Approach to prediction and receiver operating characteristic analysis of a regression model for assessing the severity of the course Lyme borreliosis in children

Introduction

Lyme borreliosis (LB) is a multisystemic zoonotic disease transmitted by the bite of infected tick vectors.The aim of the study is to develop a mathematical model for predicting the risk of severity of Lyme disease by the risk factor of the disseminated form of LB in children who have had a tick attack. To test the effectiveness of the formula for predicting the development of the disseminated stage of LB, we built a receiver operating characteristic (ROC) curve and determined the specificity and sensitivity of our model. The results of the examination of 122 patients with the confirmed local and disseminated stages of LB were taken as a basis.

Material and methods

To build a prognostic model for prediction of the risk of the developing of the stage in LB predicting the risk of severity of course in Lyme borreliosis (PRSCLB), 122 children (aged 13 ±3 years) with LB were examined using multivariate regression analysis, including 52 boys and 70 girls. Groups of patients: 79 children with erythema migrans, 16 with Lyme arthritis, and 27 with nervous system involvement by LB. The quality of the prognostic model was checked by the Nagelkerke R Square (Nagelkerke R2) and the acceptability of this model was assessed using ROC analysis.

Results

The method of multivariate regression analysis for predicting severe course and organ and system damage in LB in children, taking into account the factors and variants of the disease itself, makes it possible to develop a mathematical model for predicting the relative response factors (RRF) of severe forms of Lyme disease and will improve the effectiveness of treatment. This will create all the prerequisites for high-quality preventive measures and reduce the relative response factors rate.The initial data for predicting the severity of LB were 28 factors. According to the results of regression analysis, 24 factors were included in the model for predicting the severity of LB.

Conclusions

The results of the study showed that the multifactorial model predicts the severity and organ and system damage in LB in children with an accuracy of 95%. The ROC curve, which was built on the basis of the results, has an area under the curve of 0.94, which indicates the high efficiency of the model.

Receiver operating characteristic curve analysis in diagnostic accuracy studies: A guide to interpreting the area under the curve value

This review article provides a concise guide to interpreting receiver operating characteristic (ROC) curves and area under the curve (AUC) values in diagnostic accuracy studies. ROC analysis is a powerful tool for assessing the diagnostic performance of index tests, which are tests that are used to diagnose a disease or condition. The AUC value is a summary metric of the ROC curve that reflects the test's ability to distinguish between diseased and nondiseased individuals. AUC values range from 0.5 to 1.0, with a value of 0.5 indicating that the test is no better than chance at distinguishing between diseased and nondiseased individuals. A value of 1.0 indicates perfect discrimination. AUC values above 0.80 are generally consideredclinically useful, while values below 0.80 are considered of limited clinical utility. When interpreting AUC values, it is important to consider the 95% confidence interval. The confidence interval reflects the uncertainty around the AUC value. A narrow confidence interval indicates that the AUC value is likely accurate, while a wide confidence interval indicates that the AUC value is less reliable. ROC analysis can also be used to identify the optimal cutoff value for an index test. The optimal cutoff value is the value that maximizes the test's sensitivity and specificity. The Youden index can be used to identify the optimal cutoff value. This review article provides a concise guide to interpreting ROC curves and AUC values in diagnostic accuracy studies. By understanding these metrics, clinicians can make informed decisions about the use of index tests in clinical practice.

Discrimination in clinical diagnosis between patients with schizophrenia and healthy controls using eye movement and cognitive functions

AIM

Eye movements and cognitive functions are significantly impaired in schizophrenia. We aimed to develop promising clinical diagnostic markers that fit practical digital health applications in psychiatry using eye movement and cognitive function data from 1254 healthy individuals and 336 patients with schizophrenia.

METHODS

Multivariate analyses using logistic regression were performed to confirm net performance of eye movements and cognitive functions scored using the Wechsler Adult Intelligence Scale Third Edition and Wechsler Memory Scale-Revised. We then examined the discrimination performance of pairs containing an eye movement and a cognitive function measure to search the pairs that would be effective in practical application for the discrimination according to the diagnostic criterion between the groups.

RESULTS

The multivariate analyses confirmed that eye movements and cognitive functions were effective modalities for discriminating between patients with schizophrenia and healthy controls. The discriminant analyses of the pairs demonstrated that seven eye movement measures and seven scores from cognitive function tests showed high discrimination performance when paired with one measure from the other modality. Moreover, seven pairs of digit-symbol-coding or symbol-search and eye movement measures had high and robust discrimination performance.

CONCLUSION

Seven pairs of an eye movement and a cognitive function measure were effective, robust, and less time-consuming in assisting clinical diagnosis by categorizing healthy individuals or patients with schizophrenia. Our findings may help develop an objective auxiliary diagnosis method working even on portable devices, which facilitates the consistency of diagnosis, earlier intervention, and shared decision-making. This article is protected by copyright. All rights reserved.

Clinical risk factors for patients with myelodysplastic syndromes undergoing allogeneic hematopoietic stem cell transplantation

Objectives: Allogeneic hematopoietic stem cell transplantation (allo-HCT) is the only curative treatment for myelodysplastic syndromes (MDS), although predicting post-transplant outcomes remains inconclusive. This study evaluated patients who underwent allo-HCT for MDS to identify prognostic factors and develop a clinical risk model.Methods: We evaluated 55 patients between June 2000 and March 2015 to identify prognostic factors and develop a model for three-year overall survival (OS) and event-free survival (EFS). Cox regression analysis was performed on four factors: age ≥55 years; Hematopoietic Cell Transplant-Comorbidity Index >2; intermediate or worse cytogenetic status based on revised International Prognostic Scoring System; and unrelated donor status associated with poor OS in the univariate analysis. A clinical risk model was constructed using the sum of the regression coefficients and evaluated using receiver operating characteristic analysis and five-fold cross-validation.Results: Patient median age was 51 (range: 30-67) years. Median follow-up was 45.8 (range: 1.27-193) months; the three-year OS and EFS rates were 61.8% and 56.4%, respectively. The areas under the curves (AUCs) for OS and EFS were 0.738 and 0.778, respectively, and the average AUC for 50 times five-fold cross-validation were 0.711 and 0.723 for three-year OS and EFS, respectively.Conclusion: A four-clinical-risk-factor model that could effectively predict post-transplantation outcomes and help decision-making in MDS treatment was developed.

