Imprecision Studies Research Articles

A-306 High Sensitivity Capability of an Anti-müllerian Hormone Assay on the Beckman Coulter DxI 9000 Immunoassay Analyzer*, a Next Step Toward Enabling Ovarian Failure Staging?

Abstract Background Measurement of anti-müllerian hormone (AMH) has proven value in the evaluation of ovarian reserve using assays such as the Beckman Coulter Access AMH assay. If improved sensitivity of AMH measurement can be achieved, enhanced clinical utility during the assessment of reproductive aging and ovarian response to enable staging of ovarian failure is possible (Practice Committee of the American Society of Reproductive Medicine 2020, Cappola et al. 2023). The Beckman Coulter DxI 9000 Immunoassay Analyzer* has been designed with new technology that can be leveraged to improve assay sensitivity. Such technological advancements include the new Lumi-Phos PRO chemiluminescent substrate which yields markedly increased signal-to-noise, a new luminometer with increased dynamic range, and improved low-volume pipetting capabilities. Data herein summarize results from analytical verification studies of the Access AMH assay on the DxI 9000 Immunoassay Analyzer. Results demonstrate an example of DxI 9000 technologies enabling sensitivity claims that are up to 20-fold improved. * The official name is DxI 9000 Access Immunoassay Analyzer. Methods A method comparison study was performed based on CLSI guideline EP09c, 3rd ed. to compare results for the Access AMH assay on DxI 9000 to the predicate device, the Access AMH assay on the Access 2 Immunoassay System. Within-laboratory precision was also evaluated following CLSI EP05-A3. Finally, performance at low analyte levels was evaluated following CLSI EP17-A2, and linearity was evaluated following CLSI EP06-Ed2. Results Method comparison of the Access AMH assay on DxI 9000 compared to the Access AMH assay on the Access 2 yielded excellent agreement with a Passing-Bablok slope of 1.02 for N=126 samples. Further, bias estimates for a number of key medical decision points suggest minimal bias (≤ 2%) across the assay range, and minimal non-linearity was observed. 20-day imprecision studies yielded CV’s between 2 and 5% across a broad range of concentrations evaluated. Sensitivity studies yielded estimates of limit of quantitation (LoQ) between 0.001 and 0.003 ng/mL. This represents an approximately 10- to 20-fold improvement in sensitivity claims compared to the AMH assay on the Access 2 and other commercially available automated immunoassay analyzers. Conclusions The data herein present performance data for the Access AMH assay on the DxI 9000 Immunoassay Analyzer. The assay demonstrates excellent accuracy relative to the predicate device, while showing good linearity and imprecision. Of note, the Access AMH assay exhibits exceptional low-end performance on the DxI 9000 analyzer as demonstrated by the ability to enable sensitivity claims that are up to 20-fold improved in comparison to existing immunoassays for the measurement of AMH. The sensitivity capabilities of the Access AMH assay on DxI 9000 suggest an opportunity for the addition of further intended uses for scenarios where extremely low AMH measurements can provide additional value of clinical significance. Further studies are needed to fully understand additional clinical utilities of the Access AMH assay with high sensitivity capability on DxI 9000, including the assessment of reproductive aging for menopause diagnosis or ovarian response for fertility treatment.

Performance Evaluation of Open Channel Buhlmann Fecal Calprotectin Turbo Assay on Abbott Alinity C Analyzer.

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal (GI) tract. Fecal calprotectin (fCAL) is a noninvasive laboratory test used in the diagnosis and monitoring of IBDs such as Crohn's disease and ulcerative colitis. The fCAL send-out test that our facility has been offering so far uses an ELISA-based method. In the current study, we sought to validate the performance of a Buhlmann fCAL turbo assay in an automated Abbott Alinity C analyzer (AFCAL) in our core laboratory. Five-day imprecision studies showed good performance for both within-run (5.3%) and between-day (2.5%) measurements. The reportable range was verified as 30-20,000 µg/g. Deming regression and Bland-Altman analysis indicated a strong correlation of r = 0.99 with a low, acceptable bias of 1.8% for AFCAL relative to the predicate Buhlmann fCAL ELISA results. AFCAL's clinical performance was determined retrospectively in 62 patients with ICD codes for IBD. Overall, the implementation of AFCAL in our routine clinical testing has improved our turnaround time, reduced the cost per test, and significantly increased our clinician satisfaction.

