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At least 775 records · Page 43Linked to original sources
PubMed1997

A logistic model for trend in 2 x 2 x kappa tables with applications to meta-analyses.

There recently has been an increased interest in examining the relationship between the baseline (control) risk of an adverse outcome and the magnitude of the treatment effect (Brand and Kragt, 1992, Statistics in Medicine 11, 2077-2082; Davey Smith, Song, and Sheldon, 1993, The British Medical Journal 306, 1367-1373; Senn, 1994, Statistics in Medicine 13, 293-294). To facilitate such an examination, we propose a logistic model in which the relationship between the treatment effect, as measured by the log odds ratio, and the baseline risk is specified parametrically. This procedure is founded on a product-binomial likelihood and generates maximum likelihood estimates of the baseline event rates and two parameters characterizing the trend in the treatment effect. We fit this model to data from a meta-analysis involving the treatment of women at risk of preterm labor and contrast our findings with those of an earlier analysis.

Biometry↗
PubMed1997

A logistic-bivariate normal model for overdispersed two-state Markov processes.

We describe a logistic-bivariate normal mixture model for a two-state Markov chain in which each individual makes transitions between states according to a subject-specific transition probability matrix. The use of the bivariate normal mixing distribution facilitates inferences regarding the correlation of the random effects and hence provides insight as to the nature of the subject-to-subject variability in the transition probabilities. Tests regarding the correlation can be based on likelihood ratio, score, or Wald statistics. Estimates of the transition intensities of a latent continuous time conditionally Markov process may also be computed. We illustrate this methodology by application to a parasitic infection field study and contrast our findings with those previously published on this data set.

Biometry↗
PubMed1996

A multiple stepwise logistic regression analysis of trauma history and 16 other history and dental cofactors in females with temporomandibular disorders.

The simultaneous contribution of 11 occlusal factors, dental attrition severity, orthodontic history, trauma (motor vehicle accident [MVA] and non-MVA), and age in defining two independent large populations of females diagnosed with five mutually exclusive temporomandibular disorders was tested through multiple stepwise logistic regression analysis. Non-MVA trauma was significant in both groups in defining disc displacement (DD) with and without reduction, and osteoarthrosis (OA) (both primary and following DD). Anterior open bite was also a significant factor in defining OA in both groups. Much smaller contributions were also made by missing teeth in one of the populations with OA following DD, and by retruded contact position-intercuspal position slide lengths and overjet in one of the primary OA populations. Motor vehicle accident trauma was significant in defining myofascial pain (MP) in both populations, and laterotrusive attrition mildly defined MP in one population. Only a minority of total variance was explained: 6% to 8% of DD with reduction; 10% to 14% of DD without reduction; 11% to 20% of OA following DD; 17% to 38% of primary OA; and 4% to 10% of MP. Non-MVA trauma was the major defining feature of the temporomandibular joint intracapsular disorders, and MVA trauma explained a very small percentage of the MP patients. Implications are discussed and recommendations are made for future research.

Adolescent↗
PubMed1997

[Abnormally broad confidence intervals in logistic regression: interpretation of results of statistical programs].

This study describes the behavior of eight statistical programs (BMDP, EGRET, JMP, SAS, SPSS, STATA, STATISTIX, and SYSTAT) when performing a logistic regression with a simulated data set that contains a numerical problem created by the presence of a cell value equal to zero. The programs respond in different ways to this problem. Most of them give a warning, although many simultaneously present incorrect results, among which are confidence intervals that tend toward infinity. Such results can mislead the user. Various guidelines are offered for detecting these problems in actual analyses, and users are reminded of the importance of critical interpretation of the results of statistical programs.

Confidence Intervals↗
PubMed1997

Tree-structured logistic models for over-dispersed binomial data with application to modeling developmental effects.

