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PubMed1995

Poisson regression analysis in clinical research.

Generalized linear models (GLM) are now widely used in analyzing data from clinical trials and in epidemiological studies. In Poisson regression, which fits in the framework of a GLM, the response variable is a count that follows the Poisson distribution. This article describes the basic methodology of Poisson regression analysis and its application to clinical research. Overdispersion, model diagnostics, and sample size issues are discussed. The methodology is illustrated on a data set from a clinical trial for the treatment of bladder cancer, using a new procedure (PROC GENMOD) in the statistical package SAS.

Epilepsy↗

PubMed2000

Clinical applications of new advances in occlusal caries diagnosis.

Because of the difficulties associated with the diagnosis of occlusal caries, many clinicians have adopted the philosophy of "watch and wait". The decision to treat, be it by sealing or cavity preparation, is often made after the caries process is well established, and either bonding techniques fail, or unnecessary sound tooth structure is lost. The current diagnostic model of visual, probe, and radiographic examination is qualitative, subject to operator interpretation, and consequently can produce varied diagnoses from dentists examining the same patient. Recent advances in caries diagnosis and an understanding of the caries process, fissure morphology, and bonding principles allow early intervention. Mirror and probe examination is only 25 percent accurate in detecting early occlusal caries. The use of caries detection dye and laser caries diagnosis raises diagnostic accuracy beyond 90 percent. Hidden caries is now an historic phrase. Early and accurate diagnosis of occlusal caries enables successful prevention and minimal intervention restorative techniques, ending the common evolution from occlusal restorations through to cusp restorations, crowns, and endodontics.

Coloring Agents↗

PubMed2005

Ultra-sensitive detection of prion protein fibrils by flow cytometry in blood from cattle affected with bovine spongiform encephalopathy.

BACKGROUND: The definite diagnosis of prion diseases such as Creutzfeldt-Jakob disease (CJD) in humans or bovine spongiform encephalopathy (BSE) in cattle currently relies on the post mortem detection of the pathological form of the prion protein (PrPSc) in brain tissue. Infectivity studies indicate that PrPSc may also be present in body fluids, even at presymptomatic stages of the disease, albeit at concentrations well below the detection limits of currently available analytical methods. RESULTS: We developed a highly sensitive method for detecting prion protein aggregates that takes advantage of kinetic differences between seeded and unseeded polymerization of prion protein monomers. Detection of the aggregates was carried out by flow cytometry. In the presence of prion seeds, the association of labelled recombinant PrP monomers in plasma and serum proceeds much more efficiently than in the absence of seeds. In a diagnostic model system, synthetic PrP aggregates were detected down to a concentration of approximately 10(-8) nM [0.24 fg/ml]. A specific signal was detected in six out of six available serum samples from BSE-positive cattle. CONCLUSION: We have developed a method based on seed-dependent PrP fibril formation that shows promising results in differentiating a small number of BSE-positive serum samples from healthy controls. This method may provide the basis for an ante mortem diagnostic test for prion diseases.

Animals↗

PubMed1984

Oncologic diagnostic radiology: a model for implementation.

The implementation of an oncologic diagnostic radiology subspecialty would provide better communication between the radiologist and the clinician and a greater opportunity to teach the general principles of therapeutic radiology. Practical aspects of the development of a section in oncologic radiology are discussed.

Education, Medical↗

PubMed1994

[Modelling of temporal data and the role of graphics].

The importance of graphics for temporal data modelling, which is often used in ecopathology, is illustrated through 2 examples. The first concerns a univariate time series (tank milk germ measurements). It uses correlograms (choice of the model), plots of residuals of the model (diagnostics) and principal component analysis graphical outputs (comparison of time series). The second concerns climate multivariate monthly time series. A 3-way analysis and graphical outputs are used to give a mark to each station, describing its climate for a set of months.

Analysis of Variance↗

PubMed2005

Goodness of fit of relative survival models.

