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PubMed2005

Logistic regression model to distinguish between the benign and malignant adnexal mass before surgery: a multicenter study by the International Ovarian Tumor Analysis Group.

PURPOSE: To collect data for the development of a more universally useful logistic regression model to distinguish between a malignant and benign adnexal tumor before surgery. PATIENTS AND METHODS: Patients had at least one persistent mass. More than 50 clinical and sonographic end points were defined and recorded for analysis. The outcome measure was the histologic classification of excised tissues as malignant or benign. RESULTS: Data from 1,066 patients recruited from nine European centers were included in the analysis; 800 patients (75%) had benign tumors and 266 (25%) had malignant tumors. The most useful independent prognostic variables for the logistic regression model were as follows: (1) personal history of ovarian cancer, (2) hormonal therapy, (3) age, (4) maximum diameter of lesion, (5) pain, (6) ascites, (7) blood flow within a solid papillary projection, (8) presence of an entirely solid tumor, (9) maximal diameter of solid component, (10) irregular internal cyst walls, (11) acoustic shadows, and (12) a color score of intratumoral blood flow. The model containing all 12 variables (M1) gave an area under the receiver operating characteristic curve of 0.95 for the development data set (n = 754 patients). The corresponding value for the test data set (n = 312 patients) was 0.94; and a probability cutoff value of .10 gave a sensitivity of 93% and a specificity of 76%. CONCLUSION: Because the model was constructed from multicenter data, it is more likely to be generally applicable. The effectiveness of the model will be tested prospectively at different centers.

Adnexal Diseases↗
PubMed1999

Risk factors of delayed extubation, prolonged length of stay in the intensive care unit, and mortality in patients undergoing coronary artery bypass graft with fast-track cardiac anesthesia: a new cardiac risk score.

BACKGROUND: Risk factors of delayed extubation, prolonged intensive care unit (ICU) length of stay (LOS), and mortality have not been studied for patients administered fast-track cardiac anesthesia (FTCA). The authors' goals were to determine risk factors of outcomes and cardiac risk scores (CRS) for CABG patients undergoing FTCA. METHODS: Consecutive CABG patients undergoing FTCA were prospectively studied. Outcome variables were delayed extubation > 10 h, prolonged ICU LOS > 48 h, and mortality. Univariate analyses were performed followed by multiple logistic regression to derive risk factors of the three outcomes. Simplified integer-based CRS were derived from logistic models. Bootstrap validation was performed to assess and compare the predictive abilities of CRS and logistic models for the three outcomes. RESULTS: The authors studied 885 patients. Twenty-five percent had delayed extubation, 17% had prolonged ICU LOS, and 2.6% died. Risk factors of delayed extubation were increased age, female gender, postoperative use of intraaortic balloon pump, inotropes, bleeding, and atrial arrhythmia. Risk factors of prolonged ICU LOS were those of delayed extubation plus preoperative myocardial infarction and postoperative renal insufficiency. Risk factors of mortality were female gender, emergency surgery, and poor left ventricular function. CRSs were modeled for the three outcomes. The area under the receiver operating characteristic curve for the CRS-logistic models was not significantly different: 0.707/0.702 for delayed extubation, 0.851/0.855 for prolonged ICU LOS, and 0.657/0.699 for mortality. CONCLUSION: In CABG patients undergoing FTCA, the authors derived and validated risk factors of delayed extubation, prolonged ICU LOS, and mortality. Furthermore, they developed a simplified CRS system with similar predictive abilities as the logistic models.

Aged↗
PubMed1996

A logistic-regression model provides novel guidelines to maximize the anti-acute rejection properties of cyclosporine with a minimum of toxicity.