This article proposes tree-structured logistic regression modeling for over-dispersed binomial data. Recursive partitioning is performed using a combination of statistical tests and residual analysis. The splitting criterion in cross-validation is based on the deviance function. A nested grid algorithm to estimate the bootstrap parameters is developed. The regression tree procedure provides a new approach for exploring in detail the relationship between the binomial response and explanatory variables. The proposed procedure is used to model the relationship between the incidence of malformation and dose and fetal weight using data from a developmental experiment conducted at the National Center for Toxicological Research. A conditional Gaussian chain model is used to account for the effect of fetal weight by dose.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1996

[Logistic regression analysis of the influence of residential environment, residential hygiene and life style on the incidence and duration of acute respiratory disease in small children].

659 children aged between 1 and 2 years were examined in respect of the influence of the children's-facility, residential environment, residential hygiene, and way of life, as well as in respect of the influence of selected sociological factors on the number and duration of acute respiratory diseases (ARD). The evaluation of the results by using logistical regressions analysis came--among other things--to following factors, that correlated with a risen morbidity, respectively an extended duration of the illness (> 3 diseases in 6 months; > 20 days in 6 months). Apartments with wet walls, dark and too noisy apartments, children's-rooms with two outside walls, single window pane, outside-wall-gas-heaters, room-air-humidity too low, space for children in day-nurseries < 4 sqm, no carrying out of hardening-steps for the children, wind-influence to the open space of the children's-facility too strong, and shift-working by the mother.

Acute Disease↗
PubMed1997

Early diagnosis of acute myocardial infarction by either electrocardiogram or a logistic regression model: portability of a predictive instrument of acute cardiac ischemia to a small rural coronary care unit.

OBJECTIVE: To test the ability of a logistic regression model (LRM) that predicts acute cardiac ischemia to make an early diagnosis of acute myocardial infarction (AMI); the ability of the LRM to predict AMI was also compared with the presenting electrocardiogram (ECG). SETTING: A small rural Irish coronary care unit. METHODS: Clinical and ECG data required by the LRM to predict acute coronary ischemia were recorded in 600 consecutive patients admitted with suspected AMI. Estimates of the LRM were ranked into equal deciles in declining probability of acute cardiac ischemia (pACI), and presenting ECGs were placed into one of seven categories. RESULTS: At presentation 50% of AMI patients were in the two LRM deciles with the highest pACI, and 49% of AMI patients had ECGs with greater than 2 mm ST elevation associated with reciprocal changes. ECG categories had a 76% sensitivity for the early diagnosis of AMI and the LRM had an 84% sensitivity. The specificity, accuracy and positive predictive value for the ECG categories were 92%, 84% and 85%, respectively. The specificity, accuracy and positive predictive value of the LRM were 84%, 84% and 75%, respectively. The areas under the receiver operating characteristic curve of the LRM and ECG categories were almost identical (91% and 90%, respectively). CONCLUSION: AMI can be diagnosed early with comparable accuracy either by placing presenting ECGs into one of seven categories, or by the LRM. The best method and 'cut-off' point for the diagnosis of AMI varies according to clinical circumstances. Categorizing ECGs requires more skill in ECG interpretation, but takes less time. The previously reported performances of the LRM were replicated, confirming portability of its use into different clinical settings and patient populations.

Acute Disease↗
PubMed1998

Mixed effects logistic regression models for longitudinal binary response data with informative drop-out.

A shared parameter model with logistic link is presented for longitudinal binary response data to accommodate informative drop-out. The model consists of observed longitudinal and missing response components that share random effects parameters. To our knowledge, this is the first presentation of such a model for longitudinal binary response data. Comparisons are made to an approximate conditional logit model in terms of a clinical trial dataset and simulations. The naive mixed effects logit model that does not account for informative drop-out is also compared. The simulation-based differences among the models with respect to coverage of confidence intervals, bias, and mean squared error (MSE) depend on at least two factors: whether an effect is a between- or within-subject effect and the amount of between-subject variation as exhibited by variance components of the random effects distributions. When the shared parameter model holds, the approximate conditional model provides confidence intervals with good coverage for within-cluster factors but not for between-cluster factors. The converse is true for the naive model. Under a different drop-out mechanism, when the probability of drop-out is dependent only on the current unobserved observation, all three models behave similarly by providing between-subject confidence intervals with good coverage and comparable MSE and bias but poor within-subject confidence intervals, MSE, and bias. The naive model does more poorly with respect to the within-subject effects than do the shared parameter and approximate conditional models. The data analysis, which entails a comparison of two pain relievers and a placebo with respect to pain relief, conforms to the simulation results based on the shared parameter model but not on the simulation based on the outcome-driven drop-out process. This comparison between the data analysis and simulation results may provide evidence that the shared parameter model holds for the pain data.

