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PubMed2000

The Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardio (GISSI)-Prevenzione Trial on fish oil and vitamin E supplementation in myocardial infarction survivors.

A recent large-scale, open-label, randomized, controlled trial in 11, 324 myocardial infarction (MI) survivors has shown low-dose fish oil, but not vitamin E, to reduce significantly the cumulative rate of all-cause death, nonfatal MI, and nonfatal stroke. Neither intervention significantly reduced the other primary endpoint, the cumulate rate of cardiovascular death, nonfatal MI, and nonfatal stroke. Analysis of secondary endpoints indicated that the benefits of the 875 mg fish oil capsules containing 850 to 882 mg eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as ethyl esters was in reducing mortality and not in a reduction of nonfatal MI. It was a safe intervention. The internal validity and external validity of the data was examined and the findings placed in clinical perspective. Important questions remain about the benefits of increased plant sources of n-3 polyunsaturated fatty acids (PUFA) for those who cannot obtain or consume fish. Also the benefits of diet versus fish oil supplementation haven't been determined precisely. Although it seems reasonable to increase sources of n-3 PUFA in the diet for those at high risk of coronary heart disease, current data do not support a policy of promoting fish oil capsules for secondary prevention of coronary heart disease.

Dietary Supplements↗

PubMed2006

A validated tool for gaining insight into clinicians' preventive medicine behaviors and beliefs: the preventive medicine attitudes and activities questionnaire (PMAAQ).

OBJECTIVE: This article describes the development, reliability, and validity of the Preventive Medicine Attitudes and Activities Questionnaire (PMAAQ). METHOD: From 1995 to 2003, the PMAAQ was administered to 353 residents at six primary care residency programs in the United States. Validity was demonstrated in four ways: content validity through an expert panel, calculation of internal consistency reliabilities, demonstration of divergent validity, and external validation using a pre-existent chart review dataset. Stability measures were also calculated. RESULTS: High internal consistency reliabilities among the eight scales were seen (Cronbach's alpha = 0.74 to 0.98). Divergent validity was demonstrated by low to moderate intercorrelations among scales (r = -0.23 to 0.54). Significant correlations were seen between several PMAAQ scales and scales created from chart review data. Two-month test-retest correlations ranged from r = 0.56 to 0.87. Results suggest that clinicians' attitudes alone are not directly responsible for behaviors. CONCLUSION: The PMAAQ can validly and reliably measure residents' prevention behaviors and provide insight into their preventive healthcare attitudes. This survey could be useful in targeting areas for interventions to improve delivery of clinical preventive services, as a means of evaluating the effectiveness of such interventions, or as a quality assurance tool to monitor physician prevention activities.

Female↗

PubMedDate not supplied

The use of claims databases for outcomes research: rationale, challenges, and strategies.

Health care payers and policy makers need information about the cost and effectiveness of medical treatments. While randomized controlled trials historically are the primary source of medical information, they are expensive and labor-intensive, and often have limited utility for answering questions about "real-world" patient populations. These problems have led to an increasing reliance on claims database research in making policy decisions about treatment options. However, both researchers and decision makers should recognize the limitations and unique features of claims databases. Recommendations for avoiding or minimizing threats to internal validity, construct validity, and external validity are: (1) use of a study design that includes comparisons; (2) ensuring that the study design and conclusions are consistent with the database; (3) a priori conceptual modeling of the research question; (4) use of appropriate constructs; (5) explicit examination of alternative explanations for study findings; (6) sensitivity analyses of key assumptions; (7) awareness of the distinction between statistical and practical significance of findings; (8) generalization only when appropriate; and (9) reporting of relevant information. Given that any study design or data source has limitations, we hope that this paper will encourage a philosophy of methodological pluralism in outcomes research. Awareness and accurate reporting of validity issues will strengthen and extend the information resources currently available to decision makers.

Decision Making↗

PubMed2000

Case study methodology in tissue viability. Part 1: Methodological considerations.

Case studies are often presented in relation to tissue viability problems. Within hierarchies of evidence, case studies are sometimes seen to be on a par with expert opinion. This paper examines the case study as a research method and seeks to determine its value in tissue viability research. The term 'case study' denotes a general strategy for research where several methods of data collection are used to provide an in-depth analysis of an individual, group or institution. Three types of case study are used in research: intrinsic, instrumental and collective. All case studies utilize data triangulation within their design, that is, the use of a variety of sources of data within a study. It is one of the major strengths of the case study method. Data sources include documentary data sources, observation and interviews. As in any research, validity and reliability are important in case study methodology; in particular, construct validity, internal validity and external validity. Case studies are potentially vulnerable to observer error and observer bias. Examples are given of potential case studies in tissue viability and their strengths and weaknesses. If undertaken prospectively, with clearly defined multiple sources of data collection and a documented chain of evidence, case studies can add breadth to our knowledge and experience of caring for patients with tissue viability problems.