Comprehensive Targeted Metabolomic Study in the Lung, Plasma, and Urine of PPE/LPS-Induced COPD Mice Model

(1) Background: Progression of chronic obstructive pulmonary disease (COPD) leads to irreversible lung damage and inflammatory responses; however, biomarker discovery for monitoring of COPD progression remains challenging. (2) Methods: This study evaluated the metabolic mechanisms and potential biomarkers of COPD through the integrated analysis and receiver operating characteristic (ROC) analysis of metabolic changes in lung, plasma, and urine, and changes in morphological characteristics and pulmonary function in a model of PPE/LPS-induced COPD exacerbation. (3) Results: Metabolic changes in the lungs were evaluated as metabolic reprogramming to counteract the changes caused by the onset of COPD. In plasma, several combinations of phenylalanine, 3-methylhistidine, and polyunsaturated fatty acids have been proposed as potential biomarkers; the α-aminobutyric acid/histidine ratio has also been reported, which is a novel candidate biomarker for COPD. In urine, a combination of succinic acid, isocitric acid, and pyruvic acid has been proposed as a potential biomarker. (4) Conclusions: This study proposed potential biomarkers in plasma and urine that reflect altered lung metabolism in COPD, concurrently with the evaluation of the COPD exacerbation model induced by PPE plus LPS administration. Therefore, understanding these integrative mechanisms provides new insights into the diagnosis, treatment, and severity assessment of COPD.

Wide-Range, Rapid, and Specific Identification of Pathogenic Bacteria by Surface-Enhanced Raman Spectroscopy

Sensitive, selective, rapid, and label-free detection of pathogenic bacteria with high generality is of great importance for clinical diagnosis, biosecurity, and public health. However, most traditional approaches, such as microbial cultures, are time-consuming and laborious. To circumvent these problems, surface-enhanced Raman spectroscopy (SERS) appears to be a powerful technique to characterize bacteria at the single-cell level. Here, by SERS, we report a strategy for the rapid and specific detection of 22 strains of common pathogenic bacteria. A novel and high-quality silver nanorod SERS substrate, prepared by the facile interface self-assembly method, was utilized to acquire the chemical fingerprint information of pathogens with improved sensitivity. We also applied the mathematical analysis methods, such as the t-test and receiver operating characteristic method, to determine the Raman features of these 22 strains and demonstrate the clear identification of most bacteria (20 strains) from the rest and also the reliability of this SERS sensor. This rapid and specific strategy for wide-range bacterial detection offers significant advantages over existing approaches and sets the base for automated and onsite detection of pathogenic bacteria in a complex real-life situation.

Should fluorodeoxyglucose positron emission tomography/computed tomography be the first-line imaging investigation for restaging the laryngeal carcinoma patients?

Posttreatment detection of residual/recurrence disease in the head and neck cancers is not an easy task. Treatment induces changes create difficulties in diagnosis on conventional imaging (computed tomography [CT], magnetic resonance imaging) as well as macroscopic inspection (direct laryngoscopy). Hence, we evaluate the diagnostic performance of contract-enhanced F-18 fluorodeoxyglucose positron emission tomography (FDG PET)/CT in restaging of laryngeal carcinoma Postchemotherapy-surgery and/or radiation therapy. We retrospectively analyzed patients of carcinoma larynx (n = 100) who has completed treatment and were referred for FDG PET/CT. Two reviewers performed image analysis to determine recurrence at primary site and/lymph nodes and distant metastases. Receiver operating characteristic (ROC) was used to determine the maximum standardized uptake value (SUV_max) cut off for disease detection. Histopathological examination and clinical or imaging follow-up were taken as gold standard for recurrence. One hundred laryngeal carcinoma patients with mean age of 57.2 years (range of 40–76) were included in the present study. Among the 100 patients, 96 were male and remaining 4 were female. The average interval between completion of treatment and FDG PET/CT scan was 8.5 months (minimum 6 months). Of the 100 patients, FDG PET/CT detected FDG avid lesions in 66 patients. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of FDG PET/CT for residual/recurrence disease detection was 90.3%, 73.7%, 84.8%, 82.3%, and 84.0%, respectively (P < 0.05). In addition, in 10 patients, metachronous primaries were detected (lung-4, thyroid-2, tongue, colon, esophagus, and lymphoma-one each). On ROC curve analysis, SUVmax >6.1 had sensitivity and specificity of 80.6% and 94.7% respectively for detection of recurrent/metastatic disease. FDG PET/CT demonstrates high diagnostic accuracy for detection of residual/recurrent disease in treated laryngeal cancer patients and our findings suggest that this imaging modality should be the first-line diagnostic investigation in this cohort of patients.

The Impact of Coexistent Hashimoto's Thyroiditis on Central Compartment Lymph Node Metastasis in Papillary Thyroid Carcinoma

BACKGROUND

Hashimoto's thyroiditis (HT) is the most prevalent inflammatory disorder of the thyroid gland. Current studies have reported the coexistence rate between HT and papillary thyroid carcinoma (PTC) is quite high. The objective of this study was to evaluate the impact of HT on the predictive factors of central compartment lymph node metastasis (CLNM) in PTC.

METHODS

A retrospective investigation was performed on PTC patients. They were subclassified into HT and non-HT groups. The results of preoperative neck ultrasound (US) examinations were reviewed. The clinical characteristics and the predictive value for CLNM were explored and compared between the two groups.

RESULTS

A total of 756 patients were included in this study. There were more female patients (86.1%) in the PTC coexistent with the HT group than non-HT group. The patients with HT group had higher preoperative serum level of TSH. There was statistically significant difference between the HT patients and non-HT patients in nodular vascularization. Univariate and multivariate analyses showed that male, age ≤45 years old, tumor diameter >1 cm, and presence of suspicious central compartment lymph node on US, irregular nodular shape, multifocal carcinoma were independent predictive factors of CLNM in PTC patients. It was showed that male, age ≤45 years old, tumor diameter >1 cm, multifocality, and presence of suspicious central lymph node on US were risk factors for CLNM in non-HT patients. Only tumor diameter >1 cm and presence of suspicious central lymph node on US were independently correlated with CLNM in HT patients. The sensitivity of the multivariate model was 63.5%, and specificity was 88.9% for prediction CLNM in HT patients. For non-HT patients, the AUC was 80.6%, the sensitivity of the multivariate model was 64.5%, and specificity was 85.2.

CONCLUSION

PTC combined with HT is more common in women, and TSH level in HT group is higher than that in patients with PTC alone. Regardless of that HT is not a related risk factor of CLNM in PTC, our result suggested that different predictive systems should be used for HT and non-HT patients respectively to have a more accurate evaluation of CLNM in clinic.

