PubMed HealthSearch

SEARCH · PubMed Health

Results for “Software 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 73 records · Page 4Linked to original sources

Predicting length of stay for psychiatric diagnosis-related groups using neural networks.

OBJECTIVE: To test the effect of diagnosis on training an artificial neural network (ANN) to predict length of stay (LOS) for psychiatric patients involuntarily admitted to a state hospital. DESIGN: A series of ANNs were trained representing schizophrenia, affective disorders, and diagnosis-related group (DRG) 430. In addition to diagnosis, variables used in training included demographics, severity of illness, and others identified to be significant in predicting LOS. RESULTS: Depending on diagnosis, ANN-predictions compared with actual LOS indicated accuracy rates ranging from 35% to 70%. The validity of ANN predictions was determined by comparing LOS estimates with the treatment team's predictions at 72 hours following admission, with the ANN predicting as well as or better than did the treatment team in all cases. CONCLUSIONS: One problem in traditional approaches to predicting LOS is the inability of a derived predictive model to maintain accuracy in other independently derived samples. The ANN reported here was capable of maintaining the same predictive efficiency in an independently derived cross-validation sample. The results of ANNs in a cross-validation sample are discussed and the application of this tool in augmenting clinical decision is presented.

Adult

Automated recognition of corrupted arterial waveforms using neural network techniques.

A data acquisition system that automatically discards corrupted or undesirable signals would save untold hours of drudgery for researchers. Continuous recording of variables to provide detailed behavior patterns generates huge amounts of raw data. Unfortunately waveforms usually require visual inspection for isolating desired behavior or validating signal integrity. This tedious and time-consuming step can potentially be eliminated using a novel computer science technique. We have trained a simulated neural network to recognize corrupted arterial pressure waveforms. Our system can now evaluate the validity of the arterial waveform without human intervention with an average false positive error rate of 2.2% and an average false negative error rate of 12.6%.

Artifacts

Cellular viability in human tumor micro-organ cultures: in situ quantitation by image processing.

At present, cytotoxicity measurements using the fluorescent cytoprint assay are based on achieving complete cell death in cultures of drug-sensitive tumors. Thus, the usefulness of the assay would be extended if partial effects of chemotherapeutic drugs could be quantified. In this study, we addressed the issue by developing and validating a thresholding algorithm for automatic image processing that can be used to quantify the areas occupied by viable (i.e., fluorescent) micro-organs in the culture.

Drug Screening Assays, Antitumor

Validation of the medical expert system PNEUMON-IA.

The present study validates the expert system PNEUMON-IA. The aim of PNEUMON-IA is assessing the etiology of community-acquired pneumonias from clinical, radiological, and laboratory data obtained at the onset of the disease. Validation was performed using data from medical records of 76 patients with proven clinical diagnosis of pneumonia. The etiological diagnoses provided by PNEUMON-IA were compared to those established by five specialists unrelated to the development of the expert system. For each etiological possibility, both PNEUMON-IA and the experts provided a causal possibility, expressed as a linguistic label (i.e., "almost impossible"). Linguistic labels were then converted to numeric values. In the majority of cases, an etiological diagnosis was unavailable to be used as a gold standard. To overcome this limitation, distances between arrays of etiological possibilities given by specialists and by PNEUMON-IA were considered as an agreement measure between diagnoses. Cluster analysis based on those distances was used to classify PNEUMON-IA among experts. Results showed the same differences between specialists and PNEUMON-IA as among the specialists themselves. The method used to validate PNEUMON-IA could prove useful to assess the performance of expert systems in fields where no gold standard is available.

Adolescent

A Clarkson's sector integration routine for personal computers.

A Clarkson's sector integration scheme has been implemented on a personal computer to calculate mean scatter-air ratio (SAR) and mean tissue-air ratio (TAR) for external photon beams of irregular shape. To find where a given radial line from the point of interest intersects the edge of the radiation field, polygon clipping algorithms have been adapted from the field of image processing. The program has calculation run times of approximately 1 s on an 80387 with a math coprocessor for an integration of 36 sectors. The software was validated by comparison to program IRREG, where for various squares and clinical shapes, the agreement was typically 0.7%. The source code is available from the authors.