Data Collection↗

PubMed1997

Reliability of comparative molecular field analysis models: effects of data scaling and variable selection using a set of human synovial fluid phospholipase A2 inhibitors.

The effects of data pretreatment, data scaling, and variable selection on three-dimensional quantitative structure-activity relationships derived by comparative molecular field analysis (CoMFA) using the GRID energy function were studied in detail for a set of inhibitors of the human synovial fluid phospholipase A2 (HSF-PLA2). The quality of the models was evaluated for predictive power and ability to map the receptor binding site by (a) comparison of predicted and experimental activities using cross-validation and external validation sets and (b) comparison of the regions selected in space in the CoMFA models with a crystal structure of a HSF-PLA2-inhibitor complex, with optimized comparative binding energy analysis (COMBINE) models (Ortiz et al., 1995) and with structure-activity relationships derived previously for different sets of compounds. It is found that (1) data scaling and dielectric modeling strongly influence CoMFA results. Unscaled data and a uniform dielectric constant of 4 are well suited to GRID-CoMFA studies for the present compound set. (2) The GOLPE and Q2-GRS variable selection methods select variables in roughly the same regions in Cartesian space, but they produce different models in chemometric space and differ in their sensitivity to data scaling and pretreatment and their tendency to overfitting. (3) CoMFA models are consistent with COMBINE models in that they identify approximately the same intermolecular interactions as relevant for activity. Our study provides support for the qualitative receptor-mapping properties of CoMFA models and for the validity of variable selection when applied with care and also provides guidelines for how to evaluate the quality of CoMFA models.

Enzyme Inhibitors↗

PubMed2003

Computer-aided knowledge generation for understanding skin sensitization mechanisms: the TOPS-MODE approach.

The TOPS-MODE (topological substructural molecular descriptors) approach is used to derive models for understanding the molecular structural contribution to skin sensitization. A data set of 93 compounds was used in the development of the models; 29 new skin sensitization values (EC3) are reported here for the first time. The models developed possess high predictivity and have been validated through the use of cross-validation and external validation sets. The models have enabled the formulation of potential new structural alerts far faster and using less data than typically required by traditional approaches. Structural contributions to skin sensitization for various classes of chemicals are presented on the basis of bond contributions. The models have also been able to identify potential structural alerts for chemicals requiring metabolic activation.

Animals↗

PubMed1994

Prediction equations for the estimation of body composition in the elderly using anthropometric data.

To study the relationship between health and nutritional status in elderly populations, information about body composition is essential. To collect this information in large epidemiological studies, practical methods based on anthropometric data must be available. In the present study the relationship between body composition, determined by densitometry, and anthropometric data in 204 elderly men and women, aged 60-87 years, was analysed. Existing prediction equations described in the literature, and mainly based on young and middle-aged subjects, generally underestimated percentage body fat in the elderly study population. Therefore, new prediction equations were developed, based on sex and the sum of two (biceps and triceps) or four (biceps, triceps, suprailiaca and subscapula) skinfolds or the body mass index (BMI). Addition of age or body circumferences to the models did not improve the prediction of body density. Internal cross validation and external validation revealed that the formulas are valid for the estimation of body density in elderly subjects. The standard errors of estimate of the three models, expressed as percentage body fat, were 5.6, 5.4 and 4.8% respectively.

Aged↗

PubMed2002

A proposal for evaluation of exposure data.

There is a growing need for transparency concerning ways in which existing exposure data are weighted for their relative value and quality. Currently, this evaluation is largely subjective and is dependent on the quality of the judgement of the individual assessor or expert group. In this paper some general guidelines are presented for a quality assessment procedure. Such a predetermined procedure potentially enhances the consistency among different assessors and assessments and facilitates harmonization of assessment procedures. The guidelines are presented in the context of a decision tree with four decision rules for data quality, i.e. 'availability of occupational hygiene information', 'variability and precision issues', 'internal validity' and 'external validity'. These methodological issues are considered to be the most important aspects of data quality and will be discussed in this paper. The decision tree eventually results in three quality classes, i.e. exposure data providing sufficient information, supplementary information and data which should be excluded from the exposure assessment process. The guidelines should not be used in a rigid manner but have to be interpreted in the light of the particular circumstances and purposes of the assessment.