Additive regression models are preferred over multiplicative models in the analysis of relative survival data. Such preferences are mainly grounded in practical experience with mostly cancer registries data, where the basic assumption of the additivity of hazards is more likely to be met. Also, the interpretation of coefficients is more meaningful in additive than in multiplicative models. Nonetheless, the question of goodness of fit of the assumed model must still be addressed, and while there is an abundance of methods to check the goodness of fit of multiplicative models, the respective arsenal for additive models is almost empty. We propose here a variety of procedures for testing the null hypothesis of a good fit. These are based on partial residuals defined similarly to Schoenfeld residuals familiar for Cox model diagnostics. The tests have appropriate sizes under the null hypothesis, and good power under different alternatives. We investigate their performance through simulations and apply the methods to data from a study into survival of colon cancer patients.

Adolescent↗

PubMed2001

Management of dyspepsia across the primary-secondary healthcare interface.

Primary care remains at the frontline of care for most patients and the need to contain healthcare costs has led to a re-evaluation of the divide between primary and secondary care. Dyspepsia has a community prevalence of 25-50%, and forms 5% of the primary care physician's workload, 10% of whom are referred to a specialist. Problems presenting in primary care tend to be undifferentiated; those who do not have alarm symptoms and are under the age of 55 years are unlikely to have serious pathology. Management is largely symptom driven, on an empirical basis rather than on a diagnostic model as in secondary care where investigation rates are higher. The predictive value of symptoms for a specific diagnosis is small; primary care physicians include gastro-oesophageal reflux disease as part of the dyspepsia complex and the overall expenditure on acid suppression therapy is relatively large. The availability of open-access investigations such as endoscopy has influenced specialist referral rates and the ability to diagnose and treat patients with Helicobacter pylori-related problems has opened further opportunities. However, variations in the availability of the recommended diagnostic tests and the implications to primary care clinical practice of some of the new management recommendations (Maastricht II) in some national settings illustrate the divide with secondary care. The gap between primary and secondary care is narrowing in gastroenterology and the two groups need to continue collaboration to attain effective and cost-effective management for their patients.

Cost-Benefit Analysis↗

PubMed2005

The performance of SolarScan: an automated dermoscopy image analysis instrument for the diagnosis of primary melanoma.

OBJECTIVE: To describe the diagnostic performance of SolarScan (Polartechnics Ltd, Sydney, Australia), an automated instrument for the diagnosis of primary melanoma. DESIGN: Images from a data set of 2430 lesions (382 were melanomas; median Breslow thickness, 0.36 mm) were divided into a training set and an independent test set at a ratio of approximately 2:1. A diagnostic algorithm (absolute diagnosis of melanoma vs benign lesion and estimated probability of melanoma) was developed and its performance described on the test set. High-quality clinical and dermoscopy images with a detailed patient history for 78 lesions (13 of which were melanomas) from the test set were given to various clinicians to compare their diagnostic accuracy with that of SolarScan. SETTING: Seven specialist referral centers and 2 general practice skin cancer clinics from 3 continents. Comparison between clinician diagnosis and SolarScan diagnosis was by 3 dermoscopy experts, 4 dermatologists, 3 trainee dermatologists, and 3 general practitioners. PATIENTS: Images of the melanocytic lesions were obtained from patients who required either excision or digital monitoring to exclude malignancy. MAIN OUTCOME MEASURES: Sensitivity, specificity, the area under the receiver operator characteristic curve, median probability for the diagnosis of melanoma, a direct comparison of SolarScan with diagnoses performed by humans, and interinstrument and intrainstrument reproducibility. RESULTS: The melanocytic-only diagnostic model was highly reproducible in the test set and gave a sensitivity of 91% (95% confidence interval [CI], 86%-96%) and specificity of 68% (95% CI, 64%-72%) for melanoma. SolarScan had comparable or superior sensitivity and specificity (85% vs 65%) compared with those of experts (90% vs 59%), dermatologists (81% vs 60%), trainees (85% vs 36%; P =.06), and general practitioners (62% vs 63%). The intraclass correlation coefficient of intrainstrument repeatability was 0.86 (95% CI, 0.83-0.88), indicating an excellent repeatability. There was no significant interinstrument variation (P = .80). CONCLUSIONS: SolarScan is a robust diagnostic instrument for pigmented or partially pigmented melanocytic lesions of the skin. Preliminary data suggest that its performance is comparable or superior to that of a range of clinician groups. However, these findings should be confirmed in a formal clinical trial.

