The diagnostic accuracy of quality control rules.

Internal quality control in clinical chemistry laboratories are based on analyzing samples of stable control materials among the patient samples. The control results are interpreted by using quality control rules that usually are designed to detect systematic errors. The best rules have a high probability of error detection (Ped), i.e. to detect the maximal allowable (critical) systematic error and a low probability of false rejection (Pfr, false alarm). In this work we show that quality control rules can be represented by points on a ROC curve which appears when Ped is plotted against Pfr and only the control limit is varied. Further, we introduce a new method for choosing the optimal control limit, analogous to choosing the optimal operating point on the ROC curve of a diagnostic test. This decision needs knowledge of the pretest probability of a critical systematic error, the benefit of detecting it when it occurs and the cost of false alarm. The ROC curve analysis showed that if rules based on N = 2 are used, mean rules outperform Westgard rules because the ROC curve of the mean rules was lying above the ROC curves of the Westgard rules. A mean rule also had a lower maximum expected increase in the number of unacceptable patient results reported during the presence of an out-of-control error condition (Max E(NUF)) than comparable Westgard rules.

Quantifying Satisfaction of Degenerative Lumbar Spinal Stenosis Patients in Post-lateral Lumbar Interbody Fusion Surgery: Establishing Critical JOABPEQ Cutoff Scores.

OBJECTIVE: This retrospective study aimed to determine the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) cutoff scores for assessing patient satisfaction postlateral lumbar interbody fusion (LLIF) in degenerative lumbar spinal stenosis (DLSS) patients. METHODS: Analyzing 136 DLSS patients (83 males, 53 females), the study evaluated demographics, pain (Numeric Rating Scale), and JOABPEQ outcomes (low back pain, lumbar function, walking ability, social life, mental health). Patient satisfaction was surveyed, and based on their responses, patients were categorized into "Beneficial" and "Nonbeneficial" groups. Statistical analysis encompassed the Kolmogorov-Smirnov test, t-tests, Mann-Whitney U test, and Receiver Operating Characteristic (ROC) curve analysis for JOABPEQ cutoff determination. RESULTS: Postoperative improvements in JOABPEQ scores, especially in walking ability, social life function, and mental health, were significant. Pain intensity, assessed using the Numeric Rating Scale, also showed notable reductions. The Δ walking ability cutoff was set at 25.00, indicating substantial mobility improvement. This domain's area under the curve (AUC) was 0.815 (95% CI: 0.726-0.903), demonstrating high effectiveness in assessing patient satisfaction postsurgery. The study also found no significant differences in complication rates between groups for conditions like transient motor weakness, thigh pain/numbness, and revision surgery. CONCLUSIONS: This study underscores the value of patient-centered outcomes in evaluating LLIF surgery success for DLSS. The identified JOABPEQ cutoff values provide a quantitative tool for assessing patient satisfaction, emphasizing the necessity of comprehensive postoperative evaluations beyond traditional clinical metrics for improved patient care and life quality.

Neurotrophin growth factors and their receptors as promising blood biomarkers for Alzheimer's Disease: a gene expression analysis study.

BACKGROUND: Alzheimer's disease (AD) is a multifaceted neurological ailment affecting more than 50 million individuals globally, distinguished by a deterioration in memory and cognitive abilities. Investigating neurotrophin growth factors could offer significant contributions to understanding AD progression and prospective therapeutic interventions. METHODS AND RESULTS: The present investigation collected blood samples from 50 patients diagnosed with AD and 50 healthy individuals serving as controls. The mRNA expression levels of neurotrophin growth factors and their receptors were measured using quantitative PCR. A Bayesian regression model was used in the research to assess the relationship between gene expression levels and demographic characteristics such as age and gender. The correlations between variables were analyzed using Spearman correlation coefficients, and the diagnostic potential was assessed using a Receiver Operating Characteristic curve. NTRK2, TrkA, TrkC, and BDNF expression levels were found to be considerably lower (p-value < 0.05) in the blood samples of AD patients compared to the control group. The expression of BDNF exhibited the most substantial decrease in comparison to other neurotrophin growth factors. Correlation analysis indicates a statistically significant positive association between the genes. The ROC analysis showed that BDNF exhibited the greatest Area Under the Curve (AUC) value of 0.76, accompanied by a sensitivity of 70% and specificity of 66%. TrkC, TrkA, and NTRK2 demonstrated considerable diagnostic potential in distinguishing between cases and controls. CONCLUSION: The observed decrease in the expression levels of NTRK2, TrkA, TrkC, and BDNF in AD patients, along with the identified associations between specific genes and their diagnostic capacity, indicate that these expressions have the potential to function as biomarkers for the diagnosis and treatment of AD.

In Silico Insights into Micro-Mechanism Understanding of Extracts of Taxus Chinensis Fruits Against Alzheimer's Disease.