Although cyclosporine has become the mainstay of immunosuppression in organ transplantation, there is still no consensus on the criteria to optimize its anti-rejection activity with minimum toxicity. A clear and objective definition of target cyclosporine trough levels at different times from renal transplantation is still lacking, primarily because of the lack of a model correlating cyclosporine levels with probability of rejection or toxicity. In this study, logistic-regression model was developed that was applied to data collected retrospectively from two postoperative periods, i.e., Days 0 to 9 and 10 to 30, in 135 consecutive cadaveric renal transplant recipients, for a total of 1851 determinations. Only minimum and maximum trough levels were considered for each period. Concentration-response curves were estimated for Days 0 to 9 (P = 0.0001 for efficacy and P = 0.028 for toxicity) and for Days 10 to 30 (P = 0.015 for efficacy and P = 0.037 for toxicity). Therapeutic intervals of 330 to 430 ng/mL (parent compound in whole blood) for Days 0 to 9 and 260 to 390 ng/mL for Days 10 to 30 predicted an incidence of acute rejection of 22% and 12%, respectively, with a reasonably low toxicity that primarily consisted of elevation of serum aminotransferases.

Adult↗
PubMed1990

Global behaviour of age-dependent logistic population models.

We study the large time behaviour of a nonlinear population model with a general logistic term. It is proved that every solution must have a limit when time becomes infinite. We present conditions that guarantee the boundedness of the solution. Furthermore, we prove that in general no oscillation is possible for the total number of population. This is in sharp contrast to the linear case.

Aging↗
PubMed2002

Feasibility of predicting the risk of atrial fibrillation after coronary artery bypass surgery with logistic regression model.

BACKGROUND AND AIMS: The aim of this study was to determine the risk factors of postoperative atrial fibrillation (AF) after coronary artery bypass grafting and to create predictive model and to evaluate the effects of AF on patients outcome. MATERIAL AND METHODS: Data of 3,676 consecutive patients were analysed to identify the predictors of AF. Multivariate logistic regression model was validated prospectively in 1,107 patients. RESULTS: Increasing age (p < 0.001), preoperative use of digoxin (p = 003), need of intra-aortic balloon pump or inotropic medication in the weaning off cardiopulmonary by pass or during the first 24 hours postoperatively (p = 0.013), increasing body surface area (p = 0.006) and lower ejection fraction (p = 0.048) were independent risk factors for postoperative AF. The predictive model gave area under the receiver-operating characteristic (ROC) curve 0.682, 95% confidence interval 0.663-0.701, and p < 0.001. The patients with AF incidence had more postoperative stroke (p = 0.008), confusion (p < 0.001) severe gastrointestinal complications (p = 0.005), readmission to ICU (p < 0.001), longer ICU (p < 0.001) and hospital stay (p < 0.001) when compared with the patients who remained in sinus rhythm. CONCLUSION: Logistic regression model with the parameters used was not accurate enough for clinical purposes. Postoperative AF is associated with postoperative stroke, severe gastrointestinal complications, readmission to ICU, and longer ICU and hospital stay.

Aged↗
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↗
PubMed2005

Prediction of coronary artery disease severity in patients referred for coronary angiography.

BACKGROUND: Diagnostic coronary angiography is often followed by coronary stenting. Therapy with aspirin and clopidogrel is currently the standard treatment for patients undergoing coronary stenting. Clopidogrel loading is usually given prior to the procedure. Some pretreated patients, however, are found to have triple-vessel disease (3VD) or left main disease (LMD) that requires referral for coronary artery bypass graft (CABG) surgery. Surgery in patients pretreated with clopidogrel may be complicated by excessive bleeding or delayed to avoid that risk. HYPOTHESIS: A risk factor-based formula may predict the likelihood that patients referred for coronary angiography will have 3VD or LMD. METHODS: Consecutive patients (n = 2,180) referred for coronary angiography constitute the training subset (n = 1,296) used to build the model, and the validation subset (n = 884) used to test the model. Logistic regression models selected five variables showing strong associations with the presence of 3VD or LMD: age, gender, diabetes, hypercholesterolemia, and prior myocardial infarction (MI). A formula based on these variables and on the training subset was constructed to calculate the probability of 3VD or LMD. RESULTS: Applying this model to the validation subset predicted 3VD or LMD with 79% sensitivity, 53% specificity, 45% positive predictive value, and 83% negative predictive value. CONCLUSIONS: This simple formula based on five clinical variables is helpful in predicting the likelihood that patients, referred for coronary angiography, will have 3VD or LMD. Use of this formula can help decide in which patients clopidogrel loading prior to angiography should be avoided.

