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PubMed1987

Validation of schizoid personality scales using indices of schizotypal and borderline personality disorder in a criminal population.

The external validity of 10 schizoid personality scales was assessed against dimensional measures of DSM-III borderline (BPD) and schizotypal (SPD) personality disorders in a sample of 37 top-security prisoners. Significant relationships with SPD or BPD emerged for schizophrenism, withdrawn-disturbed relationships, hallucinatory predisposition, schizoidia, disordered thinking and perceptual aberration (r = 0.30-0.66). The first four of these scales were significantly related to SPD (r = 0.29-0.51) after partialling out the effects of BPD, indicating an intrinsic link between these scales and SPD which may constitute the genetic affinity of SPD with schizophrenia. It is suggested that scales which assess the construct of schizophrenism or 'interpersonal aversiveness' may be the most central to Meehl's (1962) 'integrative neural defect' or genetic predisposition to schizotypy.

Adult↗
PubMed2004

Developing a large electronic primary care database (Doctors' Independent Network) for research.

BACKGROUND AND OBJECTIVES: Primary care databases form a unique source of population-based clinical information on the prevalence and management of diagnosed disorders. Historically such databases have lacked individual level socio-economic markers. We describe the development of the Doctors' Independent Network (DIN) database for epidemiological and health services research. DIN includes a socio-economic marker (ACORN) based on postcode linkage at individual patient level. The validity of DIN is assessed against the General Practice Research Database (GPRD). METHODS: External validity is assessed by comparing the demographic structure and prevalence rates for treated ischemic heart disease (IHD) and treated hay fever with those from the GPRD. We assess the utility of a socio-economic measure (ACORN) based on postcode-linkage at individual patient level by examining the trend in prevalence rates of IHD and hay fever by ACORN index. RESULTS: 142 practices providing high quality data were selected, with 1827361 fully registered patients contributing data between 1992 and 2001, representing an identical age-sex structure to that for England & Wales and GPRD. Regionally adjusted prevalence of treated IHD (7.29 and 5.37%, respectively for men and women aged 35+ in 1998) in DIN was highly comparable to GPRD (7.27 and 5.42%). In DIN, the odds ratio of IHD was 1.37 (95% CI 1.30-1.44) in subjects living in "striving" compared to "thriving" areas. The prevalence of treated hay fever prevalence was similar across databases, with inverse associations seen with ACORN in DIN (higher rates in "thriving" areas). CONCLUSIONS: DIN provides comparable period prevalence rates to GPRD for two common conditions, with social trends as expected. Primary care databases such as these have the potential to replace the decennial national morbidity surveys carried out in UK general practices, with DIN having the important advantage of including a socio-economic index.

Adolescent↗
PubMed2006

Nondestructive determination of lignans and lignan glycosides in sesame seeds by near infrared reflectance spectroscopy.

Sesame (Sesamum indicum L.) contains abundant lignans including lipid-soluble lignans (sesamin and sesamolin) and water-soluble lignan glycosides (sesaminol triglucoside and sesaminol diglucoside) related to antioxidative activity. In this study, near infrared reflectance spectroscopy (NIRS) was used to develop a rapid and nondestructive method for the determination of lignan contents on intact sesame seeds. Ninety-three intact seeds were scanned in the reflectance mode of a scanning monochromator. This scanning procedure did not require the pulverization of samples, allowing each analysis to be completed within minutes. Reference values for lignan contents were obtained by high-performance liquid chromatography analysis. Calibration equations for lignans (sesamin and sesamolin) and lignan glycosides (sesaminol triglucoside and sesaminol diglucoside) contents were developed using modified partial least squares regression with internal cross-validation (n = 63). The equations obtained had low standard errors of cross-validation and moderate R2 (coefficient of determination in calibration). The prediction of an external validation set (n = 30) showed significant correlation between reference values and NIRS predicted values based on the SEP (standard error of prediction), bias, and r2 (coefficient of determination in prediction). The models developed in this study had relatively higher values (more than 2.0) of SD/SEP(C) for all lignans and lignan glycosides except for sesaminol diglucoside, which had a minor amount, indicating good correlation between the reference and the NIRS estimate. The results showed that NIRS, a nondestructive screening method, could be used to rapidly determine lignan and lignan glycoside contents in the breeding programs for high quality sesame.

Calibration↗
PubMed2001

Reliability and validity of the Danish version of the Calgary Depression Scale for Schizophrenia.

