Scandinavian Journal of Clinical & Laboratory Investigation最新文献

Objectives: To develop and present simple visual and descriptive summary measures of agreement in method comparison studies with replicated measurements and to discuss detection of drift in method comparison studies. Summary measures may serve as an exploratory data analysis guiding further agreement and decision analysis of two methods using the Bland and Altman method and mixed-effects modeling. Materials and methods: The methodological approach is illustrated using freely available clinical datasets from two published method comparison studies with repeated measurements on each subject. Results: With the use of ellipses and a numerical ideality index as summary measures for each subject with paired measurements from two clinical methods, it is possible to quickly decode a dataset's intra- and interindividual variation, differential and proportional bias, possible drift, and the number of measured subjects in clinically relevant areas for the two methods. Conclusion: Simple and intuitive exploratory method comparison analysis can be performed and interpreted even for relatively large datasets prior to more advanced statistical analysis of method comparisons using data with replicated measurements.

This study investigated the preanalytical stability of acetylcholine receptor antibodies (AChRAb) in patient samples, a crucial biomarker for diagnosing Myasthenia Gravis (MG). The objective was to evaluate the impact of delayed centrifugation, storage temperature, and repeated freeze-thaw cycles on the accuracy of AChRAb test results. Blood samples were collected from nine MG patients, and four stability studies were conducted. These studies examined: (I) the effect of delayed centrifugation on whole blood (up to 7 h at room temperature), (II) storage of serum at room temperature (up to 7 days), (III) storage of serum at -20 °C (up to 26 weeks), and (IV) the impact on serum of repeated freeze-thaw cycles (up to 3 cycles). AChRAb levels were measured using ELISA, and the results were analysed for statistical variation against baseline measurements using bias limits of ±15%. The findings revealed that AChRAb remained stable for up to 7 hours of delayed centrifugation, 5 days at room temperature, 13 weeks at -20 °C, and after 3 freeze-thaw cycles. However, the antibody levels showed instability after 7 days at room temperature and 26 weeks at -20 °C, where the percentage differences exceeded acceptable limits. Analytical variation, especially at low antibody levels, and differences between ELISA kit lots were potential factors contributing to these findings. In conclusion, AChRAb shows good stability if care is taken to avoid prolonged storage and handling times to maintain diagnostic accuracy.

Suspicion of proactive drug-facilitated sexual assault (DFSA) where the perpetrator covertly administers psychoactive drugs to the victim has been reported in considerable proportions from sexual assault centers and forensic units all over the world. Substances implicated in DFSA are often referred to as 'date-rape drugs'. This study investigated toxicological findings in cases of suspected proactive DFSA presenting to the Emergency Clinic for Rape Victims in Stockholm, Sweden within 48 h of the assault. Urine samples for toxicological analysis were collected on the first visit to the clinic. During follow-up 10-14 days later, participants provided a control urine sample and reported voluntary intake of alcohol, recreational and prescription drugs in connection with the assault according to a standardized protocol. Urine samples were subjected to extensive toxicological LC-MS/MS analysis that covered common recreational drugs and >100 DFSA-associated substances. 31 out of the 55 women who presented to the clinic after a suspected proactive DFSA during the study period returned for follow-up and completed the study. Almost all women (97%) reported voluntary alcohol intake in connection with the assault, which exceeded 70 g ethanol in half of the cases. Unexpected toxicological findings were made only in five cases (16%), with the most common substance being cocaine. No typical date-rape drug was identified in cases where involuntary intake was considered likely. In conclusion, the greatest risk factor exploited by perpetrators of DFSA appears to be voluntary alcohol intoxication, while toxicological evidence of illicit drugging is rare.

Introduction: The Fibrosis-4 (FIB-4) index is a non-invasive biomarker that is widely used to assess liver fibrosis. A limitation is that the enzyme methods (aspartate transaminase (AST) and alanine transaminase (ALT)) are not specified in studies. The aim of the present study was to define reference values for FIB-4 index using Nordic Reference Interval Project data where the results for P-AST and P-ALT are traceable to the IFCC reference measurement procedures.