Assessment of coagulation assays on Roche Cobas t711 analyzer: performance and clinical implications.

We performed an analytical assessment of five coagulation tests [i.e. prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, thrombin time (TT) and D-dimer] on the Roche Cobas t711 analyzer and a comparison study with the methodology in use at our laboratory (i.e. Werfen ACL Top 750 analyzer), expanding the analysis to the clinical implications of Cobas t711 implementation. Imprecision studies were performed following the Clinical and Laboratory Standards Institute (CLSI) H57 A:2008 guideline. Linearity of D-dimer and fibrinogen tests was analysed according to the CLSI EP06-A: 2003 recommendations. For method comparison, the results were analyzed using the Bland-Altman plot and Passing-Bablok regression. Imprecision met manufacturer claims for PT, aPTT and TT. D-dimer and fibrinogen tests showed a coefficient of variation (CV)% over manufacturer claims at certain concentration levels. Linearity ranges could not be verified. Comparison study revealed that results are not interchangeable for any test, a lower correlation for aPTT test and lower D-dimer results from Roche Cobas t711. The strength of this study relies on the analysis of the clinical implications of reporting Cobas t711 results compared to those obtained with the methodology in use at our laboratory. Different sensibility to factor deficiency, anticoagulant therapy and interferences might explain lower correlation rates obtained for the aPTT test. Different monoclonal antibodies used for D-dimer determination might explain the lower results obtained with the Cobas t711 analyzer. This aspect needs further studies given the relevance of D-dimer test to exclude thrombotic events and reinforces the need of harmonization in the haemostasis laboratory.

B-011 Analytical Validation of a New Vasoactive Intestinal Peptide Radioimmunoassay

Abstract Background Vasoactive intestinal peptide (VIP), a potent vasodilator, is produced by neuronal cells located in the central nervous system, the digestive, respiratory, and urogenital tracts, and the exocrine, thyroid, and adrenal glands. Increased circulating VIP is clinically useful to detect VIP-producing tumors in patients with chronic diarrheal diseases. Objective Develop a sensitive replacement radioimmunoassay (RIA) for VIP quantitation in human plasma due to the diminished supply of the antibody used in the previous in-house method. Method Patient VIP in EDTA plasma competes with labeled (125I) VIP for a limited number of primary rabbit polyclonal antibody (BMA Biomedicals, Augst, Switzerland) binding sites. Antibody-bound VIP is then complexed with a goat anti-rabbit secondary antibody and precipitated out of the solution with the use of polyethylene glycol and centrifugation. After the supernatant is discarded, the 125I signal from the pellet is counted on the Wizard2 gamma counter (Perkin Elmer, Waltham, MA). The measured signal is inversely proportional to the amount of VIP present in the patient’s sample. Method validation of the new assay included determination of imprecision (pooled human EDTA plasma), limits of detection and quantification, analytical measurement range (AMR), accuracy by spike recovery, interferences, cross-reactivity, stability, reference interval determination, and agreement with the current Mayo laboratory-developed assay. Results Stability studies on freshly collected EDTA plasma showed VIP is stable for 3 days ambient, 7 days refrigerated, and 14 days frozen. Intra-assay imprecision studies showed 8.3, 2.3, and 1.3%CV for mean VIP concentrations of 41, 144, and 304 pg/mL. Inter-assay imprecision was 12.9, 7.6, 5.2, and 7.5%CV for mean VIP concentrations of 30, 81, 180, and 308 pg/mL. The assay limit of detection was 29 pg/mL. The limit of quantitation was 30 pg/mL (%CV = 13%) and was established via precision profile. The AMR was 30–500 pg/mL (slope of 0.98, intercept of 3.0 pg/mL, and R2 of 0.97). The mean % spike recovery using a different preparation lot of calibrator material was 89% (range 83%–93%). The assay was not affected by up to 1000 mg/dL hemoglobin, 1000 mg/dL triglycerides, or 10 mg/dL bilirubin. Peptide histidine methionine 27, neurotensin, gastric inhibitory peptide, motilin, secretin, and glucagon do not cross-react in the assay. The 97.5th reference limit was <86 pg/mL (95% CI 81–90, n = 127). Positive percent agreement (PPA), negative percent agreement (NPA), and overall percent agreement (OPA) with the current Mayo VIP assay were 97, 82, and 90% respectively. Conclusion We have developed a replacement VIP RIA. This assay has a lower limit of quantitation and a broader AMR than the current assay. Concordance with the current assay was acceptable.