Adult↗
PubMed1998

Dieting status and its relationship to eating and physical activity behaviors in a representative sample of US adolescents.

OBJECTIVE: To determine whether adolescents engaging in extreme weight loss methods (i.e., vomiting and diet pills) and those using more moderate methods differ from each other in dietary intake (fruits, vegetables, and higher-fat foods) and physical activity, and to compare these variables in dieting and nondieting adolescents. DESIGN: Data were obtained from the 1993 Youth Risk Behavior Survey. SUBJECTS/SETTINGS: The survey was administered to a nationally representative sample of 16,296 adolescents in grades 9 through 12 in a school setting. STATISTICAL ANALYSES: Data were analyzed for 16,125 adolescents. Associations between weight control behaviors and dietary intake and physical activity were examined using mixed-model logistic regressions, controlling for grade in school, race, parental education, region of the country, and urban vs nonurban residence. RESULTS: Differences in dietary and physical activity were found among adolescents who use extreme weight loss methods and moderate methods, and between dieters and nondieters. Adolescents using moderate methods of weight control engaged in more health-promoting eating and exercise behaviors than did extreme dieters or nondieters. Girls categorized as extreme dieters were less likely to eat fruits and vegetables than were moderate dieters (odds ratio [OR] = .56) or nondieters (OR = .75), and were more likely than more moderate dieters (OR = .76) to have consumed 2 or more servings of high-fat foods during the previous day. APPLICATIONS/CONCLUSIONS: Our findings suggest the importance of distinguishing between different types of dieting behaviors in clinical settings and research studies. Adolescents engaging in extreme weight control behaviors may be at particular risk for inadequate nutritional intake. In contrast, adolescents using more moderate methods may be consuming a more healthful diet than are nondieters. For all adolescents, nutrition guidance on healthful and safe weight control strategies is needed.

Adolescent↗
PubMed2002

Dose-response relationship between probability of pathologic tumor control and glucose metabolic rate measured with FDG PET after preoperative chemoradiotherapy in locally advanced non-small-cell lung cancer.

PURPOSE: To determine the dose-response relationship between the probability of tumor control on the basis of pathologic tumor response (pTCP) and the residual metabolic rate of glucose (MRglc) in response to preoperative chemoradiotherapy in locally advanced non-small-cell lung cancer and to define the level of residual MRglc that corresponds to pTCP 50% and pTCP > or = 95%. METHODS AND MATERIALS: Quantitative dynamic 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography was performed to measure regional MRglc at the primary lesion before and 2 weeks after preoperative chemoradiotherapy in an initial group of 13 patients with locally advanced NSCLC. A simplified kinetic method was developed subsequently from the initial dynamic study and used in the subsequent 16 patients. The preoperative radiotherapy programs consisted of (1) a split course of 42 Gy in 28 fractions within a period of 28 days using a twice-daily treatment schedule for Stage IIIA(N2) NSCLC (n = 18) and (2) standard once-daily radiation schedule of 45-63 Gy in 25-35 fractions during a 5-7-week period (n = 11). The preoperative chemotherapy regimens included two cycles of cisplatin, vinblastine, and 5-fluorouracil (n = 24), cisplatin and etoposide (n = 2), and cisplatin, Taxol, and 5-fluorouracil (n = 3). Patients free of tumor progression after preoperative chemoradiotherapy underwent surgery. The degree of residual MRglc measured 2 weeks after preoperative chemoradiotherapy and 2 weeks before surgery was correlated with the pathologic tumor response. The relationship between MRglc and pTCP was modeled using logistic regression. RESULTS: Of 32 patients entered into the study, 29 (16 men and 13 women; 30 lesions) were evaluated for the correlation between residual MRglc and pathologic tumor response. Three patients did not participate in the second study because of a steady decline in general condition. The median age was 60 years (range 42-78). One of the 29 patients had two separate lesions, and MRglc was measured in each separately. The tumor histologic types included squamous cell carcinoma (n = 9), adenocarcinoma (n = 13), large cell carcinoma (n = 6), and poorly differentiated carcinoma (n = 2). The extent of the primary and nodal disease was as follows: Stage IIB (T3N0M0), Pancoast tumor (n = 2); Stage IIIA, T2-T3N2M0 (n = 18); Stage IIIB: T1-T3N3M0 (n = 5) and T4N0M0 (n = 2); a second lesion, T1 (n = 1); and localized stump recurrence (n = 2). A pathologically complete response was obtained in 14 (47%) of the 30 lesions. The remaining 16 lesions had residual cancer. The mean baseline value of the maximal MRglc was 0.333 +/- 0.087 micromol/min/g (n = 16), and it was reduced to 0.0957 +/- 0.059 micromol/min/g 2 weeks after chemoradiotherapy (p = 0.011). The correlation between residual MRglc and pTCP was made using an increment value of 0.02 micromol/min/g between the maximal and minimal values of MRglc. A pathologically complete response was obtained in 6 of 6 patients with residual MRglc of < or = 0.050 micromol/min/g, 3 of 4 with < or = 0.070, 4 of 7 with < or = 0.090, 0 of 4 with < or = 0.110, 1 of 3 with < or = 0.130, and 0 of 6 with > or = 0.130 micromol/min/g. The fitted logistic model showed that residual MRglc corresponding to pTCP 50% and pTCP > or = 95% was 0.076 and < or = 0.040 micromol/min/g, respectively. CONCLUSION: The correlation between the gradient of residual MRglc after chemoradiotherapy and pTCP is an inverse dose-response relationship. Residual MRglc of 0.076 and < or = 0.040 micromol/min/g, representing pTCP 50% and pTCP > or = 95%, respectively, may be useful surrogate markers for the tumor response to radiotherapy or chemoradiotherapy in lung cancer.

