SEARCH · PubMed Health

Results for “Internal validation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources

PubMed2000

The Addiction Severity Index: a field study of internal consistency and validity.

This study investigated whether the use of the Addiction Severity Index (ASI) in a network of inner-city alcohol and drug abuse clinics under nonideal conditions would yield internally consistent and valid data. A sample of 8,984 ASI scores was collected over a 34-month period. Construct validity was examined by computing the internal consistency of all subscales. Convergent and divergent validity of composite scores and of severity ratings were evaluated using correlation matrices. Findings demonstrated that ASI scores were internally consistent and valid, even though the recommended administration protocol may not always have been followed as faithfully as might be desirable. This robustness bodes well for the use of the ASI in on-line clinical environments. Results should be viewed with caution until the reliability of ASI administration is tested under similar nonideal conditions and until permissible deviations from standard protocol can be quantified.

Adult↗

PubMed2001

The OECD program to validate the rat uterotrophic bioassay to screen compounds for in vivo estrogenic responses: phase 1.

The Organisation for Economic Co-operation and Development has completed the first phase of an international validation program for the rodent uterotrophic bioassay. This uterotrophic bioassay is intended to identify the in vivo activity of compounds that are suspected agonists or antagonists of estrogen. This information could, for example, be used to help prioritize positive compounds for further testing. Using draft protocols, we tested and compared two model systems, the immature female rat and the adult ovariectomized rat. Data from 19 participating laboratories using a high-potency reference agonist, ethinyl estradiol (EE), and an antagonist, ZM 189,154, indicate no substantive performance differences between models. All laboratories and all protocols successfully detected increases in uterine weights using EE in phase 1. These significant uterine weight increases were achieved under a variety of experimental conditions (e.g., strain, diet, housing protocol, bedding, vehicle). For each protocol, there was generally good agreement among laboratories with regard to the actual EE doses both in producing the first significant increase in uterine weights and achieving the maximum uterine response. Furthermore, the Hill equation appears to model the dose response satisfactorily and indicates general agreement based on calculated effective dose (ED)(10) and ED(50) within and among laboratories. The feasibility of an antagonist assay was also successfully demonstrated. Therefore, both models appear robust, reproducible, and transferable across laboratories for high-potency estrogen agonists such as EE. For the next phase of the OECD validation program, both models will be tested against a battery of weak, partial estrogen agonists.

Animals↗

PubMed1998

Comparative binding energy analysis of HIV-1 protease inhibitors: incorporation of solvent effects and validation as a powerful tool in receptor-based drug design.

A comparative binding energy (COMBINE) analysis (Ortiz et al. J. Med. Chem. 1995, 38, 2681-2691) has been performed on a training set of 33 HIV-1 protease inhibitors, and the resulting regression models have been validated using an additional external set of 16 inhibitors. This data set was originally reported by Holloway et al. (J. Med. Chem. 1995, 38, 305-317), who showed the usefulness of molecular mechanics interaction energies for predicting the activity of novel HIV-1 protease inhibitors within the framework of the MM2X force field and linear regression techniques. We first used the AMBER force field on the same set of three-dimensional structures to check up on any possible force-field dependencies. In agreement with the previous findings, the calculated raw ligand-receptor interaction energies were highly correlated with the inhibitory activities (r2 = 0.81), and the linear regression model relating both magnitudes had an acceptable predictive ability both in internal validation tests (q2 = 0.79, SDEPcv = 0.61) and when applied to the external set of 16 different inhibitors (SDEPex = 1.08). When the interaction energies were further analyzed using the COMBINE formalism, the resulting PLS model showed improved fitting properties (r2 = 0.89) and provided better estimations for the activity of the compounds in the external data set (SDEPex = 0.83). Computation of the electrostatic part of the ligand-receptor interactions by numerically solving the Poisson-Boltzmann equation did not improve the quality of the linear regression model. On the contrary, incorporation of the solvent-screened residue-based electrostatic interactions and two additional descriptors representing the electrostatic energy contributions to the partial desolvation of both the ligands and the receptor resulted in a COMBINE model that achieved a remarkable predictive ability, as assessed by both internal (q2 = 0.73, SDEPcv = 0.69) and external validation tests (SDEPex = 0.59). Finally, when all the inhibitors studied were merged into a single expanded set, a new model was obtained that explained 91% of the variance in biological activity (r2 = 0.91), with very high predictive ability (q2 = 0.81, SDEPcv = 0.66). In addition, the COMBINE analysis provided valuable information about the relative importance of the contributions to the activity of individual residues that can be fruitfully used to design better inhibitors. All in all, COMBINE analysis is validated as a powerful methodology for predicting binding affinities and pharmacological activities of congeneric ligands that bind to a common receptor.