Depressive symptoms within the range of schizophrenic syndromes constitute a major diagnostic and therapeutic problem. Earlier research has indicated that available depression scales are not adequate when examining mood disturbances in patients with schizophrenia. We have made an attempt to estimate the reliability and validity of the Danish version of the Calgary Depression Scale for Schizophrenia. The external validity has been analysed in relation to the Major Depression Inventory (MDI). The internal validity has been analysed by using Loevinger's coefficient of homogeneity as the primary statistic. For the inter-observer reliability the intra-class coefficients have been calculated. It was shown that a subscale of the Calgary scale has sufficient reliability and validity.

Adult↗
PubMed2001

Competitive CYP2C9 inhibitors: enzyme inhibition studies, protein homology modeling, and three-dimensional quantitative structure-activity relationship analysis.

This study describes the generation of a three-dimensional quantitative structure activity relationship (3D-QSAR) model for 29 structurally diverse, competitive CYP2C9 inhibitors defined experimentally from an initial data set of 73 compounds. In parallel, a homology model for CYP2C9 using the rabbit CYP2C5 coordinates was built. For molecules with a known interaction mode with CYP2C9, this homology model, in combination with the docking program GOLD, was used to select conformers to use in the 3D-QSAR analysis. The remaining molecules were docked, and the GRID interaction energies for all conformers proposed by GOLD were calculated. This was followed by a principal component analysis (PCA) of the GRID energies for all conformers of all compounds. Based on the similarity in the PCA plot to the inhibitors with a known interaction mode, the conformer to be used in the 3D-QSAR analysis was selected. The compounds were randomly divided into two groups, the training data set (n = 21) to build the model and the external validation set (n = 8). The PLS (partial least-squares) analysis of the interaction energies against the K(i) values generated a model with r(2) = 0.947 and a cross-validation of q(2) = 0.730. The model was able to predict the entire external data set within 0.5 log units of the experimental K(i) values. The amino acids in the active site showed complementary features to the grid interaction energies in the 3D-QSAR model and were also in agreement with mutagenesis studies.

Animals↗
PubMedDate not supplied

The relevance of searching for effects under a clinical-trial lamppost: a key issue.

In economic evaluations of new medical technologies, analysts often need to use data from randomized controlled trials. Trials are designed to achieve high internal validity; however, their selected populations and often highly artificial environments may imply low external validity. Thus, the use of trial data in an economic evaluation may bias the results, since economic evaluation is concerned not with theoretical capability in a trial but with likely performance in the practice environment. This paper indicates both the probable bias of one aspect of artificiality in the trial environment--selected populations--and a method of adjusting the analysis so that results will be more likely to reflect actual practice. The judicious use of extra-trial information can be used to correct the biases of clinical trials.

Antibodies, Monoclonal↗
PubMed2002

Clustering women's health behaviors.

This study attempts to characterize health lifestyles by subgrouping women with similar behavior patterns. Data on background, health behaviors, and perceptions were collected via phone interview from 1,075 Israeli women aged 50 to 74. From a cluster analysis conducted on health behaviors, three clusters emerged: a "health promoting" cluster (44.1%), women adhering to recommended behaviors; an "inactive" cluster (40.3%), women engaging in neither health-promoting nor compromising behaviors; and an "ambivalent" cluster (15.4%), women engaging somewhat in both health-promoting and compromising behaviors. Clustering was cross-tabulated by demographic and perceptual variables, further validating the subgrouping. The cluster solution was also validated by predicting another health behavior (mammography screening) for which there was an external validating source. Findings are discussed in comparison to published cluster solutions, culminating in suggestions for intervention alternatives. The concept of lifestyle was deemed appropriate to summarize the clustering of these behavioral, perceptual, and structural variables.

Aged↗
PubMed2000

Psychometric properties of the Swedish version of the Well-Being Questionnaire in a sample of patients with diabetes type 1.

OBJECTIVES: The aim of the present investigation was to further test the psychometric properties of a Swedish version of the Well-Being Questionnaire (WBQ) in order to determine whether it could be suitable for measuring health-related quality of life among type 1 diabetic patients. METHODS: In total, 94 patients who fulfilled the inclusion criteria were selected for the study and of these 85% participated. Reliability was tested with Cronbach's alpha coefficient and the internal validity by means of principal component analysis and multitrait analysis. To test the external validity, comparisons were made with two other questionnaires, the Short form-36 and a Swedish Mood Adjective Check List. RESULTS: The results show that, above all, the Swedish version of the WBQ measures psychological well-being, and thus must also be complemented with scales that measure other consequences of the illness and/or treatment, i.e. physical symptoms. The questionnaire has low discriminatory validity between subscales, which casts doubt on the appropriateness of using the four subscales as separate measures. The two scales measuring anxiety and depression are not sensitive enough for use among type 1 diabetics without complications and high or normal levels of psychological well-being. CONCLUSIONS: The Well-Being Questionnaire alone does not give any more information about subjective health status among type 1 diabetic patients than, for example, the generic SF-36.

