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PubMed2003

Classification and regression tree analysis in public health: methodological review and comparison with logistic regression.

BACKGROUND: Audience segmentation strategies are of increasing interest to public health professionals who wish to identify easily defined, mutually exclusive population subgroups whose members share similar characteristics that help determine participation in a health-related behavior as a basis for targeted interventions. Classification and regression tree (C&RT) analysis is a nonparametric decision tree methodology that has the ability to efficiently segment populations into meaningful subgroups. However, it is not commonly used in public health. PURPOSE: This study provides a methodological overview of C&RT analysis for persons unfamiliar with the procedure. METHODS AND RESULTS: An example of a C&RT analysis is provided and interpretation of results is discussed. Results are validated with those obtained from a logistic regression model that was created to replicate the C&RT findings. Results obtained from the example C&RT analysis are also compared to those obtained from a common approach to logistic regression, the stepwise selection procedure. Issues to consider when deciding whether to use C&RT are discussed, and situations in which C&RT may and may not be beneficial are described. CONCLUSIONS: C&RT is a promising research tool for the identification of at-risk populations in public health research and outreach.

Decision Trees↗
PubMed1987

The relationship between antidepressant response and tricyclic antidepressant plasma concentrations. A retrospective analysis of the literature using logistic regression analysis.

The relationship between the antidepressant effect of the tricyclic antidepressants and their plasma concentrations was reviewed. Logistic regression was utilised as an analytical tool to facilitate the evaluation. The currently available literature allowed the construction of 4 tricyclic data sets of sufficient size to warrant statistical analysis. Inspection of the distribution of the data and the logistic regression analyses resulted in several conclusions regarding the existence of 'therapeutic windows' for these drugs. Firstly, no relationship between amitriptyline plasma concentrations and therapeutic response was apparent. Secondly, curvilinear relationships were apparent for 2 of the other tricyclic antidepressants studied. The currently recommended therapeutic range of 60 to 150 micrograms/L for nortriptyline was found to be the range most likely to produce a positive antidepressant effect. Desipramine concentrations between 108 and 158 micrograms/L were most commonly associated with beneficial therapeutic responses. Finally, a linear relationship was noted for imipramine in which an imipramine therapeutic plasma concentration threshold of 244 micrograms/L and above was most commonly associated with a beneficial response to the drug.

Animals↗
PubMedDate not supplied

An application of a microcomputer compiler program to multiple logistic regression analysis.

Microcomputer programs for multiple logistic regression analysis were written in BASIC language to determine the usefulness of microcomputers for multivariate analysis, which is an important method in epidemiological studies. The program, carried out by an interpreter system, required a comparatively long computing time for a small amount of data. For example, it took approximately thirty minutes to compute the data of 6 independent variables and 63 matched sets of case and controls (1:4). The majority of the calculation time was spent computing a matrix. The matrix computation time increased cumulatively in proportion to additions in the number of subjects, and increased exponentially with the number of variables. A BASIC compiler was utilized for the program of multiple logistic regression analysis. The compiled program carried out the same computations as above, but within 4 minutes. Therefore, it is evident that a compiler can be an extremely convenient tool for computing multivariate analysis. The two programs produced here were also easily linked with spreadsheet packages to enter data.

Computers↗
PubMed2002

Early and late recurrences after gastrectomy for gastric cancer: a multiple logistic regression analysis.

PURPOSE: Although many studies have focused on clinical risk factors for prognosis of patients with surgically treated gastric cancer, little information is available regarding the timing of recurrent malignant disease. The purpose of this study was to determine the factors that are predictive of early and late recurrences after gastrectomy. PATIENTS AND METHODS: We reviewed the hospital records of patients with hisotological proof of gastric cancer who were admitted to Sendai National Hospital during the period from 1985 to 1995. A total of 923 records were examined, and 251 patients with recurrent disease were identified. The patients were divided into an "early recurrence group" consisting of 195 patients (died within one year after surgery) and a "late recurrence group" of 56 patients (died two years or more after surgery). Clinicopathological characteristics were examined, and independent risk factors influencing the timing of recurrence were determined by a multiple logistic regression analysis. RESULTS: The mean tumor size of early recurrence cases was larger than that of late recurrence cases (p=0.0294). Tumors penetrating the serosa with direct invasion to continuous structures were found more frequently in the early recurrence group than in the late recurrence group. The patients with early recurrence showed a higher tendency to have nodal involvement, lymphatic invasion and vascular invasion. The relative risks of early and late recurrences associated with different variables were estimated by a multiple logistic regression method. The following variables were found to be significant risk factors for early recurrence: male gender (p=0.0382), lymph node metastasis (p=0.0016), and vascular invasion (p=0.0006). CONCLUSION: Male patients who have node-positive gastric cancer with vascular invasion have a high risk of early recurrence.

