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[A program for analysis of dose-response relationship with logistic model].

In order to avoid the defects in common methods for analysis of dose-response curves, we fit groups of dose-response curves simultaneously or separately on computer by using logistic model, with the EC50 and slope factor as the basic parameters. The pD2 and pA2 values were calculated from the best estimated EC50s. This method shows a good compatibility with the original experimental data. The BASIC program can be conveniently run on microcomputers.

Animals↗

Factors predisposing to healing complications after internal fixation of femoral neck fracture. A stepwise logistic regression analysis.

A stepwise logistic regression analysis was made to assess the influence of various factors on the rate of healing complications after femoral neck fracture. A prospective series comprising 101 patients with fresh fractures treated by closed reduction and internal fixation was included in a roentgenographic follow-up study. The single most important factor was the quality of reduction, followed by the type of fracture, and the position of the internal fixation material. Age, gender, and type of internal fixation device (three screws or three nails) were not found to influence the healing complication rate. The predicted probability of a healing complication for different combinations of the three most important factors ranged from 0.05 to 0.99. The highest value was found for the combination Garden Type IV fracture, which had unacceptable reduction and position of the internal fixation material. The results show that failure to achieve adequate reduction should be a strong argument in favor of primary hip arthroplasty.

Adult↗

Pneumoconiosis risk assessment in agate workers--multiple logistic model.

A multivariate logistic model for measuring and comparing pneumoconiosis risk is described. In the first stage variables are screened on the basis of contributed variability via Pearson Chi Square statistic. Age, dust years and pack years so chosen as explanatory variables are fitted in the above model. The coefficients are estimated as linear discriminant function co-efficient. The model gives quite a good fit between observed and expected frequencies. Dust years discriminate maximum between the normal and pneumoconiosis group. Nearly sixty per cent of the variation is explained by these variables.

Adult↗

Application of a generalized logistic equation to simulate a fed-batch process.

The whole of fed-batch with two constant flow is successfully described by a generalized logistic equation. The research results show that (1) the adequacy of the simulation of the process depends to a considerable degree on the selection of simulated accuracy; (2) there is a quantitative relation between the specific growth rate of cells mu and the specific substrate consumption rate qs and content of RNA in microbial cells.

Data Interpretation, Statistical↗

[Multivariate analysis on prognostic factors for acute myocardial infarction during acute period noncondition stepwise logistic model].

The relationship between baseline factors defined at 4.3 +/- 1.8 hr after onset of acute myocardial infarction and 28-day survival in 319 patients admitted into the China Medical University was evaluated. The case fatality rate during acute period was 17.9%. Univariate statistics identified a significant relationship between 5 of these factors and survival. Multivariate noncondition stepwise logistic model analysis identified four factors as being most closely related to survival: (1) heart failure; (2) arrhythmia; (3) age; (4) history of essential hypertension. It is concluded that heart failure during the acute period of acute myocardial infarction is the most important baseline factor for prediction of 28-day survival.

Aged↗

Bladder neck mobility and the outcome of surgery for genuine stress urinary incontinence. A logistic regression analysis of lateral bead-chain cystourethrograms.

Bladder neck position, as determined by preoperative and postoperative resting and straining lateral bead-chain cystourethrograms, was analyzed by logistic regression analysis in 94 women undergoing 98 operations for genuine stress incontinence. A total of 384 roentgenograms were analyzed in an attempt to build a model that would predict the likelihood of surgical success in a given patient based on the preoperative films and explain a successful surgical outcome based on the characteristics of the postoperative films. The most important predictors of success were the number of previous incontinence operations, a large distance between the bladder neck and the pubic symphysis at rest, and increased mobility of the bladder neck before surgery. Successful surgery appeared to be related most closely to decreasing mobility of a previously hypermobile bladder neck.

Female↗

Advantages and inconveniences of the Cox model compared with the logistic model: application to a study of risk factors of nursing cow infertility.

The survival Cox model and the logistic model were compared on a data set obtained from an ecopathological survey relative to the risk factors of nursing cow infertility. The risk factors resulting from the 2 models were the same. The Cox model has the advantage of preserving the variable in its original quantitative form, and of using a maximum of information. However, very restrictive conditions of application of this model make its use rather limited.

Animals↗

CART and logistic regression analyses of risk factors for first dose hypotension by an ACE-inhibitor.