Adult↗
PubMed2025

Large Language Model and Knowledge Graph-Driven AJCC Staging of Prostate Cancer Using Pathology Reports.

Background/Objectives: To develop an automated American Joint Committee on Cancer (AJCC) staging system for radical prostatectomy pathology reports using large language model-based information extraction and knowledge graph validation. Methods: Pathology reports from 152 radical prostatectomy patients were used. Five additional parameters (Prostate-specific antigen (PSA) level, metastasis stage (M-stage), extraprostatic extension, seminal vesicle invasion, and perineural invasion) were extracted using GPT-4.1 with zero-shot prompting. A knowledge graph was constructed to model pathological relationships and implement rule-based AJCC staging with consistency validation. Information extraction performance was evaluated using a local open-source large language model (LLM) (Mistral-Small-3.2-24B-Instruct) across 16 parameters. The LLM-extracted information was integrated into the knowledge graph for automated AJCC staging classification and data consistency validation. The developed system was further validated using pathology reports from 88 radical prostatectomy patients in The Cancer Genome Atlas (TCGA) dataset. Results: Information extraction achieved an accuracy of 0.973 and an F1-score of 0.986 on the internal dataset, and 0.938 and 0.968, respectively, on external validation. AJCC staging classification showed macro-averaged F1-scores of 0.930 and 0.833 for the internal and external datasets, respectively. Knowledge graph-based validation detected data inconsistencies in 5 of 150 cases (3.3%). Conclusions: This study demonstrates the feasibility of automated AJCC staging through the integration of large language model information extraction and knowledge graph-based validation. The resulting system enables privacy-protected clinical decision support for cancer staging applications with extensibility to broader oncologic domains.

artificial intelligence↗
PubMed2005

Atom, atom-type and total molecular linear indices as a promising approach for bioorganic and medicinal chemistry: theoretical and experimental assessment of a novel method for virtual screening and rational design of new lead anthelmintic.

Helminth infections are a medical problem in the world nowadays. In this paper a novel atom-level chemical descriptor has been applied to estimate the anthelmintic activity. Total and local linear indices and linear discriminant analysis were used to obtain a quantitative model that discriminates between anthelmintic and non-anthelmintic drug-like compounds. The discriminant model has an accuracy of 90.11% in the training set, with a high Matthews' correlation coefficient (MCC=0.80). To assess the robustness and predictive power of the obtained model, internal (leave-n-out) and external validation process was performed. The QSAR model correctly classified 88.55% of compounds in this external prediction set, yielding a MCC of 0.77. Another LDA model was carried out to outline some conclusions about the possible modes of action of anthelmintic drugs. It has an accuracy of 93.50% in the training set, and 80.00% in the external prediction set. After that, the developed model was used in the virtual--in silico--screening and several compounds from the Merck Index, Negwer's Handbook and Goodman and Gilman were identified by the model as anthelmintic. Finally, the experimental assay of an organic chemical (a furylethylene derivative) by an in vivo test permits us to carry out an assessment of the model. An accuracy of 100% with the theoretical predictions was observed. These results suggest that the proposed method will be a good tool for studying the biological properties of drug candidates during the early state of the drug-development process.

Anthelmintics↗
PubMed2006

Conceptual, methodological and computational issues concerning the compartmental modeling of a complex biological system: Postprandial inter-organ metabolism of dietary nitrogen in humans.

A multi-compartmental model has been developed to describe dietary nitrogen (N) postprandial distribution and metabolism in humans. This paper details the entire process of model development, including the successive steps of its construction, parameter estimation and validation. The model was built using experimental data on dietary N kinetics in certain accessible pools of the intestine, blood and urine in healthy adults fed a [15N]-labeled protein meal. A 13-compartment, 21-parameter model was selected from candidate models of increasing order as being the minimum structure able to properly fit experimental data for all sampled compartments. Problems of theoretical identifiability and numerical identification of the model both constituted mathematical challenges that were difficult to solve because of the large number of unknown parameters and the few experimental data available. For this reason, new robust and reliable methods were applied, which enabled (i) a check that all model parameters could theoretically uniquely be determined and (ii) an estimation of their numerical values with satisfactory precision from the experimental data. Finally, model validation was completed by first verifying its a posteriori identifiability and then carrying out external validation.

Adult↗
PubMed2005

Prospective validation of two models predicting pregnancy leading to live birth among untreated subfertile couples.