Drug Design↗

PubMed2005

The Serbian QOLIE-AD-48: translation, cultural adaptation, and preliminary psychometric evaluation.

PURPOSE: The goals of the work described in this article were to translate and adapt into Serbian the Quality of Life in Epilepsy Inventory for Adolescents (QOLIE-AD-48), and to evaluate the psychometric properties of the translation. METHODS: Translation/backtranslation, cultural adaptation, and pretesting were performed first. For validity, internal consistency, and sensitivity testing, the Serbian version was administered to a sample of 67 adolescents with epilepsy. RESULTS: All subscales (Epilepsy Impact, Memory/Concentration, Attitudes toward Epilepsy, Physical Functioning, Stigma, Social Support, School Behavior, and Health Perceptions) contributed significantly to the summary measure. Mean scores for the subscales ranged from 75.4 to 91.3, and showed a tendency to decrease as illness severity increased. Internal consistency reliability (Cronbach's alpha) was 0.92 for the entire questionnaire. CONCLUSIONS: The QOLIE-AD-48 Serbian version is a valid and reliable instrument for health-related quality-of-life assessment in youths with epilepsy. It can be administered in 15 minutes, and can be used in clinical practice, as well as in quality-of-life research.

Adaptation, Psychological↗

PubMedDate not supplied

National survey of radionuclide gastric emptying studies.

A survey was mailed to all institutions in Canada licensed to use radiopharmaceuticals. Questions addressed meal type; mode of preparation; and means, ranges and SD of emptying times. Seventy-eight per cent of 222 facilities responded, including all 55 teaching centres. Eighty-five per cent of teaching and 56% of nonteaching centres perform solid phase gastric emptying studies (GES). The majority use 99mTc sulphur colloid (Tc-SC) added to eggs before cooking as the standard meal. Twenty-five per cent of teaching and 21% of nonteaching centres perform liquid phase GES. Most use a watery solution of 111Indiethylenetriamine pentaacetic acid. Gastric emptying for solid phase GES, expressed as time for 50% emptying (mean t1/2), varied from 42 to 105 mins for centres using the Tc-SC egg meal. Twenty-eight per cent of teaching centres used +/- 2 SD to define their normal range, 26% used +/- 1 SD, 6% used +/- 1.5 SD, and 40% did not know the number of SD used. Twenty per cent of nonteaching centres used +/- 2 SD, 12% used +/- 1 SD and 68% did not know how many SD were used. For liquid phase GES, mean t1/2 varied from 20 to 60 mins. Eighteen per cent of centres used healthy volunteers to establish or validate normal ranges. There is substantial variability among the normal ranges for radionuclide solid and liquid phase GES in both teaching and nonteaching centres across Canada. A minority of facilities have established or validated their own normal ranges in healthy volunteers. There is a need for a more standardized protocol and range of normal, with internal validation by each institution.

Canada↗

PubMed1990

Evaluation of the Craig Lipreading Inventory.

Responses to the Craig Lipreading Inventory have not been subjected to rigorous statistical analysis. No normative data currently exist. The purposes of this study were to evaluate the internal validity and interest reliability and to obtain normative data. The inventory was administered to 150 children, ages 3 to 8 yr. The internal consistency was very high for each subtest. Significant correlations were obtained among the subtests. Significant differences in scores were noted for the three age groups, indicating the need for standards at each age group. Preliminary Z-scores and percentile ranks were computed for each age group. It was concluded that the inventory is a valuable, reliable tool of lipreading evaluation in children.

Child↗

PubMed1986

European general practice research workshop (EGPRW). Is international cooperation worth while?