BACKGROUND: The taxus chinensis fruit (TCF) shows promises in treatment of aging-related diseases such as Alzheimer's disease (AD). However, its related constituents and targets against AD have not been deciphered. OBJECTIVE: This study was to uncover constituents and targets of TCF extracts against AD. METHODS: An integrated approach including ultrasound extractions and constituent identification of TCF by UPLC-QE-MS/MS, target identification of constituents and AD by R data-mining from Pubchem, Drugbank and GEO databases, network construction, molecular docking and the ROC curve analysis was carried out. RESULTS: We identified 250 compounds in TCF extracts, and obtained 3,231 known constituent targets and 5,326 differential expression genes of AD, and 988 intersection genes. Through the network construction and KEGG pathway analysis, 19 chemicals, 31 targets, and 11 biological pathways were obtained as core compounds, targets and pathways of TCF extracts against AD. Among these constituents, luteolin, oleic acid, gallic acid, baicalein, naringenin, lovastatin and rutin had obvious anti-AD effect. Molecular docking results further confirmed above results. The ROC AUC values of about 87% of these core targets of TCF extracts was greater than 0.5 in the two GEO chips of AD, especially 10 targets with ROC AUC values greater than 0.7, such as BCL2, CASP7, NFKBIA, HMOX1, CDK2, LDLR, RELA, and CCL2, which mainly referred to neuron apoptosis, response to oxidative stress and inflammation, fibroblast proliferation, etc.Conclusions:The TCF extracts have diverse active compounds that can act on the diagnostic genes of AD, which deserve further in-depth study.

Preliminary identification of clinical cut-off of the vegetarian vegan eating disorder screener (V-EDS) in a community and self-reported clinical sample of vegetarians and vegans.

BACKGROUND: The vegetarian vegan eating disorder screener (V-EDS) is an 18-item self-report screening tool designed to assess the unique elements of eating disorder symptomology in vegetarians and vegans. Previous results have suggested strong initial psychometric properties in non-clinical community samples of vegetarians and vegans. The present study sought to identify a preliminary threshold cut-off score to discriminate eating disorder pathology in a self-reported clinical and community sample. METHODS: This study involved secondary analysis using data collected in McLean et al. (Development and preliminary validation of a novel eating disorder screening tool for vegetarians and vegans: the V-EDS, 2023), comprising 599 non-clinical participants and 51 self-reported clinical participants. Receiver operating characteristic (ROC) curve analysis was used to compute possible cut-off values for the V-EDS. RESULTS: ROC analysis indicated good performance of the V-EDS (area under the curve = 0.87), with integration of the Youden index demonstrating a global score of ≥ 18 to be optimal in predicting clinical caseness with good sensitivity (0.804) and specificity (0.843). CONCLUSIONS: The present study fills an important gap as the first to investigate an optimal V-EDS score to discriminate level of impairment from eating disorder pathology in a sample of vegetarian and vegan community and self-reported clinical participants. We extend the utility of the V-EDS in discovering good discrimination power in classifying clinical caseness with a cut-off score of 18 shown to optimise the trade-off between sensitivity and specificity. Future research should focus on expanding the psychometric properties of the V-EDS in larger and more diverse participant groups, including gender, age, cultural identity, and eating disorder history.

This study builds on the preliminary validation of a novel eating disorder screening tool for people adhering to a vegetarian and vegan diet called the V-EDS. In this study, we set out to develop a cut-off score for the V-EDS to distinguish people needing further evaluation for a possible eating disorder within the community. We found a global V-EDS score of ≥ 18 to be ideal in distinguishing between eating disorder symptomatic and non-eating disorder groups. In future, the V-EDS may prove useful for initial screening and symptom progression of eating disorders across both clinical and research settings.

[Validation of the flexion-relaxation test to define a lumbar deficit with tetrapolar electrodes]. / Validación de test de flexión-relajación para definir un déficit lumbar con electrodos tetrapolares.

INTRODUCTION AND OBJECTIVE: To obtain a new cut-off point (CP) for a lumbar flexion-relaxation (RF) test established with tetrapolar (e.) electrodes, from values already defined with bipolar devices. MATERIALS AND METHODS: The study sample consists of 47 patients in a situation of temporary disability due to low back pain (DL). They were evaluated by means of an isometric dynamometry test, a kinematic test and an assessment of the FR phenomenon. Two experiments with ROC curves are proposed. The first, with 47 patients who consecutively performed the RF test with both types of electrodes, using the cut-off point (CP) known for the e. bipolar (2.49µV). In the second, with the EMG data recorded with e. tetrapolar in 17 patients, a DeLong test was performed that compares the 2 ROC curves that were constructed on the one hand, by classifying the sample from dynamometry and kinematic tests, and on the other, by classifying them with the bipolar EMG values. RESULTS: A total of 34 patients adequately completed the evaluations of the first experiment and 17 patients the second. The first study shows a cut-off point of 1.2µV, with an AUC of 87.7%; Sensitivity 84.2% and Specificity 80%. The second shows a PC for e. bipolars of 1.21µV (AUC 87.5%) and for e. tetrapolar values of 1.43 (AUC 82.5%) with a DeLong test without significant differences between both curves (p>0.4065). CONCLUSIONS: The validation methodology with ROC curves has made it possible to obtain a new PC for the RF test in a practical way, simply by simultaneously performing both tests on the same group of patients until a significant sample is obtained.

