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PubMed1980

Concept and implementation of a program for treatments and statistical or logical interrogations of a file: LOGIST.

LOGIST is a general program which can be used for the usual statistical interrogations and also for other basic operations such as a validity check, the transcoding and the listing of data essential to biomedicine and the human sciences. The objectives laid down for this program have enabled almost total transferability (using FORTRAN IV exclusively), simplicity in the interrogation language, clear presentation of results, reduction to a minimum of computer running time and working storage required and the facility for modification of program or addition of new sub-programs. All the possible statistical procedures have not been included yet but any such additions are quite simple. This program, despite its considerable size, can be satisfactorily used on a mini-computer. At present, it is installed on a Mitra 15 computer with a total memory capacity of 32 K words of 16 bits. Use with larger more powerful machines will increase its potential. Routine application to diverse problems (quality control of a file, transcoding, linking of data, etc....) is very satisfactory.

Computers↗
PubMed1984

The results of logistic analyses when the variables are highly correlated: an empirical example using diet and CHD incidence.

We provide an example which includes highly correlated variables in multivariate logistic analyses relating four nutrients to the incidence of coronary heart disease in 10 years for over 7000 men. Paradoxical results occur for both the inferences to be drawn and variable selection. Different models exist which show that any particular variable both is and is not related significantly to coronary heart disease incidence, and step-up and step-down variable selection algorithms provide drastically different results.

Coronary Disease↗
PubMed1984

Selection of neighborhood controls: logistics and fieldwork.

This paper describes the logistics and fieldwork involved in assembling 123 neighborhood controls for a case-control study investigating the relationship between cholecystectomy and right-side colon cancer. All neighborhood controls were matched pairwise to cases on sex, age at diagnosis (+/- years), and race. Eighty-six percent of the neighborhood controls were also matched on street of residence and the remaining 14% on census tract. Study subjects were contacted by mail and then interviewed by telephone with regard to their gastrointestinal surgical history. The mean number of necessary households contacted to obtain each control was nine. When data were stratified by age, the mean number of necessary households contacted increased with increasing age of the cases. Only 3.3% (35/1065) of the residents from these households refused complete participation in the telephone interview. The distribution of fieldwork activities by hours worked is also reported. Similar findings were observed for males and females. Neighborhood controls are a commonly used comparison series. Data from this report may be used to modify the general impression that assembling neighborhood controls can be a difficult task. We urge other investigators to report fieldwork activities used in identifying their control series. These data will be valuable in planning and budgeting case-control studies.

Aged↗
PubMed1987

Comparison of the logistic and Cox regression models when outcome is determined in all patients after a fixed period of time.

This paper presents an evaluation of the logistic and Cox regression models for a prospective study when the outcome is binary and is determined in all patients after a fixed period of time. The similarities and differences between the regression coefficients and test statistics are given for the two-sample case. Extension of results to the multivariate case and under product binomial sampling are discussed. The results are illustrated using data from a clinical trial designed to evaluate the effect of a lipid lowering drug on progression of coronary artery disease.

Coronary Disease↗
PubMed1995

An introduction to logistic regression with an application to the analysis of language recovery following a stroke.

The aim of a statistical model is to present a simplified representation of the underlying structure in a data set by separating systematic features from random variation. Sometimes the purpose of a statistical model is to provide a simple descriptive summary of the data and sometimes it is to use the data for comparative or inferential purposes. In practice, the specification of a statistical model requires a thorough understanding of the substantive area of application, an assessment of the validity of the assumptions of the model, and an evaluation of the fit of the model to the data. In this paper, as an illustration of these aspects of the statistical modeling of data, we consider the specification, application, and interpretation of a logistic regression model for the investigation of relationships between binary response data and a collection of explanatory variables. We illustrate applications of the methodology using data from a prospective study of spontaneous language recovery following a stroke (Holland, Greenhouse, Fromm, & Swindell, 1989).

Brain↗
PubMed1995

Multiple estimation of concentrations in immunoassay using logistic models.

Immunoassay techniques yield estimates of concentrations of analytes based on comparison to known concentrations of a reference solution. The use of the nonlinear logistic model makes the error estimates and confidence levels approximate. When the goal of such a study is estimation of several unknowns, methods in common usage do not account for 'simultaneous' inference, i.e. the repeated use of the standard curve for estimating several concentrations. Alternative methods are described which take multiple use of the reference curve into account. Simulations using normally distributed data with variance proportional to a power of the mean compare different methods of obtaining calibration intervals and illustrate the approximate nature of all such techniques. Calibration intervals based on simple, commonly used methods do not provide the coverage promised, even for one-at-a-time estimation, and are not suited for multiple estimation and comparison.

Analysis of Variance↗
PubMed1988

Neuroendocrine aspects of primary endogenous depression. VII. Logistic regression analysis of matched patient-control hormone data for discrimination between groups.