General practice is a novice in the academic world. We need to stand together both nationally and internationally to establish general practice as a true academical discipline. To strengthen our credibility we have to do research of high quality. European General Practice Research Workshop (EGPRW) is a partly unformal international body with the aim "to encourage research, to foster and coordinate multinational studies, to exchange experiences and with it develop a validated international scientific base for general practice". The group was established November 1974 and the activities during its short existence are summarised and commented.

Congresses as Topic↗

PubMed1985

Ventilation thresholds may be misinterpreted with the presentation of mean data.

Past research has used either individual or mean data to illustrate the determination of the ventilation thresholds. Although an individual's data may represent the best rather than the typical response, the accuracy and validity of threshold determinations can be assessed. In contrast, the presentation of mean data may not allow the reader to evaluate the internal validity of the results.

Exercise Test↗

PubMed2000

Swedish universities Scales of Personality (SSP): construction, internal consistency and normative data.

OBJECTIVE: A thorough revision of the Karolinska Scales of Personality (KSP) was made by reducing the number of items and improving the psychometric quality as concerns face validity, internal consistency and response differentiation. The revised version was labelled The Swedish universities Scales of Personality (SSP) and now include 91 items divided into 13 scales. METHOD: The SSP were evaluated in a normative, randomly drawn sample (n = 741). All scales were found to be approximately normally distributed. RESULTS: The Cronbach's alpha coefficients ranged from 0.59 to 0.84. The mean inter-item correlations (MIIC) ranged from 0.17 to 0.43. The scale intercorrelation matrix yielded a three-factor solution with Factor 1 reflecting Neuroticism; Factor 2 Aggressiveness; and Factor 3 reflecting Extraversion. CONCLUSION: The original KSP scales were revised, shortened, modernized and psychometrically evaluated. The psychometric properties and the usefulness of the test battery were found to be substantially improved.

Adult↗

PubMed2007

OECD validation of the rodent Hershberger assay using three reference chemicals; 17alpha-methyltestosterone, procymidone, and p,p'-DDE.

The rodent Hershberger assay is being validated as an in vivo test method for detecting androgenic or antiandrogenic compounds by the Organization for Economic Cooperation and Development (OECD). As part of the international validation work, we studied 17alpha-methyltestosterone for evaluating androgenic activity, and procymidone and p,p'-DDE for evaluating antiandrogenic activity. Male Sprague-Dawley rats were castrated at postnatal day 42, and only the rats that showed preputial separation were used in this study. Seven days after castration, chemicals were administered daily by gavages to groups of rats for 10 days, as recommended by OECD phase-2 protocol. Administration of 17alpha-methyltestosterone induced increases of weights of accessory sex tissues and glands in a dose-dependent manner. Administration of procymidone and p,p'-DDE produced a dose-dependent decrease of weights of accessory sex tissues and glands in the rats co-treated with testosterone propionate (0.4 mg/kg/day) subcutaneously. Our data strongly suggested that the current protocol of OECD Hershberger assay (phase-2) should be used as a reliable method for the detection of endocrine related toxicity of other chemicals.

Administration, Oral↗

PubMed2000

An international approach to laboratory diagnosis of animal diseases.

During the past thirteen years, and as part of an overall support program for developing countries, the Joint FAO/IAEA Division has developed a series of standardized and internationally validated ELISA-based systems for the diagnosis and surveillance of the major epizootics affecting livestock in the developing world. Linked to comprehensive internal and external quality assurance protocols and to the use of standardized equipment and data management software, veterinary laboratories in many developing countries are now able to provide quality assured results on the prevalence of the major diseases affecting their livestock. This internationally standardized approach can rapidly enable developing countries to both monitor the effectiveness of their disease control and eradication programs and to meet requirements for international disease status recognition and for trade in livestock and livestock products.

Animal Diseases↗

PubMed2026

Machine learning-based clinical prediction model and multi-omics integration for assessing pancreatic cancer risk in new-onset diabetes.

