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At least 487 records · Page 27Linked to original sources
PubMed1992

Accuracy of investment risk models varies.

Financial analysis of proposed capital investments must include an assessment of risk as well as return. Four assessment techniques can be used to provide insight into the risk inherent in any capital investment project: breakeven analysis, sensitivity analysis, scenario analysis, and Monte Carlo simulation. The most complete picture of a project's stand-alone risk is provided by a Monte Carlo simulation, which generates a profitability probability distribution. The primary concern of most hospital decision makers, however, is the amount of risk the capital investment adds to the riskiness of the hospital in the aggregate.

Capital Expenditures↗
PubMed2002

Cost-effectiveness analyses in obstetrics & gynecology. Evaluation of methodologic quality and trends.

OBJECTIVE: To evaluate methodologic quality and trends of cost-effectiveness analyses (CEAs) published in Obstetrics & Gynecology. STUDY DESIGN: Ten methodologic principles that should be incorporated in CEAs are used to evaluate CEAs published in Obstetrics & Gynecology from 1966 through 1999. We included articles that were cost-effectiveness or cost-benefit analyses or performed such analyses as part of their studies. RESULTS: Thirty-four CEAs met our inclusion criteria. Seven (20%) analyses adhered to 10, five (15%) to 9, and two (6%) to 8 of the 10 methodologic principles. The mean (+/- SD, median) number of principles to which studies adhered was 5.7 (+/- 3.3, 4). Studies had high compliance (> or = 85%) with principles of research questions, probabilities and effectiveness measures. Studies significantly improved over time in adherence to principles of time frame, perspective, costs, incremental analysis, sensitivity analysis, discounting and total score (all P < .05). CONCLUSION: The CEAs evaluated adhered to approximately half the methodologic principles for performing CEAs but showed significant improvements in quality over time. Understanding the methodology of CEAs is critical for researchers, editors and readers to accurately interpret the results of the growing body of CEA studies.

Cost-Benefit Analysis↗
PubMed2002

Pharmacoeconomics.

Today, spiraling costs of medical care coupled with limited resources have led to an explosive increase in the number of pharmacoeconomic analyses being carried out. The first step in a pharmacoeconomic analysis is to measure the costs and benefits of the therapeutic regimens being compared. Then one compares these costs and benefits by calculating a cost: benefit ratio for each regimen. Four types of economic analyses are commonly used for this purpose. While cost minimization analysis ignores the benefits and focuses only on costs of treatment, cost-effectiveness analysis measures costs in monetary terms and benefits or outcome in their natural clinical units. Cost benefit analysis on the other hand, places monetary values on both-costs and outcome of therapy. Finally, cost utility analysis measures costs in monetary terms, and outcome in a single utility-based unit of measurement. Utility based measures like quality adjusted life-years (QALY) measure the contribution made by the regimens to the patient's quality of life. Finally study designs generally used for generating data for a pharmacoeconomic analysis are mentioned, and concepts like marginal analysis, sensitivity analysis and discounting are explained in the context of health economics.

Cost-Benefit Analysis↗
PubMed1989

[Construction of a decision tree for preoperative diagnosis in urinary incontinence].

In order to analyse the decisions used in non-urodynamic preoperative diagnosis of female urinary incontinence we constructed a decision tree, consisting of decision nodes and probability nodes. Each branch of the decision tree leads to an end point (terminal node), to which an utility must be assigned. We describe the different steps in the construction of the decision tree: 1. listing of all possible decisions (questionnaire, clinical stress test, both, no preoperative tests), 2. assignment of probabilities to the different events (e.g. cure, failure, operation in the absence of genuine stress incontinence), and 3. assignment of utility factors to the end points. We used previously published probabilities from our clinic, utility was assigned arbitrarily using a score from -10 to +90. The decision tress allows not only the calculation of the strategy with the highest expected utility, but also threshold analysis, sensitivity analysis and cost-benefit analysis. We feel that decision trees are valuable tools for analysing how medical decisions are reached and are particularly useful in teaching situations.

Adult↗
PubMed1985

Economic decisions in veterinary practice: a method for field use.

A technique is presented that allows economic decision analysis, sensitivity analysis, and threshold analysis to be done rapidly in field situations. The method allows the practitioner to choose between 2 interventions with different costs and different probabilities of success. A graphic approach is presented, which speeds and simplifies the analysis.

Animals↗
PubMedDate not supplied

Meta-analysis: an update.