Angiotensin converting enzyme inhibitors (ACEI) are established drugs for the treatment of congestive heart failure. Cases of symptomatic hypotension, especially on the first day of treatment, have been reported occasionally. The database we analysed consisted of 1,177 patients, mean age approximately 70 yrs, with congestive heart failure NYHA functional class II or III. These patients were treated and observed prospectively according to a uniform protocol, starting therapy with 2.5 mg enalapril and measuring blood pressure at hourly intervals for eight hours thereafter. 94.6% of the patients experienced no symptomatic hypotension, 4.75% moderate symptoms (e.g. dizziness, headache) and 0.59% severe symptoms (e.g. fainting, collapse, renal failure). For the analyses of risk factors a large number of baseline variables were analysed univariately to select those significant for inclusion in a multivariate stepwise logistic regression. Alternatively the CART-(classification and regression tree) technique was used. Both techniques showed diastolic blood pressure < or = 70 mmHg to be the single most significant risk factor. CART-analyses showed also pretreatment with nitrates and systolic blood pressure < or = 120 mmHg to be of prognostic relevance. Thus CART is a valuable complement when looking for prognostic factors.

Aged↗

Clinical and nutritional factors predictive of plasma lipid unsaturation deficiency in advanced liver cirrhosis: a logistic regression analysis.

AIM: To identify those clinical and nutritional factors associated with plasma lipid unsaturation deficiency in cirrhosis. METHODS: Fatty acid profiles of plasma phospholipids (PL) and cholesteryl esters (CE) were measured in 101 inpatients with advanced cirrhosis and in 44 age- and sex-matched healthy controls. Double-bond index (DBI) was calculated for each fraction and binarily categorized in each patient using the 5th percentile of the control group as the cut-off limit. The association of 12 routine clinical, biological, and nutritional variables with derangement of each DBI was multivariately assessed by means of stepwise logistic regression analysis. RESULTS: The DBI of PL and CE were below the 5th percentile of the control group in 60 and 68 of 101 cirrhotic patients, respectively. After multivariate analyses, the variables found to be independent predictors of impaired unsaturation were: 1) The presence of moderate/severe malnutrition (odds ratio: 1.3-8.0 (95% CI); p < 0.05) and serum tau-GT > 1 mukat/L (odds ratio: 0.2-1.0; NS) for plasma PL, and 2) the presence of moderate/severe malnutrition (odds ratio: 1.8-17.4; p < 0.05), serum bilirubin > 50 mumol/L (odds ratio 1.7-14.5; p < 0.05) and serum tau-GT > 1 mukat/L (odds ratio 0.1-1.1; NS) for CE. CONCLUSION: Malnutrition appears to be a major factor for impaired lipid unsaturation in advanced cirrhosis. Thus, the possibility of improving plasma lipid unsaturation in these patients by means of nutritional support should be further investigated.

Adult↗

Maximum likelihood estimation of the attributable fraction from logistic models.

Bruzzi et al. (1985, American Journal of Epidemiology 122, 904-914) provided a general logistic-model-based estimator of the attributable fraction for case-control data, and Benichou and Gail (1990, Biometrics 46, 991-1003) gave an implicit-delta-method variance formula for this estimator. The Bruzzi et al. estimator is not, however, the maximum likelihood estimator (MLE) based on the model, as it uses the model only to construct the relative risk estimates, and not the covariate-distribution estimate. We here provide maximum likelihood estimators for the attributable fraction in cohort and case-control studies, and their asymptotic variances. The case-control estimator generalizes the estimator of Drescher and Schill (1991, Biometrics 47, 1247-1256). We also present a limited simulation study which confirms earlier work that better small-sample performance is obtained when the confidence interval is centered on the log-transformed point estimator rather than the original point estimator.

Biometry↗

Analysis of several risks factors involved in dental caries through multiple logistic regression.

Through multiple logistic regression an epidemiological study was undertaken of the following factors: age, gender, socio-economic status, dental care, toothbrushing, chewing gum, snacking, fluoride, and of their influence on the development of tooth decay. The factors are analysed individually and globally (global model). An initial model was constructed, establishing the interactions, and developing a final model. Risk factors shown to be involved were: low social class status, lack of dental care in the previous 12 months, absence of toothbrushing, and belonging to the age group 9-12 years old. An interaction was established between the following variables: socio-economic status and toothbrushing, and dental care and age.

Adolescent↗

[Conditional logistic regression analysis of risk factors on congenital birth defects in Baotou].

Congenital defects are one of the common diseases in the newborns, and are important factors affecting the quality of the population. This survey was done to find risk factors related to congenital defects and to provide scientific basis for promoting birth quality. In this paper, a case-control study on 90 cases using 1:2 matching was carried out in Baotou area, and conditional logistic regression analysis showed that the following six major risk factors were associated with birth defects, i.e.: intake of certain drugs during pregnancy, exposure to radioactive rays, and contacting certain harmful chemical substances, common cold and fever during the period of pregnancy, smoking addiction of baby's father and the family history of certain defects of baby's parents.