BACKGROUND: Models predicting clinical outcome need external validation before they can be applied safely in daily practice. This study aimed to validate two models for the prediction of the chance of treatment-independent pregnancy leading to live birth among subfertile couples. METHODS: The first model uses the woman's age, duration and type of subfertility, percentage of progressive sperm motility and referral status. The second model in addition uses the result of the post-coital test (PCT). For validation, these characteristics were collected prospectively in two University hospitals for 302 couples consulting for subfertility. The models' ability to distinguish between women who became pregnant and women who did not (discrimination) and the agreement between predicted and observed probabilities of treatment-independent pregnancy (calibration) were assessed. RESULTS: The discrimination of both models was slightly lower in the validation sample than in the original sample which provided the model. Calibration was good: the observed and predicted probabilities of treatment-independent pregnancy leading to live birth did not differ for both models. CONCLUSIONS: The chance of pregnancy leading to live birth was reliably estimated in the validation sample by both models. The use of PCT improved the discrimination of the models. These models can be useful in counselling subfertile couples.

Birth Rate↗
PubMed2001

Scoring systems and risk assessment for upper gastrointestinal bleeding.

Mortality associated with acute upper gastrointestinal bleeding remains high despite advances in diagnosis and therapy. This was emphasized by the findings of the seminal English National Audit of acute gastrointestinal haemorrhage undertaken by Rockall and associates in the mid-1990s. The apparent lack of progress is largely due to less selective reporting in an ageing population with greater co-morbidity. Thus some deaths will be unavoidable even with exemplary treatment. Managing high risk patients in a dedicated area with close cooperation between medical and surgical gastroenterologists has been shown to improve outcome. The challenge is to select those patients who have most to gain from such a scarce and expensive resource so that their treatment can be optimized. Various risk factors have been identified to help achieve this end. Rockall's national audit data suggest that avoidable deaths remain a problem in most district general hospitals. A simple numerical score was derived from these audit data (Rockall score) to predict rebleeding and mortality. The score is based on five variables: age, shock, co-morbidity, endoscopic diagnosis and stigmata of recent haemorrhage. It has the advantage that pre-endoscopic assessment can be made by inexperienced medical or nursing staff. The system was validated internally in a second audit by Rockall and co-workers, and subsequent external validation has come from New Zealand and the Netherlands. The score is less reliable at predicting rebleeding than death and so is, as yet, an imperfect instrument. The scoring system has also proven valuable in selecting low risk patients for early discharge (resulting in health care economies) and for comparing outcome data from different hospitals or populations. Endoscopic treatment has recently been shown to reduce rebleeding rates and perhaps mortality. These advances in therapy are becoming more widely adopted and may influence the predictive ability of the Rockall score. The study from Edinburgh, in this issue, although small and with wide confidence intervals, supports the ability of the Rockall score to identify high risk cases amongst those given endoscopic treatment. It also suggests that an adjustment of the score may be required in these circumstances to prevent overcalling the risk of rebleeding and death.

Endoscopy, Gastrointestinal↗
PubMed2002

Identification of coryneform bacteria and related taxa by Fourier-transform infrared (FT-IR) spectroscopy.

An extensive Fourier-transform infrared (FT-IR) spectroscopy database for the identification of bacteria from the two suborders Micrococcineae and Corynebacterineae (Actinomycetales, Actinobacteria) as well as other morphologically similar genera was established. The database consists of averaged IR spectra from 730 reference strains, covering 220 different species out of 46 genera. A total of 192 species are represented by type strains. The identity of 352 reference strains was determined by comparative 16S rDNA sequence analysis and, if necessary, strains were reclassified accordingly. FT-IR frequency ranges, weights and reproducibility levels were optimized for this section of high-G+C gram-positive bacteria. In an internal validation, 98.1% of 208 strains were correctly identified at the species level. A simulated external validation which was carried out using 544 strains from 54 species out of 16 genera resulted in a correct identification of 87.3% at the species level and 95.4% at the genus level. The performance of this identification system is well within the range of those having been reported in the literature for the identification of coryneform bacteria by phenotypical methods. Coryneform and related taxa display a certain degree of overlapping distribution of different taxonomical markers, leading to a limited differentiation capacity of non-genotypical identification methods in general. However, easy handling, rapid identification within 25 h starting from a single colony, a satisfactory differentiation capacity and low cost, render FT-IR technology clearly superior over other routine methods for the identification of coryneform bacteria and related taxa.

Actinomycetales↗
PubMed2003

A risk score to predict arrhythmias in patients with unexplained syncope.