Algorithms↗

PubMed2025

Identification of Biomarkers for Right Ventricular Dysfunction in Idiopathic Dilated Cardiomyopathy Via Urinary Proteomics and Machine Learning.

BACKGROUND: Right ventricular dysfunction (RVD) is a common complication of idiopathic dilated cardiomyopathy linked to poor outcomes. However, reliable noninvasive biomarkers for RVD remain lacking. This study aimed to identify urinary proteomic markers using mass spectrometry and machine learning. METHODS: In this prospective cohort, patients with idiopathic dilated cardiomyopathy were classified by cardiac magnetic resonance imaging into groups with RVD (RV ejection fraction <45%) and without RVD groups. Baseline urine samples were profiled by data-independent acquisition mass spectrometry. Differentially expressed proteins were identified and selected by least absolute shrinkage and selection operator regression to build a diagnostic model, developed in a training set, and validated in a test set. The primary end point was a composite of cardiovascular death, heart failure rehospitalization, left ventricular assist device implantation, or heart transplantation. RESULTS: The study enrolled 147 patients with idiopathic dilated cardiomyopathy (64 with RVD, 83 without), with a median follow-up of 19.3 months. Of 3579 quantified urinary proteins, 46 were differentially expressed between groups. A 3-protein panel (RARRES1 [retinoic acid receptor responder protein 1], MVB12B [multivesicular body subunit 12B], GSK3A [glycogen synthase kinase 3 alpha]) was identified and showed excellent diagnostic accuracy (training area under the curve 0.946; validation area under the curve0.935), outperforming both NT-proBNP (N-terminal pro-brain natriuretic peptide) and tricuspid annular plane systolic excursion. The risk score derived from this panel effectively stratified patients, with the high-risk group exhibiting significantly worse outcomes than the low-risk group (hazard ratio, 3.24 [95% CI, 1.56-6.71], P=0.002). CONCLUSIONS: The urinary proteomic panel developed in this study demonstrates diagnostic and prognostic potential for identifying RVD in idiopathic dilated cardiomyopathy, providing a promising noninvasive tool for precise detection and clinical risk stratification.

Humans↗

PubMed1981

Description and application of an evaluation scheme for assessment from a decision-making perspective.

Described a scheme for evaluating the utility of test data in decision-making. The scheme, which is based upon a dispositional model of assessment, asks three sequential, binary questions about the total assessment procedure. The three questions focus on whether meaningful referral questions are asked, whether an accurate understanding of the client is achieved, and whether the available interventions are related effectively to the individual client's needs. The scheme is applied to a group of vocational rehabilitation clients (N = 58) from a rural area. Results showed the scheme to be reliable in evaluating the results of the assessments. The categorization showed a surprisingly high percentage of cases in which no meaningful referral questions were asked. Further, the scheme highlighted the differences between a diagnostic model of testing and dispositional assessment. For example, requiring the assessor to understand the treatment context as well as the client results in a more conservative estimate of the assessments' successes. It also results in evaluations that are more meaningful in terms of meeting the client's goals. Finally possible effects of the rural context in which the assessments were conducted on the types of errors made were discussed.

Adolescent↗

PubMed1978

Drug response and psychiatric nosology.

The possibility that pharmacological response might help to refine psychiatric nosology has been the subject of recurrent speculation, but few clear-cut results have been obtained. Only bipolar depressives and several other minor patient subgroups manifest consistent drug responses in association with characteristic psychobiological features. The presence of multiple intervening variables, such as individual differences in drug metabolism, drug-taking behaviour and biological sensitivity to drugs, may mitigate against the reliable identification of clinically distinguishable drug-responding subgroups. Futhermore, the majority of available psychoactive drugs have either multiple or broad spectrum effects inconsistent with hypotheses utilizing the mechanism or site of drug action to argue for a diagnosis-specific biological disorder at such sites. Nonetheless, the successful use of drug-response models in other areas of medicine suggests a rationale for continued exploration in this area, and a number of recent advances make this approach potentially more productive. Pharmacological developments have rendered it possible to assess the biological availability of drugs in potential responders, thus eliminating some of the confounding intervening variables. Further consideration should also be given to the use of drugs with more specific neurochemical effects, even when they themselves are not necessarily therapeutic. The comparison of drug responder and non-responder group has also been made more meaningful by the availability of more reliable methods of assessing clinical phenomena, more sophisticated diagnostic models and the introduction of other biological measures. Combining several of these approaches may allow the use of one to validate the other.