Evaluation of four automated clinical analyzers for the determination of total 25(OH)D in comparison to a certified LC-MS/MS.

The aim of this study was to compare the results of five methods for the determination of total 25(OH)D. For that purpose, two mass spectrometry and three immunoassay methods were used. A total of 124 serum samples were analyzed on five different methods (i.e.,a reference LC-MS/MS, Cascadion, Lumipulse, Roche Elecsys II and Roche Elecsys III). Analytical performance against LC-MS/MS was evaluated and compared to the Milan models 1 (analytical performance based on the clinical outcome using thresholds of 12,20 and 30ng/mL) and 2 (analytical performance based on biological variation). Additionally, imprecision studies and accuracy using NIST SRM972a samples were carried out. Compared to the reference LC-MS/MS method, theLumipulse and the Roche Elecsys III assays reached theoptimal criterion for bias, while the Cascadion met the desirable one. The Roche Elecsys II was not able to reach theminimal criteria. The proportion of correctly classified patients was higher using the Cascadion (95.2%) compared to the three immunoassays. In addition to its better precision, the Cascadion was not impacted by a high concentration of3-epi-25(OH)D3 compared to the three immunoassays. Compared to the LC-MS/MS reference method, the Cascadion presented the highest level of concordance atmedical decision cut-offs for total 25(OH)D and reached the desirable specification for bias. Moreover, the presence of 3-epi-25(OH)D3 in enriched samples was only problematic in immunoassay methods, and especially considering Roche Elecsys methods. The release of performant fully automated mass spectrometry assays with high throughput might therefore facilitate the wide scale adoption of LC-MS/MS, even in non-specialized clinical laboratories.

Analytical evaluation and bioclinical validation of new aldosterone and renin immunoassays.

Aldosterone and renin determinations play an important role in the etiological diagnosis of secondary hypertension. The analytical performances of new aldosterone and renin immunoassays on the Lumipulse G600II® system (Fujierbio) were investigated and compared with those of the iSYS® system (IDS) on patients concerned by medical investigations in a context of suspected or proven Primary aldosteronism. By using the Lumipulse® G Aldosterone and Renin assays we performed imprecision study, linearity and method comparison (n=107). Accuracy of this new renin assay was tested using the International Standard (WHO IS 68/356). We also assessed the equivalence of the different samples types (n=29). The imprecision evaluation showed all CVs <3% and <6% for Lumipulse® G Aldosterone and Renin assays respectively. The linearity was excellent over the clinical range and the comparison with the iSYS® assays (n=79) showed a strong correlation (R2=1) despite a slight tendency to underestimation (bias of-17.53pg/mL or 48.56pmol/L for aldosterone and-15.395pg/mL for renin). Moreover, the contingency studies based on diagnostic criteria showed that Lumipulse® G results lead to the same clinical diagnosis that iSYS® results. A clear correlation was obtained between EDTA and heparin plasma as well as with the serum for all range of measures. The Lumipulse® G Aldosterone and Renin assays present performances compatible with a routine usein medical laboratories. The precise quantification in the low range can be of interest in some clinical contexts especially standing/laying tests. However, the standardisation against the WHO International Standard Renin would be advisable.

Quality of Life after Bariatric Surgery-A Systematic Review.

Background: Most studies analyzing the health-related quality of life (HRQOL) after bariatric treatment ceased at five years post-surgery or even earlier, and it is unclear whether the HRQOL benefit persists for a longer time. This paper reviews sparse evidence regarding HRQOL in patients who underwent bariatric surgery at least nine years prior. Materials and Methods: A of PubMed, Scopus and Google Scholar between 2007–2021 was carried out for the studies investigating HRQOL as an outcome measure in patients after bariatric surgery of any type and having at least a 9-year follow-up. Inconsistent reporting of weight loss or postgraduate study results unrelated to QoL were not included in the study. The study used the PICO procedure. Results: The review of 18 identified publications demonstrated that bariatric treatment seems to provide a persistent benefit in terms of HRQOL, especially its physical component score. Due to psychological predispositions, some patients appear to be less likely to benefit from bariatric treatment, whether in terms of HRQOL or bodyweight reduction. Inconsistent and imprecise studies may limit the evidence included in a review. Conclusions: The early identification of such patients and providing them with holistic care, including psychological intervention, would likely further improve the outcomes of bariatric treatment.