Female↗
PubMedDate not supplied

Benchmark matrix and guide: Part I. Headquarters Air Force Logistics Command, Wright-Patterson Air Force Base, OH.

The President's Award for Quality and Productivity Improvement is the highest recognition of improvements in quality and productivity in the federal government and is equivalent to the Malcolm Baldrige Award. It is awarded to agencies, or major components of agencies, that have implemented total quality management (TQM) in an exemplary manner resulting in high quality products and services, and effective use of taxpayers' dollars. On May 23, 1991, Headquarters Air Force Logistics Command at Wright-Patterson Air Force Base was notified that it had won this prestigious award. This first article of a three-part series was authored by a special working group within Headquarters Air Force Logistics Command that was tasked with developing a benchmarking system to measure progress in implementing total quality management (TQM). The tasking was in support of the near-term vision initiative to develop a guideline pamphlet for measurement. This benchmark matrix should be used periodically to identify those categories that need additional emphasis, but it should be seen as a self-assessment tool only. The intent was to provide a method of measuring behaviorally oriented activity that can be documented or observed. Real process improvement can begin only when a process cna be understood and measured. Benchmarking is a viable means to do this and should be used in combination with other TQM methodology.

Outcome and Process Assessment, Health Care↗
PubMed2001

[Multivariate logistic regression analysis on the risk factors of type 2 diabetes mellitus].

OBJECTIVE: To explore the relationship between multivariate factors and type 2 diabetes mellitus. METHODS: Polymorphisms of microsatellite markers in uncoupling protein 3 (UCP3) gene, hormone-sensitive lipase (HSL) gene and protein tyrosine phosphatase-1B (PTP-1B) gene were tested in 106 patients with type 2 diabetes and 102 control subjects by performing polymerase chain reaction (PCR), polyacrylamide gel electrophoresis and silver staining. Multivariate logistic regression analysis was performed by all factors. RESULTS: Through univariate analysis, type 2 diabetes had significantly positive associations with age, systolic blood pressure (SBP), fasting insulin (FINS) level, cholesterol, triglyceride, low-density lipoprotein, apolipoprotein B (ApoB), alpha lipoprotein, UCP3 gene allele 6, UCP3 gene allele 7, HSL gene allele 9, and negative associations with UCP3 gene allele 1 and 3, HSL gene allele 5, high-density lipoprotein. The results of multivariate logistic analysis showed that UCP3 gene allele 6, UCP3 gene allele 7, SBP, ApoB, alpha lipoprotein were still positively related to type 2 diabetes, while HSL gene allele 5, high-density lipoprotein were still negatively related to type 2 diabetes. CONCLUSION: Our data showed that UCP3 gene allele 6, UCP3 gene allele 7, SBP, abnormity of plasma ApoB and alpha lipoprotein might play a role in the development of type 2 diabetes. HSL gene allele 5, high-density lipoprotein might play some protective role in the development of type 2 diabetes.

Blood Pressure↗
PubMed2002

Constrained four parameter logistic model.

The constrained four parameter logistic model has found wide application in describing dose response relationships across many assay systems. This discussion examines the basic model and its practical application to potency testing in the context of the 96 well plate. A two step procedure is recommended for the analysis: (i) the constrained logistic model to generate potency estimates, (ii) a linear mixed-effects model to account for within-plate and between plate variability for producing the final combined estimate of potency. The method is outlined in a case study. Design issues related to possible location effects on the plate may be ameliorated by use of a Latin square design.

Biological Assay↗
PubMed2002

Predicting amphipod toxicity from sediment chemistry using logistic regression models.

Individual chemical logistic regression models were developed for 37 chemicals of potential concern in contaminated sediments to predict the probability of toxicity, based on the standard 10-d survival test for the marine amphipods Ampelisca abdita and Rhepoxynius abronius. These models were derived from a large database of matching sediment chemistry and toxicity data, which includes contaminant gradients from a variety of habitats in coastal North America. Chemical concentrations corresponding to a 20, 50, and 80% probability of observing sediment toxicity (T20, T50, and T80 values) were calculated to illustrate the potential for deriving application-specific sediment effect concentrations and to provide probability ranges for evaluating the reliability of the models. The individual chemical regression models were combined into a single model, using either the maximum (P(Max) model) or average (P(Avg) model) probability predicted from the chemicals analyzed in a sample, to estimate the probability of toxicity for a sample. The average predicted probability of toxicity (from the P(Max) model) within probability quartiles closely matched the incidence of toxicity within the same ranges, demonstrating the overall reliability of the P(Max) model for the database that was used to derive the model. The magnitude of the toxic effect (decreased survival) in the amphipod test increased as the predicted probability of toxicity increased. Users have a number of options for applying the logistic models, including estimating the probability of observing acute toxicity to estuarine and marine amphipods in 10-d toxicity tests at any given chemical concentration or estimating the chemical concentrations that correspond to specific probabilities of observing sediment toxicity.