A fairly new type of research, termed meta-analysis, attempts to analyze and combine the results of previous reports. In 1992 we updated our 1987 survey of 86 meta-analyses of randomized control trial reports in the english language literature with an additional 78. We evaluated the quality of these meta-analyses using a scoring method that lists 23 items in six major areas: study design, combinability, control of bias, statistical analysis, sensitivity analysis, and application of results. Of the 23 individual items, the mean number satisfactorily addressed was 7.63 +/- 2.84 (mean +/- S.D.) for 40 papers published from 1955 through 1982, 6.80 +/- 3.86 for 66 papers published from 1983 through 1986, and 11.91 +/- 4.79 for 58 papers published from 1987 through 1990 (F = 31.3, p < .001). We noted that methodology has definitely improved since our first survey of meta-analyses, but an urgent need still exists for a better search of the literature, quality evaluation of trials, and a synthesis of the results. Recently, meta-analysis has expanded to cover non-randomized studies, including evaluation of diagnostic tests and pooling of epidemiologic studies. There is growing concern for standards, and several methodologic issues remain unresolved.

Bias↗
PubMed1996

Risk analysis in the valuation of medical practices.

Risk analysis techniques used in valuing medical practices are discussed. Employing these techniques provides superior information to the analyst than using a single estimate for uncertain variables. Examples of scenario analysis, sensitivity analysis, and simulation are presented. These tools can be easily implemented with spreadsheet software.

Computer Simulation↗
PubMed2003

Entering the black box of neural networks.

OBJECTIVES: Artificial neural networks have proved to be accurate predictive instruments in several medical domains, but have been criticized for failing to specify the information upon which their predictions are based. We used methods of relevance analysis and sensitivity analysis to determine the most important predictor variables for a validated neural network for community-acquired pneumonia. METHODS: We studied a feed-forward, back-propagation neural network trained to predict pneumonia among patients presenting to an emergency department with fever or respiratory complaints. We used the methods of full retraining, weight elimination, constant substitution, linear substitution, and data permutation to identify a consensus set of important demographic, symptom, sign, and comorbidity predictors that influenced network output for pneumonia. We compared predictors identified by these methods to those identified by a weight propagation analysis based on the matrices of the network, and by logistic regression. RESULTS: Predictors identified by these methods were clinically plausible, and were concordant with those identified by weight analysis, and by logistic regression using the same data. The methods were highly correlated in network error, and led to variable sets with errors below bootstrap 95% confidence intervals for networks with similar numbers of inputs. Scores for variable relevance tended to be higher with methods that precluded network retraining (weight elimination) or that permuted variable values (data permutation), compared with methods that permitted retraining (full retraining) or that approximated its effects (constant and linear substitution). CONCLUSION: Methods of relevance analysis and sensitivity analysis are useful for identifying important predictor variables used by artificial neural networks.

Algorithms↗
PubMed2005

New hyphenated methodologies in high-sensitivity glycoprotein analysis.

High-sensitivity glycoprotein analyses are of particular interest in modern biomedical and clinical research, as well as in the development of recombinant protein products. The evolution of new hyphenated methodologies in high-sensitivity glycoprotein analysis is highlighted in this thematic review. These methodologies include, in particular, capillary LC/MALDI/TOF/TOF MS in conjunction with online permethylation platform, and silica-based lectin microcolumns interfaced to MS. The potential of these methodologies in glycomic and glycoproteomic analysis is demonstrated for model glycoproteins as well as total glycomes and glycoproteomes derived from biological samples. Additionally, the applications of CE-MS, CEC, and nanoLC with graphitized carbon in the areas of glycomics and glycoproteomics are described.

Chromatography, Ion Exchange↗
PubMed2003

Global analysis of ligand sensitivity of estrogen inducible and suppressible genes in MCF7/BUS breast cancer cells by DNA microarray.

To obtain comprehensive information on 17beta-estradiol (E2) sensitivity of genes that are inducible or suppressible by this hormone, we designed a method that determines ligand sensitivities of large numbers of genes by using DNA microarray and a set of simple Perl computer scripts implementing the standard metric statistics. We used it to characterize effects of low (0-100 pM) concentrations of E2 on the transcriptome profile of MCF7/BUS human breast cancer cells, whose E2 dose-dependent growth curve saturated with 100 pM E2. Evaluation of changes in mRNA expression for all genes covered by the DNA microarray indicated that, at a very low concentration (10 pM), E2 suppressed approximately 3-5 times larger numbers of genes than it induced, whereas at higher concentrations (30-100 pM) it induced approximately 1.5-2 times more genes than it suppressed. Using clearly defined statistical criteria, E2-inducible genes were categorized into several classes based on their E2 sensitivities. This approach of hormone sensitivity analysis revealed that expression of two previously reported E2-inducible autocrine growth factors, transforming growth factor alpha and stromal cell-derived factor 1, was not affected by 100 pM and lower concentrations of E2 but strongly enhanced by 10 nM E2, which was far higher than the concentration that saturated the E2 dose-dependent growth curve of MCF7/BUS cells. These observations suggested that biological actions of E2 are derived from expression of multiple genes whose E2 sensitivities differ significantly and, hence, depend on the E2 concentration, especially when it is lower than the saturating level, emphasizing the importance of characterizing the ligand dose-dependent aspects of E2 actions.