The estimation of duration of maternally-derived antibodies against Akabane, Aino, and Chuzan virus in calves by the receiver operating characteristic analysis

The duration of maternally-derived antibodies against three arboviruses was investigated in calves, using the results of arbovirus serosurveillance performed in Kagoshima Prefecture during 2002–2016. The duration of maternally-derived antibodies against Akabane virus (AKAV), Aino virus (AINOV), and Chuzan virus (CHUV) was estimated to be 178 (sensitivity: 0.769, specificity: 0.730), 156 (sensitivity: 0.806, specificity: 0.791), and 156 days of age (sensitivity: 0.845, specificity: 0.814), by receiver operating characteristic analysis. The duration of maternally-derived antibodies against AKAV, AINOV, and CHUV differed 7–14, 22–28, and 20–31 days in the same calf types between the regions far from each other although it was similar between the adjacent regions. The dairy calves showed 6–29 days longer duration than the beef calves rearing in a similar region.

Nonparametric confidence regions for the symmetry point-based optimal cutpoint and associated sensitivity of a continuous-scale diagnostic test

In medical research, diagnostic tests with continuous values are widely employed to attempt to distinguish between diseased and non-diseased subjects. The diagnostic accuracy of a test (or a biomarker) can be assessed by using the receiver operating characteristic (ROC) curve of the test. To summarize the ROC curve and primarily to determine an "optimal" threshold for test results to use in practice, several approaches may be considered, such as those based on the Youden index, on the so-called close-to-(0,1) point, on the concordance probability and on the symmetry point. In this paper, we focus on the symmetry point-based approach, that simultaneously controls the probabilities of the two types of correct classifications (healthy as healthy and diseased as diseased), and show how to get joint nonparametric confidence regions for the corresponding optimal cutpoint and the associated sensitivity (= specificity) value. Extensive simulation experiments are conducted to evaluate the finite sample performances of the proposed method. Real datasets are also used to illustrate its application.

[Comparison of Detectability for the New Image Processing and Conventional Image Processing by ROC Analysis: A Phantom Study of Chest Radiography]

The purpose of this study is to compare the detectability of diseases the new image processing and the conventional image processing by receiver operating characteristic (ROC) analysis and to show the usefulness of the new image processing. Radiographs with and without nodular cancer models in the chest phantom were used for observation samples. Totally 200 radiographs were evaluated by 10 radiological technologists (each readers had over 20 years or under 4 years of experience). The mean area under the curve (AUC) calculated from the over 20 years group was 0.754 for the new processing and 0.771 for the conventional processing (p value=0.651, 95% confidence interval=-0.084/0.049 (lower bound/upper bound)). On the other hand, the average AUC calculated from under 4 years group was 0.819 for the new processing and 0.678 for the conventional processing (p value= 0.041, 95% confidence interval=0.019/0.262 (lower bound/upper bound)). New image processing provides high detectability in less than 4 years group compared to conventional processing.

Assessment of the therapeutic accuracy of cone beam computed tomography-guided nasopharyngeal carcinoma radiotherapy

The aim of the present study was to determine the ability of cone beam computed tomography (CBCT) to improve the accuracy of nasopharyngeal carcinoma (NPC) radiotherapy by analyzing the setup and inter-fraction errors at different levels and directions of the target volumes. A total of 113 patients with NPC who were undergoing intensity-modulated radiotherapy were recruited for the present study. Each patient had at least three CBCT exams prior to the start of radiation therapy. Three anatomic bony landmarks, including the upper neck, lower neck and head, were used to represent the different levels of assessment. The positioning errors were registered in three planes throughout the course of radiotherapy: The right-left (RL), superior-inferior (SI) and anterior-posterior (AP) directions. The planning CT images were matched with the CBCT images to determine the naso-pharynx shifts. A receiver operating characteristic curve was plotted to establish the specificity and sensitivity of CBCT. The planning target volume margin (MPTV) for the head was 0.9 mm, 1.4 mm for the upper neck and 2.0 mm for the lower neck. MPTVs of 1.5, 0.6 and 2.2 mm in the RL, SI and AP directions, respectively, were detected. In addition, there was evidence of setup errors in the three planes (RL, SI and AP) with the greatest error observed in the AP direction. Furthermore, the setup uncertainties in the neck region were greater than those of the head. In conclusion, CBCT could greatly improve the accuracy of radiotherapy by minimizing the setup errors and MPTV.

[Image Evaluation with Paired Comparison Method Using Automatic Analysis Software: Comparison of CT Images with Simulated Levels of Exposure Dose]

To simplify a procedure of the observer study with Ura's method of Scheffé's paired comparison and to improve experimental accuracy, we developed a software package to automatically analyze observer study data obtained by using a computer interface developed specially for the ROC observer study. Simulated low-dose CT images were used to demonstrate practical utility of this proposed method with a software package, in terms of a statistical analysis of the change of noise property due to the change of exposure dose. Six radiological technologists were participated in this observer study and compared each of six sample images selected at lower lung and liver slices with dose levels of 100, 80, 60, 40, 20, 10% per case. In the statistical analysis, the average psychological measures were highly correlated with the dose levels (lower lungs: R=0.95, liver: R=0.99). In addition, there were statistically significant differences in all combination of dose levels in liver slices. In conclusion, we demonstrated practical utility of this proposed method in terms of simplification of experimental procedure and the consistency of the analytic results.

Prefrontal activity predicts individual differences in optimal attentional strategy for preventing motor performance decline: a functional near-infrared spectroscopy study

Directing attention to movement outcomes (external focus; EF), not body movements (internal focus; IF), is a better cognitive strategy for motor performance. However, EF is not effective in some healthy individuals or stroke patients. We aimed to identify the neurological basis reflecting the individual optimal attentional strategy using functional near-infrared spectroscopy. Sixty-four participants (23 healthy young, 23 healthy elderly, and 18 acute stroke) performed a reaching movement task under IF and EF conditions. Of these, 13 healthy young participants, 11 healthy elderly participants, and 6 stroke patients showed better motor performance under EF conditions (EF-dominant), whereas the others showed IF-dominance. We then measured prefrontal activity during rhythmic hand movements under both attentional conditions. IF-dominant participants showed significantly higher left prefrontal activity than EF-dominant participants under IF condition. In addition, receiver operating characteristic analysis supported that the higher activity in the left frontopolar and dorsolateral prefrontal cortices could detect IF-dominance as an individual's optimal attentional strategy for preventing motor performance decline. Taken together, these results suggest that prefrontal activity during motor tasks reflects an individual's ability to process internal body information, thereby conferring IF-dominance. These findings could be applied for the development of individually optimized rehabilitation programs.