The Comparison of the Point-of-Care Serum Procalcitonin Assay Method with the BRAHMS Certified Method

Background and Aims: As a method for the diagnosis and management of sepsis, the serum procalcitonin assay is routinely used, especially in the emergency department (ED) and intensive care units (ICU). Procalcitonin has reasonable diagnostic accuracy for bacteremia in hospitalized patients of all age groups with suspected infection or sepsis. This study aimed to compare the Getein Biotech procalcitonin point of care method with the ADVIA Centaur® BRAHMS serum procalcitonin method.&#x0D; Materials and Methods: Linearity,recovery, accuracy, and imprecision studies were carried out to evaluate the analytical performance. Bland-Altman plots and Passing-Bablok regression analysis were used to compare patient results. The Kappa test assessed the concordance between the results at cut-off levels of 0.5ng/mL and 2.0ng/mL.&#x0D; Results: In the linearity study performed by obtaining serial dilutions from high and low-level serum pools, the regression equations were "y=-0.03(-0.07 to 0.05)+1.01(0.7 to 1.08)x" and "y=0.463(-1.16 to 2.01)+0.912(0.72 to 1.04)x" respectively. There is no deviation from linearity with the Cusum test (p=0.99 and 0.57). Average recovery value:86%. The CV% values of Control Level-1,2 were 3.75% and 4.2%. 0.1-50.0ng/ml range shows deviation from linearity determined by Cusum test (p=0.01). There was no deviation from linearity in the range of 0.1-2.0ng/ml (p=0.42). Kappa values were calculated as 0.864 and 0.800 (p&lt;0.001).&#x0D; Conclusions: Getein1600 Procalcitonin test should be used for triage or screening purposes. However, a high constant error and deviation from linearity detected at high concentrations indicate that this test should not be used to initiate an antibiotic therapy or alter the current therapy course.

Using median survival in meta-analysis of experimental time-to-event data

BackgroundTime-to-event data is frequently reported in both clinical and preclinical research spheres. Systematic review and meta-analysis is a tool that can help to identify pitfalls in preclinical research conduct and reporting that can help to improve translational efficacy. However, pooling of studies using hazard ratios (HRs) is cumbersome especially in preclinical meta-analyses including large numbers of small studies. Median survival is a much simpler metric although because of some limitations, which may not apply to preclinical data, it is generally not used in survival meta-analysis. We aimed to appraise its performance when compared with hazard ratio-based meta-analysis when pooling large numbers of small, imprecise studies.MethodsWe simulated a survival dataset with features representative of a typical preclinical survival meta-analysis, including with influence of a treatment and a number of covariates. We calculated individual patient data-based hazard ratios and median survival ratios (MSRs), comparing the summary statistics directly and their performance at random-effects meta-analysis. Finally, we compared their sensitivity to detect associations between treatment and influential covariates at meta-regression.ResultsThere was an imperfect correlation between MSR and HR, although the opposing direction of treatment effects between summary statistics appeared not to be a major issue. Precision was more conservative for HR than MSR, meaning that estimates of heterogeneity were lower. There was a slight sensitivity advantage for MSR at meta-analysis and meta-regression, although power was low in all circumstances.ConclusionsWe believe we have validated MSR as a summary statistic for use in a meta-analysis of small, imprecise experimental survival studies—helping to increase confidence and efficiency in future reviews in this area. While assessment of study precision and therefore weighting is less reliable, MSR appears to perform favourably during meta-analysis. Sensitivity of meta-regression was low for this set of parameters, so pooling of treatments to increase sample size may be required to ensure confidence in preclinical survival meta-regressions.

Effectiveness of mindfulness-based interventions for people with dementia and mild cognitive impairment: A meta-analysis and implications for future research.