BACKGROUND: Given that pancreatic cancer (PC) is typically diagnosed at an advanced stage but is often preceded by new-onset diabetes mellitus (NODM), providing a window for early detection, we sought to develop and validate an interpretable machine-learning model integrated with multi-omics profiling to identify early biomarkers of NODM-associated PC. METHODS: In a population-based cohort, individuals with NODM-associated PC and NODM without PC were identified and randomly divided (70:30) into training and validation sets after feature selection. Eight machine learning (ML) classifiers were compared using fivefold cross-validation, and model performance was evaluated in terms of discrimination, calibration, and decision curve–based clinical utility. We evaluated interpretability using the Shapley additive explanations (SHAP) analyses. Mechanistically, Olink proteomic profiling and metabolomics were analyzed through clinical classifications and model-defined risk strata. RESULTS: Categorical boosting achieved the best performance in the independent validation set (AUROC = 0.844). The NODM cohort was stratified into high- (n = 2,362) and low-risk (n = 5,030) groups, and internal validation together with SHAP analyses demonstrated consistent model performance and identified clinically interpretable predictors. Proteomic and metabolomic analyses under clinical and risk-based grouping identified 39 overlapping differentially expressed proteins and 145 overlapping metabolites with enriched across 11 shared KEGG pathways. Cross-platform validation highlighted PLTP, CRTAC1, and ITGAV as serum biomarkers with a strong potential for early NODM-PC detection. CONCLUSIONS: We developed an interpretable ML framework centered on NODM enables practical risk stratification for early PC detection by multi-omics and provides a pathway of ML-based triage followed by biomarker confirmation for earlier detection and diagnosis.

Humans↗

PubMed2004

Benchmarking lung cancer mortality rates in current and former smokers.

STUDY OBJECTIVES: To develop and validate a model for estimating the risk of lung cancer death in current and former smokers. The model is intended for use in analyzing a population of subjects who are undergoing lung cancer screening or receiving lung cancer chemoprevention, to determine whether the intervention has altered lung cancer mortality. DESIGN/SETTING/PATIENTS: Model derivation was based on analyses of the placebo arm of the Carotene and Retinol Efficacy Trial. Model validation was based on analyses of three other longitudinal cohorts. MEASUREMENTS: Observed and predicted number of deaths due to lung cancer. RESULTS: In internal validation, the model was highly concordant and well calibrated. In external validation, the model predictions were similar to what was observed in all of the validation analyses. The predicted and observed deaths within 6 years were very similar when assessed in the Johns Hopkins Hospital trial of chest radiography and sputum cytology screening (176 predicted, 184 observed, p = 0.53), the Memorial Sloan-Kettering Cancer Center trial of chest radiography and sputum cytology screening (108 predicted, 114 observed, p = 0.57), and the National Health and Nutrition Evaluation Survey part I (24 predicted, 21 observed, p = 0.52). CONCLUSIONS: The number of lung cancer deaths in a population of current or former smokers can be accurately predicted, making model-based evaluations of prevention and early detection interventions a useful adjunct to definitive randomized trials. We illustrate this potential use with a small example.

Adult↗

PubMed2003

[A multidisciplinary organizational Emergency Department model for trauma patients in hypovolemic shock].

UNLABELLED: Hypovolemic shock in trauma patients causes high mortality because of exanguination, secondary brain damage, multiple organ disfunction. Good organization and operative protocols are vital to patients in need of a prompt and multidisciplinary treatment. PATIENTS AND METHODS: We collected data about resuscitative and diagnostic process, severity scores and outcome of all trauma patients in hypovolemic shock admitted to the Ospedale Maggiore in Bologna (Italy) after the organization of an Internal Trauma System. RESULTS: We obtained a reduction of both diagnostic and therapeutic times and mortality during the last 14 years. CONCLUSIONS: A valid internal organization can improve mortality of trauma patients without expenditure of extra resources.

Accidents, Traffic↗

PubMed2003

A new measure of the alcohol dependence syndrome: the severity scale of alcohol dependence.

The purpose was to develop a diagnostic instrument of the Alcohol Dependence Syndrome defined by Edwards and Gross (1976) since comparable scales show some limitations. The methods include three studies carried out in order to develop the SEverity Scale of Alcohol dependence (SESA; total n = 774 alcohol-dependent patients), and three further studies served for validation (total n = 603 alcohol dependents). The findings reveal that the SESA, a 33-item questionnaire including 7 subscales which cover the criteria of the Alcohol Dependence Syndrome, proved to be internally consistent. The subscales are correlated with respective information from internationally validated interview instruments for the diagnosis of alcohol dependence according to DSM and ICD (CIDI, SCAN): six subscales are correlated with six of eight CIDI items and with eight of nine SCAN items selected for the purpose of validation. In addition, there are positive correlations with the Munich Alcoholism Test, the Michigan Alcoholism Test as well as single items of the WHO Alcohol Use Disorders Identification Test. It is concluded from the results that the SESA shows good validity.