Risk analysis, ideal observers, and receiver operating characteristic curves for tasks that combine detection and estimation

Previously published work on joint estimation/detection tasks has focused on the area under the estimation receiver operating characteristic (EROC) curve as a figure of merit (FOM) for these tasks in imaging. Another FOM for these joint tasks is the Bayesian risk, where a cost is assigned to all detection outcomes and to the estimation errors, and then averaged over all sources of randomness in the object ensemble and the imaging system. Important elements of the cost function, which are not included in standard EROC analysis, are that the cost for a false positive depends on the estimate produced for the parameter vector, and the cost for a false negative depends on the true value of the parameter vector. The ideal observer in this setting, which minimizes the risk, is derived for two applications. In the first application, a parameter vector is estimated only in the case of a signal present classification. For the second application, parameter vectors are estimated for either classification, and these vectors may have different dimensions. In both applications, a risk-based estimation receiver operating characteristic curve is defined and an expression for the area under this curve is given. It is also shown that, for some observers, this area may be estimated from a two alternative forced choice test. Finally, if the classifier is optimized for a given estimator, then it is shown that the slope of the risk-based estimation receiver operating characteristic curve at each point is the negative of the ratio of the prior probabilities for the two classes.

Development of a multiplex real-time PCR assay using two thermocycling platforms for detection of major bacterial pathogens associated with bovine respiratory disease complex from clinical samples

Bovine respiratory disease complex (BRDC) is one of the most significant diseases of cattle. Bacterial pathogens involved in BRDC include Mannheimia haemolytica, Mycoplasma bovis, Histophilus somni, and Pasteurella multocida. We developed and evaluated a multiplexed real-time hydrolysis probe (rtPCR) assay using block-based Peltier and rotary-based thermocycling on lung tissue, nasal swabs, and deep nasopharyngeal swabs. The rtPCR results were compared to culture or a gel-based M. bovis PCR using statistical analysis to determine optimum quantification cycle (Cq) cutoffs to maximize agreement. The limits of detection were 1.2-12 CFU/reaction for each pathogen. M. haemolytica was the most prevalent organism detected by rtPCR, and was most frequently found with P. multocida. The rtPCR assay enabled enhanced levels of detection over culture for all pathogens on both thermocycling platforms. The rotary-based thermocycler had significantly lower Cq cutoffs (35.2 vs. 39.7), which maximized agreement with gold standard culture or gel-based PCR results following receiver operating characteristic analysis to maximize sensitivity (Se) and specificity (Sp). However, overall assay Se and Sp were similar on both platforms (80.5% Se, 88.8% Sp vs. 80.1% Se, 88.3% Sp). Implementation of these tests could enhance the detection of these pathogens, and with high-throughput workflows could reduce assay time and provide more rapid results. The assays may be especially valuable in identifying coinfections, given that many more antemortem samples tested in our study were positive for 2 or more pathogens by rtPCR ( n = 125) than were detected using culture alone ( n = 25).

Tournament leave-pair-out cross-validation for receiver operating characteristic analysis

Receiver operating characteristic analysis is widely used for evaluating diagnostic systems. Recent studies have shown that estimating an area under receiver operating characteristic curve with standard cross-validation methods suffers from a large bias. The leave-pair-out cross-validation has been shown to correct this bias. However, while leave-pair-out produces an almost unbiased estimate of area under receiver operating characteristic curve, it does not provide a ranking of the data needed for plotting and analyzing the receiver operating characteristic curve. In this study, we propose a new method called tournament leave-pair-out cross-validation. This method extends leave-pair-out by creating a tournament from pair comparisons to produce a ranking for the data. Tournament leave-pair-out preserves the advantage of leave-pair-out for estimating area under receiver operating characteristic curve, while it also allows performing receiver operating characteristic analyses. We have shown using both synthetic and real-world data that tournament leave-pair-out is as reliable as leave-pair-out for area under receiver operating characteristic curve estimation and confirmed the bias in leave-one-out cross-validation on low-dimensional data. As a case study on receiver operating characteristic analysis, we also evaluate how reliably sensitivity and specificity can be estimated from tournament leave-pair-out receiver operating characteristic curves.

How to Perform a Systematic Review and Meta-analysis of Diagnostic Imaging Studies

A systematic review is a comprehensive search, critical evaluation, and synthesis of all the relevant studies on a specific (clinical) topic that can be applied to the evaluation of diagnostic and screening imaging studies. It can be a qualitative or a quantitative (meta-analysis) review of available literature. A meta-analysis uses statistical methods to combine and summarize the results of several studies. In this review, a 12-step approach to performing a systematic review (and meta-analysis) is outlined under the four domains: (1) Problem Formulation and Data Acquisition, (2) Quality Appraisal of Eligible Studies, (3) Statistical Analysis of Quantitative Data, and (4) Clinical Interpretation of the Evidence. This review is specifically geared toward the performance of a systematic review and meta-analysis of diagnostic test accuracy (imaging) studies.

Deriving low-risk gambling limits from longitudinal data collected in two independent Canadian studies

AIMS

To derive low-risk gambling limits using the method developed by Currie et al. (2006) applied to longitudinal data.

DESIGN

Secondary analysis of data from the Quinte Longitudinal Study (n = 3054) and Leisure, Lifestyle and Lifecycle Project (n = 809), two independently conducted cohort studies of the natural progression of gambling in Canadian adults.

SETTING

Community-dwelling adults in Southeastern Ontario and Alberta, Canada.

PARTICIPANTS

A total of 3863 adults (50% male; median age = 44) who reported gambling in the past year.

MEASUREMENTS

Gambling behaviours (typical monthly frequency, total expenditure and percentage of income spent on gambling) and harm (experiencing two or more consequences of gambling in the past 12 months) were assessed with the Canadian Problem Gambling Index.

FINDINGS

The dose-response relationship was comparable in both studies for frequency of gambling (days per month), total expenditure and percentage of household income spent on gambling (area under the curve values ranged from 0.66 to 0.74). Based on the optimal sensitivity and specificity values, the low-risk gambling cut-offs were eight times per month, $75CAN total per month and 1.7% of income spent on gambling. Gamblers who exceeded any of these limits at time 1 were approximately four times more likely to report harm at time 2 [95% confidence interval (CI) = 2.9-6.6].

CONCLUSIONS

Longitudinal data in Canada suggest low-risk gambling thresholds of eight times per month, $75CAN total per month and 1.7% of income spent on gambling, all of which are higher than previously derived limits from cross-sectional data. Gamblers who exceed any of the three low-risk limits are four times more likely to experience future harm than those who do not.

