 3.5, 95%CI 1.9-6.3; P<0.001) and FFS (HR 3.1, 95%CI 1.7-5.5; P<0.001). Pre-treatment testosterone levels were lower than during-treatment levels (P<0.0001) and low pre-treatment testosterone levels (<0.143 nmol/L) were associated with shorter median PFS (12.6 v. 20.5 months, P<0.01) and FFS (12.6 v. 22.5 months, P<0.01). CONCLUSION: The results of this study suggest that low serum testosterone levels during and prior to enzalutamide treatment can predict progression in mCRPC patients and identifies tumors resistant to next-in-line enzalutamide treatment. Validation in a prospective cohort is warranted.

Serum testosterone measured by liquid chromatography-tandem mass spectrometry is an independent predictor of response to castration in metastatic hormone-sensitive prostate cancer.

BACKGROUND: Although testosterone levels have been associated with progression-free survival (PFS) in metastatic hormone-sensitive prostate cancer (mHSPC) patients, this has primarily been investigated using inaccurate immunoassays (IA). Here, we investigated whether castrate testosterone levels determined by a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay is an independent risk factor for treatment response in mHSPC. METHODS: In total, 106 mHSPC patients treated with luteinizing-hormone releasing-hormone (LHRH) agonists were retrospectively analyzed between March 2018 and August 2021. Testosterone levels in serum samples were quantitated using an LC-MS/MS assay. In a subset of patients, IA (Roche Cobas Pro) values were compared with LC-MS/MS results. Survival analysis was performed using Kaplan-Meier curves and Cox proportional hazard models. RESULTS: Median PFS was shorter for high testosterone levels (>0.231 nmol/L, 18.4 v. 42.6 months, HR 1.7, p = 0.018). Low testosterone levels and a PSA response below 4 ng/mL was associated with longer median PFS (46.2 months) than the remaining combinations (13.8-19.3 months, 3.4-5.8, overall p < 0.01). In 67 patients, testosterone levels below the median remained associated with longer PFS, whereas IA measurements did not show a similar difference. CONCLUSION: Our results suggest that high castration testosterone levels measured by LC-MS/MS is an independent response predictor for mHSPC patients.

Modeling strategies to analyse longitudinal biomarker data: An illustration on predicting immunotherapy non-response in non-small cell lung cancer.

Serum tumor markers acquired through a blood draw are known to reflect tumor activity. Their non-invasive nature allows for more frequent testing compared to traditional imaging methods used for response evaluations. Our study aims to compare nine prediction methods to accurately, and with a low false positive rate, predict progressive disease despite treatment (i.e. non-response) using longitudinal tumor biomarker data. Bi-weekly measurements of CYFRA, CA-125, CEA, NSE, and SCC were available from a cohort of 412 advanced stage non-small cell lung cancer (NSCLC) patients treated up to two years with immune checkpoint inhibitors. Serum tumor marker measurements from the first six weeks after treatment initiation were used to predict treatment response at 6 months. Nine models with varying complexity were evaluated in this study, showing how longitudinal biomarker data can be used to predict non-response to immunotherapy in NSCLC patients.

Moving average quality control of routine chemistry and hematology parameters - a toolbox for implementation.

OBJECTIVES: Moving average quality control (MA QC) is a patient-based real-time quality control system. Advantages compared to conventional periodic internal quality control (IQC) include absence of commutability problems and continuous monitoring of performance. We implemented MA QC for multiple routine hematology and chemistry parameters. We describe the evaluation process and provide practical tools to aid MA QC implementation. METHODS: Nine parameters (serum sodium, calcium, bicarbonate and free thyroxine, hemoglobin [Hb], mean corpuscular volume, mean corpuscular hemoglobin concentration [MCHC], reticulocyte count and erythrocyte sedimentation rate [ESR]) were chosen for initial consideration. Using data extractions from the laboratory information system (LIS; General Laboratory Information Management System), evaluation of usefulness and optimization of MA QC settings was performed using bias detection curves. After this, MA QC settings were incorporated in our LIS for further evaluation and implementation in routine care. RESULTS: Three out of nine parameters (Hb, ESR, and sodium) were excluded from MA QC implementation due to high variation and technical issues in the LIS. For the six remaining parameters, MA QC showed added value to IQC and was therefore implemented in the LIS. For three parameters a direct MA alarm work-up method was set up, including newly developed built-in features in the LIS. For the other parameters, we identified MA utilization beyond real-time monitoring. CONCLUSIONS: Implementation of MA QC has added value for our laboratory setting. Additional utilization beyond real-time QC monitoring was identified. We find MA QC especially useful for trend monitoring, detection of small shifts after maintenance and inter-analyzer comparisons.