Algorithms

Hybrid systems: a promising solution for better decision support tools.

This paper describes HYCONES II, a tool to enable construction of tightly coupled Hybrid Connectionist Expert Systems to solve classification problems. HYCONES II integrates frames with neural networks in its hybrid knowledge base. Three neural network models (CNM, the Fuzzy ARTMAP, and the Semantic ART - SMART) are available to the knowledge engineer. SMART is a new model, introduced by this research group and based on a combination of two previous models. The validation section compares the performance of these three neural models to solve diagnostic problems in two medical domains. Finally, the present status of this project and its future developments are presented.

Algorithms

[3D automatic expansion: clinical application].

The determination of the various volumes (GTV: gross target volume, CTV: clinical target volume, PTV: planned target volume) recommended by the ICRU 50 report is a critical step in conformal treatment planning, since treatment optimisation procedures and documentation rely on accurate dose-volume histograms. The shape and the size of the CTV vary with the computer algorithm, the patient image acquisition parameters, the definition of the GTV and the margins surrounding it. The automatic expansion programs included in commercially available treatment planning system require careful validation and control before and during their routine use by the clinicians. Significant differences have been observed between 2D- and 3D-based expansions, with a usual underestimation of the PTV by 2D algorithms.

Algorithms

Evaluation of the VALAB expert system.

The validation of a clinical laboratory report is a process that guarantees the results contained in the report have been obtained under satisfactory metrological conditions and that they are compatible with the information available on the patient. This validation is generally carried out manually by a clinical laboratory professional, but also may be done by an expert system properly programmed, such as the VALAB system. The evaluation presented in this article consists of comparing human and system decisions of validation for 500 randomly selected clinical laboratory reports from hospitalized patients. In this evaluation, 84.8% of the reports examined by the VALAB are accepted directly without any human aid, and only 15.2% require examination by clinical biochemists.

Clinical Chemistry Tests

Multiagency outcome evaluation of children's services: a case study.

Outcome monitoring has become a focus of accountability for public and nonprofit human service agencies. Besides providing answers to funders' questions about the services' impact, outcome monitoring helps administrators improve program effectiveness. After a three-year development period and a one-year implementation experience, SumOne for Kids represents a technically advanced outcome-monitoring system for children's mental health and/or child welfare services. Initiated, designed, and tested by 31 children's service agencies throughout Pennsylvania, and with state bureaucrats' and policy makers' encouragement, SumOne for Kids represents an effort to create a bottom-up/top-down process for implementing a statewide outcome-monitoring system. This article describes the genesis of this outcome-monitoring system, primary design principles, use of social validation for outcome selection, resolution of methodological difficulties, and reasons for selecting functional over clinical outcomes. The article reviews lessons learned through the development experience instructive to children's service managers, program evaluators, and industry leaders interested in establishing outcome-monitoring systems.

Child

Validation procedures for the Hamilton Thorne Integrated Visual Optical System sperm and cell analyzer.

The Hamilton Thorne Integrated Visual Optical System (IVOS) analyzer is a combined internal optical and computer system widely applied to laboratory animals, such as rat, rabbit, and canine, sperm in reproductive toxicology. It measures sperm motility, progressive motility, velocity, motion parameters, and concentration. The system is specially designed to facilitate on-site validation. Digital encoding allows image storage with absolute replay fidelity for later reexamination, enabling on-site validation complying with Good Laboratory Practices. A NIST-certified scale provides the length standard on which validation is based. Sperm typically move in wavy tracks, which must be characterized and validated. Playback of exact sperm tracks allows visual validation of sperm head position, given as Cartesian coordinates, and visual determination of motility from the playback screen. A cursor checks coordinate values, and manual confirmation of sperm motion parameters may be performed directly from the validated coordinates. Agreement to within 0.2% is obtained between manual and IVOS computation. Concentration is determined using a specific DNA stain that enables discrimination between sperm and somatic cell nuclei. The IVOS concentration of sperm nuclei in homogenized rat testis and cauda epididymis has been determined to be within 5% of manual hemacytometer counts of the same homogenate.