Is There an Association Between Hemoglobin A1C and Deep Postoperative Infection After TKA?

BACKGROUND

Despite substantial research into the use of glycemic markers to stratify infection risk in patients with diabetes mellitus, there is little evidence to support a perioperative hemoglobin A1c (HbA1c) level associated with an increased risk of deep postoperative infection after TKA.

QUESTIONS/PURPOSES

(1) Is there an association between perioperative HbA1c level in patients with diabetes and deep postoperative infection after primary TKA? (2) Is the perioperative HbA1c level in patients with diabetes a useful test as an independent predictor for postoperative infection after TKA?

METHODS

We queried the PearlDiver Patient Records Database Humana dataset for patients who underwent primary TKA. This is a for-fee insurance patient-records database that contains records for more than 20 million patients with orthopaedic diagnoses from 2007 to the second quarter of 2015. The data for patients from this study were taken from the Humana dataset since this is the only insurer that includes laboratory data among the available databases. Although it is difficult to calculate attrition in this database, in the current study the minimum number of patients with at least 1 year followup was 86%. Patients with diabetes who had an HbA1c level obtained within 3 months of surgery were identified, stratified based on their HbA1c level in 0.5 mg/dL increments, and then compared with patients with diabetes without an HbA1c level within 3 months of surgery. Patients who had an HbA1c level within 3 months of surgery had slightly higher rates of polyneuropathy, chronic renal failure, and chronic kidney disease Stages 2 and 3. Otherwise, these groups were similar regarding rates of peripheral vascular disease, microvascular ischemic disease, metabolic syndrome, gastroparesis, end stage renal disease, age, and gender. Deep infection was defined as an infection resulting in operative intervention within 1 year of the primary TKA, and the incidence of such intervention for each HbA1c group then was identified. A receiver operating characteristic (ROC) analysis was performed to determine a threshold value of the HbA1c, and an area under the curve (AUC) analysis was performed to measure the accuracy and clinical utility of HbA1c as an independent predictor for postoperative infection.

RESULTS

The rate of infection requiring operative intervention ranged from a low of 0.8% with an HbA1c of 5.49 mg/dL or less, up to 3.5% for patients with HbA1c level greater than 11.5 mg/dL. The ROC analysis indicated that the best threshold was an HbA1c of 8.0 mg/dL (1.7; 95% CI, 1.2-2.4 mg/dL; p = 0.004), however, the AUC of 0.548 (95% CI, 0.50-0.59; p = 0.025) indicated that this threshold was inaccurate and only slightly better than chance, and thus alone could not serve as an independent discriminator of infection risk.

CONCLUSIONS

The risk of deep postoperative infection requiring surgical intervention after TKA in patients with diabetes mellitus increases as the perioperative HbA1c increases. While a threshold HbA1c level of 8.0 mg/dL was identified, it cannot by itself serve as an independent predictor of postoperative infection in patients with diabetes mellitus because its sensitivity is so low. Future studies should determine what other confounders other than an elevated HbA1c level contribute to increased infection risk and whether decreasing HbA1c levels before TKA will decrease the subsequent risk of infection after surgery.

LEVEL OF EVIDENCE

Level III, diagnostic study.

A three-long noncoding RNA signature as a diagnostic biomarker for differentiating between triple-negative and non-triple-negative breast cancers

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive cancer with unfavorable outcome and it is useful to explore noninvasive biomarkers for its early diagnosis. Here, we identified differentially expressed long noncoding RNAs (lncRNAs) in blood samples of patients with TNBC to assess their diagnostic value.

METHODS

Differential expression of lncRNAs in plasma of patients with TNBC (n = 25) and non-TNBC (NTNBC; n = 35) and in healthy controls was compared by microarray analysis and validated by real-time PCR. lncRNA expression between plasma and BC tissues was compared using Pearson correlation test. Logit model was used to obtain a new lncRNA-based score. Receiver operating characteristic analysis was performed to assess the diagnostic value of the selected lncRNAs.

RESULTS

Microarray data showed that 41 lncRNAs were aberrantly expressed. Among these, antisense noncoding RNA in the INK4 locus (ANRIL), hypoxia inducible factor 1alpha antisense RNA-2 (HIF1A-AS2), and urothelial carcinoma-associated 1 (UCA1) were markedly upregulated in plasma of patients with TNBC compared with patients with NTNBC (P < 0.01). HIF1A-AS2 expression was positively associated with its tissue levels (r = 0.670, P < 0.01). AUC (95% CI) of ANRIL, HIF1A-AS2, and UCA1 was 0.785 (0.660-0.881), 0.739 (0.610-0.844), and 0.817 (0.696-0.905), respectively. TNBCSigLnc-3, a new score obtained using the logit model, showed excellent diagnostic performance, with AUC of 0.934 (0.839-0.982), sensitivity of 76.0%, and specificity of 97.1%.

CONCLUSION

ANRIL, HIF1A-AS2, and UCA1 expression was significantly increased in plasma of patients with TNBC, suggesting their use as TNBC-specific diagnostic biomarkers.

Can mid-upper arm circumference and calf circumference be the proxy measures to detect undernutrition among elderly? Findings of a community-based survey in rural Puducherry, India

Introduction:

Major proportion of the elderly with under nutrition is undetected in the community. One of the feasible ways to detect under nutrition among elderly would be screening in the field settings. in this study, we aimed to identify the utility of alternate anthropometric measures such as mid-upper arm circumference (MUAC), calf circumference, and skin fold thickness in identifying under nutrition among elderly.

Materials and Methods:

A community-based cross-sectional survey was done among elderly in one of the randomly selected subcenters. Anthropometric measures such as weight, arm span, MUAC, and triceps skinfold thickness were measured as per the standard measurement guidelines by a trained medical graduate. The elderly were identified as undernourished if body mass index (BMI) is <18.5 kg/m². Utility of alternate anthropometric markers against BMI is represented by area under the curve (AUC) value from receiver operating characteristic curve and correlation coefficient (r).

Results:

Mean MUAC, calf circumference, and triceps skinfold thickness measured among 271 elderly were 25.6 cm ± 3.7 cm, 27.6 cm ± 3.7 cm, and 3.0 mm ± 1.3 mm, respectively. Among all three proxy anthropometric measures, MUAC had the highest AUC value (AUC = 0.88) Triceps skinfold thickness had the least AUC (AUC = 0.61). The correlation of anthropometric measurements such as MUAC, calf circumference, and triceps skinfold thickness with BMI was 0.74, –0.04, and 0.64, respectively.