Amphipoda↗
PubMed2003

[Improvement of the logistical organization of ambulatory care for cancer patients].

Development and successful use of new logistical know-how provide means of improving the standards of oncological service. It is a particularly urgent problem at the grass roots level, yet it has not been appreciated to the full. A possible solution may be deployment of outpatient oncological departments within the framework of polyclinics which will en sure that the available diagnostic and therapeutic facilities are used more effectively. Such an arrangement will provide expertise and logistics standards inaccessible for a consulting oncologist. According to a five-year survey of the performance of an outpatient oncological department at a municipal polyclinic in a Mid-Urals town, more cancer patients have been given better medical service due to use of earlier and faster diagnostic procedures.

Ambulatory Care↗
PubMed1992

[Anti-C100-3 antibody titration using 4-parameter logistic curve (results in its application to hepatitis C cases treated with interferon].

We evaluated titers of C100-3 antibody by ELISA using a 4-parameter logistic fitting curve and examined the transition of the values in the cases of interferon treatment. The 4-parameter logistic fitting curve produced a standard curve in a wider range using a micro plate reader than the logarithmic curve. The values of C100-3 antibody during and after the treatments of interferon were changed in parallel with the alterations of ALT. The anti-C100-3 antibody titers assayed in the complete or partial responders were significantly reduced at the end of interferon therapy. These findings suggest the clinical usefulness of the evaluation of anti C100-3 antibody titers.

Antigens, Viral↗
PubMedDate not supplied

[The logistics of population health protection].

The health protection of population is a subsystem of a macrosystem, i.e. of social sphere. The social sphere, in its turn, is a logistic macrosystem, therefore, the logistical principles can be applied to its subsystems. The system of population health protection is regarded from such standpoint in the paper; the dynamics of human resources are described in detail including an independent author's classification of it. A scheme is presented of how to manage the human resources evolution; effects exerted by the subsystem through the infrastructure on human resources are elucidated.

Health Services Administration↗
PubMed1991

Chemical-biological warfare: medical logistics and defense.

In this article, the authors discuss some of the hard realities of chemical and biological warfare defense in terms of the medical and medical logistics implications. In the opinion of the authors, there are no adequate defensive measures at present which would protect troops and sailors from the effects of either chemical or biological warfare tactics. An overview of the current world situation is presented, as well as some of the clinical and logistical responses to chem-bio war. The effectiveness of vaccinations or other medical approaches to protecting service members from chem-bio attacks is questioned in light of the technology and of the unpredictability in guessing the agent's strain or nature (e.g. viral, bacterial, or chemical). An analysis of Mission Oriented Protective Posture gear, gas masks, and other potential external protection devices reveals them to be inadequate, impractical, or expensive. In short, whether facing known war arsenals or unknown terrorist possibilities, the armed forces of the United States when meeting chemical or biological agents will be hard-pressed to protect and heal themselves, much less the nation's civilian population.

Biological Warfare↗
PubMed1991

Basic logistical considerations for rapid medical deployment.

Fixed wing aircraft are the primary means of deployment for designated U.S. contingency forces. The majority of logistical constraints medical units encounter during deployment (in support of contingency forces) are a direct result of limited airframes dedicated to their movement into an area of operations. The competition is intense for these air assets, and gaining access to airframes by medical support units will be predicated on a number of factors: the units' medical and logistical capabilities; their ability to respond to deployment notification within determined time constraints; the units' ability to configure to air movement; and the medical impact the units will have on the initial efforts of a military campaign once they are operational.

Aviation↗
PubMed1989

Generalized likelihood ratio concept and logistic regression analysis for multiple diagnostic categories.

Albert (Clin Chem 1982;28:1113-9) has proposed estimation of likelihood ratios by logistic regression analysis. The usual likelihood-ratio approach for estimation of post-test probability of disease from sensitivity and specificity data of a diagnostic test has been extended by Birkett (J Clin Epidemiol 1988; 41:491-4) for situations with more than two diagnostic categories. We suggest here a combination of these ideas, demonstrating this by a re-evaluation of previously published data on the validity of neopterin as a tool for differential diagnosis between chronic non-A, non-B hepatitis and fatty liver. Analysis of neopterin data in combination with the ratio between serum concentrations of aspartate aminotransferase and of alanine aminotransferase yielded a good discrimination between three mutually exclusive diagnostic categories, namely, fatty liver and chronic persistent and chronic aggressive non-A, non-B hepatitis. The approach is flexibly applicable to situations with different pre-test probabilities. The sum of estimated post-test probabilities deviates slightly from the sum of pre-test probabilities. This deviation is a function of the coefficients obtained in logistic regression, and an analytical expression for the deviation is given. The generalized likelihood-ratio approach appears promising in complex diagnostic situations when multiple diagnostic tests are available.