Testosterone analysis in castrated prostate cancer patients: suitability of the castration cut-off and analytical accuracy of the present-day clinical immunoassays.

OBJECTIVES: Testosterone testing is relevant for evaluating castration adequacy and diagnosis of castration-resistant prostate cancer (PCa). However, the recommended testosterone cut-off of 1.7 nmol/L (50 ng/dL) to define adequate castration is based on consensus and not validated for the automated immunoassays (AIA) used in today's medical laboratories. Furthermore, appropriate population intervals have not been determined by a state-of-the-art assay. We investigated the analytical suitability of this cut-off and the accuracy of the present-day AIAs for testosterone analysis in castrated PCa patients. METHODS: Leftover serum from 120 PCa patients castrated with luteinizing hormone-releasing hormone agonists was analysed for testosterone by five methods: Architect i2000 (Abbott), Access (Beckman), Cobas 6000 (Roche), Atellica (Siemens), LC-MS/MS. For all assays, the castration 95th, 97.5th and 99th percentile upper limits were determined. Furthermore, Passing-Bablok regression, mean bias and Spearman's correlation coefficients were compared to the LC-MS/MS method and total error based on biological variation. RESULTS: All castration upper limits, ranging from 0.472 nmol/L (LC-MS/MS) to 1.25 nmol/L (Access) (95% percentile), were significantly lower than the current castration cut-off (1.7 nmol/L). Slopes of Passing-Bablok regressions comparing the AIA with the LC-MS/MS method ranged from 1.4 (Cobas and Atellica) to 3.8 (Access). The Architect showed the highest correlation with LC-MS/MS (ρ=0.58). All AIA failed to meet the desirable total error criterion. CONCLUSIONS: These results suggest that a lower general testosterone castration cut-off may be more appropriate in evaluating the adequacy of castration in PCa and that present-day AIA lack analytical accuracy to quantify testosterone levels in castrated PCa.

Technical quality assurance and quality control for medical laboratories: a review and proposal of a new concept to obtain integrated and validated QA/QC plans.

Technical quality assurance (QA) and quality control (QA/QC) are important activities within medical laboratories to ensure the adequate quality of obtained test results. QA/QC tools available at medical laboratories include external QC and internal QC, patient-based real-time quality control (PBRTQC) tools such as moving average quality control (MAQC), limit checks, delta checks, and multivariate checks, and finally, analyzer flagging. Recently, for PBRTQC tools, new optimization and validation methods based on error detection simulation have been developed to obtain laboratory-specific insights into PBRTQC error detection. These developments have enabled implementation and application of these individual tools in routine clinical practice. As a next step, they also enable performance comparison of the individual QA/QC tools and integration of all the individual QA/QC tools in order to obtain the most powerful and efficient QA/QC plans. In this review, a brief overview of the individual QA/QC tools and their characteristics is provided and the error detection simulation approaches are explained. Finally, a new concept entitled integrated quality assurance and control (IQAC) is presented. To enable IQAC, a conceptual framework is suggested and demonstrated for sodium, based on available published data. The proposed IQAC framework provides ways and tools by which the performance of different QA/QC tools can be compared in a so-called QA/QC error detection table to enable optimization and validation of the overall QA/QC plan in terms of alarm rate as well as pre-analytical, analytical, and post-analytical error detection performance.