Chemical Industry↗

PubMedDate not supplied

Customization of pain treatments: single-case design and analysis.

The aim of this paper is to acquaint pain researchers and practitioners with recent developments in the single-case experimental approach and their potential to allow for tailoring the treatment and its evaluation to the specific complaints, aptitudes, or profile of the individual patient, without violating the canons of good science and practice. After contrasting the single-case experimental approach and the case-study approach, we show the possibilities of customization in design, measurement, and test statistics. This is done by distinguishing 2 types of single-case designs--alternation designs and phase designs--and 2 types of replication strategies--simultaneous replications and sequential replications. In addition, tailor-made randomization tests are proposed for alternation, phase, and simultaneous replication designs and the combining of P values to perform a meta-analysis on designs that are sequentially replicated. With our emphasis on: 1) randomization in the design; 2) the possibilities for a statistical test (together with the determination of power and the calculation of effect sizes); 3) the importance of reliable and valid measurement; and 4) the role of replication, we demonstrate how internal validity, statistical-conclusion validity, construct validity, and external validity concerns can be dealt with within a single-case experimental approach framework. Finally, the many research examples and references to clinical work illustrate the usefulness of the approach.

Data Interpretation, Statistical↗

PubMed1992

The structure of the Mental Health Inventory among Chinese in Taiwan.

This study attempted to ascertain the construct validity and external validity of the Mental Health Inventory in a Chinese population in Taiwan and contrast these results with results obtained from studies of several U.S. populations. In particular, a series of measurement models were specified and evaluated to address the issues of reliability and validity. Data were collected from personal interviews of a probability sample of 1,194 Chinese respondents 14 years of age and older in four townships in southwest Taiwan. The Mental Health Inventory was found to involve two major components: positive well-being and psychological distress. As a hierarchical structure, each component consists of one second-order and two or three first-order factors. The relationships between well-being and distress can be characterized as substantially independent and modestly bipolar depending on the level and specification.

Adolescent↗

PubMed2005

The surgical management of primary tumorsof the spine: initial results of an ongoing prospective cohort study.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To prospectively validate the application of appendicular surgical oncology principles to the treatment of primary bone tumors of the spine at a quaternary care spine center using local recurrence, survival, and health-related quality of life as outcome measures. SUMMARY OF BACKGROUND DATA: There is clear evidence that violating the margins of a sarcoma or other malignancy during surgical resection will risk local recurrence and diminish overall survival. Previous publications have retrospectively demonstrated this oncologically sound approach to spine tumor management to be internally valid. The external validity or limited generalizability has not been assessed. METHODS: Included were all patients who underwent en bloc surgical resection of a primary tumor of the spine between January 1994 and November 2003, at the authors' institution. Patients were uniformly staged before surgery and baseline demographic and surgical variables were recorded, as well as a cross-sectional evaluation of generic health-related quality of life. RESULTS: Twenty-six patients (12 males and 14 females) were eligible for the study. Average age was 42 (range 16 to 70). There were 19 malignant tumors and 7 benign. There are 20 surviving patients with an average follow-up of 41.5 months (range 6 to 111 months), 15 of whom had malignant tumors. None of these patients have evidence of local recurrence, and one has evidence of systemic disease. The health-related quality of life, using the SF-36, shows acceptable morbidity of these procedures (physical component summary = 37.73 +/- 11.52, MCS = 51.69 +/- 9.54). CONCLUSIONS: Principles of wide surgical resection, commonly applied in appendicular oncology, can and should be used for the treatment of primary bone tumors of the spine with anticipated acceptable morbidity and satisfactory survival.

Adolescent↗

PubMed1996

Using vignettes to collect data for nursing research studies: how valid are the findings?

Vignettes are simulations of real events which can be used in research studies to elicit subject's knowledge, attitudes or opinions according to how they state they would behave in the hypothetical situation depicted. Advantages associated with the use of vignettes as research tools include: the ability to collect information simultaneously from large numbers of subjects, to manipulate a number of variables at once in a manner that would not be possible in observation studies, absence of observer effect and avoidance of the ethical dilemmas commonly encountered during observation. Difficulties include problems establishing reliability and validity, especially external validity. This paper considers the advantages and disadvantages associated with the use of vignettes as data collection tools, concluding with a check-list to help critique vignettes studies.

Bias↗

PubMed2007

VaxiJen: a server for prediction of protective antigens, tumour antigens and subunit vaccines.