Material and methods: FIB-4 values from 1161 subjects (550 males and 611 females) in the NORIP study were used to calculate reference intervals for the index. The 2.5th and 97.5th percentiles for these markers were calculated according to the International Federation of Clinical Chemistry guidelines.

Results: Age (18-<39.9, 40-59.9 and 60-85 years) and sex-specific reference intervals were calculated. Of the components used to calculate the FIB-4 index the age had the greatest impact. In the cohort older than 60 years, 7.5% of the females and 18.2% of the males were above the 2.67 limit for high risk of advanced fibrosis. In the same age group 84.2% of the females and 77.6% of the males had FIB-4 values above the 1.3 limit for intermediate risk and further evaluation required. These are very high proportions which means that a very large proportion of the patients will have false positive results when testing populations with a low disease prevalence.

Conclusion: FIB-4 index increases with age, potentially leading to overestimation of fibrosis in elderly patients if age specific decision values are not used.

Analyzing the local pericardial fluid (PF) surrounding the heart can provide insights into the function of myocardial and pericardial epithelial cells. Kynurenine (KYN) metabolites have been associated with endothelial dysfunction and the progression of atherosclerosis. This study investigated the relationship between KYN pathway metabolites in serum and PF and the severity of coronary atherosclerosis, as assessed by the Syntax Score (SS). The study involved 101 patients (mean age: 60 years). Of the participants, 17% were female. KYN and its metabolite levels were measured using API SCIEX 3200 LC-MS/MS methods. Statistical analysis was performed using IBM SPSS 25.0. The mean serum levels of tryptophan (TRP), 3-hydroxykynurenine (3-HK), and 3-hydroxyanthranilic acid were significantly higher (p < 0.01) when compared to the mean PF levels. In the SS-low group, PF IDO activity was significantly higher than serum IDO activity (p = 0.040). In the SS-high group, PF IDO activity was significantly higher than serum IDO activity (p = 0.002). The mean 3-HK measurements showed significant differences between the SS groups (p < 0.05). In this study, higher IDO enzyme activity in the PF compared to systemic circulation suggests the presence of inflammatory activity in the pericardial endothelial cells. This research aimed to uncover the role of amino acid metabolism, which is poorly understood in atherosclerosis. Specifically, 3-HK, a metabolite from the KYN pathway, may contribute to the development of atherosclerosis. These findings indicate that localized kynurenine pathway activation in the PF may contribute to coronary atherosclerosis, highlighting its potential as a biomarker or therapeutic target.

Therapeutic drug monitoring (TDM) is an important tool for securing optimal treatment of drugs like beta-lactam antibiotics in hospitalized patients. Developing accurate and robust methods for quantification of the pharmacologically active fraction is needed. A LC-MS/MS assay, using ultrafiltration for selection of the non-protein bound (i.e. pharmacologically active) fraction followed by a 5.5 min chromatographic separation was developed and validated for simultaneous determination of Ampicillin (AMPI), Cefuroxime (CEFU), Meropenem (MERO) and Piperacillin (PIPE)/Tazobactam (TAZO). Inter-batch imprecision was <10%. Recovery was 88-115% from lowest level of quantification (LLOQ) to 2500 mg/L for MERO, PIPE and TAZO and LLOQ-500 mg/L for AMPI and CEFU. Storage temperature had great impact on measured concentrations, with PIPE being most instable. No effect of temperature during ultrafiltration was found for the measured beta-lactams. When evaluating one-year routine clinical use of the analysis, representing 581 (mainly ICU) patient samples, >50% of patients treated with PIPE (and AMPI), and about 30% treated with MERO and CEFU, exhibited beta-lactam levels higher than the local guidelines for maximum recommended levels. Potential toxic levels were found in several patients. We believe that the analytical method developed in this study represents an accurate measure of the pharmacologically active beta-lactam fraction. Evaluation of patient data after one-year use of the method shows higher than expected beta-lactam levels, highlighting the potential benefit of TDM. More studies are needed to determine the clinical significance of TDM in beta-lactam antibiotics.

