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Disregarded Measurement Uncertainty Contributions and Their Magnitude in Measuring Plasma Glucose
(2020)
Background:
Each measurement is subject to measurement uncertainty (MU). Consequently, each measurement of plasma glucose concentration used for diagnosis and monitoring of diabetes mellitus (DM) is affected. Although concepts and methods of MU are well established in many fields of science and technology, they are presently only incompletely implemented by medical laboratories, neglecting MU of target values of internal quality control (IQC) materials.
Methods:
An empirical and practical approach for the estimation of MU based on the analysis of routine IQC using control samples with assigned target values is presented. Its feasibility is demonstrated exemplarily by analyzing IQC data from one year obtained for glucose employing the hexokinase method with IQC of two different concentrations.
Results:
Combined relative extended (k = 2) MU comprising bias, coefficient of variation (CV), and MU of the target values assigned to control materials were about 9% with a lower (~ 56 mg/dL; ~3.1 mmol/L) and 8% with a higher (~ 346 mg/dL; ~19.2 mmol/L) concentration sample, analyzing IQC of one year from three different devices.
Conclusions:
Estimation of MU in this study is quite reliable due to the large number of IQC data from one year. The MU of the target values of the commercial control material in this study was considerably larger than other MU contributions, ie, standard deviation and bias. In the future, the contribution of MU of commercial IQC should be addressed more carefully and technologies to measure glucose should be geared toward smaller MU possible, as needed, especially for glucose concentration measurements in diagnosis and management of DM.
Infections are often caused by pathobionts, endogenous bacteria that belong to the microbiota. Trauma and surgical intervention can allow bacteria to overcome host defences, ultimately leading to sepsis if left untreated. One of the main defence strategies of the immune system is the production of highly specific antibodies. In the present proof-of-concept study, plasma antibodies against 9 major pathogens were measured in sepsis patients, as an example of severe systemic infections. The binding of plasma antibodies to bacterial extracellular proteins was quantified using a semi-automated immunoblot assay. Comparison of the pathogen-specific antibody levels before and after infection showed an increase in plasma IgG in 20 out of 37 tested patients. This host-directed approach extended the results of pathogen-oriented microbiological and PCR diagnostics: a specific antibody response to additional bacteria was frequently observed, indicating unrecognised poly-microbial invasion. This might explain some cases of failed, seemingly targeted antibiotic treatment.
Abstract
Aim
The aim of this study was to evaluate the effect of non‐surgical periodontal therapy on circulating levels of the systemic inflammation‐associated biomarkers orosomucoid (ORM), high‐sensitivity C‐reactive protein (hsCRP), chemerin, and retinol‐binding protein 4 (RBP4) in overweight or normal‐weight patients with periodontitis at 27.5 months after therapy.
Materials and methods
This exploratory subanalysis includes patients from the ABPARO‐trial (ClinicalTrials.gov NCT00707369). The per‐protocol collective provided untreated periodontitis patients with high (≥28 kg/m2) or moderate (21–24 kg/m2) BMI. Out of the per‐protocol collective, 80 patients were randomly selected and stratified for BMI group, sex, and treatment group (antibiotics/placebo), resulting in 40 overweight and normal‐weight patients. Patients received non‐surgical periodontal therapy and maintenance at 3‐month intervals. Plasma samples from baseline and 27.5 months following initial treatment were used to measure the concentrations of ORM, hsCRP, chemerin, and RBP4.
Results
At the 27.5‐month examination, ORM and hsCRP decreased noticeably in the overweight group (ORM: p = .001, hsCRP: p = .004) and normal‐weight patients (ORM: p = .007, hsCRP: p < .001). Chemerin decreased in the overweight group (p = .048), and RBP4 concentrations remained stable.
Conclusion
Non‐surgical periodontal therapy reduced systemically elevated inflammation‐associated biomarkers in periodontitis patients. These improvements were more pronounced in overweight patients than in normal‐weight patients.
Variability of Thyroid Measurements from Ultrasound and Laboratory in a Repeated Measurements Study
(2020)
Background: Variability of measurements in medical research can be due to different sources. Quantification of measurement errors facilitates probabilistic sensitivity analyses in future research to minimize potential bias in epidemiological studies. We aimed to investigate the variation of thyroid-related outcomes derived from ultrasound (US) and laboratory analyses in a repeated measurements study. Subjects and Methods: Twenty-five volunteers (13 females, 12 males) aged 22–70 years were examined once a month over 1 year. US measurements included thyroid volume, goiter, and thyroid nodules. Laboratory measurements included urinary iodine concentrations and serum levels of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), and thyroglobulin. Variations in continuous thyroid markers were assessed as coefficient of variation (CV) defined as mean of the individual CVs with bootstrapped confidence intervals and as intraclass correlation coefficients (ICCs). Variations in dichotomous thyroid markers were assessed by Cohen’s kappa. Results: CV was highest for urinary iodine concentrations (56.9%), followed by TSH (27.2%), thyroglobulin (18.2%), thyroid volume (10.5%), fT3 (8.1%), and fT4 (6.3%). The ICC was lowest for urinary iodine concentrations (0.42), followed by fT3 (0.55), TSH (0.64), fT4 (0.72), thyroid volume (0.87), and thyroglobulin (0.90). Cohen’s kappa values for the presence of goiter or thyroid nodules were 0.64 and 0.70, respectively. Conclusion: Our study provides measures of variation for thyroid outcomes, which can be used for probabilistic sensitivity analyses of epidemiological data. The low intraindividual variation of serum thyroglobulin in comparison to urinary iodine concentrations emphasizes the potential of thyroglobulin as marker for the iodine status of populations.