We previously reported significant alterations in hypothalamo-pituitary-adrenal cortical (HPA) and thyroid (HPT) axis function in a group of 40 primary, RDC definite endogenous depressives compared to 40 individually matched normal control subjects. In those reports, univariate statistical tests for matched samples were used (paired t-tests). We next wished to use both the HPA and the HPT measures in a multivariate analysis to discriminate the patients from the controls, but the paired nature of the hormone data obviated the use of standard techniques. With an adaptation of the BMDP PLR statistical program, we performed a matched logistic regression analysis, in stepwise fashion, which resulted in a model incorporating two HPA variables and one HPT variable. From this model, odds ratios which associate being depressed or not with levels of the HPA and HPT measures were estimated. The median odds ratio for the 40 matched pairs was 7.8. To illustrate the model, we present graphs of estimated odds ratios of patients with selected hormone values compared to a typical normal subject with hormone values close to the median values of the 40 controls in our study.

Adult↗
PubMed1985

Survival probabilities of infants delivered prior to the 34th week of pregnancy as estimated by means of a logistic model.

Survival of 188 infants born alive before the 34th wk of pregnancy is assessed in relation both to birthweight and duration of pregnancy. A logistic model is used which describes, based on these parameters, probabilities of 1-yr survival of relatively small populations in a continuous way. Although there may be differences between measured and estimated birthweight, this method might enable the perinatologist to estimate before birth the survival probabilities if he knows the duration of pregnancy and estimated birthweight.

Birth Weight↗
PubMed1985

Intra- or extrauterine transport? Comparison of neonatal outcomes using a logistic model.

In a retrospective study a comparative analysis of mortality by way of transport (maternal, neonatal, or not referred) was performed on 163 liveborn newborns with a gestational age of less than 32 wk or a birth weight of less than 1500 g. The occurrence of potential mortality risk factors in the subgroups was taken into account. Of these, caesarean section, sex, Apgar score, intubation after delivery, birth weight and gestational age showed a relationship with mortality. Logistic regression analysis regarding the relationship between mortality and way of transport revealed that mortality in the neonatal transport group was significantly higher than in the maternal transport group, taking into account the confounding risk factors sex, caesarean section, fetal growth retardation, birth weight and gestational age.

Apgar Score↗
PubMed1986

Frequency-dependent selection in logistic growth models.

This paper describes the dynamics of a continuously reproducing diploid population with two alleles at one locus. The dependent variables are allele frequency and population density. We modify the basic density-dependent logistic growth model by inserting three possible types of frequency dependence in the fitness functions. These models are analyzed and contrasted with the purely density-dependent situation. Examples are given of periodic fluctuations in allele frequency and population density, which would be impossible for purely density-dependent fitness functions.

Animals↗
PubMed1984

Use of logistic regression analysis to improve prediction of prognosis in acute myeloid leukaemia.

The prognostic usefulness of a range of factors has been examined for patients with acute myeloid leukaemia. Although there was a statistical association between some of these factors and remission rate, the association was only partial. To improve the usefulness of the data, multiple logistic regressional analysis was used. The features selected for use in the analysis were age, blood blast count, FAB classification and colony growth pattern. The last three features could be used as categorical variables, since blood blast counts of greater than 100 X 10(9)/1, FAB group 1 and a prolific pattern of colony growth were associated with a low remission rate. Age was used as a continuous variable. Using these features, eight regression groups were defined. Thus when this data for an individual patient is analysed, it is possible to obtain a value for the probability of that patient achieving remission.

Adult↗
PubMed1992

Nonconditional logistic regression analysis of risk factors in rheumatic heart disease.

The prognostic risk factors in 4323 patients with rheumatic heart disease, admitted from 1970 to 1990, were analysed. The overall mortality was 31.75% in this group of patients. Single factor analysis indicated that cardiac functional classification, time of death, month of death, cardiothoracic ratio, valvular lesions, cardiogenic shock, digitalis-induced arrhythmias, intercurrent pneumonia, pleurorrhea, and hypotension were related to the overall mortality and cardiac death. Multiple factor logistic analysis indicated that for the overall mortality, the independent prognostic factors included presence of cardiac functional classification, cardiothoracic ratio and cardiogenic shock; for cardiac death, the independent factors included cardiac functional classification, cardiothoracic ratio, cardiogenic shock, digitalis-induced arrhythmias and valvular lesions. The data analysis showed that these five factors were contributory to rheumatic heart disease with synergism.

Adolescent↗
PubMed1993

Dose-response relationship between total cadmium intake and metallothioneinuria using logistic regression analysis.