ObjectiveTo assess the effectiveness of mindfulness-based interventions on people with dementia and mild cognitive impairment.MethodsWe searched several electronic databases, namely Cochrane Library, EMBASE, and MEDLINE with no limitations for language or document type (last search: 1 February 2020). Randomized controlled trials of mindfulness-based interventions for people with dementia and mild cognitive impairment compared to active-control interventions, waiting lists, or treatment as usual were included. Predefined outcomes were anxiety symptoms, depressive symptoms, cognitive function, quality of life, mindfulness, ADL and attrition. We used the random effects model (DerSimonian-Laird method) for meta-analysis, reporting effect sizes as Standardized Mean Difference. Heterogeneity was assessed with the I2 statistics.ResultsEight randomized controlled trials, involving 276 patients, met the eligibility criteria and were included in the meta-analysis. We found no significant effects for mindfulness-based interventions in either the short-term or the medium- to long-term on any outcomes, when compared with control conditions. The number of included studies and sample sizes were too small. Additionally, the quality of evidence was low for each randomized controlled trial included in the analysis. This is primarily due to lack of intent-to-treat analysis, high risk of bias, and imprecise study results. The limited statistical power and weak body of evidence prevented us from reaching firm conclusions.ConclusionsWe found no significant effects of mindfulness-based interventions on any of the outcomes when compared with control conditions. The evidence concerning the efficacy of mindfulness-based interventions in this population is scarce in terms of both quality and quantity. More well-designed, rigorous, and large-scale randomized controlled trials are needed.

Evaluation of a Capillary Electrophoresis System for the Separation of Proteins.

Serum protein electrophoresis is one of the core investigations for screening for monoclonal proteins. Among the available capillary systems, the Helena V8 system has been evaluated in a limited number of studies. In total, 310 sera samples were assessed on the Helena V8 system and compared with the Sebia Capillarys instrument. Abnormalities suggestive of monoclonal proteins were confirmed by immunofixation. Imprecision studies and reference intervals were determined. The imprecision of the Helena V8 was inferior or equal to 5.8%. The mean bias of Helena V8 vs Sebia Capillarys was about -0.9 g/L for albumin; -0.2 g/L for alpha-1; 1.1 g/L for alpha-2; -0.2 g/L for beta; 0.3 g/L for gamma; -0.5 g/L for monoclonal protein in beta; and 0.3 g/L for monoclonal protein in gamma. Among the 56 samples with monoclonal proteins confirmed by immunofixation, all were seen on both methods, with only 1 discordant result at a cutoff of 5.0 g/L. Reference intervals were statistically different between the 2 analyzers, except for the beta fraction. Our evaluation confirms the good analytical performance of the Helena V8 analyzer as a suitable alternative to the Sebia Capillarys instrument.

Performance evaluation of five lipoprotein(a) immunoassays on the Roche cobas c501 chemistry analyzer

ObjectivesMeasurement of lipoprotein(a) [Lp(a)] is used in risk assessment of atherosclerotic cardiovascular disease (ASCVD). The aim of the current study was to evaluate performance characteristic of five different Lp(a) assays using the cobas c501 (Roche Diagnostics) analyzer. Design and methodsLp(a) was measured using five Lp(a) assays (Diazyme, Kamiya, MedTest, Randox, and Roche) configured to mg/dL units. Assays from Diazyme and Kamiya were also configured using nmol/L units in separate experiments. Studies included sensitivity, imprecision, linearity, method comparison, and evaluation of healthy subjects. Imprecision (intra-day, 20 replicates; inter-day, duplicates twice daily for five days) and linearity were evaluated using patient pools. Linearity assessed a minimum of five patient splits spanning the analytical measurement range (AMR). Method comparison used 80 residual serum samples. Specimens from 120 self-reported healthy subjects (61 females / 59 males) were also tested. Method comparison for two assays in nmol/L units was conducted using 96 residual serum samples. ResultsAssay sensitivities met all manufacturer claims. Imprecision studies demonstrated %CVs ranging from 2.5 to 5.2% for the low pool (average concentration from 7.3 to 12.4 ​mg/dL); high pool %CVs ranged from 0.8 to 3.0% (average concentrations from 31.5–50.2 ​mg/dL). Linearity was confirmed for all assays. Variation in accuracy was observed when comparing results to an all method average. Lp(a) results were higher in females versus males in self-reported healthy subjects. ConclusionsAll assays performed according to manufacturer described performance characteristics, although differences were observed across Lp(a) assays tested when compared to an all method average.