Breast Neoplasms↗
PubMed2003

[The analysis of the sensitivity and the specificity of the mass screening system of BSE].

Since the first infected case of BSE(Bovine Spongiform Encephalopathy) was identified in September, 2001 in Japan, Japanese people have been deeply concerned about safety of meat despite a mass screening system established by Japanese government. In the system all the cows for food must be examined with ELISA as screening and additionally with more accurate tests such as western blot etc. if the screened result is positive. To investigate the accuracy of the system, we calculated the number of false negatives and positives using computer simulation. Consequently, the sensitivity analysis towards ELISA showed that even if Japanese cattle were in a low risk group, a few of them are likely to be misdiagnosed as "negative" in spite of true BSE under the current screening system. Also we indicated how to improve the current system to get less false negatives. We believe the analysis of this study can contribute to risk communication with people to minimize the fear or irrationality caused by BSE epidemic.

Animals↗
PubMed1989

[A simulation model for the spread of AIDS and an analysis of its sensitivity].

The author describes the basic module of simulation models of the spread of AIDS created according to the principles of the general method of multicompartmental models. In the model are distinguished susceptible persons infected persons who do not yet transmit the infection, infected and infecting persons those with clinical symptoms of AIDS, and those who died from AIDS. The basic module was already used for the creation of a simulation model of the spread of AIDS in the community of homo- and bisexuals differentiating them as to their level of sexual promiscuity. The model makes it also possible to study the influence of changes in sexual behaviour and practices as a result of health education etc. The sensitivity analysis of this model indicates that only by very rapid and marked changes in sexual behaviour and practices it will be possible to achieve a substantial reduction of the impact of the AIDS epidemic.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Systematic screening for Chlamydia trachomatis: estimating cost-effectiveness using dynamic modeling and Dutch data.

OBJECTIVE: To estimate the cost-effectiveness of a systematic one-off Chlamydia trachomatis (CT) screening program including partner treatment for Dutch young adults. METHODS: Data on infection prevalence, participation rates, and sexual behavior were obtained from a large pilot study conducted in The Netherlands. Opposite to almost all previous economic evaluations of CT screening, we developed a dynamic Susceptible-Infected-Susceptible (SIS) model to estimate the impact of the screening program on the incidence and prevalence of CT in the population. SIS models are widely used in epidemiology of infectious diseases, for modeling the transmission dynamics over time. Subsequently, a predictive decision model was used to calculate the complications averted by the screening program. Cost-effectiveness was expressed as the net costs per major outcome averted (MOA) and was estimated in the baseline analysis and in sensitivity analysis. RESULTS: The overall prevalence decreased from 1.79% to 1.05% as a result of the screening program directed at both men and women. The program costs were mainly offset by the averted costs, although not fully. Resulting net costs per MOA were 373 euro sin the baseline analysis. Sensitivity analysis showed that partner treatment and sending a reminder are important aspects improving cost-effectiveness. Additionally, restricting the screening to women only was estimated to save costs. CONCLUSIONS: Our cost-effectiveness analysis shows that the Dutch society has net to pay for the prevention of CT-complications through screening young men and women. One could argue although that 373 euros per MOA presents a reasonable cost. A screening program consisting of screening women only should always be adopted from a pharmacoeconomic point of view. Our dynamic approach appreciates better the specific characteristics of an infectious disease, such as CT.

Adult↗
PubMed1992

Decision analysis as a quality-assurance screening tool.

BACKGROUND: The purpose of this pilot study was to examine whether the technique of decision analysis, including sensitivity analysis, could be used in a clinical quality-assurance program. METHODS: This research was performed in a family practice residency clinical practice. A computerized decision analysis model was developed for selection of initial drug therapy for hypertension. The medical records of 52 resident-managed patients with hypertension were then reviewed. The residents' drug prescribing was evaluated by faculty reviewers and also by the decision analysis model, including a sensitivity analysis. RESULTS: Faculty reviewers rated the residents' drug choices as "most appropriate" or "acceptable" in 59.6% of cases. There was good agreement between faculty reviewers and the computerized decision analysis model. For example, in those cases in which the resident chose the computer model's first-choice drug, faculty deemed the management as "most appropriate" or "acceptable" 93.3% of the time. When residents selected the computer model's third or fourth choice, faculty judged the residents' therapy as "inappropriate" or "an alternate drug would have been more desirable" in 61.9% of cases. CONCLUSION: The results suggest that computerized decision analysis techniques may be a useful adjunct to other clinical quality-assurance procedures in residency training programs.

