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PubMed2001

Data augmentation priors for Bayesian and semi-Bayes analyses of conditional-logistic and proportional-hazards regression.

Data augmentation priors have a long history in Bayesian data analysis. Formulae for such priors have been derived for generalized linear models, but their accuracy depends on two approximation steps. This note presents a method for using offsets as well as scaling factors to improve the accuracy of the approximations in logistic regression. This method produces an exceptionally simple form of data augmentation that allows it to be used with any standard package for conditional-logistic or proportional-hazards regression to perform Bayesian and semi-Bayes analyses of matched and survival data. The method is illustrated with an analysis of a matched case-control study of diet and breast cancer.

Algorithms↗
PubMed1993

A comparison of logistic regression to decision-tree induction in a medical domain.

This paper compares the performance of logistic regression to decision-tree induction in classifying patients as having acute cardiac ischemia. This comparison was performed using the database of 5773 patients originally used to develop the logistic-regression tool and test it prospectively. Both the ability to classify cases and the ability to estimate the probability of ischemia were compared on the default tree generated by the C4 version of ID3. They were also compared on a tree optimized on the learning set by increased pruning of overspecified branches, and on a tree incorporating clinical considerations. Both the LR tool and the improved trees performed at a level fairly close to that of the physicians, although the LR tool definitely performed better than the decision tree. There were a number of differences in the performance of the two methods, shedding light on their strengths and weaknesses.

Algorithms↗
PubMed1998

Using a logistic model to predict malignancy of adnexal masses based on menopausal status, ultrasound morphology, and color Doppler findings.

In the present study we aimed to develop a formula for predicting adnexal malignancy based on menopausal status, ultrasound morphology, and color Doppler findings. Logistic regression analysis was performed retrospectively in 79 adnexal masses (59 benign and 20 malignant) in 73 unselected and consecutive patients. All these masses had been preoperatively evaluated using transvaginal color Doppler ultrasonography. In logistic analysis menopausal status (premenopausal vs postmenopausal), color Doppler findings (no flow or lowest resistance index >0.45 vs lowest resistance index </=0.45) and ultrasound morphology (nonsuspicious vs suspicious) were entered as categorical variables. Morphology and color Doppler were found to be independent predictors, whereas menopausal status was not. To assess the validity of the developed mathematical formula, this was applied prospectively in a second series of 58 consecutive and unselected patients diagnosed of adnexal mass and scheduled for surgery. The probability of malignancy was estimated in each case. Overall, 56 of 58 (96.5%) adnexal masses were correctly classified. We conclude that the formula developed in this study is easy to apply and could be useful to predict malignancy or benignity of adnexal masses.

Female↗
PubMed1991

Adjusting risk factors in spontaneous abortion by multiple logistic regression.

A cross-sectional case-control study was performed to identify some obstetric and gynaecologic factors that can influence spontaneous abortion. Statistical and epidemiologic analyses were done by multiple logistic regression to adjust OR through the beta coefficient. A dicotomized outcome variable, representing spontaneous abortion, and different independent variables, representing distinct medical factors, were designed. The analysis was carried out with a personal computer and an appropriate statistic package. The variables representing age over 35 and previous spontaneous abortions were shown to be risk factors, adjusted for the rest of variables. The variables representing parity and late menarcheal age lost significance when they were adjusted with multiple logistic regression.

Abortion, Spontaneous↗
PubMed1993

Logistic regression model to estimate the risk of unbalanced offspring in reciprocal translocations.

The aim of this study was to estimate the risk of viable unbalanced offspring for a parental carrier of reciprocal translocation. On a large computerized database of reciprocal translocations we used logistic regression to model this risk. The status of the progeny is the outcome variable. Explanatory covariates are cytogenetic characteristics of the translocation, age and sex of the parental carrier, and potential viability of the gametes. The results obtained by the logistic model demonstrate the important role of certain variables such as the sex of the parental carrier and the R band length of the translocated segments. Within the group of lower risk (risk of viable unbalanced offspring less than 5%), 97% of the individuals are correctly classified with this model. For this group, the choice prenatal diagnosis can be best discussed by considering both the risk for viable unbalanced offspring and the risk of induced abortion following prenatal diagnosis.

Adolescent↗
PubMed1999

Evaluation of the predictive impact of cephalometric variables. Logistic regression and ROC curves.

