Analytical Performance Specifications for Input Variables: Investigation of the Model of End-Stage Liver Disease.

BACKGROUND: Artificial intelligence models constitute specific uses of analysis results and, therefore, necessitate evaluation of analytical performance specifications (APS) for this context specifically. The Model of End-stage Liver Disease (MELD) is a clinical prediction model based on measurements of bilirubin, creatinine, and the international normalized ratio (INR). This study evaluates the propagation of error through the MELD, to inform choice of APS for the MELD input variables. METHODS: A total of 6093 consecutive MELD scores and underlying analysis results were retrospectively collected. "Desirable analytical variation" based on biological variation as well as current local analytical variation was simulated onto the data set as well as onto a constructed data set, representing a worst-case scenario. Resulting changes in MELD score and risk classification were calculated. RESULTS: Biological variation-based APS in the worst-case scenario resulted in 3.26% of scores changing by ≥1 MELD point. In the patient-derived data set, the same variation resulted in 0.92% of samples changing by ≥1 MELD point, and 5.5% of samples changing risk category. Local analytical performance resulted in lower reclassification rates. CONCLUSIONS: Error propagation through MELD is complex and includes population-dependent mechanisms. Biological variation-derived APS were acceptable for all uses of the MELD score. Other combinations of APS can yield equally acceptable results. This analysis exemplifies how error propagation through artificial intelligence models can become highly complex. This complexity will necessitate that both model suppliers and clinical laboratories address analytical performance specifications for the specific use case, as these may differ from performance specifications for traditional use of the analyses.

No Detectable Coagulation Activation After Vitamin K (MK-7) Supplementation in Patients on Dialysis With Functional Vitamin K Deficiency: A One-Year Randomized, Placebo-Controlled Study.

OBJECTIVE: Patients on dialysis treatment have poor functional vitamin K status, and this may increase the risk of vascular calcification. Vitamin K supplementation may therefore be relevant in patients on dialysis, but the procoagulant effects have not been studied. We evaluated effects of menaquinone-7 (MK-7) supplementation on biomarkers of coagulation in patients on dialysis. METHODS: Double-blinded, placebo-controlled study in 123 patients on dialysis randomized to 52 weeks of vitamin K (MK-7, 360 µg/daily, n = 61) or placebo (n = 62). Measurements at baseline and after 52 weeks of intervention included thrombin generation (endogenous thrombin potential, peak thrombin concentration, time to peak, and lag time); clot activities of vitamin K-dependent coagulation factors (F) II, VII, IX, and X; prothrombin fragment 1 + 2 (F1+2); and proteins induced by vitamin K absence II (PIVKA-II). Between-group differences (vitamin K vs. placebo) at 52 weeks were determined with an analysis of covariance. Within-group changes in vitamin K and placebo groups were analyzed with a paired t-test. Vascular adverse events and serious adverse events were registered based on hospital records, laboratory data, and participant interviews and compared between groups using Fisher's exact test or Pearson's Chi-Squared test. RESULTS: A between-group difference at 52 weeks was observed for PIVKA-II (P < .001). PIVKA-II decreased significantly from baseline to 52 weeks in the vitamin K group, but not in the placebo group. We observed no between-group differences or within-group changes for biomarkers of coagulation, except for FVII clot activity which was reduced in the placebo group (P = .04), and no between-group differences in adverse events and serious adverse events. CONCLUSION: One year of vitamin K supplementation in patients on dialysis has no detectable effects on biomarkers of coagulation activation, clot activities of vitamin K-dependent coagulation factors, and vascular events or death, indicating no procoagulant effects of this treatment.

Sensitivity and performance of three novel quantitative assays of SARS-CoV-2 nucleoprotein in blood.

To assess if SARS-CoV-2 (COVID-19) systemic disease can be determined by available nucleoprotein assays, we compared the performance of three commercial SARS-CoV-2 nucleoprotein (N) assays in plasma. A total of 272 plasma samples collected in the period November-December 2021 were analyzed by the methods Simoa SARS CoV-2 N Protein Advantage Kit [Quanterix Simoa], Solsten SARS-CoV-2 Antigen enzyme immunosorbent assay (ELISA) [Solsten ELISA], and Elecsys SARS-CoV-2 Antigen electrochemiluminescence immunoassay [Elecsys ECLIA]. Additionally, a dilution series of inactivated virus culture was analyzed by the three assays. The SARS CoV-2 PCR-status was not known for the patients. Linear correlation in the pairwise correlation between assays as well as linearity of dilution series of inactivated virus culture was estimated by Spearman score. Sensitivity and specificity were estimated by pairwise comparison. The three assays showed poor agreement on patient samples with regards to concentration. Performance on virus culture was excellent but with different level of detection (LOD). Positive vs negative results show comparable sensitivity and specificity of Quanterix Simoa and Solsten ELISA, with a higher LOD in Elecsys ECLIA and thus lower sensitivity and high specificity. N by all tested assays can be used as a marker for systemic COVID-19 disease.