Antidepressive Agents, Tricyclic↗

PubMed2003

Social support reduces the impact of partner violence on health: application of structural equation models.

BACKGROUND: Intimate partner violence (IPV) is associated with poorer health, yet pathways through which IPV affects either mental or physical health are not well characterized. METHODS: Structural equation modeling was used to test a model in which physical-IPV and battering were considered as separate independent variables. The sample included 191 women currently experiencing either physical IPV or battering. Emotional support provided to women experiencing IPV was hypothesized to mediate the impact of IPV on current mental and physical health (dependent variables). RESULTS: Higher scores on emotional support were associated with better physical (beta = -0.23, P < 0.01) and mental health (beta = -0.27, P < 0.001). Physical IPV was directly associated with poorer mental health (beta = 0.023, P < 0.01) and indirectly associated with poorer physical health (beta = 0.18, P < 0.001) and mental health (beta = -0.04, P < 0.05), primarily through battering. Higher battering scores were directly associated with less emotional support (beta = -0.33, P < 0.001) and indirectly associated with poorer physical (beta = 0.12, P < 0.01) and mental health (beta = 0.09, P < 0.01), primarily through emotional support. Model diagnostics indicated a good fit (chi(2) = 20.44, P = 0.37, GFI = 0.98, CFI = 0.99, RMSEA = 0.02). CONCLUSIONS: Higher levels of emotional support may modify the effect of IPV on health. Interventions to increase social and emotional support to abused women may reduce mental and physical health consequences.

Adult↗

PubMed2006

Clinical predictors for hepatocellular carcinoma in patients with primary biliary cirrhosis.

BACKGROUND & AIMS: Although hepatocellular carcinoma (HCC) occurs with increased frequency in patients with primary biliary cirrhosis (PBC), the exact frequency is relatively low. Optimal selection of PBC patients for HCC screening needs to be determined for effective screening. In this study, we aimed to explore clinical predictors of HCC in PBC patients. METHODS: We performed a case-control study using 17 PBC patients with HCC identified from 1976 to 2002 at the Mayo Clinic. Control PBC patients who had no evidence of HCC were selected for each case by matching the first year of their visit to the Mayo Clinic. All medical information was collected within 2 years from when the cases were diagnosed with HCC. Logistic regression models were used for the analyses. RESULTS: Age, sex, history of blood transfusion, current smoking, histologic stage at PBC diagnosis, any signs of portal hypertension, Mayo score, hemoglobin level, platelet count, aspartate aminotransferase level, and albumin level were associated with the presence of HCC (P < .05 for each). In multivariable analysis, older age (OR, 1.7; 95% confidence interval [CI], 1.1-2.5 for 5 years), male sex (OR, 9.7; 95% CI, 1.4-68.3), history of blood transfusion (OR, 5.0; 95% CI, 1.0-24.3), and any signs of portal hypertension (OR, 22.9; 95% CI, 3.4-155.3) were associated significantly with increased odds of HCC and yielded an excellent diagnostic performance (area under the receiver operating characteristics curve rate, 0.91). CONCLUSIONS: Older age, male sex, history of blood transfusion, and any signs of portal hypertension or cirrhosis indicate higher likelihood of HCC and should be considered for HCC screening. Further studies in larger patient cohorts are required to verify the diagnostic model.

Adult↗

PubMed2004

The simultaneous use of telomerase, cytokeratin 20 and CD4 for bladder cancer detection in urine.