In the context of orthodontic treatment planning, the decisions to be made are often affected by the assumption of future growth patterns, especially the direction of mandibular rotation. Using longitudinally available lateral cephalograms from the Belfast Growth Study, it was examined whether, on the basis of the cephalometric variables at the ages of 7, 9 and 11, the direction of mandibular rotation can be predicted in the respective subsequent 4-year intervals. For statistical analysis of this problem, logistic regression models were applied to describe and quantify the influence of potential explanatory variables on the direction of mandibular rotation (dependent variable). In addition, graphical methods taken from the field of medical diagnostics were applied for prediction and for determination of predictive accuracy. The use of logistic regression models revealed no relations between the explanatory variables SN-MeGo and S-Go/N-Me and the subsequent mandibular growth pattern. Only the upper and lower parts of the gonial angle showed a minor predictive impact. A graphical evaluation of their prognostic impact by means of "receiver operating characteristics" (ROC) curves, complemented by determination of the areas under the curves, confirmed the relations discovered. Nevertheless the prognostic limits of the lateral cephalogram emerged clearly for all variables investigated.

Adolescent↗
PubMedDate not supplied

Logistic regression and discriminant analyses of hepatic failure after liver resection for carcinoma of the biliary tract.

Stepwise logistic and discriminant analyses were used to define the risk factors for hepatic failure after liver resection for carcinoma of the biliary tract and to predict this complication. The logistic analysis identified the linear pattern of oral glucose tolerance test, cholangitis, pancreatoduodenectomy, and indocyanine green disappearance rate as the factors most related to hepatic failure among 18 pre- and perioperative parameters of the past 84 hepatectomized cases (55 hilar bile duct carcinomas and 29 gallbladder carcinomas). Our discriminant formula using five variables, including the above-mentioned four plus the liver resection rate, could distinguish the patients with posthepatectomy liver failure (n = 25) from those without (n = 59) with 86.9% accuracy, 96.0% sensitivity, and 83.1% specificity. The cross-validation test has confirmed that this model was robust for discriminant analysis. The results of this study show that statistical multifactorial analysis makes possible the preoperative prediction of hepatic failure after liver resection for carcinoma of the biliary tract.

Adult↗
PubMed2000

Factors predicting the non-utilisation of immunisation services using logistic regression technique.

A cross sectional study was conducted to determine the variables which have an individual predictive power on nonutilization of immunisation services using logistic regression model. Children between 12 and 23 months of age were assessed and enrolled using a pretested interview schedule. Statistical analysis was done using descriptive statistics, univariate analysis using Chi Square tests and multivariate logistic regression analysis. Of the 200 children studied 56% were fully immunised. Only illiterate mothers (p < 0.05) and poor access (> 3 km) to health facility (p < 0.001) were found to have an independent predictive power on the nonutilization of immunisation services. Sex of the child, parity levels, socioeconomic status did not independently influence the utilisation pattern. It is possible to identify these still existing small pockets of nonusers of immunisation services through the predictive variables and target them through special efforts.

Health Services Accessibility↗
PubMed2001

Evaluation of the logistic organ dysfunction system for the assessment of organ dysfunction and mortality in critically ill patients.

OBJECTIVES: To evaluate the performance of the logistic organ dysfunction (LOD) system for the assessment of morbidity and mortality in multiple organ dysfunction/failure (MOD/F) in an independent database and to evaluate the use of sequential LOD measurements for the prediction of outcome. DESIGN AND SETTING: Prospective, multicentric cohort study in 13 adult medical, surgical, and mixed intensive care units (ICUs) in Austria. PATIENTS: A total of 2,893 consecutive admissions to the ICUs. MEASUREMENTS AND MAIN RESULTS: Patient vital status at ICU and hospital discharge was recorded. Univariate analysis showed that the LOD was able to distinguish between survivors and nonsurvivors (2 vs. 6 median score). Within organ systems, higher levels of the severity of organ dysfunction were consistently associated with higher mortality. For the prediction of hospital mortality, the original prognostic LOD model did not perform well in our patients, as indicated by the goodness-of-fit C statistic. Using multiple logistic regression we developed a prognostic model with a satisfactory fit in our patients. The integration of further measurements during the ICU stay increased discrimination but not calibration. CONCLUSIONS: The LOD system is well correlated well with the numbers and levels of organ dysfunctions and discriminates well between survivors and nonsurvivors. It can thus be used to quantify the baseline severity of organ dysfunction. Moreover, after customization of the predictive equation the LOD predicted hospital mortality in our patients with high precision. It thus provides a combined measure of morbidity and mortality for critically ill patients with MOD/F.

Aged↗
PubMed2006

Morphometric sum optical density as a surrogate marker for ploidy status in prostate cancer: an analysis in 180 biopsies using logistic regression and binary recursive partitioning.