Analgesics↗
PubMed1998

Predisposing factors of life-threatening deep neck infection: logistic regression analysis of 214 cases.

OBJECTIVE: In the era of antibiotics, most deep neck infections can be cured by conservative treatment, but some still result in life-threatening complications. In this study, we discuss whether or not there are predisposing factors of complicated deep neck infection. DESIGN: A retrospective chart review of patients presenting between 1988 and 1996 was conducted. METHOD: Among 214 deep neck infection patients, 18 cases resulted in lethal complications. We used the "dummy" variable with logistic regression as the statistical analysis method. RESULTS: Patients with an underlying disease, neck swelling, and delay time had a positive correlation that was statistically significance (p < .05). Patients who were older, male, with complete blood count/differential count-positive finding and fever had positive correlation, but this was not statistically significant (p > .05). CONCLUSION: Although complicated deep neck infection is a rapidly progressive disease with a high mortality, we can not thoroughly predict the prognosis or avoid it happening completely. But, if we can detect and pay more attention to the high-risk group of patients with use of aggressive therapy, the incidence of complicated deep neck infection may be reduced.

Abscess↗
PubMedDate not supplied

Helicobacter pylori infection and age on the development of intestinal metaplasia--a multiple logistic regression analysis.

BACKGROUND/AIMS: Both intestinal metaplasia (IM) and Helicobacter pylori (H. pylori) infection have been linked to gastric carcinogenesis in an age-dependent manner. However, their relationship remains ill defined, especially with respect to age. METHODOLOGY: Three hundred and two asymptomatic subjects (167 males and 135 females; mean age 44.3+/-11.1 years) underwent complete endoscopic examination and biopsy at the antrum and the corpus. H. pylori infection was diagnosed according to histopathology and serology, while IM was determined by histopathology. RESULTS: Eighty-four patients (27.8%) had IM, while 185 patients (61.3%) were seropositive to H. pylori. The frequency of IM was higher in patients with gastric ulcer (9/14, 64.3%) than in those with minimal change (68/229, 29.7%) or duodenal ulcer (7/59, 11.9%), both p<0.01. Patients with IM had a higher mean age (49.5+/-14.1 vs. 42.3+/-9.0, p<0.01) and a higher H. pylori prevalence than those without IM (61/84, 72.6% vs. 124/218, 56.9%, p<0.01). The concordance rate of H. pylori infection between histopathologic and serologic diagnosis was lower in patients with IM (67/84, 79.8%) than those without (196/218, 89.9%, p<0.05). Using logistic regression analyses, the development of IM was noted to be independently related to both H. pylori infection (odds ratio=1.97, 95% confidence interval: 1.1(3.53)) and age (odds ratio = 1.93, 95% confidence interval: 1.51(2.47)). CONCLUSIONS: These data suggest that age and H. pylori infection are independent risk factors for the development of IM. Furthermore, H. pylori infection may have been underestimated in patients with IM because of the use of a single method of detection.

Aged↗
PubMed2001

Large-scale quarantine following biological terrorism in the United States: scientific examination, logistic and legal limits, and possible consequences.