Humans

Methodological issues in validating decision-support systems for insulin dosage adjustment.

Safety and reliability of advice from new computer systems should be confirmed before embarking on prospective hospital trials. This process of preliminary testing is termed 'validation'. Though it forms a fundamental stage in system development, few standards exist for choosing and implementing tests. In the present paper, a validation methodology is developed in the domain of diabetes and intended for general use in chronic health management. It is based on a peer review protocol and incorporates empirical measures indicating: applicability of results to the real environment; variation among doctors; comparisons between doctors' and computer advice; and relative merits of different computer algorithms.

Algorithms

[Bacterio-expert: an integrated system for assisting in the validation of antibiotic sensitivity tests. Retrospective application in 4053 Staphylococcus].

Bacterio-expert is a simple expert system for assisting in the validation of antibiotic sensitivity testing. This system is incorporated in a data acquisition and editing program for bacteriologic test (Bacterio program written in Turbo-Pascal for personal computer users by the same authors). The principles of this system are explained and results with 4,053 antibiotic sensitivity tests on Staphylococcus aureus isolates are reported. Approximately 10% of tests required corrections.

Anti-Bacterial Agents

Validation of a detailed computer model for the electric fields in the brain.

A computer model has been designed for the calculation of the electrical fields in the head, based on the finite difference method. This method has not previously been applied for head modelling. The model was validated by using three concentric spheres and comparing it with an analytic model. Three levels of accuracy were tested. The forward solutions show that the finite difference algorithm works correctly and, by selecting the size of the volume elements properly, accurate results are obtained. The model will be applied to accurate and realistic geometries of the human head obtained from magnetic resonance images.

Brain

Measuring resource use in the ICU with computerized therapeutic intervention scoring system-based data.

BACKGROUND AND OBJECTIVE: In this era of health-care reform, there is increasing need to monitor and control health-care resource consumption. This requires the development of measurement tools that are practical, uniform, reproducible, and of sufficient detail to allow comparison among institutions, among select groups of patients, and among individual patients. We explored the feasibility of generating an index of resource use based on the Therapeutic Intervention Scoring System (TISS) from hospital electronic billing data. Such an index is potentially comparable across institutions, allows assessment of care at many levels, is well understood by clinicians, and captures many of the resources relevant to the ICU. DESIGN: We developed an automated mapping of the hospital billing database into the different items of TISS and generated computerized active TISS scores on 1,372 ICU days. The computerized score was then validated by comparison to prospectively gathered active TISS scores by trained data collectors. SETTING: Eight ICUs within a university teaching institution. PATIENTS: We studied 1,229 general medical and surgical ICU patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Active TISS scores ranged from 0 to 31 points. The two scores were well correlated (R2=0.53) and highly calibrated (as assessed by regression of active TISS on mean computerized active TISS [R2=0.85]). The scores were identical on 756 days (55.6%) and differed by < or = 3 TISS points on an additional 387 (28.2%) days. Interreliability assessment suggested substantial agreement (kappa statistic=0.71). The discriminatory power of the computerized score to identify different levels of ICU resource use was excellent as assessed by area under the receiver operating characteristics curves at four threshold points (0.91, 0.87, 0.89, and 0.88). Performance of the computerized score was similar across medical, coronary, and surgical ICU patient groups. CONCLUSION: An automated algorithm can reproduce valid TISS scores from standard hospital billing data, allowing comparison of patients and groups of patients in order to better understand ICU resource use.

Accounting

Development of a clinical chart to compute different disease activity indices for systemic lupus erythematosus.