We sought to identify morphometric descriptors predictive of nondiploidy in prostatic adenocarcinoma on prostate needle biopsies using logistic regression (LR) and binary recursive partitioning (BRP) and compare the equivalence of both methods. A total of 180 prostate needle biopsies diagnosed as prostatic adenocarcinoma were selected. Deoxyribonucleic acid ploidy and morphometry were performed separately on Feulgen-stained sections from these biopsies using the CAS-200 system and Nuclear Morphometry Suite, respectively. Seven morphometric predictors were tested as predictor variables, including nuclear area, circularity, elongation, sum optical density (OD), configuration run length, coefficient of variation (CV), and angularity. Logistic regression (LR) identified a two-parameter model including sum OD and circularity that had a 93.9% overall correct prediction rate (area under curve=0.950; 95% CI: 0.913, 0.987). A reduced model including only sum OD was equally good without any significant loss of predictive accuracy (93.3% correct overall classification rate). BRP also selected sum OD as the most predictive parameter; a sum OD cut-off of 7.73 in this model identified 93.3% of the nondiploid cases correctly. Morphometric OD can be used as a surrogate marker of nondiploidy. LR and BRP models are both equivalent in identifying and correctly classifying nondiploid cases of prostate cancer using sum OD as the predictor variable.

Adenocarcinoma↗
PubMed2005

Prediction of minor head injured patients using logistic regression and MLP neural network.

In this study it is aimed to assess the posttraumatic cerebral hemodynamia in minor head injured patients. Eighty patients with minor head injury (Group 1) evaluated in the early 8 h of posttraumatic period between July 2003 and February 2004. The control group (Group 2) has composed of 32 healthy people. Bilateral blood flow velocities of middle cerebral arteries (MCA) had measured using transtemporal technique while internal carotid arteries were evaluated by submandibular examination. Two different mathematical models such as the traditional statistical method on the basis of logistic regression and a multi-layer perceptron (MLP) neural network are used to classify the age, sex, velocitiy parameters of MCA, mean velocity of extracranial ICAs and V(MCA)/ V(ICA) ratios. The neural network was trained, cross-validated and tested with subject's transcranial Doppler signals. As a result of these classifications, we found the success rate of logistic regression, the success rate of MLP neural network is 88.2 and 89.1%, respectively. The classification results show that MLP neural network is offering the best results in the case of diagnosis.

Age Factors↗
PubMed2006

The use of logistic regression to enhance risk assessment and decision making by mental health administrators.

Development of policies and procedures to contend with the risks presented by elopement, aggression, and suicidal behaviors are long-standing challenges for mental health administrators. Guidance in making such judgments can be obtained through the use of a multivariate statistical technique known as logistic regression. This procedure can be used to develop a predictive equation that is mathematically formulated to use the best combination of predictors, rather than considering just one factor at a time. This paper presents an overview of logistic regression and its utility in mental health administrative decision making. A case example of its application is presented using data on elopements from Missouri's long-term state psychiatric hospitals. Ultimately, the use of statistical prediction analyses tempered with differential qualitative weighting of classification errors can augment decision-making processes in a manner that provides guidance and flexibility while wrestling with the complex problem of risk assessment and decision making.

Adult↗
PubMed1989

Limitations of a conventional logistic regression model based on left ventricular ejection fraction in predicting coronary events after myocardial infarction.

The clinical utility of conventional logistic regression models based on left ventricular ejection fraction (LVEF) for the prediction of cardiac events (death or recurrent infarction) was assessed in 646 postinfarction patients undergoing radionuclide ventriculography at rest and during exercise. The discriminant power of 2 different models (LVEF at rest alone vs LVEF at rest plus LVEF at peak exercise) was quantified in terms of the area under receiver-operating characteristic curves based on knowledge of patient outcome in the year after testing and the logistic probability of that outcome. Although LVEF at rest provided a significant amount of prognostic information (receiver-operating characteristic curve area = 62 +/- 4%, p less than 0.001), several limitations were observed: (1) powerful predictors of risk were uncommon (32% of patients with an LVEF at rest less than 0.20 had a cardiac event, but only 3% of the population had such extreme values); (2) the accuracy of predictions for high risk patients was less than for low risk patients (28 vs 98%, p less than 0.001); (3) addition of exercise LVEF to the model did not improve the accuracy of prediction (receiver-operating characteristic curve area = 68 +/- 4%, p = 0.11); and (4) predictions for individual patients were very imprecise (the 95% confidence interval of percent risk for an LVEF at rest of 0.20 [11 to 36%] overlapped that for an LVEF at rest of 0.60 [0 to 14%]).(ABSTRACT TRUNCATED AT 250 WORDS)

Death, Sudden↗
PubMedDate not supplied

Nonparametric mixture logistic regression models for clinical disposition.