In intensive care units (ICU), malnutrition is very common and closely related to severe inflam-matory states. The aim of this study was to develop and validate a nutritional inflammatory prognostic score (NIPS) predictive of short-term mortality, and to verify the validity of existing scores. A total of 606 ICU patients were included in a longitudinal study. The population was randomly divided into two groups: development (383) and validation (223). The NIPS score was developed from nutritional and inflammatory parameters using multi-adjusted Cox proportional regression. Validation of NIPS as a prognostic score was tested using the area under the ROC curve (AUC), Cox proportional regression, and the Kaplan-Meier curve. The validity of five selected scores was also assessed. The NIPS score was developed from C-reactive protein to prealbumin ratio, total cholesterol, procalcitonin and neutrophil to lymphocyte ratio. With an AUC of 0.89 and a cutoff of 5.0, NIPS predicted short-term mortality with a sensitivity of 80.5% and a specificity of 93.8%. The risk of mortality was fivefold higher in the high nutritional risk group (RR= 5.0, [3.1-7.9], p < 0.0001). The crude cumulative incidence of mortality was significantly higher in the high-risk group (pLog-Rank < 0.0001). The five selected scores had a significant, but, lower prognostic value, compared with the developed score (AUC between 0.59 and 0.70). This study provides a new nutritional risk score, based on widely available biological parameters, with proven efficiency in predicting ICU mortality risk. Nutritional risk screening should be routinely performed at the earliest admission stages.

Publications of systematic studies on analyte stability after repeated freezing and thawing of samples are rare. We examined the stability of 17 endocrine analytes in pooled serum and/or EDTA plasma after one to four cycles of repeated freezing at -80 °C and thawing. Pooled serum and plasma samples were used. Following baseline measurements in fresh samples (T0), four aliquots (T1-T4) were frozen at -80 °C, and subjected to one to four cycles of freezing and thawing before analysis on the same day. Results were compared to baseline measurements (T0) and to samples frozen once (T1), and were adjusted using quality control material to account for analytical variation between the two time points of analysis. Analytes were considered stable based on statistical significance and percent change compared to allowable bias (AB) based on biological variation. According to criteria based on AB, serum 17-OH progesterone, aldosterone, androstenedione, anti-müllerian hormone, cortisol, dehydroepiandrosterone sulphate, proinsulin C-peptide and sexual-hormone-binding-globulin, and plasma aldosterone and cortisol were stable for four cycles of freezing and thawing. Only serum free thyroxine was considered unstable. For serum erythropoietin, estradiol, free triiodothyronine, human chorionic gonadotropin, human growth hormone, insulin-like growth factor-1, prolactin and plasma free thyroxine, human growth hormone, parathyroid hormone results were not conclusive. Based on average results of pooled samples, eight out of 17 analytes appeared stable for four freeze-thaw cycles compared to AB, while free thyroxine in serum increased more than AB.

This study examines the measurement uncertainties (MU) associated with osmolality (OSM), a crucial parameter in clinical diagnostics and treatment. The research compares the uncertainties of directly measured osmolality (dOSM) with those of estimated osmolality (eOSM), which is calculated based on sodium, glucose, and urea levels. Using ISO/TS 20914 guidelines, the study evaluates the MUs of eOSM across different analyzer models and internal quality control (IQC) lots and compares these values with dOSM. In the materials and methods section, sodium, glucose, and urea analyses were performed using two different analyzers (Atellica CH and Advia Chemistry XPT, Siemens Healthineers). OSM was measured using the freezing point depression method (Osmomat Auto, Gonotec) and data were collected to calculate eOSM. MU (k = 2, 95% confidence) calculations were conducted according to the ISO/TS 20914 standard for each system. The results show that the expanded standard MU (k = 2, 95% confidence) for dOSM is low at 5.56 mOSM/L, while the MU for eOSM is 8.54 mOSM/L for the Atellica CH system and 11.13 mOSM/L for the Advia Chemistry XPT system. These findings indicate that eOSM has higher uncertainty, suggesting it should be used with caution in clinical practice.