Conclusion:

As MUAC and calf circumference are easy to measure and they are highly correlating with BMI, they can be used routinely by peripheral field workers to assess undernutrition in elderly during their regular house visits.

Molecular-based allergy diagnosis of allergic bronchopulmonary aspergillosis in Aspergillus fumigatus-sensitized Japanese patients

BACKGROUND

Distinguishing between patients with allergic bronchopulmonary aspergillosis (ABPA) and Aspergillus fumigatus (Af)-sensitized asthmatic patients without ABPA is sometimes difficult owing to the IgE-cross-reactivity between Af and other fungal allergens.

OBJECTIVE

To establish the usefulness of molecular-based allergy diagnostics using allergen components from Af in distinguishing ABPA from Af-sensitized asthma without ABPA.

METHODS

Sera from Japanese patients with ABPA (n = 53) and Af-sensitized asthma without ABPA (n = 253) were studied. The levels of IgE and IgG antibodies to allergen components from Af and IgE antibodies to different fugal allergen extracts were measured by ImmunoCAP. Comorbid atopic dermatitis (AD) was taken into consideration in the sensitization profile analysis.

RESULTS

Patients with ABPA possessed significantly higher levels of IgE antibodies to Asp f 1, and Asp f 2 than asthmatic patients without ABPA. The areas under the receiver operating characteristic curves for the levels of IgE to Asp f 1 and Asp f 2 as diagnostic markers of ABPA were 0.75 and 0.78, respectively. The presence of IgE positivity to Asp f 1 and/or Asp f 2 resulted in increased sensitivity while losing little specificity. Comorbid AD was associated with higher levels of IgE to Asp f 6 (manganese superoxide dismutase from Af, a ubiquitous pan-allergen in fungi) and low but positive levels of IgE to other Af-components, which hampered the serological discrimination of ABPA.

CONCLUSIONS AND CLINICAL RELEVANCE

The levels of IgE to Asp f 1 and/or Asp f 2 can effectively differentiate ABPA from Af-sensitized asthma, suggesting that the amounts of IgE specific for these molecules are markers for genuine Af-sensitization in ABPA. However, comorbid AD must be taken into consideration in the interpretation of high IgE to Asp f 6. Establishing of IgE-sensitization profiles using panel of Af-allergen components provides valuable information for distinguishing genuine vs. cross-reactive sensitization in Af-sensitized patients.

Predicting anatomical results of surgical treatment of idiopathic macular hole

AIM

To determine the parameters most informative in predicting the anatomical results of surgical treatment of idiopathic full-thickness macular hole (IMH).

METHODS

One hundred and sixty-two consecutive patients (170 eyes) after primary operation for IMH were enrolled. Outcomes were classified as anatomical success when both IMH closure and restoration of the outer retinal structure were achieved. "Prospective" group included 108 patients (115 eyes) followed with optical coherence tomography (OCT) and microperimetry for 1y after surgery. Potential prognostic criteria, except microperimetry data, were tested in "retrospective" group (54 patients, 55 eyes). Prognostic value of each parameter was determined using receiver operating characteristic (ROC) analysis. Combined predictive power of the best prognostic parameters was tested with the use of linear discriminant analysis.

RESULTS

IMH closure was achieved in 106 eyes (92%) in the prospective group and 49 eyes (89%) in the retrospective group. Despite anatomical closure, the outer retinal structure was not restored in two eyes in the first group and in one eye in the second group. Preoperative central subfield retinal thickness demonstrated the best discriminatory capability between eyes with anatomical success and failure: area under the ROC-curve (AUC) 0.938 (95% CI: 0.881-0.995), sensitivity 64% at fixed specificity 95% (cut-off value 300 µm) in the prospective group; sensitivity 57% and specificity 90% in the retrospective group. Other continuous parameters except tractional hole index (AUC: 0.796, 95% CI: 0.591-1.000) had significantly lower AUCs (P<0.05). The best combination of the parameters, established by discriminant analysis in the prospective group, could not confirm its predictive value in the retrospective group.

CONCLUSION

Preoperative central subfield retinal thickness is a strong and probably the best predictor of anatomical results of IMH surgical treatment.

ESSENCE-Q - a first clinical validation study of a new screening questionnaire for young children with suspected neurodevelopmental problems in south Japan

BACKGROUND

Early identification of autism spectrum disorder, intellectual developmental disorder, attention-deficit/hyperactivity disorder, and other neurodevelopmental disorders/problems is crucial, yet diagnosis is often delayed for years under the often misguided "wait-and-see" paradigm. The early symptomatic syndromes eliciting neurodevelopmental clinical examinations-questionnaire (ESSENCE-Q) is a brief (12-item) screening questionnaire developed specifically for the purpose of speeding up the identification process of a wide variety of neurodevelopmental problems. The aims were to 1) estimate the reliability of the ESSENCE-Q, 2) evaluate the clinical cutoff levels suggested by the author of the ESSENCE-Q, and 3) propose optimal cutoff levels based on receiver operating characteristic analysis.

METHODS

The ESSENCE-Q was used for 1 year by a psychiatrist in Kochi, Japan, assessing children under the age of 6 years referred for developmental problems. The children were also clinically assessed with regard to whether or not they met criteria for a developmental disorder (diagnosis positive and diagnosis negative groups). We contrasted the results of the ESSENCE-Q and those of clinical diagnostic assessments in 130 cases.

RESULTS

Cronbach's alpha was 0.82, sensitivity was 0.94 (95% confidence interval [CI]: [0.88, 0.98]), and specificity 0.53 (95% CI: [0.28, 0.77]), which are reasonable psychometrics for a first-step screening tool. Based on receiver operating characteristic analysis, we recommended an optimal cutoff level of yes ≥2 or maybe/a little ≥3 on the ESSENCE-Q (0.87 (95% CI: [0.79, 0.92]) sensitivity and 0.77 (95% CI: [0.50, 0.93]) specificity).

CONCLUSION AND IMPLICATION

The ESSENCE-Q can be a good instrument for use as a screening tool for aiding in the process of early identification of neurodevelopmental disorders in clinical settings. To establish the broader validity and reliability of the ESSENCE-Q, case-control studies and general population studies of children in different age groups are needed.

Clinical and pathological predictors of estimated GFR decline in patients with type 2 diabetes and overt proteinuric diabetic nephropathy

BACKGROUND

The effect of clinical and pathological parameters on the estimated glomerular filtration rate (eGFR) decline has not been investigated in patients with type 2 diabetes and overt proteinuric biopsy-proven diabetic nephropathy.