Psychiatric hospitalization is one of the most important decisions in the care of patients. This is attributed to the complexity and intensity of treatment and isolation of patients from the family and community into a typically highly controlled and supervised setting. Logistic regression models are fitted to assess the relationship between DSM-III axes and psychiatric hospitalization decisions. Since the apparent error rate tends to underestimate the true error rate, the estimate for the downward bias of the apparent error was computed. A generalization of the logistic regression model is fitted where the intercept is assumed to be a random parameter.

Adolescent↗
PubMed1990

Radiosurgery and the double logistic product formula.

The double logistic product formula is proposed as a method for predicting the probability of developing brain necrosis after high dose irradiation of small target volumes as used in stereotactic radiosurgery. Dose-response data observed for the production of localized radiation necrosis for treating intractable pain with the original Leksell gamma unit were used to choose the best fitting parameters for the double logistic product formula. This model can be used with either exponential or linear quadratic formulas to account for the effects of dose, fractionation and time in addition to volume. Dose-response predictions for stereotactic radiosurgery with different sized collimators are presented.

Brain↗
PubMed1991

Predictors of outcome in children hospitalized with maxillofacial infections: a linear logistic model.

The purpose of this study was to determine factors predictive of clinical outcome for pediatric patients with maxillofacial infections. Using linear logistic regression, four important variables, age, admission temperature, admission white blood cell count, and source of infection, were identified. Relevant study variables were abstracted from the records of all children less than 15 years old admitted to San Francisco General Hospital (SFGH) with facial infections between 1982 and 1986 (n = 105). An unfavorable clinical outcome was defined as a length of hospital stay (LOS) greater than or equal to 4 days and/or the need for an operation to resolve the infection. A favorable outcome was a LOS less than 4 days and no operation. To develop and validate the linear logistic model, the original group of patients (n = 105) was divided into index and validation sets. The index set was created by randomly selecting 80 of the original patients. The model was then applied to a validation set of the 25 remaining children. The model predicted that 13.95 of the patients in the validation set would have an unfavorable outcome. The actual number of unfavorable outcomes was 16. To further test the model's validity, a third data set was collected. It was composed of pediatric patients admitted to SFGH between January 1, 1987 and June 30, 1989 (n = 24). The model predicted that 15.99 of these patients would have an unfavorable outcome; 17 patients actually did have an unfavorable outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Infections↗
PubMed1993

Dose-response relationship between total cadmium intake and beta 2-microglobulinuria using logistic regression analysis.

The dose-response relationship between total cadmium intake and beta 2-microglobulinuria was investigated using logistic regression analysis in order to consider the effect of age on this association. The target population consisted of 1850 inhabitants of the cadmium-polluted Kakehashi River basin in Ishikawa prefecture, Japan. They were divided into 58 subgroups (27 in the men and 31 in the women) by four factors of sex, age, rice cadmium concentration and length of residence in cadmium-polluted areas. Logistic regression analysis was performed for this dose-response relationship, and both age and total cadmium intake were significantly associated with beta 2-microglobulinuria. It was confirmed that total cadmium intake had a significant association with beta 2-microglobulinuria, independent of the aging effect.

Age Factors↗
PubMed1992

Decreased concentration of myofibrils and myofiber hypertrophy are structural determinants of impaired left ventricular function in patients with chronic heart diseases: a multiple logistic regression analysis.

OBJECTIVES: The aim of this study was to perform a multiple logistic regression analysis to identify independent structural determinants of impaired left ventricular function. BACKGROUND: The association between contractile failure and structural alterations of the myocardium has been demonstrated in several studies, and multiple interactions between myocardial structure and cardiac performance are likely. METHODS: Morphometric data assessed from 130 left ventricular biopsy specimens were analyzed. The endomyocardial specimens were obtained from 57 patients with normal coronary arteries (17 with normal left ventricular ejection fraction and 40 with impaired left ventricular function [dilated cardiomyopathy]), 15 patients with hypertrophic cardiomyopathy and 32 patients with aortic valve disease. Transmural biopsy specimens were assessed in 6 donor hearts before heart transplantation and in 20 patients with left anterior descending coronary artery disease whose specimens were obtained from the left ventricular anterior wall during aortocoronary bypass surgery. Global or regional left ventricular function was evaluated from left cineventriculograms. The volume fraction of cardiac fibrous tissue, intracellular volume fraction of myofibrils, volume fraction of myofibrils related to myocardial tissue (including fibrosis) and myofiber diameters were determined from semithin sections of the biopsy specimens with the use of light microscopic morphometry. RESULTS: Multiple logistic regression analysis revealed decreased volume fraction of myofibrils (p < 0.005) and increased fiber diameter (p < 0.002) as independent determinants of impaired left ventricular function. CONCLUSIONS: These data indicate that, independent of the underlying heart disease, both decreased concentration of contractile proteins and myocyte hypertrophy are independently associated with impaired left ventricular function.

Age Factors↗