OBJECTIVES: To develop and validate a risk score predicting arrhythmias for patients with syncope remaining unexplained after emergency department (ED) noninvasive evaluation. METHODS: One cohort of 175 patients with unexplained syncope (Geneva, Switzerland) was used to develop and cross-validate the risk score; a second cohort of 269 similar patients (Pittsburgh, PA) was used to validate the system. Arrhythmias as a cause of syncope were diagnosed by cardiac monitoring or electrophysiologic testing. Data from the patient's history and 12-lead emergency electrocardiography (ECG) were used to identify predictors of arrhythmias. Logistic regression was used to identify predictors for the risk-score system. Risk-score performance was measured by comparing the proportions of patients with arrhythmias at various levels of the score and receiver operating characteristic (ROC) curves. RESULTS: The prevalence of arrhythmic syncope was 17% in the derivation cohort and 18% in the validation cohort. Predictors of arrhythmias were abnormal ECG (odds ratio [OR]: 8.1, 95% confidence interval [CI]=3.0 to 22.7), a history of congestive heart failure (OR: 5.3, 95% CI=1.9 to 15.0), and age older than 65 (OR: 5.4, 95% CI=1.1 to 26.0). In the derivation cohort, the risk of arrhythmias ranged from 0% (95% CI=0 to 6) in patients with no risk factors to 6% (95% CI=1 to 15) for patients with one risk factor, 41% (95% CI=26 to 57) for patients with two risk factors, and 60% (95% CI = 32 to 84) for those with three risk factors. In the validation cohort, these proportions varied from 2% (95% CI=0 to 7) with no risk factors to 17% (95% CI=10 to 27) with one risk factor, 35% (95% CI=24 to 46) with two risk factors, and 27% (95% CI=6 to 61) with three risk factors. Areas under the ROC curves ranged from 0.88 (95% CI=0.84 to 0.91) for the derivation cohort to 0.84 (95% CI=0.77 to 0.91) after cross-validation within the same cohort and 0.75 (95% CI=0.68 to 0.81) for the external validation cohort. CONCLUSIONS: In patients with unexplained syncope, a risk score based on clinical and ECG factors available in the ED identifies patients at risk for arrhythmias.

Aged↗
PubMed2000

Overcoming challenges in outcome evaluations of school mental health programs.

Significant growth and improvement of school mental health programs has occurred in recent years. However, evaluation of outcomes for children receiving these services is needed to provide accountability data and ensure the sustainability of these programs. When designing studies, evaluators must overcome several challenges that may threaten the validity of their conclusions. In this paper, threats or challenges to the internal and external validity of results from evaluation studies are reviewed. Suggestions are provided for overcoming these challenges, in order to encourage future evaluation activities in this developing field and to document the impact of services for youth and their families.

Adolescent↗
PubMedDate not supplied

Estimation by data augmentation in regression models with continuous and discrete covariates measured with error.

Estimation methods are considered for regression models which have both misclassified discrete covariates and continuous covariates measured with error. Adjusted parameter estimates are obtained using the method of data augmentation, where the true values of the covariates measured with error are regarded as missing data. Validation data on the covariates are assumed to be available. The distinction between internal and external validation data is emphasized, and its effects on the analysis are examined. The method is illustrated with simulated data.

Algorithms↗
PubMed2004

Tree and spline based association analysis of gene-gene interaction models for ischemic stroke.

In the biology of complex disorders, such as atherothrombosis, interactions among genetic factors may play an important role, and theoretical considerations suggest that gene-gene interactions are quite common in such diseases. We used a nested case-control sample from the Physicians' Health Study, a randomized trial assessing the effects of aspirin and beta-carotene on cardiovascular disease and cancer among 22071 US male physicians, to examine these relationships for ischemic stroke. Data were available on 92 polymorphisms from 56 candidate genes related to inflammation, thrombosis and lipid metabolism, assessed in 319 incident cases of ischemic stroke and 2090 disease-free controls. We used classification and regression trees (CART) and multivariate adaptive regression spline (MARS) models to explore the presence of genetic interactions in these data. These models offer advantages over typical logistic regression methods in that they may uncover interactions among genes that do not exhibit strong marginal effects. Final models were selected using either the Bayes Information Criterion or cross-validation. Model fit was assessed using 10-fold cross-validation of the entire selection process. Both the CART and two-way MARS-logit models identified an interaction between two polymorphisms linked to inflammation, the P-selectin (val640leu) and interleukin-4 (C(582) T) genes. Internal validation of these models, however, suggested that effects of these polymorphisms are additive. Although further external validation of these models is necessary, these methods may be valuable in exploring and identifying potential gene-gene as well as gene-environment interactions in association studies.

Adult↗