Concern for potential bioterrorist attacks causing mass casualties has increased recently. Particular attention has been paid to scenarios in which a biological agent capable of person-to-person transmission, such as smallpox, is intentionally released among civilians. Multiple public health interventions are possible to effect disease containment in this context. One disease control measure that has been regularly proposed in various settings is the imposition of large-scale or geographic quarantine on the potentially exposed population. Although large-scale quarantine has not been implemented in recent US history, it has been used on a small scale in biological hoaxes, and it has been invoked in federally sponsored bioterrorism exercises. This article reviews the scientific principles that are relevant to the likely effectiveness of quarantine, the logistic barriers to its implementation, legal issues that a large-scale quarantine raises, and possible adverse consequences that might result from quarantine action. Imposition of large-scale quarantine-compulsory sequestration of groups of possibly exposed persons or human confinement within certain geographic areas to prevent spread of contagious disease-should not be considered a primary public health strategy in most imaginable circumstances. In the majority of contexts, other less extreme public health actions are likely to be more effective and create fewer unintended adverse consequences than quarantine. Actions and areas for future research, policy development, and response planning efforts are provided.

Bioterrorism↗
PubMed1999

Logistic regression analysis of small round cell neoplasms: a cytologic study.

The diagnosis of small round cell neoplasms (SRCN) in children is difficult by both histologic and cytologic methods. These neoplasms are unified morphologically by the scanty cytoplasm surrounding relatively round nuclei containing a primitive chromatin pattern. Further categorization is achieved histologically by the recognition of architectural differentiation and cytoplasmic features. Numerous series and case reports documenting the cytologic features of SRCN have been published in the English-language literature, but relatively few studies have statistically analyzed the diagnostic utility of these features. Our logistic regression analysis of 59 cases of SRCN indicates that the presence of an extremely scanty cytoplasm favors the diagnosis of Ewing's sarcoma (P = 0.004), as does the positive expression of cytoplasmic vacuoles (P = 0.02). Strap or tadpole cells closely correlate with the diagnosis of rhabdomyosarcoma (P < 0.001). The positive expression of rosettes strongly supports the presence of a neuroblastoma (P < 0.001). The diagnosis of Wilms' tumor is confirmed by the expression of tubules (P < 0.001). The presence of lymphoglandular bodies strongly favors the diagnosis of lymphoma (P < 0.001). While some cytologic features are highly correlated with specific SRCN, these features are not invariably present, and definitive diagnosis may require immunohistochemical or ultrastructural analysis performed on cell block material.

Carcinoma, Small Cell↗
PubMed1982

A logistic model based on enzyme activities for the prediction of response of breast cancer patients to chemotherapy.

A logistic regression model, utilizing the activities of certain selected glycolytic enzymes and ER status measured on primary or recurrent lesions, has been applied to predict for response to combination chemotherapy regimens administered to women with advanced breast cancer. The clinical outcome of response or no response was evaluated retrospectively using criteria employed by cooperative group protocols. In 93 cases, 58/61 patients classified as nonresponders and 22/32 patients demonstrating objective responses would have been correctly designated, based on the 50% estimated probability as the level for separation of responders from nonresponders. The overall predictive accuracy of this model was 86%, with apparently greater accuracy for prediction of lack of response. Addition of estrogen receptor status to the model imparted no gain in accuracy of prediction. Application of this model to a prospective study is warranted.

Adult↗
PubMed1988

A step-wise logistic regression analysis of hepatocellular carcinoma. An aspiration biopsy study.

Fine needle aspiration biopsy (FNAB) has become a popular method to diagnose mass lesions of the liver. Although several reports have listed FNAB criteria to be used to diagnose both primary and metastatic tumors of the liver, none have separated key cytologic criteria from secondary criteria. We reviewed the FNAB smears from 35 patients with proven hepatocellular carcinoma and 74 patients with proven metastatic tumors in the liver. All specimens were coded as to the presence or absence of the following variables: polygonal cells with centrally placed nuclei; well-defined, granular cytoplasm; large nucleoli; small cytoplasmic vacuoles; large cytoplasmic vacuoles; bile; polymorphonuclear leukocytes; malignant cells separated by sinusoidal vessels; endothelial cells surrounding tumor cell clusters; multinucleated tumor giant cells; basophilic intracytoplasmic inclusions; eosinophilic intracytoplasmic inclusions; and intranuclear cytoplasmic inclusions. A step-wise logistic regression analysis was performed on the data to determine the variables predictive of hepatocellular carcinoma. The statistical analysis selected polygonal cells with centrally placed nuclei, malignant cells separated by sinusoidal capillaries, and bile as the key cytologic criteria for hepatocellular carcinoma. Endothelial cells surrounding tumor cell clusters and intranuclear cytoplasmic inclusions were selected as secondary criteria by this analysis.