METHODS

Among 198 patients with type 2 diabetes who underwent renal biopsy and were confirmed to have pure diabetic nephropathy according to the recent classification, 128 patients with overt proteinuria were enrolled. Receiver operating characteristic, net reclassification improvement (NRI) and integrated discrimination improvement (IDI) analyses were performed using models adjusted for various clinical and pathological covariates to determine the best predictors of rapid eGFR decline [defined as >14.9%/year (median eGFR decline)].

RESULTS

A model that incorporated proteinuria showed the largest area under the curve (AUC) among clinical models, which suggested that proteinuria was the best clinical predictor. Although a model incorporating interstitial fibrosis and tubular atrophy (IFTA) score did not display a significantly larger AUC than the model with proteinuria (0.843 vs 0.812, respectively, p = 0.47), a model with both IFTA score and proteinuria had a significantly larger AUC than the model with proteinuria alone (0.875 vs 0.812, respectively, p = 0.014). Similarly, the addition of IFTA score resulted in a significantly greater net reclassification improvement and integrated discrimination improvement than the model with proteinuria alone [NRI: 0.78 (95% CI: 0.43-1.13; p < 0.001), IDI: 0.13 (95% CI: 0.07-0.19; p < 0.001)].

CONCLUSIONS

Our results suggest that not only proteinuria but also tubulointerstitial lesions should be assessed to predict rapid eGFR decline in patients with type 2 diabetes who have overt proteinuria and biopsy-proven diabetic nephropathy.

Reduced expression levels of let-7c in human breast cancer patients

Circulating microRNAs (miRNAs) are important in the diagnosis of a number of diseases, since serum or plasma miRNAs are more stable compared with miRNA isolated from blood samples. The aim of the present study was to investigate the association between the expression levels of serum let-7c miRNA and the clinical diagnosis of breast cancer (BC). The circulating let-7c levels of 90 BC patients and 64 healthy controls were determined by performing a reverse transcription-quantitative polymerase chain reaction assay. The results demonstrated that let-7c expression was downregulated in the BC tissues compared with the paracarcinoma control tissues. In addition, the let-7c expression in the serum of BC patients was significantly lower compared with the healthy controls (P<0.01). Using a cutoff value of 0.374×10³ copies/ml, the serum expression levels of let-7c exhibited 87.5% sensitivity and 78.9% specificity for distinguishing BC patients from healthy controls (area under the receiver operating characteristic curve, 0.848; 95% confidence interval, 0.785-0.911). Furthermore, the results demonstrated that the serum expression levels of let-7c were significantly higher in premenopausal compared with postmenopausal patients (P<0.05), supporting the hypothesis that postmenopausal status may affect the serum expression levels of let-7c. However, no statistically significant differences were detected in the serum levels of let-7c between ER (or PR)-positive and -negative patients. Therefore, the current study hypothesized that serum let-7c may be used as a novel and valuable biomarker for the diagnosis of BC.

A study for proposal of use of regulatory T cells as a prognostic marker and establishing an optimal threshold level for their expression in chronic lymphocytic leukemia

Although regulatory T cells (Tregs) have been extensively studied in chronic lymphocytic leukemia, there is no uniform guideline or consensus regarding their use as a prognostic marker. This study describes the methodology used to develop an optimal threshold level for Tregs in these patients. Treg levels were assessed in the peripheral blood of 130 patients and 150 controls. Treg frequencies were linked to established prognostic markers as well as overall survival and time to first treatment. The cut-offs for Treg positivity were assessed by receiver operating characteristic (ROC) analysis. A cut-off of 5.7% for Treg cell percentage and of 35 cells/μL for absolute Treg cell count were determined as optimal in patients with CLL along with a median Treg percentage of 15.5% used to separate patients with low- and high-risk disease. The experiments presented here will possibly aid in the use of Treg frequencies as a potential prognostic marker in CLL.

A primer on receiver operating characteristic analysis and diagnostic efficiency statistics for pediatric psychology: we are ready to ROC

OBJECTIVE

To offer a practical demonstration of receiver operating characteristic (ROC) analyses, diagnostic efficiency statistics, and their application to clinical decision making using a popular parent checklist to assess for potential mood disorder.

METHOD

Secondary analyses of data from 589 families seeking outpatient mental health services, completing the Child Behavior Checklist and semi-structured diagnostic interviews.

RESULTS

Internalizing Problems raw scores discriminated mood disorders significantly better than did age- and gender-normed T scores, or an Affective Problems score. Internalizing scores <8 had a diagnostic likelihood ratio <0.3, and scores >30 had a diagnostic likelihood ratio of 7.4.

CONCLUSIONS

This study illustrates a series of steps in defining a clinical problem, operationalizing it, selecting a valid study design, and using ROC analyses to generate statistics that support clinical decisions. The ROC framework offers important advantages for clinical interpretation. Appendices include sample scripts using SPSS and R to check assumptions and conduct ROC analyses.

Differentiation of branch duct intraductal papillary mucinous neoplasms from serous cystadenomas of the pancreas using contrast-enhanced sonography

OBJECTIVES

The purpose of this study was to determine whether contrast-enhanced sonography can improve the ability to differentiate branch duct intraductal mucinous neoplasms from serous cystadenomas of the pancreas compared to conventional (unenhanced) sonography alone.

METHODS

Between March 2008 and May 2012, there were 20 patients with branch duct intraductal mucinous neoplasms and 25 with serous cystadenomas in our institute, for whom preoperative conventional and contrast-enhanced sonographic results were available. The final diagnosis was obtained by histopathology. Various conventional and contrast-enhanced sonographic characteristics were retrospectively evaluated by 2 radiologists in consensus. A receiver operating characteristic curve analysis was used to evaluate the diagnostic value of conventional and contrast-enhanced sonography for discriminating between the two entities.

RESULTS

Three conventional sonographic characteristics (microcysts, cysts with internal echoes, and main pancreatic duct dilatation) and 2 contrast-enhanced sonographic characteristics (communication between the lesion and main pancreatic duct and enhancement of mural nodules) significantly improved the ability to differentiate branch duct intraductal mucinous neoplasms from serous cystadenomas. The area under the receiver operating characteristic curve increased from 0.691 with conventional sonography to 0.859 with combined contrast-enhanced and conventional ultrasonography (P = .043).

CONCLUSIONS

In this series of patients, the addition of contrast-enhanced sonography to conventional sonography improved the ability to differentiate branch duct intraductal mucinous neoplasms from serous cystadenomas.