Adult↗
PubMed2006

Comparative study of parameter sensitivity analyses of the TCR-activated Erk-MAPK signalling pathway.

Parameter estimation is a major challenge for mathematical modelling of biological systems. Given the uncertainties associated with model parameters, it is important to understand how sensitive the model output is to variations in parameter values. A local sensitivity analysis determines the model sensitivity to parameter variations over a localised region around the nominal parameter values, whereas a global sensitivity analysis (GSA) investigates the sensitivity over the entire parameter space. Using a T-cell receptor-activated Erk-MAPK signalling pathway model as an example, the authors present a comparative study of a variety of different sensitivity analysis techniques. These techniques include: local sensitivity analysis, existing GSA methods of partial rank correlation coefficient, Sobol's, extended Fourier amplitude sensitivity test, as well as a weighted average of local sensitivities and a new GSA method to extract global parameter sensitivities from a parameter identification routine. Results of this study revealed critical reactions in the signalling pathway and their impact on the signalling dynamics and provided insights into embedded regulatory mechanisms such as feedback loops in the pathway. From this study, a recommendation emerges for a general sensitivity analysis strategy to efficiently and reliably infer quantitative, dynamic as well as topological properties from systems biology models.

Algorithms↗
PubMed1979

Keratoplasty sensitivity.

Analysis of graft sensitivity showed a return to normal after 3 years in only one-third of the eyes. It is not known whether this is due to regeneration of abnormal or superficial nerve fibres. Contact lens wearers showed less sensitivity than spectacle wearers.

Contact Lenses↗
PubMed2006

Preventing sudden death with n-3 (omega-3) fatty acids and defibrillators.

BACKGROUND: Because interventions that prevent and treat events due to cardiovascular disease are applied to different, but overlapping, segments of the population, it can be difficult to estimate their effectiveness if formal calculations are not available. METHODS: Markov chain analysis, including sensitivity analysis, was used with a hypothetical population resembling that of Olmsted County, MN, aged 30 to 84 in the year 2000 to compare the estimated impact of three interventions to prevent sudden death: (1) raising blood levels of n-3 (omega-3) fatty acids, (2) distributing automated external defibrillators (AEDs), and (3) implanting cardioverter defibrillators (ICDs) in appropriate candidates. The analysis was performed in 2004, 2005, and 2006. RESULTS: Raising median n-3 fatty acid levels would be expected to lower total mortality by 6.4% (range from sensitivity analysis = 1.6% to 10.3%). Distributing AEDs would be expected to lower total mortality by 0.8% (0.2% to 1.3%), and implanting ICDs would be expected to lower total mortality by 3.3% (0.6% to 8.7%). Three fourths of the reduction in total mortality due to n-3 fatty acid augmentation would accrue from raising n-3 fatty acid levels in the healthy population. CONCLUSIONS: Based on central values of candidacy and efficacy, raising n-3 fatty acid levels would have about eight times the impact of distributing AEDs and two times the impact of implanting ICDs. Raising n-3 fatty acid levels would also reduce rates of sudden death among the subpopulation that does not qualify for ICDs.

Adult↗
PubMed1996

[Medical and economic evaluation of donated blood screening for hepatitis C and non-A, non-B, non-C hepatitis].

The aim of this study was to evaluate the cost of hepatitis C and non-A non-B non-C screening strategy in donated blood, currently used in French transfusion centres and to assess the effect in the blood transfusion centres according to the prevalence of the disease and the intrinsec values of tests. This screening strategy was based on alanine aminotransferase assay, and HBc and HCV antibodies detection. In 1993, a survey was conducted in 26 French transfusion centers to estimate the costs of the screening strategy currently used. Average expenditure on diagnostic sets, equipment, staff and administration charges for hepatitis C and non-A non-B non-C screening were calculated. From these results, we estimated the cost of the previous strategy which did not involve HCV antibody testing, so as to determine the incremental cost between the two strategies. We used clinical decision analysis and sensitivity analysis to estimate the incremental cost-effectiveness ratio with data gathered from the literature and examine the impact on blood transfusion centre. Implemented for 100,000 volunteer blood donations, the incremental cost of the new strategy was FF 2,566,111 (1992) and the marginal effectiveness was 180 additional infected donations detected. The sensitivity analysis showed the major influence of infection prevalence in donated blood on the incremental cost-effectiveness ratio: the lower the prevalence, the higher the cost-effectiveness ratio per contaminated blood product avoided.

Adult↗