Between 1990 and 1995 a European Consensus Group carried out a multicenter study to reach agreement of the definition of disease activity in systemic lupus erythematosus (SLE). A new index, the European Consensus Lupus Activity Measurement (ECLAM) index, was developed. In a second phase of the study, a prospective survey aimed at validating ECLAM and 4 other scales as steady-state and transition indices for disease activity in SLE was completed. We present the results of this survey. A standardized clinical chart was developed, together with a computer program that could automatically calculate the ECLAM score, as well as the scores for some of the disease activity scales most widely used at present, i.e., the British Isles Lupus Assessment Group, Systemic Lupus Activity Measure, SLE Disease Activity Index, and the SLE Index Score (SIS). With the participation of 28 centers in 15 different European countries, data from 121 prospectively selected new lupus patients were collected. The validity of the 5 activity scales was assessed by comparing the computed scores for each patient to a gold standard, i.e., the physician's subjective judgment on disease activity measured using a semiquantitative scale. All the indices were found to be valid instruments for measuring disease activity in SLE in both the steady-state and transition phases. The results for the various indices closely correlated with one another. Thus, the computerized chart developed by the European Consensus Group offers a simple and reliable instrument to assess disease activity and could be used to monitor lupus patients both in clinical practice and in clinical trials.

Computer Simulation

A performance evaluation of the expert system ANEMIA.

This paper reports the results of an evaluation study of the current level of performance given by ANEMIA, a knowledge-based consultation system addressing the clinical problem of managing anemic patients. ANEMIA was developed on a mainframe using the AI programming scheme EXPERT and then translated into a version running on a personal computer. At present the system is able to provide assistance in the diagnosis and management of 65 disease entities. After extensive local testing of accuracy, completeness, and consistency of the knowledge base included into ANEMIA, we designed a study to evaluate whether the system is able to appropriately mirror also the reasoning of well-known hematologists other than those who provided the knowledge. We were also interested in testing whether there were conflicting opinions among hematologists. Thus, we designed a validation study in which ANEMIA's performance could be compared with that of six hematologists and the interexpert consensus evaluated. ANEMIA's overall performance was judged acceptable in 87% (26/30) of the cases, while expert evaluators agreed with their colleagues in 90% (27/30) of them. A low interexpert consensus was found: considering the ratings given by different hematologists to the same ANEMIA performance, complete agreement occurred only 47% of the time.

Adult

Bioassay from two parabolas.

The paper deals with potency ratio estimation of parallel curve analytic dilution assays in case log dose-response relationship could be reasonably described by a parabola. It comprises: (1) testing the adequacy and validity of the quadratic model by the analysis of variance; and (2) estimation of the relative potency of an unknown in relation to a standard preparation, its standard deviation and fiducial limits for its true value. The method is applicable whenever successive doses of an unknown are a constant multiple of a standard in randomized blocks or completely randomized design. The method can be generalized to polynomial models of higher order.

Analysis of Variance

GeneGenerator--a flexible algorithm for gene prediction and its application to maize sequences.

MOTIVATION: We developed GeneGenerator because of the need for a tool to predict gene structure without knowing in advance how to score potential exons and introns in order to obtain the best results, pertinent in particular to less well-studied organisms for which suitable training sets are small. GeneGenerator is a very flexible algorithm which for a given genomic sequence generates a number of feasible gene structures satisfying user-defined constraints. The specific implementation described in detail requires minimum scoring for translation start and donor and acceptor splice sites according to previously trained logitlinear models. In addition, potential exons and introns are required to exceed specified minimal lengths and threshold scores for coding or non-coding potential derived as log-likelihood ratios of appropriate Markov sequence models. RESULTS: A database of 46 non-redundant genomic sequences from maize is used for illustration. It is shown that the correct gene structures do not always maximize the considered target function. However, in most cases, the correct or nearly correct structures are found in a small set of high-scoring structures. A critical review of the generated structures sometimes allows the choices to be narrowed by considering additional variables such as predicted splice site strength or local optimality of splice site scores. Summary statistics for prediction accuracy over all 46 maize genes are derived under cross-validation and non-cross-validation training conditions for the Markov sequence models. The algorithm achieved exon sensitivity of 0.81 and specificity of 0.75 on an independent set of 14 novel maize genomic segments. AVAILABILITY: GeneGenerator runs under Borland-Pascal 7.0 using MS-DOS and C on UNIX work stations. The source code is available upon request. CONTACT: jkleffe@euler.grumed.fu-berlin-de

Algorithms