Lipid accumulation product is an effective predictor of metabolic syndrome in non-obese women with polycystic ovary syndrome.

Objective: To explore the correlation of lipid accumulation product (LAP) with metabolic syndrome (MS) and to assess the predictive value of LAP for MS risk in polycystic ovary syndrome (PCOS) with different body mass index (BMI). Methods: A total of 242 PCOS patients and 150 controls were recruited and divided into normal-weight, overweight, and obese groups, then further divided into MS and without MS subgroups. Clinical and anthropometric variables and laboratory results were recorded. LAP was calculated from waist circumference (WC) and triglyceride using sex-specific formulae. Logistic regression analysis and receiver operating characteristic (ROC) curve were applied to determine and analyze the predictive value of LAP for MS. Results: The prevalence of MS among PCOS patients was 45.04%, which was significantly higher than that of the controls (10%). Stratified by BMI, the incidence of MS in the normal-weight, overweight, and obese PCOS groups were 15.58%, 41.43%, and 71.58%, respectively. Logistic regression analysis indicated that LAP was an independent risk factor for MS in both normal-weight and overweight groups; however, the results were not significant in the obese group. ROC curve analysis showed that LAP had an outstanding discrimination index for MS in normal-weight (AUC=0.960, cut-off value=42.5) and overweight (AUC=0.937, cut-off value=47.93) PCOS patients, with a sensitivity of 0.917/0.931 (normal-weight/overweight) and a specificity of 0.969/0.854 (normal-weight/overweight), respectively. Conclusion: Normal-weight and overweight PCOS patients also have a fairly high incidence of MS and should receive as much attention as obese patients. Compared to applying multiple clinical indicators, LAP is more convenient and facilitates acquiring early and accurate diagnoses of MS among non-obese PCOS patients using fewer MS markers.

New index for the diagnosis of liver fibrosis in Schistosomiasis mansoni / Novo índice biológico para o diagnóstico da fibrose hepática na Esquistossomose mansoni

ABSTRACT BACKGROUND Periportal fibrosis is the major pathological consequence of the Schistosoma mansoni infection. OBJECTIVE To evaluate the accuracy of serum markers and to construct an index to assess fibrosis. METHODS Patients (n=116) with schistosomiasis were evaluated by ultrasound scan and measurements of serum levels of aminotransferases, γ-glutamyl transferase, alkaline phosphatase, hyaluronic acid, cytokines and platelets. Ultrasound images were used to evaluate the fibrosis using Niamey's classification and identified 19 patients without periportal fibrosis (patterns A and B), 48 with mild to moderate fibrosis (C and D) and 49 with advanced fibrosis (E and F). RESULTS Using multivariate analysis, a model was created, which involved alkaline phosphatase and platelets and could separate patients with different patterns of fibrosis. This index showed a better performance in separating patients without fibrosis from with advanced periportal fibrosis. The biological index showed an area under the ROC curve of 1.000. Using values below the lowest or above the highest cut-off point, the presence or absence of advanced fibrosis could be predicted in all patients. CONCLUSION The index constructed can be used to separate patients with different patterns of periportal fibrosis, specially to predict advanced fibrosis in schistosomiasis patients.

RESUMO CONTEXTO A fibrose periportal é a maior consequência patológica da infecção pelo Schistosoma mansoni. OBJETIVO Avaliar a acurácia de marcadores séricos e construir um índice para avaliar a fibrose. MÉTODOS Pacientes (n=116) com esquistossomose foram avaliados pela ultrassonografia e dosados os níveis de aminotransferases, γ-glutamil transferase, fosfatase alcalina, ácido hialurônico, citocinas e plaquetas. Imagens de ultrasom foram utilizadas para avaliar a fibrose através de classificação de Niamey e identificados 19 pacientes sem fibrose periportal (padrão A e B), 48 com fibrose média a moderada (C e D) e 49 com fibrose avançada (E e F). RESULTADOS Através de análise multivariada, um modelo foi criado, que envolveu a fosfatase alcalina e plaquetas e conseguiu separar pacientes com diferentes padrões de fibrose periportal. Este índice mostrou um melhor desempenho em separar pacientes sem fibrose dos pacientes com fibrose avançada. O índice biológico mostrou uma área sob a curva ROC de 1,000. Usando valores infereiores e acima do ponto de corte, a presença ou ausência de fibrose avançada pode ser prevista em todos os pacientes. CONCLUSÃO O índice construído pode ser usado para separar os pacientes com diferentes padrões de fibrose periportal, especialmente para prever fibrose avançada em pacientes com esquistossomose.