Vitamin K supplementation and bone mineral density in dialysis: results of the double-blind, randomized, placebo-controlled RenaKvit trial.

BACKGROUND: Vitamin K deficiency is highly prevalent in patients on dialysis and may contribute to their low bone mineral density (BMD) and increased risk of fracture. This study investigated the effect of menaquinone-7 (MK-7) supplementation on BMD in patients on chronic dialysis. METHODS: In a multicentre, double-blind, placebo-controlled intervention trial, 123 patients on chronic dialysis were randomised to a daily oral supplement of either MK-7 360 µg or placebo for 2 years. BMD of the distal radius (1/3, mid, ultradistal and total), femoral neck, lumbar spine (L1-L4) and whole body was assessed by dual-energy X-ray absorptiometry. Serum levels of vitamin K1 and MK-7 and plasma levels of total osteocalcin, dephosphorylated-uncarboxylated matrix Gla protein and protein induced by vitamin K absence II were measured to assess vitamin K status. RESULTS: After 2 years, an accelerated BMD loss of the 1/3 distal radius was found with MK-7 supplementation {mean difference of changes relative to placebo -0.023 g/cm2 [95% confidence interval (CI) -0.039 to -0.008]}, whereas the decrease in lumbar spine BMD seen in the placebo group was prevented [mean difference of changes between groups 0.050 g/cm2 (95% CI 0.015-0.085)]. No significant effects were observed at the remaining skeletal sites. Vitamin K status strongly improved in MK-7-supplemented participants. CONCLUSION: Compared with placebo, an accelerated BMD loss of the 1/3 distal radius was found after 2 years of MK-7 supplementation, whereas a decline in lumbar spine BMD was prevented. As such, MK-7 supplementation might modify BMD site-specifically in patients on dialysis. In aggregate, our findings do not support MK-7 supplementation to preserve bone in patients on dialysis.

Quantifying SARS-CoV-2 nucleocapsid antigen in oropharyngeal swabs using single molecule array technology.

This study aimed to develop a highly sensitive SARS-CoV-2 nucleocapsid antigen assay using the single molecule array (Simoa) technology and compare it with real time RT-PCR as used in routine clinical practice with the ambition to achieve a comparative technical and clinical sensitivity. Samples were available from 148 SARS-CoV-2 real time RT-PCR positive and 73 SARS-CoV-2 real time RT-PCR negative oropharyngeal swabs. For determination of technical sensitivity SARS-CoV-2 virus culture material was used. The samples were treated with lysis buffer and analyzed using both an in-house and a pre-commercial SARS-CoV-2 nucleocapsid antigen assay on Simoa. Both nucleocapsid antigen assays have a technical sensitivity corresponding to around 100 SARS-CoV-2 RNA molecules/mL. Using a cut-off at 0.1 pg/mL the pre-commercial SARS-CoV-2 nucleocapsid antigen assay had a sensitivity of 96% (95% CI 91.4-98.5%) and specificity of 100% (95% CI 95.1-100%). In comparison the in-house nucleocapsid antigen assay had sensitivity of 95% (95% CI 89.3-98.1%) and a specificity of 100% (95% CI 95.1-100%) using a cut-off at 0.01 pg/mL. The two SARS-CoV-2 nucleocapsid antigen assays correlated with r = 0.91 (P < 0.0001). The in-house and the pre-commercial SARS-CoV-2 nucleocapsid antigen assay demonstrated technical and clinical sensitivity comparable to real-time RT-PCR methods for identifying SARS-CoV-2 infected patients and thus can be used clinically as well as serve as a reference method for antigen Point of Care Testing.

The Soluble Urokinase-Type Plasminogen Activator Receptor as a Biomarker for Survival and Early Treatment Effect in Metastatic Colorectal Cancer.

The soluble urokinase-type plasminogen activator receptor (suPAR) is prognostic for overall survival (OS) in colorectal cancer (CRC). Our study explored the association between baseline suPAR and OS and progression-free survival (PFS) in metastatic CRC (mCRC). It is also the first study to explore the association between the initial change in suPAR level and OS, PFS and the first CT response evaluation. The study included 132 patients with mCRC treated with chemotherapy (FOLFIRI) with or without an EGFR-inhibitor. Blood samples were drawn before the first treatment cycle and in between the first and second treatment cycle. suPAR levels were determined using an ELISA assay. Using the Kaplan-Meyer method, we demonstrated a significantly shorter OS for patients with suPAR levels above the median (HR = 1.79, 95%CI = 1.10-2.92, p = 0.01). We also showed association between plasma suPAR level, gender and performance status (PS). However, we could not show any association with PFS, and analysis on the change in suPAR level provided no significant results. The results showing association between baseline suPAR and OS are in line with previous findings.