BACKGROUND: Vaccine development in the post-genomic era often begins with the in silico screening of genome information, with the most probable protective antigens being predicted rather than requiring causative microorganisms to be grown. Despite the obvious advantages of this approach--such as speed and cost efficiency--its success remains dependent on the accuracy of antigen prediction. Most approaches use sequence alignment to identify antigens. This is problematic for several reasons. Some proteins lack obvious sequence similarity, although they may share similar structures and biological properties. The antigenicity of a sequence may be encoded in a subtle and recondite manner not amendable to direct identification by sequence alignment. The discovery of truly novel antigens will be frustrated by their lack of similarity to antigens of known provenance. To overcome the limitations of alignment-dependent methods, we propose a new alignment-free approach for antigen prediction, which is based on auto cross covariance (ACC) transformation of protein sequences into uniform vectors of principal amino acid properties. RESULTS: Bacterial, viral and tumour protein datasets were used to derive models for prediction of whole protein antigenicity. Every set consisted of 100 known antigens and 100 non-antigens. The derived models were tested by internal leave-one-out cross-validation and external validation using test sets. An additional five training sets for each class of antigens were used to test the stability of the discrimination between antigens and non-antigens. The models performed well in both validations showing prediction accuracy of 70% to 89%. The models were implemented in a server, which we call VaxiJen. CONCLUSION: VaxiJen is the first server for alignment-independent prediction of protective antigens. It was developed to allow antigen classification solely based on the physicochemical properties of proteins without recourse to sequence alignment. The server can be used on its own or in combination with alignment-based prediction methods. It is freely-available online at the URL: http://www.jenner.ac.uk/VaxiJen.

Algorithms↗

PubMed2006

Systematic review of prognostic models in traumatic brain injury.

BACKGROUND: Traumatic brain injury (TBI) is a leading cause of death and disability world-wide. The ability to accurately predict patient outcome after TBI has an important role in clinical practice and research. Prognostic models are statistical models that combine two or more items of patient data to predict clinical outcome. They may improve predictions in TBI patients. Multiple prognostic models for TBI have accumulated for decades but none of them is widely used in clinical practice. The objective of this systematic review is to critically assess existing prognostic models for TBI METHODS: Studies that combine at least two variables to predict any outcome in patients with TBI were searched in PUBMED and EMBASE. Two reviewers independently examined titles, abstracts and assessed whether each met the pre-defined inclusion criteria. RESULTS: A total of 53 reports including 102 models were identified. Almost half (47%) were derived from adult patients. Three quarters of the models included less than 500 patients. Most of the models (93%) were from high income countries populations. Logistic regression was the most common analytical strategy to derived models (47%). In relation to the quality of the derivation models (n:66), only 15% reported less than 10% pf loss to follow-up, 68% did not justify the rationale to include the predictors, 11% conducted an external validation and only 19% of the logistic models presented the results in a clinically user-friendly way CONCLUSION: Prognostic models are frequently published but they are developed from small samples of patients, their methodological quality is poor and they are rarely validated on external populations. Furthermore, they are not clinically practical as they are not presented to physicians in a user-friendly way. Finally because only a few are developed using populations from low and middle income countries, where most of trauma occurs, the generalizability to these setting is limited.

Brain Injuries↗

PubMed1992

Development of an interview-based geriatric depression rating scale.

The geriatric depression rating scale (GDRS) is a new interview-based depression rating scale designed for use with adults 60 years of age or older. The scale was developed to fill a need for an instrument that would be sensitive to the problems encountered in assessing depression among older adults. The GDRS was designed by using items from the self-report Geriatric Depression Scale (GDS) as topic areas in a structured clinical interview similar to that of the Hamilton Rating Scale for Depression (HRSD). The 35-item rating scale was administered to 68 older individuals with a range of affective disturbance. The scale was found to have internal consistency and split-half reliability comparable to the HRSD and GDS. Concurrent validity, construct validity, external criterion validity, sensitivity, and specificity were all found to be acceptable.

Aged↗

PubMed1978

A critique of project evaluations.