Decreased levels of serum cytokeratin 19 fragment CYFRA 21-1 predict objective response to chemotherapy in patients with non-small cell lung cancer

Diagnostic tools capable of predicting early responses to chemotherapy are required to improve the individual management of cancer patients. The present study aimed to evaluate the prognostic significance of the serum tumor markers CYFRA 21-1, carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), carbohydrate antigen (CA) 125, and CA 19-9 for predicting responses to different chemotherapy regimens in patients with non-small cell lung cancer (NSCLC). A total of 276 patients with postoperative stage I–IV NSCLC were retrospectively reviewed. The five tumor markers were measured before and after at least two cycles of chemotherapy using an electrochemiluminescent assay. Multivariate analysis revealed that performance status, age, postoperative stage and surgery were significantly associated with the response to chemotherapy. High baseline CYFRA 21-1 and CA 19-9 levels were associated with poor effectiveness of chemotherapy. Significant reductions in CYFRA 21-1 levels were associated with a positive response to various chemotherapy regimens. CEA, CA 125 and CA 19-9 expression was only associated with a positive response in patients receiving paclitaxel, docetaxel, pemetrexed and the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). NSE expression was only associated with a positive response to gemcitabine. Receiver operating characteristic (ROC) curve analysis indicated that CYFRA 21-1 is the most sensitive of the tumor markers in predicting the response to chemotherapy. Serum CYFRA 21-1 is a useful surrogate marker for predicting the response to different chemotherapy regimens used to treat NSCLC and is a more sensitive marker than CEA, CA125, CA19-9 and NSE.

Restricted ROC curves are useful tools to evaluate the performance of tumour markers

In Clinical Epidemiology, receiver operating characteristic (ROC) analysis is a standard approach for the evaluation of the performance of diagnostic tests for binary classification based on a tumour marker distribution. The area under a ROC curve is a popular indicator of test accuracy, but its use has been questioned when the curve is asymmetric. This situation often happens when the marker concentrations overlap in the two groups under study in the range of low specificity, corresponding to a subset of values useless for classification purposes (non-informative values). The partial area under the curve at a high specificity threshold has been proposed as an alternative, but a method to identify an optimal cut-off that separates informative from non-informative values is not yet available. In this study, a new statistical approach is proposed to perform this task. Furthermore, a statistical test associated with the area under a ROC curve corresponding to informative values only (restricted ROC curve) is provided and its properties are explored by extensive simulations. Finally, the proposed method is applied to a real data set containing peripheral blood levels of six tumour markers proposed for the diagnosis of neuroblastoma. A new approach to combine couples of markers for classification purposes is also illustrated.

Predicting the distribution of urinary schistosomiasis in Tanzania using satellite sensor data

In this paper, remotely sensed (RS) satellite sensor environmental data, using logistic regression, are used to develop prediction maps of the probability of having infection prevalence exceeding 50%, and warranting mass treatment according to World Health Organization (WHO) guidelines. The model was developed using data from one area of coastal Tanzania and validated with independent data from different areas of the country. Receiver operating characteristic (ROC) analysis was used to evaluate the model's predictive performance. The model allows reasonable discrimination between high and low prevalence schools, at least within those geographical areas in which they were originally developed, and performs reasonably well in other coastal areas, but performs poorly by comparison in the Great Lakes area of Tanzania. These results may be explained by reference to an ecological zone map based on RS-derived environmental data. This map suggests that areas where the model reliably predicts a high prevalence of schistosomiasis fall within the same ecological zone, which has common intermediate-host snail species responsible for transmission. By contrast, the model's performance is poor near Lake Victoria, which is in a different ecological zone with different snail species. The ecological map can potentially define a template for those areas where existing models can be applied, and highlight areas where further data and models are required. The developed model was then used to provide estimates of the number of schoolchildren at risk of high prevalence and associated programme costs.

Wavelet compression on detection of brain lesions with magnetic resonance imaging

The purpose of this report is to assess clinically acceptable compression ratios on the detection of brain lesions at magnetic resonance imaging (MRI). Four consecutive T2-weighted and the corresponding T1-weighted images obtained in 20 patients were studied for 109 anatomic sites including 50 with lesions and 59 without lesions. The images were obtained on a 1.5-T MR unit with a pixel size of 0.9 to 1.2 x 0.47 mm and a section thickness of 5 mm. The image data were compressed by wavelet-based algorithm at ratios of 20:1, 40:1, and 60:1. Three radiologists reviewed these images on an interactive workstation and rated the presence or absence of a lesion with a 50 point scale for each anatomic site. The authors also evaluated the influence of pixel size on the quality of image compression. At receiver operating characteristic (ROC) analysis, no statistically significant difference was detected at a compression ratio of 20:1. A significant difference was observed with 40:1 compressed images for one reader (P = .023), and with 60:1 for all readers (P = .001 to .012). A root mean squared error (RMSE) was higher in 0.94- x 0.94-mm pixel size images than in 0.94- x 0.47-mm pixel size images at any compression ratio, indicating compression tolerance is lower for the larger pixel size images. The RMSE, subjective image quality, and error images of 10:1 compressed 0.94- x 0.94-mm pixel size images were comparable with those of 20:1 compressed 0.94- x 0.47-mm pixel size images. Wavelet compression can be acceptable clinically at ratios as high as 20:1 for brain MR images when a pixel size at image acquisition is around 1.0 x 0.5 mm, and as high as 10:1 for those with a pixel size around 1.0 x 1.0 mm.

Significance of urinary type IV collagen in patients with diabetic nephropathy using a highly sensitive one-step sandwich enzyme immunoassay

Urinary concentrations of type IV collagen in patients with diabetic nephropathy were measured by a highly sensitive, one-step sandwich enzyme immunoassay. Samples from 298 patients with noninsulin-dependent diabetes mellitus (NIDDM) and 80 healthy controls were examined. In diabetic patients with macroalbuminuria or renal insufficiency, the concentrations of urinary type IV collagen were significantly higher than those of diabetic patients with normoalbuminuria or healthy controls (P < 0.001). Urinary type IV collagen concentration in diabetic patients with microalbuminuria was significantly higher than that in diabetic patients with normoalbuminuria or that in healthy controls (P < 0.001). In contrast, there were no significant changes in the concentration of serum type IV collagen between microalbuminuric patients and normoalbuminuric patients. The area under the receiver operating characteristic (ROC) curve for the urinary type IV collagen concentration was equivalent to that of urinary albumin. It was concluded that urinary type IV collagen concentration determined using this method might be a useful marker for the early detection of diabetic nephropathy.