Biopsy, Needle↗
PubMed1988

Prognostic factors in advanced nonseminomatous testicular cancer. A multivariate logistic regression analysis.

In order to define prognostic factors for advanced stage of nonseminomatous germ cell tumors (NSGCT) of the testis, the authors reviewed 84 patients treated from 1978 through 1985. The survival rate was 51% at 3 years. Patients with elevated seric levels of human chorionic gonadotropin (HCG) and/or alpha-fetoprotein (AFP), or the presence of an abdominal mass had significantly worse survival. Only HCG and AFP levels retained their significance when multivariate Cox analysis was performed. The probability that a patient achieves a complete remission (CR) was assessed by a function of certain patient characteristics using a multivariate logistic regression analysis. The significant variables were a function of HCG and AFP values. Since both variables are related to the CR rate and survival the authors define the obtention of a CR as a unique outcome of interest. The probability of a CR greater than 70% adequately separates the patients into two prognostic subgroups. This model currently is being used to enrole NSGCT patients in a prospective modulated clinical trial according to these prognostic factors.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Prognostic factors influencing cisplatin-induced emesis. Definition and validation of a predictive logistic model.

Data obtained from 209 patients who entered different prospective randomized antiemetic trials were analyzed to establish the prognostic value of some variables on the control of cisplatin-induced emesis. The antiemetic regimens evaluated included the following: metoclopramide (M) at 1, 2, and 4 mg/kg total dose and a combination of M (4 mg/kg) with dexamethasone (D) (40 mg). Vomiting lasting more than 1 hour (no protection [NP]) was the endpoint selected for the analysis. A logistic model carried out, first on the 110 subjects receiving the M + D regimen and then on the whole sample, selected sex (P = 0.0001), Eastern Cooperative Oncology Group performance status (PS) (P = 0.006), and age (P = 0.01) among the six factors considered. Since the prognostic value of these variables is mostly related to their interaction, three major risk classes were identified. The corresponding NP rates were 26.3%, 42.4%, and 70.8% for the low-risk, intermediate-risk, and high-risk groups, respectively (P = 0.000002). Except for the lowest M level, the observed NP rates were significantly associated to the risk classes, whereas the antiemetic regimen influenced the antiemetic outcome only in the low-risk class. Regardless of the regimen employed, certain patient characteristics, such as sex, PS, and age, significantly affect cisplatin-related emesis and should be carefully considered in planning further studies.

Adult↗
PubMed1981

Duchenne muscular dystrophy carrier detection using logistic discrimination: serum creatine kinase and hemopexin in combination.

Creatine kinase (CK) activity and hemopexin concentration were measured in 208 serum samples from 104 normal females and 22 obligate carriers of Duchenne muscular dystrophy (DMD) 20-40 years old. Logistic discrimination was used to assess the effectiveness of the parameters alone or in combination in identifying DMD carriers. In this approach, a serum sample with particular CK, hemopexin, or a combination of CK and hemopexin values is given a probability that if drawn at random from a defined mixture of controls and carriers, it comes from a carrier. The carrier probability based on the biochemical tests can be directly combined with the carrier probability determined from a woman's pedigree to yield a final posterior probability that she is a carrier. When CK and hemopexin were considered individually, 65 and 27% of the carriers, respectively, could be distinguished from 95% of the controls. When the two tests were used in combination, 82% of the carriers could be distinguished from 95% of the controls. When the two-test method was applied to 93 possible carriers, 35 women were classified as carriers, whereas only 29 were identified using CK alone. This method can be extended to include other variables in order to further improve the identification of DMD carriers. It can also be applied to carrier detection in other genetic disorders.

Adolescent↗