Home Management of Warfarin Treatment Through a Real-Time Supervised Telemedicine Solution: A Randomized Controlled Trial.

BACKGROUND: Many patients are undergoing oral anticoagulation treatment with vitamin K antagonists, which necessitates measuring international normalized ratio (INR) several times each month. INTRODUCTION: Patients can learn to measure their INR at home and choose their own dose for the next period with potential gains in treatment quality and reduced healthcare expenses. This is, however, connected to the potential problem of losing tight external control of the patient treatment. MATERIALS AND METHODS: We performed a randomized controlled trial using the telemedicine software CSO/AC together with the INR point-of-care-test CoaguChek XS for 10 months to investigate the use of criteria-driven healthcare interactions. A total of 87 patients were divided into two groups. The patient self-management (PSM) group was surveilled using the criteria INR <1.8, INR >4.5, change in warfarin/week >1.25 mg, missing INR or dosage. The patient self-testing (PST) group was handled as routine care. RESULTS: A total of 84 patients were followed for 10 months. No differences were seen in average INR or fraction of INR in therapeutic range (2-3) in the two groups or the start compared with the end. The PST group was handled using 4.2 interactions per month whereas the PSM group used 1.1 interactions per month. No adverse effects of PSM were observed. DISCUSSION: Using criteria-driven interactions enabled a considerable reduction in interactions per month. The two groups were comparable in terms of treatment effect and safety. CONCLUSIONS: Using criteria to guide PSM interactions maintains good treatment effect while reducing healthcare expenses.

Standardised Resting Time Prior to Blood Sampling and Diurnal Variation Associated with Risk of Patient Misclassification: Results from Selected Biochemical Components.

BACKGROUND: According to current recommendations, blood samples should be taken in the morning after 15 minutes' resting time. Some components exhibit diurnal variation and in response to pressures to expand opening hours and reduce waiting time, the aims of this study were to investigate the impact of resting time prior to blood sampling and diurnal variation on biochemical components, including albumin, thyrotropin (TSH), total calcium and sodium in plasma. METHODS: All patients referred to an outpatient clinic for blood sampling were included in the period Nov 2011 until June 2014 (opening hours: 7am-3pm). Each patient's arrival time and time of blood sampling were registered. The impact of resting time and the time of day for all components was analysed using simple linear regression. The "maximum allowable bias" was used as quality indicator for the change in reference interval. RESULTS: Significant diurnal variation was found for albumin (n = 15,544; p<2×10-16), TSH (n = 20,019; p<2×10-16), calcium (n = 13,588; p = 2.8×10-12) and sodium (n = 51,917; p<2×10-16). Further significant influence for resting time was found for albumin (p = 2.6×10-4), TSH (p = 0.004), calcium (p = 8.9×10-7) and sodium (p = 8.7×10-16). Only TSH and albumin were clinically significantly influenced by diurnal variation. Resting time had no clinically significant effect. CONCLUSIONS: We found no need for resting 15 minutes prior to blood sampling. However, diurnal variation was found to have a significant and considerable impact on TSH and, to a minor degree, albumin. This has to be taken into account to ensure that reference intervals provided by the laboratory are valid on a 24-hour basis.

A BRCA2 mutation incorrectly mapped in the original BRCA2 reference sequence, is a common West Danish founder mutation disrupting mRNA splicing.

Inherited mutations in the tumor suppressor genes BRCA1 and BRCA2 predispose carriers to breast and ovarian cancer. The authors have identified a mutation in BRCA2, 7845+1G>A (c.7617+1G>A), not previously regarded as deleterious because of incorrect mapping of the splice junction in the originally published genomic reference sequence. This reference sequence is generally used in many laboratories and it maps the mutation 16 base pairs inside intron 15. However, according to the recent reference sequences the mutation is located in the consensus donor splice sequence. By reverse transcriptase analysis, loss of exon 15 in the final transcript interrupting the open reading frame was demonstrated. Furthermore, the mutation segregates with a cancer phenotype in 18 Danish families. By genetic analysis of more than 3,500 Danish breast/ovarian cancer risk families, the mutation was identified as the most common BRCA2 mutation in West Denmark, while it is rare in Central and East Denmark and not identified in South Sweden. Haplotype analysis using dense SNP arrays indicated a common founder of the mutation approximately 1,500 years ago.