Using receiver operating characteristic curve analysis in detecting excess adiposity in 9-13-year old South African children / Uso del análisis de la curva de las características operativas del receptor (ROC) para detectar el exceso de adiposidad en niños Sudafricanos de 9 a 13 años de edad

OBJECTIVE: Little is known concerning the applicability of receiver operating characteristic (ROC) curve analysis in detecting excess adiposity in preadolescent South African children. Therefore, the purpose of this study was to evaluate the sensitivity and specificity of body mass index (BMI) and skinfold thickness:BMI (subcutaneous to overall fat) in detecting excess adiposity in preadolescent urban South African school children. METHODS: This was a cross-sectional survey of 1136 randomly selected children (548 boys and 588 girls) aged 9-13 years old in urban (Pretoria Central) South Africa. Body mass, stature, skinfolds (subscapular, triceps, supraspinale and biceps) and waist circumference were measured. Receiver operating characteristic curve analysis was used to assess the sensitivity and specificity of BMI, and log10 SF4:BMI to detect excess adiposity. Excess adiposity was defined as levels of log10 SF4 greater than the internally derived 85th percentile (log10 SF4 > 85th percentile). RESULTS: Compared to log10 SF4:BMI, BMI had a high specificity (0.88; 95% CI 0.84, 0.90). The log10 SF4:BMI identified excess adiposity with a sensitivity and specificity of 0.62 (95% CI 0.60, 0.67) and 0.68 (95% CI 0.64, 0.70), respectively. Besides, a decrease in overall misclassification with the use of log10 SF4:BMI instead of BMI at the 95th percentile (9.7% versus 27.1%) was observed. CONCLUSION: Similar to other studies, although with varying degrees, the present study confirms that log10 SF4:BMI at conventional cut-off points has a relatively high sensitivity and specificity in detecting excess adiposity, and therefore could be used to identify the excess adiposity in South African children. As such, defining obesity based on population-specific percentiles rather than using cut-off points derived from other geographical settings with contrasting levels of socio-economic development becomes imperative.

OBJETIVO: Poco se sabe acerca de las posibilidades de aplicación del análisis de la curva de las características operativas del receptor (ROC) para detectar el exceso de adiposidad en preadolescentes sudafricanos. Por consiguiente, el propósito de este estudio fue evaluar la sensibilidad y especificidad del índice de masa corporal, y grosor de los pliegues cutáneos:IMC (subcutáneo con respecto a la grasa general) a la hora de detectar el exceso de adiposidad en los escolares preadolescentes urbanos de Sudáfrica. MÉTODOS: Se realizó un estudio transversal de 1136 niños seleccionados de manera aleatoria (548 varones y 588 hembras) de 9 a 13 años de edad en la Sudáfrica urbana (Pretoria Central). Se midieron la masa corporal, la estatura, los pliegues cutáneos (subescapular, supraespinal, así como del tríceps y el bíceps) y la circunferencia de la cintura. Se hizo uso del análisis de la curva de las características operativas del receptor para evaluar la sensibilidad y especificidad del IMC, y el log10 PC4: IMC, a fin de detectar el exceso de adiposidad. El exceso de adiposidad fue definido en términos de la medida en que los niveles del log10 PC4 fueran mayores que el percentil 85 (log10 PC4 > percentil 85). RESULTADOS: Comparado con el log10 SF4:IMC, el IMC tenía una alta especificidad (0.88; 95% CI 0.84, 0.90). El log10 SF4:IMC identificó exceso de adiposidad con una sensibilidad y especificidad de 0.62 (95% CI 0.60, 0.67) y 0.68 (95% CI 0.64, 0.70), respectivamente. Además, una disminución en los errores de clasificación global con el uso del log10 SF4:IMC en lugar del IMC en el percentil 95 (9.7% frente a 27.1%) se observó. CONCLUSIÓN: Similar a otros estudios, aunque con diferencias de grados, el estudio presente confirma que el log10 SF4:IMC a ciertos puntos convencionales límites, posee una sensibilidad y una especificidad relativamente altas a la hora de detectar la adiposidad en exceso, y por consiguiente podría usarse para identificar el exceso de adiposidad en los niños sudafricanos. Siendo así, resulta imperativo definir la obesidad sobre la base de los percentiles específicos de la población, más bien que a partir del uso de puntos de corte derivados de otros sitios geográficos con niveles contrastantes de desarrollo económico.