In recent years an increased stress has been placed on the evaluation of mental health, education, and welfare service programs. The majority of studies readily available to most evaluators represent local project evaluations which usually contain diverse references to different aspects of the evaluative process. For evaluative results to be even minimally useful to other projects, however, certain requirements must be met. These are: (1) internal validity, (2) external validity, (3) specification of the population and treatment being implemented, and (4) standardization of indicators of treatment impact. To determine the extent to which published project impact evaluations meet these criteria, a study was undertaken to "evaluate the evaluations" themselves within heroin addiction treatment programs. Six high-yield journals and 100 random sources were systematically searched for reports of evaluations which provided measures of success in terms of the consumer. Articles were analyzed in regard to our four prerequisites for cross-project comparisons regarding process variables, impact variables, and methodologies. It became clear, however, that our original objectives in evaluating either the usefulness of published project evaluations or testing any specific impact hypotheses were not achievable due to the state of evaluative measurement and reporting practices at this time. The major problems we eoncountered in our inability to complete a necessary and potentially fruitful comparative assessment of project evaluations are discussed in detail with recommendations for future work.

Heroin Dependence↗

PubMed2026

Analysis of end-stage renal disease mediated by cuproptosis-related genes.

OBJECTIVE: The complex pathophysiological mechanism of end-stage renal disease (ESRD) has not been fully understood. Cuproptosis is a newly discovered type of programmed cell death. Therefore, this study attempts to clarify the relationship between cuproptosis-related genes (CRGs) and the phenotype of ESRD. MATERIALS AND METHODS: The National Center for Biological Information Gene Expression Omnibus database was applied to obtain the GSE37171 dataset comprising whole-genome microarray analysis of peripheral blood samples. A 3 : 1 case-control design was employed with 75 ESRD patients and 20 healthy controls who were frequency-matched for age, sex, and ethnicity. Based on differentially expressed genes (DEGs) and genes related to cuproptosis, CRGs were identified. Thereafter, we explored two different subpopulations based on the cuproptosis gene and analyzed their expression and immune infiltration. Genes specific to the CRG cluster were identified through the weighted gene co-expression network analysis algorithm, and the best prediction model was determined and verified by four machine learning methods. RESULTS: The study identified 14 differentially expressed CRGs, among which ATP7B, SLC31A1, LIAS, LIPT1, DLD, MTF1, CDKN2A, DBT, and DLST had relatively high expression levels in the ESRD samples. Compared with the control group, expression levels of FDX1, DLAT, PDHA1, PDHB, and GLS were significantly lower in the ESRD group, and CRGs played a key role in the regulation of immune infiltration in ESRD. Two cuproptosis-related molecular clusters were identified in the ESRD samples. Cluster2 was more correlated with the immune infiltration of ESRD. By analyzing the intersection points between CRG cluster and key genes of ESRD, a total of 888 specific DEGs were identified. Functional differences related to specific DEGs were further explored using gene set variation analysis. Five significant genes (SMC5, USP47, USP53, AGA, and DMXL1) were identified by the support vector machine model as key predictors for ESRD disease risk, achieving an area under the curve (AUC) of 1.00 in internal validation. However, external validation in independent cohorts is required prior to clinical application. Individual gene analysis showed an AUC > 0.81 in discriminating ESRD patients from healthy controls, and the expression of all 5 genes in ESRD patients was significantly lower than in the control group. CONCLUSION: This study clarified the relationship between CRGs and the phenotype of ESRD, analyzed their specific roles in the immune microenvironment, and obtained a predictive model, providing new insights for the study of its potential therapeutic targets.

Humans↗

PubMed2007

Incorporating quality of evidence into decision analytic modeling.

Our objective was to illustrate the effects of using stricter standards for the quality of evidence used in decision analytic modeling. We created a simple 10-parameter probabilistic Markov model to estimate the cost-effectiveness of directly observed therapy (DOT) for individuals with newly diagnosed HIV infection. We evaluated quality of evidence on the basis of U.S. Preventive Services Task Force methods, which specified 3 separate domains: study design, internal validity, and external validity. We varied the evidence criteria for each of these domains individually and collectively. We used published research as a source of data only if the quality of the research met specified criteria; otherwise, we specified the parameter by randomly choosing a number from a range within which every number has the same probability of being selected (a uniform distribution). When we did not eliminate poor-quality evidence, DOT improved health 99% of the time and cost less than 100,000 dollars per additional quality-adjusted life-year (QALY) 85% of the time. The confidence ellipse was extremely narrow, suggesting high precision. When we used the most rigorous standards of evidence, we could use fewer than one fifth of the data sources, and DOT improved health only 49% of the time and cost less than 100,000 dollars per additional QALY only 4% of the time. The confidence ellipse became much larger, showing that the results were less precise. We conclude that the results of decision modeling may vary dramatically depending on the stringency of the criteria for selecting evidence to use in the model.

CD4 Lymphocyte Count↗