APS calculator: a data-driven tool for setting outcome-based analytical performance specifications for measurement uncertainty using specific clinical requirements and population data

OBJECTIVES

According to ISO 15189:2022, analytical performance specifications (APS) should relate to intended clinical use and impact on patient care. Therefore, we aimed to develop a web application for laboratory professionals to calculate APS based on a simulation of the impact of measurement uncertainty (MU) on the outcome using the chosen decision limits, agreement thresholds, and data of the population of interest.

METHODS

We developed the "APS Calculator" allowing users to upload and select data of concern, specify decision limits and agreement thresholds, and conduct simulations to determine APS for MU. The simulation involved categorizing original measurand concentrations, generating measured (simulated) results by introducing different degrees of MU, and recategorizing measured concentrations based on clinical decision limits and acceptable clinical misclassification rates. The agreements between original and simulated result categories were assessed, and values that met or exceeded user-specified agreement thresholds that set goals for the between-category agreement were considered acceptable. The application generates contour plots of agreement rates and corresponding MU values. We tested the application using National Health and Nutrition Examination Survey data, with decision limits from relevant guidelines.

RESULTS

We determined APS for MU of six measurands (blood total hemoglobin, plasma fasting glucose, serum total and high-density lipoprotein cholesterol, triglycerides, and total folate) to demonstrate the potential of the application to generate APS.

CONCLUSIONS

The developed data-driven web application offers a flexible tool for laboratory professionals to calculate APS for MU using their chosen decision limits and agreement thresholds, and the data of the population of interest.

Association of the methionine sulfoxide reductase A rs10903323 gene polymorphism with functional activity and oxidative modification of alpha-1-antitrypsin in COPD patients

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is multi-factorial disorder which results from environmental influences and genetic factors. We aimed to investigate whether methionine sulfoxide reductase A (MSRA) rs10903323 gene polymorphism is associated with COPD development and severity in Serbian adult population.

METHODS

The study included 155 patients with COPD and 134 healthy volunteers. Genotyping was determined performing home-made polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The difference between the inhibitory activities of normal and oxidized Alpha-1-Antitrypsin (A1AT) against elastase and trypsin was used for determination of Oxidized Alpha-1-Antitrypsin (OxyA1AT) (expressed as % and g/L). Functional activity of A1AT was presented as a specific inhibitor activity to elastase (SIA-Elastase, kU/g).

RESULTS

Frequencies of the genotypes AA, AG and GG were 80.0%, 20.0%, 0% in COPD patients and 80.5%, 18.5% and 1.5% in the control group, and there was no significant difference in genotype or allele distributions between groups. Serum level of A1AT (g/L) and OxyA1AT was significantly higher in COPD patients than in the control group, but functional activity of A1AT (SIA-Elastase) was significantly lower in COPD patients than in the control group. In COPD group, increased level of OxyA1AT was present in G allele carriers who were smokers relative to G allele carriers who were not smokers. In the smoker group of patients with severe and very severe COPD (GOLD3+4), significant increase in OxyA1AT level was present in G allele carriers compared to AA homozygotes.

CONCLUSION

These findings suggest that MSRA rs10903323 gene polymorphism is probably not a risk for COPD by itself but could represent a COPD modifier, since minor, G allele, is associated with an increased level of oxidized A1AT, indicating impaired ability of MSRA to repair oxidized A1AT in COPD-smokers, and in severe form of COPD.