OBJECTIVE: Because of the low sensitivity of urinary cytological diagnosis of urinary bladder carcinoma, new molecular diagnostic methods have been proposed. We decided to verify the expression of telomerase mRNA coding for the catalytic component (hTRT), cytokeratin 20 (CK20) and CD4 antigen mRNAs in urine as possible diagnostic tool. METHODS: Evaluation of hTRT, CK20, CD4 mRNAs was performed in 50 ml of naturally voided urine of 205 patients of which 153 with bladder cancer (Tis, n = 11; TaGx, n = 4; TaG1, n = 25; TaG2, n = 26; TaG3, n = 8; T1G1, n = 16; T1G2, n = 17; T1G3, n = 20; T2G2, n = 6; T2G3, n = 13; T3G3, n = 7) and 52 controls. A quantitative expression of hTRT at mRNA level versus TRAP (telomeric repeat amplification protocol) assay was performed in 20 patients and 14 controls. The expression of RT-PCR for hTRT, CK20, CD4 versus urinary cytology was analysed in 44 patients with bladder cancer. Evaluating the three molecular markers together, the result was considered correct when at least two of the markers were positive, suspected when only one marker was positive and negative for diagnosis of tumour when all markers were negative. The performance of the diagnostic model resulted from the logistic analysis evaluated with receiver operating characteristics (ROC) curve analysis. RESULTS: The sensitivity detected for each tumour marker was as follows: for hTRT 90.8%, for CK20 84.3% and for CD4 was 64.7%, while the specificity was 94.2% for CD4 and 78.8% for both hTRT and CK20. When a simultaneous evaluation of the three tumour markers was considered, 88.2% of the diagnoses were correct, 11.8% were suspected for tumour and none were mistaken. When compared with cytology, the simultaneous use of the three markers allowed reaching a correct diagnosis in 88% of the cases in comparison to 25% by urinary cytology. The sensitivity in the detection of bladder cancer was higher for hTRT at mRNA level in comparison with the enzymatic activity detection with TRAP (90% vs. 35%) while the specificity for both markers resulted very high (100%). CONCLUSIONS: These data show that in the future the diagnostic improvement of urine based molecular markers for the detection of bladder cancer in the urine could improve the sensitivity of urinary cytology reducing the need of a cystoscopy.

Biomarkers, Tumor↗

PubMed1999

Establishment of predictive variables associated with testicular sperm retrieval in men with non-obstructive azoospermia.

Although testicular biopsy for sperm extraction is a procedure with a potential for complications, sperm retrieval is successful in 30-70% of patients with non-obstructive azoospermia. In order to predict the probability of retrieving at least one testicular spermatozoon we conducted a prospective study of a set of variables in 40 patients with non-obstructive azoospermia. Using the receiver operating characteristic curves, we determined the probability estimates of testicular volume, plasma follicle stimulating hormone (FSH) concentration, Johnsen score and visualization of testicular spermatids in discriminating between patients with successful and failed testicular sperm extraction. Visualization of testicular spermatids provided the best estimate of success of testicular sperm extraction. Of the factors studied using logistic-regression analysis (age, maternal and paternal age at birth, body mass index, luteinizing hormone, testosterone, FSH, testicular volume, the presence of testicular spermatids and Johnsen score), only the presence of spermatids and Johnsen score were independent variables able to predict the success of testicular sperm extraction. The visualization of the presence of spermatids gave a correct prediction of 77% and Johnsen score of 71%. The diagnostic model derived from these independent predictors when validated in 40 patients using the Jackknife technique gave a correct overall prediction of 87%. The probability of successful testicular sperm extraction in patients with non-obstructive azoospermia could be objectively predicted on the basis of simple histopathological criteria represented by the visualization of testicular spermatids and Johnsen score.

Biopsy↗

PubMed1988

Identifying Mycobacterium tuberculosis cultures by gas-liquid chromatography and a computer-aided pattern recognition model.