Analytical evaluation of the novel VITROS BRAHMS procalcitonin immunoassay

To determine the analytical performance of Novel VITROS BRAHMS Procalcitonin Immunoassay on VITROS 3600 and correlation with BRAHMS PCT sensitive KRYPTOR reference method. Analytical performances including imprecision studies, linearity, limit of detection (LoD) and determination of hemolysis index were performed for VITROS BRAHMS PCT assay. Imprecision was assessed on plasma pool and internal control with 2 levels. The method comparison was performed using 162 plasma obtained from clinical departments. The total imprecision was acceptable and all CV were <5%. The LoD was in accordance with manufacturer’s claims. The equation of linearity in the lower range was found to be y = 1.0014x – 0.0091, with r2 = 1. No interference to hemoglobin up to 11 g/L was observed. Correlation studies showed a good correlation between PCT measurements using VITROS BRAHMS PCT assay against KRYPTOR system including for values lower than 2 µg/L. The novel VITROS BRAHMS PCT assay from OrthoClinical Diagnostics shows analytical performances acceptable for clinical use. In addition, the concordance with KRYPTOR method was fine at all clinical cut-offs.

A Single-Column Gas Chromatography Method for Quantifying Toxic Alcohols.

Rapid identification and quantification of toxic alcohols and ethylene glycol is imperative for appropriate treatment. Clinical laboratories frequently rely on direct injection gas chromatography (GC) methods, but these methods require inlet maintenance and multiple GC systems. To overcome these challenges, we developed a single-column headspace GC method for both toxic alcohols and glycols that streamlines patient sample analysis for toxic alcohol ingestion. Optimal parameters for nonderivatized (volatile) and derivatized (glycol) plasma samples were determined using a 7890 A headspace sampler, an Agilent 7697 A GC system, a DB-200 column, and a flame ionization detector. Limit of Quantification (LoQ), linearity, imprecision, carry-over, method comparison, and interference studies were performed using quality control materials and prepared plasma samples. Our volatile method is linear to 3000 mg/L (ethanol) with LoQ concentrations below 20 mg/L (ethanol). The glycol method is linear to 2000 mg/L (ethylene glycol) with LoQ concentrations below 40 mg/L (ethylene glycol). Total assay impression ranged from 1.7% for ethanol to 13.3% for propylene glycol. Both methods were free of sample carryover and compared favorably with a similar clinical method at an outside laboratory. Propionic acid, an accumulating metabolite in methylmalonic acidemia that interferes with ethylene glycol identification by a different method, did not interfere with the ethylene glycol method reported here. Our single-column headspace GC method provides reliable, robust, and rapid identification and quantification of commonly encountered toxic alcohols. Clinical laboratories relying on direct injection Gas Chromatography (GC) for toxic alcohol analysis face challenges including frequent inlet maintenance, sample carryover, or the need for separate GC systems for volatile and glycol analysis. We summarize our development and optimization of two headspace GC methods for nonderivatized (volatile) and derivatized (glycol) plasma samples that use a single DB-200 analytical column. These methods are comparable to other GC methods, not prone to sample carryover, eliminate the need for multiple GC systems or columns, and are readily applicable to other laboratories that provide toxic alcohol analysis.

How early is early? Effect of oxybutynin on bladder dynamics within the first year of life in patients with spina bifida

Early proactive treatment of patients with high-risk neurogenic bladder from spina bifida (SB) may preserve renal function and decrease the need for bladder augmentation later in life. Timing of initiation of anticholinergic therapy (AC) medication and clean intermittent catheterization (CIC) is variable and based on imprecise studies. The authors hypothesized that initiation of AC after the initial video-urodynamic study (VUDS) may benefit bladder capacity even in children who do not meet the standard hostile criteria for starting AC. A retrospective review of a prospectively maintained VUDS database from August 2015 to March 2019 was performed. Patients with SB who had undergone initial VUDS between 1 and 7 months of age and had a subsequent follow-up study between 9 and 18 months of age were included. Multiple VUDS and clinical parameters including expected bladder capacity, actual capacity reached, pressure at actual capacity, presence of detrusor overactivity, presence of urinary tract dilation and reflux, and whether or not AC was started were extracted and compared. P-value of <0.05 was considered statistically significant. A total of 69 patients completed an initial study at median age of 2 months, and follow-up study at median age of 13 months. Anticholinergic therapy was started in 21 patients (10F, 11M). Decision to initiate AC was at discretion of the attending pediatric urologist performing the VUDS in real time. Changes between the initial and repeat VUDS are listed in the summary table below. Adverse effects of AC were reported in 25% (5/21) patients: urinary retention/UTIs (3), allergic reaction (1), and fatigue (1). The authors findings suggest that AC stabilizes storage pressure for those who initially have a higher storage pressure, while in those with initial low storage pressures, storage pressures worsened over time in the absence of AC. Patients started on AC experienced a faster rate of increase in bladder capacity. Limitations to this study included the unknown long term and sustainability of the improvement in bladder parameters, the lack of uniform criteria for the initiation of AC or CIC, and an unknown long-term degree of upper tract protection. This study found early initiation of AC in SB at 2 months of age had significant positive effects on growth of bladder capacity and stabilization of storage pressure. However, long-term effects of AC are still undetermined, and thus, longitudinal studies are needed to understand the precise indications for initiation of early AC treatment.