Adult↗

PubMed2006

Validation of the functional assessment of cancer therapy esophageal cancer subscale.

BACKGROUND: To develop and validate a quality of life subscale for patients with esophageal cancer to be used with the Functional Assessment of Cancer Therapy-General (FACT-G). METHODS: Prospective cohort study of patients with esophageal cancer treated with surgery alone or neoadjuvant chemoradiotherapy and surgery evaluating the validity, internal consistency, and responsiveness to change of the FACT-Esophageal (FACT-E) when comparing it with the European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ 30) and esophageal (OES 24) as well as clinical factors. RESULTS: The FACT-E demonstrated very good convergent and divergent validity when compared with the EORTC QLQ30 and OES 24 and clinical variables. Internal consistency was also good with coefficient alpha > 0.70 for all subscales and individual items. Stability coefficients were > 0.80. Changes in clinical status were reflected in changes in FACT-E scores demonstrating responsiveness to change, particularly in patients receiving neoadjuvant chemoradiotherapy before surgery. CONCLUSIONS: The FACT-E met or exceeded all standards for validity, providing an option to measure health-related quality of life for different treatment strategies for esophageal cancer.

Activities of Daily Living↗

PubMed1987

A taxometric method for diagnosis of tardive dyskinesia.

A taxometric method for diagnosis of drug-induced tardive dyskinesia is described. The method, using items from the Abnormal Involuntary Movement Scale (AIMS) as indicators of the syndrome, is applied in a sample of children diagnosed earlier as autistic and participating in an ongoing treatment program. The method includes procedures for estimation of the prevalence rate of the syndrome and the valid positive and false positive rates for each indicator of the syndrome and it includes tests (referred to as "consistency tests") for checking the internal validity or goodness-of-fit of the statistical model. The agreement of the taxometric classification with that obtained by using criteria suggested by Schooler and Kane was very good. In general, the results were encouraging enough to warrant further study of this kind of method for the detection and diagnosis of tardive dyskinesia.

Antipsychotic Agents↗

PubMed2000

Risk assessment and standardized nosocomial infection rate in critically ill children.

OBJECTIVES: To develop and validate a pediatric nosocomial infection risk (PNIR) assessment model, and to compare the daily trends in risk factors between patients with nosocomial infection (cases) and without nosocomial infection (controls) in the pediatric intensive care unit (ICU). DESIGN: Prospective cohort. SETTING: A 16-bed pediatric ICU in an urban, university-affiliated, multidisciplinary, regional referral center. PATIENTS: Patients available for study included consecutive admissions to the unit between May 1, 1992, and April 30, 1993, and between May 9, 1995, and December 11, 1995. Patients from both data collection periods were pooled and randomly divided into training (70%) and validation (30%) samples. MEASUREMENTS AND MAIN RESULTS: In the logistic regression analysis using admission day data, three factors were shown to remain as independent risk factors. Invasive device use, parenteral nutrition, and the interaction between severity of illness-modified Pediatric Risk of Mortality III-24 score and postoperative care were associated with 2, 6, and 1.5 times the risk of developing nosocomial infection, respectively. This PNIR model performed well in both the training and validation samples as indicated by the goodness-of-fit test, which evaluated standardized nosocomial infection rates (observed vs. predicted nosocomial infection rates). The internal validity of the PNIR model was good. In trend analysis, severity of illness and invasive device use appear to have similar trend patterns, during the first week of pediatric ICU stay. There was no difference in any of these risk factors between cases and controls after 7 days of pediatric ICU stay. CONCLUSIONS: The PNIR assessment model incorporates intrinsic factors, such as patient severity of illness, and extrinsic factors contributing to the development of nosocomial infection in this high-risk population. The methodology using intrinsic and extrinsic factors to adjust for nosocomial infections should be taken into consideration when evaluating interhospital comparison of nosocomial infection rates, quality assessment, intervention strategies, and use of treatment modalities.

Child, Preschool↗