The dose-response relationship for environmental cadmium exposure was assessed using logistic regression analysis. The prevalence of metallothioneinuria was employed as a response variable, while age and total cadmium intake, calculated from the average cadmium concentration in rice and duration of residence in the cadmium-polluted area, were used as explanatory variables. The target population comprised of 1843 cadmium-exposed and 240 non-exposed inhabitants of Ishikawa, Japan. The individuals were divided into 96 subgroups by sex, age (4 categories), cadmium concentrations in rice (3 categories) and length of residence in the polluted area (4 categories). Only total cadmium intake had a significant association with the prevalence of metallothioneinuria. In the non-exposed subjects total cadmium intakes corresponding to 2.5% prevalence of metallothioneinuria were calculated. Based on metallothionein levels expressed as either microgram/l urine or microgram/g creatinine, the total intakes were: 2.221 or 2.207 g in men and 2.365 or 0.319 g in women, respectively. Most of these values were similar to those reported by us previously, employing simple regression analysis. It is concluded, therefore, that a maximum allowable intake of about 2 g cadmium is a reasonable estimate for preventing the cadmium-induced renal dysfunction.

Age Factors↗
PubMed1991

Prediction of survival from resuscitation: a prognostic index derived from multivariate logistic model analysis.

Despite advances in resuscitation, the ability to predict survival at cardiac arrests remains unsophisticated. We identified the factors determining outcome of all cardiopulmonary resuscitations performed at our institution over a 4-year period, and used a Cox multivariate regression model to design prognostic indices to assess the probability of successful resuscitation and hospital discharge. Cardiac arrests (710) were studied, and 193 (28%) were successfully resuscitated. The most influential variables, judged by the size and significance of their logistic regression coefficients, were rhythm, resuscitation delay, and age (for successful resuscitation), and rhythm, performance of intubation and defibrillation, defibrillation delay, and age (for survival until discharge). The combination of these in a prognostic index reliably predicted both outcome (area under the receiver operating curve of 0.78), and survival until discharge (area under the curve of 0.80).

Aged↗
PubMed2005

Logistics of companion animal rehabilitation.

Setting up rehabilitation services presents several challenges to the veterinary practitioner. Members of the rehabilitation team need to have a solid knowledge base of acute and chronic orthopedic and neurologic disorders and a knowledge of rehabilitation principles and applications. The working environment has to be adapted to patients with limited mobility, specific equipment and supplies are to be used, and a fee structure should be implemented. This article reviews these logistic aspects of companion animal rehabilitation.

Animals↗
PubMed2006

Logistical considerations for endoscopy simulators.

A variety of endoscopy simulators have been produced during the last several decades. Multiple factors have influenced the types of simulators that have been developed and the ongoing evolution of existing models. Realistic simulation is only one issue in providing simulation-based training in GI endoscopy. Details such as cost, technologic limitations, management and availability of training facilities, personnel, animal welfare and the procurement, handling, and disposal of animal parts are all major factors when considering the options available among existing endoscopy simulators. Table 1 summarizes the logistical factors for the different types of endoscopy simulator. These considerations clearly are of major importance in simulator design and development and in the conceptualization and organization of simulator-based curricula and courses.

Animals↗
PubMed2006

Logistics of therapy with the ibritumomab tiuxetan regimen.

Radioimmunotherapy is an important new modality for treating patients with B-cell non-Hodgkin's lymphoma (NHL). Clinical trials have shown the safety and efficacy of agents that deliver radiation directly to malignant cells by attaching the (131)I or (90)Y radionuclide to monoclonal antibodies against CD20. In clinical trials, (90)Y ibritumomab tiuxetan has produced rates of response as high as 83% in patients with relapsed or refractory CD20+ NHL. The ibritumomab tiuxetan regimen is conveniently given in an outpatient setting over the course of 7-9 days. This article describes the logistics for initiating treatment, coordinating a multidisciplinary team, identifying eligible patients, and delivering the imaging and therapeutic doses of ibritumomab tiuxetan. The standard radiation safety procedures to protect family members and healthcare professionals involved in the care of patients treated with (90)Y ibritumomab tiuxetan are also reviewed. Treatment with the ibritumomab tiuxetan regimen involves only standard precautions needed to minimize radiation exposure to other persons.

Antibodies, Monoclonal↗
PubMed2006

Neck-focused panic attacks among Cambodian refugees; a logistic and linear regression analysis.

Consecutive Cambodian refugees attending a psychiatric clinic were assessed for the presence and severity of current--i.e., at least one episode in the last month--neck-focused panic. Among the whole sample (N=130), in a logistic regression analysis, the Anxiety Sensitivity Index (ASI; odds ratio=3.70) and the Clinician-Administered PTSD Scale (CAPS; odds ratio=2.61) significantly predicted the presence of current neck panic (NP). Among the neck panic patients (N=60), in the linear regression analysis, NP severity was significantly predicted by NP-associated flashbacks (beta=.42), NP-associated catastrophic cognitions (beta=.22), and CAPS score (beta=.28). Further analysis revealed the effect of the CAPS score to be significantly mediated (Sobel test [Baron, R. M., & Kenny, D. A. (1986). The moderator-mediator variable distinction in social psychological research: conceptual, strategic, and statistical considerations. Journal of Personality and Social Psychology, 51, 1173-1182]) by both NP-associated flashbacks and catastrophic cognitions. In the care of traumatized Cambodian refugees, NP severity, as well as NP-associated flashbacks and catastrophic cognitions, should be specifically assessed and treated.

Adult↗