Analytical performances of a novel point-of-care procalcitonin assay

ObjectivesWe report the analytical performances of a new point-of-care (POC) procalcitonin (PCT) fluorescence immunoassay that uses the AFIAS-6© system from Boditech and its concordance with results of the standard method Kryptor Compact plus from the central laboratory. Designand methods: Analytical performances including imprecision studies, limit of blank (LoB), limit of detection (LoD) and limit of quantification (LOQ) were determined. The method comparison was performed using plasma vs. whole blood for Kryptor CompactPlus© vs. AFIAS-6©, respectively. ResultsThe total imprecision was far from the CV of 4.5% claimed by the manufacturer and close to 10%, for levels of PCT at 0.4 and 8.3 μg/L. The LoD of this novel PCT assay was found to close to the LoD provided by the manufacturer at 0.04 μg/L. The LOQ was higher than that claimed by the manufacturer (0.1 vs 0.002, respectively). The equation of linearity in the lower range was found to be y = 1.056x – 0.039 with r2 = 0.993 with a mean recovery percentage of 86 ± 15%. Correlation studies showed a good correlation between PCT measurements using plasma on Kryptor system and on corresponding whole blood with POC reaching a bias of −0.04 in the range from 0.02 to 2 μg/L. ConclusionThe novel PCT assay on AFIAS-6© is an acceptable POC alternative for the diagnosis and management of sepsis at EDs to improve the flow of patients, as results are consistent with those of the standard PCT Kryptor Compact Plus© assay, despite its higher imprecision.

Evaluation of the i-STAT Alinity Point-of-Care Analyzer

Objectives The objective of this study was to evaluate the analytical performance of CG4+ and CHEM8+ cartridges on the i-STAT Alinity analyzer prior to use in patient testing. We also evaluated the ease of use, design, and safety features to determine its suitability for use by the clinicians in our hospital. Methods The Abbott i-STAT System Performance Verification Protocol was observed for the imprecision study and was performed over the course of 2 days using 2 levels of control material (Abbott i-STAT TriControl Level 1 and Level 3). The CLSI-EP6-A guideline was used to verify the assay reportable range performance using 5 levels of linearity material (Abbott i-Stat TriControl Calibration Verification Set). The method comparison study was performed using up to 60 leftover anonymized heparinized whole-blood samples and serum samples against existing laboratory instruments (Siemens Rapidpoint 500, Abbott Architect C16000, and Sysmex XN9000). Results Precision was good (coefficient of variation <2%) for electrolytes, glucose, lactate, and pH, and satisfactory (coefficient of variation <5.2%) for blood gases, urea, creatinine, and hematocrit. Linearity concentrations spanning the analytical measuring ranges were demonstrated for all analytes. Method comparison studies revealed that agreement between the i-STAT Alinity analyzer and the central laboratory analyzers was good and clinically acceptable. Conclusions The i-STAT Alinity analyzer has good analytical performance, and we established the analyzer meets our safety and regulatory requirements and therefore suitable for use in our hospital as a point-of-care testing device.

Evaluation of Bio-Rad D-10® and arkray adams HA-8160® HPLC analyzers in HbA1c measurement

Glycosylated hemoglobin A1c (HbA1c) is an important parameter used for the assessment of time-dependent glycemic status and the diagnosis and follow-up of diabetes. This study aimed to evaluate the analytical performance of two HPLC analyzers, the Bio-Rad D-10®, and the Arkray Adams HA-8160®. Accuracy and imprecision studies were conducted, and a method comparison study was performed with 105 samples. Samples were collected on five consecutive days and measured on both analyzers within two hours. Bland-Altman and regression analyses were used for statistical evaluation of the data. Low and high-level within-day CV values were calculated as 1.22% and 0.60% for the Arkray analyzer and 1.2% and 0.30% for the Bio-Rad analyzer, respectively. They were calculated as 1.27% and 2.52% for the Arkray analyzer and 2.32% and 3.44% for the Bio-Rad analyzer, respectively, between days. The within-day CV values for both analyzers were below the limit of 2.5% specified by the International Federation of Clinical Chemistry (IFCC). The bias average for three months was 3.2% for the Arkray analyzer and 1.2% for the Bio-Rad analyzer. The Spearman correlation coefficient (r) was 0.973 (p