A procedure that uses gas-liquid chromatography and a pattern recognition computer model was developed for distinguishing cultures of Mycobacterium tuberculosis from cultures of other mycobacteria, common bacteria, and fungi. In this procedure, a sample of a culture preparation is methanolyzed and trimethylsilylated sequentially and injected into a gas chromatograph equipped with a flame ionization detector. A pattern recognition procedure computes an error score by comparing the gas-liquid chromatography peak responses of a culture to those of a standard M. tuberculosis culture. Ten M. tuberculosis cultures were used in the development of the pattern recognition model. Computed error scores of 5 or less were established for identifying an M. tuberculosis culture. The method was evaluated with two sets of test samples, non-M. tuberculosis and M. tuberculosis cultures. Sample identification was correct for all 14 M. tuberculosis cultures (M. tuberculosis or non-M. tuberculosis), 45 fungal cultures, 94 bacterial cultures, and all but 1 of 18 cultures of mycobacteria other than tuberculosis (MOTT). The false prediction represented an isolate of M. fortuitum. For M. tuberculosis, fungal, bacterial, and MOTT cultures, the ranges of error scores were 1 to 5, 16 to 33, 13 to 34, and 4 to 26, respectively. Therefore, we have demonstrated that this diagnostic model can distinguish M. tuberculosis from non-M. tuberculosis cultures with a high degree of accuracy.

Bacteria↗

PubMed2004

The tip of the iceberg for child abuse: the critical roles of the pediatric trauma service and its registry.

BACKGROUND: The incidence of child abuse is approximately 10% of all children presenting to an emergency department (ED), with a mortality rate less than 1%. By contrast, the characteristics of the subset of abused children presenting to a pediatric trauma service (PTS) is not well defined. METHODS: This study was a retrospective evaluation of prospectively collected information from an urban Level I pediatric trauma registry from 1990 to 2002 (n = 11,919). Child abuse cases and their perpetrators were identified by E-codes. Patterns of injuries were examined by integer International Classification of Diseases, Ninth Revision codes, and diagnostic model was evaluated by discrimination and goodness-of-fit. RESULTS: A total of 171 cases of child abuse (1.4%) were identified, and the majority were boys (59%, p > 0.05 vs. nonabuse cases). The median age of the abused cohort was younger than 1 year old, and the number of abuse cases did not differ over time (mean, 11 per year.) Abused children present with a higher median Injury Severity Score (10 vs. 4, p < 0.01), more severe injuries of the head and integument, longer hospital lengths of stay (4 vs. 1 day, p < 0.01), and a higher mortality rate (12% vs. 2%, p < 0.01). The following variables emerged with significant association to abuse: fracture of base or vault of skull, contusion of eye, rib fracture, intracranial bleeding, multiple burns, and age. A new Diagnostic Index for Physical Child Abuse was created. CONCLUSION: Significant characteristics of the abused children in this pediatric trauma service include higher Injury Severity Score (especially in the head and integument), requirement for longer lengths of stay, and a nearly 10-times higher risk of death compared with the ED population. The Diagnostic Index for Physical Child Abuse is proposed as a new tool to assist in the identification of child abuse among pediatric trauma patients. An epidemiologic triangle for child abuse is described, with different prevalence and severity of child abuse seen at different levels of our health care system, starting with primary care providers, followed by the ED, the PTS, and ultimately the medical examiners. The number of cases decreases from the bottom to the top of the health care system, but the mortality rate increases as abuse escalates through the triangle. This establishes the PTS as possibly the final gatekeeper before an abused case becomes a fatality. These data emphasize the need for rigorous registry evaluation and subsequent evidence-based prevention initiatives.

Baltimore↗

PubMed1995

Applications of neural networks in histopathology.

ANN methods are one of several nonparametric approaches to classification. They are based on an adaptive, connectionist model of information storage and processing and learn by example rather than explicitly programmed classification rules. Their greatest strength probably is the ease with which they capture nonlinear and interactive feature effects during training, though at a higher risk of overtraining then is found with traditional classifiers. ANN can be used to process image data, but so far not to classify complex natural images directly. Instead, image dimensionality is reduced to a set of extracted features for ANN input. ANN finds growing use in time series signal processing and radiology. In anatomic pathology, ANN pilot studies are published for tumor classification. Pap smear analysis, and chromosome identification. Each application requires proper sampling technique, minimising bias in training and testing to assure the ANN classifier will perform prospectively as expected. With careful arrangement of input features, ANN can be used for prognostic as well as diagnostic models.

Humans↗