Epigenetic Aspects of a New Probiotic Concept-A Pilot Study

Several studies report the important role of an altered gut microbiota in the development of obesity, highlighting the potential use of probiotics in the treatment of obesity. The aim of this study is to investigate the effect of a novel probiotic approach on the expression of specific miRNAs and mRNAs associated with obesity in combination with the hypocholesterolemic octacosanol. Twenty overweight/obese women participated in a randomized, placebo-controlled, double-blind study and were randomly divided into two groups: the intervention group (daily one capsule containing Lactobacillus plantarum 299v (DSM9843), Saccharomyces cerevisiae var. boulardii, and 40 mg octacosanol; N = 12) and the placebo group (N = 8). Changes in lipid parameters and expression of miRNAs and mRNAs were assessed before (T0) and after the 12-week intervention (T1). After the intervention, the expression of miR-155-5p (9.38 ± 0.85 vs. 8.38 ± 1.06, p = 0.05) and miR-24-3p (3.42 ± 0.38 vs. 2.71 ± 0.97, p = 0.031) showed significant decreases in the intervention group when compared to the control group. At T1, the expression of miR-155-5p (8.69 ± 1.31 vs. 9.3 ± 0.85, p = 0.04), miR-125b-5p (5.41 ± 1.18 vs. 5.99 ± 1.36, p = 0.049), and TNF-α (10.24 ± 1.66 vs. 11.36 ± 1.12, p = 0.009) were significantly decreased in the intervention group. No changes in lipids and anthropometric parameters were observed. The novel probiotic approach had a positive effect on regulating the expression of certain miRNAs and mRNAs important for regulating inflammation and adipogenesis, which are essential for obesity onset and control.

The Effects of Disease-Modifying Therapies on Oxidative Stress in Patients With Relapsing-Remitting Multiple Sclerosis

OBJECTIVE

Oxidative stress (OS) has a role in the pathogenesis and progression of multiple sclerosis. The effects of disease-modifying therapies (DMTs) on OS are unclear. We aimed to explore the association between DMTs and OS in patients with relapsing-remitting multiple sclerosis (RRMS).

METHODS

The study conducted in 167 patients (102 received and 65 not received the DMTs). The DMTs included interferon beta-1a (n = 15), interferon beta-1b (n = 20), glatiramer acetate (n = 10), and sphingosine-1-phosphate receptor modulators (n = 57). Oxidative stress assessed by total antioxidant status (TAS) and total oxidant status (TOS) (determined by spectrophotometric method), oxidative index (OSI was calculated), and urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG/creatinine was determined by high-performance liquid chromatography and tandem mass spectrometry). Patients were classified by Multiple Sclerosis Severity Score (MSSS) to mild/moderate (MSSS, <6.7) and severe (MSSS, >6.7).

RESULTS

Disease-modifying therapies are associated with increased TAS, decreased TOS, OSI, and 8-oxodG/creatinine. Regardless of therapy, women had a less favorable redox status (lower TAS, higher TOS and OSI). Patients with MSSS>6.7 and without DMTs had higher OSI than patients who received DMTs. Women with MSSS>6.7 without DMTs had lower TAS than women with DMTs, whereas in the same stage of MS, men without DMTs had higher TOS than patients with DMTs. Women with MSSS<6.7 and with DMTs had lower 8-oxodG/creatinine compared with those without DMT therapy.

CONCLUSIONS

The antioxidant effects of DMTs were evidenced in this study. The gender-related effects of DMTs on the OS imply the personalized antioxidant pharmacotherapy, especially for the women. The OS biomarkers have a potential as the prognostic for the assessment of DMTs outcomes in patients with RRMS.

An approach for determining allowable between reagent lot variation

Clinicians trust medical laboratories to provide reliable results on which they rely for clinical decisions. Laboratories fulfil their responsibility for accurate and consistent results by utilizing an arsenal of approaches, ranging from validation and verification experiments to daily quality control procedures. All these procedures verify, on different moments, that the results of a certain examination procedure have analytical performance characteristics (APC) that meet analytical performance specifications (APS) set for a particular intended use. The APC can in part be determined by estimating the measurement uncertainty component under conditions of within-laboratory precision (uRw), which comprises all components influencing the measurement uncertainty of random sources. To maintain the adequacy of their measurement procedures, laboratories need to distinguish aspects that are manageable vs. those that are not. One of the aspects that may influence uRw is the momentary significant bias caused by shifts in reagent and/or calibrator lots, which, when accepted or unnoticed, become a factor of the APC. In this paper, we postulate a model for allocating a part of allowable uRw to between-reagent lot variation, based on the need for long-term consistency of the measurement variability for that specific measurand. The allocation manages the ratio between short-term and long-term variation and indicates laboratories when to reject or correct certain variations due to reagent lots.