Analytical performance evaluation of the new GEM® Premier™ 5000 analyzer in comparison to the GEM® Premier™ 4000 and the RapidPoint® 405 systems

Aim of the studyBlood gas analysis (BGA) is essential for the diagnosis and management of acid-base imbalances. We evaluated and compared the analytical characteristics of the new GEM® Premier™ 5000 (GP5000) (Instrumentation Laboratory, Bedford, MA, United States) BGA point-of-care (POC) device with those of the GEM® Premier™ 4000 (GP4000) (Instrumentation Laboratory, Bedford, MA, United States) and RapidPoint® 405 (RP405) (Siemens Healthcare, Milan, Italy) POC analyzers. The effect of sample mixing on patient results was also studied. Material and methodsQuantitative measurement of pH, pCO2, pO2, Na+, K+, Cl−, iCa2+, glucose, lactate, tHb, COHb, MetHb, O2Hb, HHb and Hct were carried out. The imprecision study (IS) and method comparison study (MS) were performed according to CLSI EP guidelines, using respectively internal as well as external quality controls (IS) and whole blood samples collected from the routine analysis (MS). ResultsGP5000 demonstrated satisfactory characteristics in the IS showing comparable (GM4000) or even better (RP405) imprecision results than the routine POC devices. Good performance was observed in the MS both using GP4000 and RP405 as reference instruments. Pre-analytical sample management can heavily affect the accuracy of BGA results. In the specimen mixing evaluation, a significant improvement in results accuracy was observed when mixing procedures were more meticulous. ConclusionsConsidering the overall analytical performance observed, the ease of use of the system, the rapid time-to-results and the innovative Intelligent Quality Management technology (iQM2®), GP5000 seems suitable to be used in clinical care for safe patient management. Additionally, effective sample mixing upon draw and before analysis is strongly advisable in order to ensure the most clinically reliable BGA results.

How low can you go? Analytical performance of five automated testosterone immunoassays

BackgroundTestosterone is commonly measured using immunoassays, yet concerns with the accuracy and quality of testing by these methods exist, particularly for low testosterone concentrations. Study objectives were to evaluate selective performance characteristics, including functional sensitivity (FS), of 5 automated immunoassays for total testosterone. MethodsFS, imprecision, assay interference, limit of blank, linearity, and accuracy were assessed using the Abbott ARCHITECT i2000SR, SIEMENS ADVIA Centaur and IMMULITE 2000, Beckman Coulter DxI 800, and Roche MODULAR E170. Comparisons to an in-house liquid chromatography-tandem mass spectrometry (LC-MS/MS) method were performed using patient samples from men, women, boys, and girls. ResultsFS at 20% coefficient of variation (CV) for the ARCHITECT, Centaur, DxI, E170 and IMMULITE assays were 0.14, 1.23, 0.36, 0.77, 3.49 nmol/L, respectively. Total CVs for the 5-day imprecision study were ≤ 9.0% for all methods. All assays met manufacturer's claims for hemolysis, icterus, and lipemia interference and limit of blank. Dilution linearity studies had deviations from the target recoveries ranging from 3.4% (ARCHITECT) to 14.3% (DxI). Using National Institute of Standards and Technology Standard Reference Material 971, recoveries ranged from 79.2–149.2% (DxI, male and female, respectively). When compared to LC-MS/MS, more immunoassays under-recovered in men and women and over-recovered in boys and girls. Slopes ranged from 0.71 (IMMULITE, women) to 1.35 (DxI, boys). The combined average for percent bias was higher in boys (28.0%) than men (11.6%), women (22.8%), and girls (25.7%). ConclusionsChallenges with accurately measuring testosterone appear to remain for some immunoassays, but not all. While most immunoassays remain optimized for concentrations observed in healthy men, some showed acceptable performance when challenged at lower concentrations.