Alanine Transaminase↗
PubMed1989

[Analysis of conditional logistic regression for risk factors of lung cancer in Dachang Tin Mine].

An increased risk of lung cancer in Dachang Tin Mine of Guangxi has been reported. To investigate the factors of the excessive risk of lung cancer, the authors conducted a matched pair case-control study in the mine area and analysed the effect of multiple factors, such as condition of living and housing, occupational exposure and smoking by statistical method of conditional logistic regression. The patients group consisted of 69 patients with primary bronchogenic cancer including 55 deceased. The control group consisted of 138 persons also including 55 deceased. The results showed that the factors of the excessive risk of lung cancer in the mine area were mainly related to the occupational exposure. The risk factors with statistical significance in conditional logistic regression analysis were exposure time of smelting, time of underground drilling, and age of beginning mining underground. In the study model of all cases matched against living controls, daily number of cigarette also was a risk factor besides the above three factors. Furthermore, there was a synergic action among the factors. The relationship between the risk factors and lung cancer is discussed.

Humans↗
PubMed1989

Logistic regression analysis of risk factors for intra-amniotic infection.

The identification of risk factors for intra-amniotic infection may allow changes in obstetric management and reduce complications. In a pilot study, stepwise logistic regression identified duration of ruptured membranes and duration of interval monitoring as significant risk factors for intra-amniotic infection. Using the preliminary regression equation, we established critical durations (risk criteria) to predict a 20% or greater probability of intra-amniotic infection. Subsequently, 2908 patients were screened prospectively for risk criteria and/or the presence of intra-amniotic infection. Seven hundred five patients of the 2908 (24%) met the risk criteria, and 107 of 124 cases of intra-amniotic infection (86%) met the risk criteria. In patients meeting the risk criteria, the relative risk of intra-amniotic infection was 19.7. In addition, 81 of 705 (12%) of mothers developed endometritis. Ten neonates of mothers with criteria developed sepsis or pneumonia. A stepwise logistic regression performed on the prospectively gathered data showed that among patients meeting risk criteria, parity, duration of internal monitoring, and duration of membrane rupture were the significant risk factors for intra-amniotic infection.

Adult↗
PubMed1988

[Application of logistic curve fitting to cell-mediated cytotoxicity tests].

Blood mononuclear cells from 6 healthy adults were examined for LAK activity against 16 cell lines derived from human malignant tumors. The cytotoxicity curves obtained from a linear plot of the log of E/T ratio versus the percentage of the target cells killed were found to well fit the logistic curves. As the logistic distribution is known to approximate to the normal distribution, and the K/2 value is the function value for the representative, the K/2 value is reasonably selected as the % lysis value for the lytic unit calculation. Values of the three parameters, K as the maximum cytotoxicity, A as the scale parameter and B as the shape parameter, were analyzed using the experimental data. Eleven targets had three or more significantly fitted curves. Six among them were selected as highly sensitive cell lines to LAK activity, because the average values for K were higher than 80% (coefficients of variation were from 0.02 to 0.11) and analyzed further. The average values for B were relatively constant (range: 1.09-1.56) and the average values for A varied from 3.5 to 20.3 (conefficients of variation were from 0.26 to 0.71). The shape of the curves were nearly the same. These results indicate that the 6 cell lines are useful as the targets for the LAK activity.

Cytotoxicity Tests, Immunologic↗
PubMed1988

The use of multiple logistic function to predict surgical risk.

A method for preoperative assessment of surgical risk, in function of several risk factors, was developed using the multiple logistic function, as a model of multivariate statistical analysis. This model has the advantage to express the two considered outcomes (perioperative complications and death) in numerical terms of probability. The data were obtained from 8630 consecutive patients admitted to 62 hospitals located in various regions of Italy. The patients were divided at random into two groups: group A (6040) was used to develop the method, and group B (2590) was used as control. The method is based on the role played by seven risk factors, that were shown to be significantly related to the two outcomes. These factors are age, systolic blood pressure, pathological changes of renal function, presence of concomitant diseases, estimated duration of surgical procedure, type (major or minor) and timing of surgery, (elective, delayed or emergency). The relative and independent role of each of these factors (beta) and the value of constant alpha were estimated by maximum likelihood method. The surgical risk is assessed by solving the multiple logistic equation, and multiplying the beta values by the corresponding individual coded values of the risk factors represented by the various x's. When the method was tested by applying the computed values of alpha and beta's to assess the outcomes in the control group, the predictions resulted highly accurate (r = 0.99). To simplify the calculation of surgical risk, in appendix a computer program in Basic, already predisposed to receive in code the individual values of x's, is reported.

Adolescent↗