Effects of short-term magnesium supplementation on ionized, total magnesium and other relevant electrolytes levels

This study aimed to investigate the short-term effects of three magnesium (Mg) dietary supplements containing mineral immediately available for absorption on Mg biochemical status indices (ionized and total Mg), as well as their effects on electrolytes levels in healthy female young adults (n = 61). After a 10-days intervention period supplementation with powder/granulate containing Mg oxide led to an increase in both ionized Mg concentration and % in total Mg in comparison with the baseline. Supplementation with Mg citrate was associated with the significant increase in % of ionized fraction and decrease in serum total Mg concentration. By contrast, among participants consuming Mg carbonate in the form of effervescent tablets ionized Mg concentration and % in total Mg decreased, without detectable changes in serum total Mg. In conclusion, after the short-term supplementation period, Mg oxide demonstrated superior bioavailability compared to the other examined Mg supplements without affecting other minerals' levels.

Improving the laboratory result release process in the light of ISO 15189:2012 standard

The ISO 15189:2012 standard section 5.9.1 requires laboratories to review results before release, considering quality control, previous results, and clinical information, if any, and to issue documented procedures about it. While laboratory result reporting is generally regarded as part of the post-analytical phase, the result release process requires a general view of the total examination process. Reviewing test results may follow with troubleshooting and test repetition, including reanalyzing an individual sample or resampling. A systematic understanding of the result release may help laboratory professionals carry out appropriate test repetition and ensure the plausibility of laboratory results. In this paper, we addressed the crucial steps in the result release process, including evaluation of sample quality, critical result notification, result reporting, and recommendations for the management of the result release, considering quality control alerts, instrument flags, warning messages, and interference indexes. Error detection tools and plausibility checks mentioned in the present paper can support the daily practice of results release.

Stress hormones at rest and following exercise testing predict coronary artery disease severity and outcome

OBJECTIVES

Despite considerable knowledge regarding the importance of stress in coronary artery disease (CAD) pathogenesis, its underestimation persists in routine clinical practice, in part attributable to lack of a standardized, objective assessment. The current study examined the ability of stress hormones to predict CAD severity and prognosis at basal conditions as well as during and following an exertional stimulus.

MATERIALS AND METHODS

Forty Caucasian subjects with significant coronary artery lesions (≥50%) were included. Within 2 months of coronary angiography, cardiopulmonary exercise testing (CPET) on a recumbent ergometer was performed in conjunction with stress echocardiography (SE). At rest, peak and after 3 min of recovery following CPET, plasma levels of cortisol, adrenocorticotropic hormone (ACTH) and NT-pro-brain natriuretic peptide (NT-pro-BNP) were measured by immunoassay sandwich technique, radioimmunoassay, and radioimmunometric technique, respectively. Subjects were subsequently followed a mean of 32 ± 10 months.

RESULTS AND DISCUSSION

Mean ejection fraction was 56.7 ± 9.6%. Subjects with 1-2 stenotic coronary arteries (SCA) demonstrated a significantly lower plasma cortisol levels during CPET compared to those with 3-SCA (p < .05), whereas ACTH and NT-pro-BNP were not significantly different (p > .05). Among CPET, SE, and hormonal parameters, cortisol at rest and during CPET recovery demonstrated the best predictive value in distinguishing between 1-, 2-, and 3-SCA [area under ROC curve 0.75 and 0.77 (SE = 0.11, 0.10; p = .043, .04) for rest and recovery, respectively]. ΔCortisol peak/rest predicted cumulative cardiac events (area under ROC curve 0.75, SE = 0.10, p = .049).

CONCLUSIONS

Cortisol at rest and following an exercise test holds predictive value for CAD severity and prognosis, further demonstrating a link between stress and unwanted cardiac events.