Case-Control Studies↗

Concept formation vs. logistic regression: predicting death in trauma patients.

This paper discusses two classification models, one based on concept formation and the other using standard logistic regression. The models are first explained in some detail and then evaluated on the same population of trauma patients. The goal of both systems is to predict the outcome of those patients. The results are summarized and explained in terms of differing algorithms of the two models.

Artificial Intelligence↗

[Logistic model in diagnosis of lung cancer].

Specificity of the diagnosis of lung cancer (l.c.) based upon clinical and radiological criteria was investigated in patients who died in Hospital of Lung Diseases in Lódź between in 1985 and 1989. Autopsy revealed diagnostic errors in 37% cases. Twenty most common disease features were taken into consideration. Logistic analysis helped to create clinical-mathematical model which allows for interpretation of disease features in two distinct categories: l.c. (non-neoplasmatic lung disease). Eight features proved to be significant (changes in RBC, weight loss, chest pain, increased sputum production, haemoptisis, hilar tumor, pleural effusion, peripheral round shadow on chest X-ray). Diagnostic usefulness of the model was checked in prospective study a group of patients who died from properly diagnosed l.c. (499 cases). Our model allowed for proper diagnosis of neoplasmatic cause of the disease with higher probability than morphological methods (including both intravital and autopsy examination).

Diagnostic Errors↗

[A statistical investigation of the influence of allergic factors on intractable asthma by multiple logistic regression].

The relationships of the development of intractability in bronchial asthma with 17 factors, namely 1) sex, 2) age, 3) age of onset, 4) period from onset, 5) severity of asthma, 6) type of asthma, 7) family history of asthma within the third degree of consanguinity, 8) history of smoking, 9) past history of atopic dermatitis, 10) past history of allergic rhinitis, 11) past history of chronic sinusitis, 12) past history of nasal polyp, 13) necessity of oral beta-adrenergic agonists, 14) necessity of inhaled beta-adrenergic agonists, 15) necessity of oral xanthine agents, 16) necessity of inhaled anticholinergic agents and 17) necessity of inhaled corticosteroids, were analyzed by multiple logistic regression in 160 asthmatic patients. Evaluation of each factor according to the relative risk indicated that asthmatic patients tended to become intractable with the following categories (relative risk--reference category): more than 40 years old (5.2 in the fifth and sixth decades, 4.4 in the seventh and eighth decades--the third and fourth decades); the fifth decade or later onset (7.3--the first decade); non-atopic type (2.1--atopic type); positive family history of asthma (2.8--negative one); an ex- and current smoker (3.1--no smoker); negative past histories of atopic dermatitis and allergic rhinitis (4.1 in the former, 2.4 in the latter--positive one respectively); positive past histories of chronic sinusitis and nasal polyp (5.1 in the former, 6.6 in the latter--negative one respectively). Especially, relative risk in asthmatic patients with simultaneous positive past histories of chronic sinusitis and nasal polyp was about 16 times as high as in ones without both histories. This finding suggested these histories strongly participated in the development of intractability in bronchial asthma.

Adult↗

Prognostic factors for short-term survival in alcoholic hepatitis in Japan: analysis by logistic regression.

Prognostic factors for the outcome of patients with alcoholic hepatitis were identified by logistic regression analysis. To predict the outcome immediately after admission, clinical data from 97 patients with alcoholic hepatitis on admission were introduced to multivariate analysis. Independent prognostic factors for favorable outcome were hepaplastin time, peripheral white blood cell count, age (40 to 60 years), and serum creatinine level (below 1.4 mg/dl). Sensitivity, specificity, positive predictive value, negative predictive value, and predictive accuracy were 0.78, 0.89, 0.78, 0.89, and 0.86, respectively. The resultant equation for the death rate was applied to another set of patients with alcoholic hepatitis as a validation study. Predictive accuracy estimated 0.95 in validation. The prognostic index derived was simple, accurate, and useful in the prediction of the outcome in patients with alcoholic hepatitis. Furthermore, it provides the clinician with an indication of the necessity for the intensive care of patients in a critical condition.

Adult↗

[Dichotomization of continuous variables in logistic regression models].

It is highly to observe in the biomedical literature, that the continuous variables such as systolic blood pressure and cholesterol, are dichotomized and used in such manner in a given statistical analysis. The consequences of such transformation can be very varied. In this article, how the dichotomization of a continuous exposure variable affects the quality of the prediction of a response using the logistic regression is examined. One can conclude that, in almost all the studied stimulation, the percentages of misclassification can increase drastically, reaching over there times the probability of misclassification of the ones using the original variable. Therefore, we recommend to avoid dichotomization.

Logistic Models↗