Adult↗
PubMed1997

The role of social influences and tobacco availability on adolescent smokeless tobacco use.

OBJECTIVE: To examine the potential explanatory effect of various demographic, social influence, sanction, and tobacco availability variables on the use of smokeless tobacco (ST) by adolescent males. DESIGN: The data used in our analyses are from a community-based tobacco policy intervention trial that included a 60-item baseline school survey. During Spring 1993, all 8th, 9th, and 10th-grade students enrolled in 14 school districts in small Minnesota cities were surveyed. We used mixed-model logistic regression to determine which variables were significantly correlated with smokeless tobacco use by males in the past week. RESULTS: Of this sample of 2924 adolescent males, 10% (n = 291) reported using smokeless tobacco in the past week. Compared to the overall sample, smokeless tobacco users reported higher family and friend use of smokeless tobacco. In addition, 64% of users reported smoking in the past 30 days, and almost half (49.1%) said they had attempted to purchase tobacco in the past 30 days. Variables found to be significantly associated with smokeless tobacco use in the past week included younger age, having a best friend using tobacco, inflated perceptions of their peers' use of tobacco products, beliefs that school and parental sanctions are not high for tobacco use, recent tobacco purchase, and perceived belief that tobacco is not difficult to obtain from social sources. CONCLUSIONS: This study confirms previous research correlating demographic and social influence factors with ST use and demonstrates the role that sanction and availability variables play in ST use.

Adolescent↗
PubMed2003

Orofacial trauma and rugby in France: epidemiological survey.

A stratified epidemiological survey was carried out among the best French rugby players to assess the prevalence of trauma to the lower or middle part of the face (TLMPF) and the frequency at which the mouthguards (MGs) were worn. The 1140 randomized players (elite 1, elite 2 and national 1 clubs) filled in the same form anonymously. The variables were first subjected to univariate analysis (Chi-square, anova). Secondly, they were included in a multivariate model (logistic regression). Some 29.57% of players had already been affected by a TLMPF. The risk increased for the oldest forward players. It also increased with the number of yearly competitions and number of hours of weekly training. Some 64.3% of players used a MG. The frequency at which it was worn increased with the number of yearly competitions, for those who had experinced a previous trauma and for the pack players who had been playing for a long time.

Adult↗
PubMed2005

Dyslipidaemia and microvascular disease in the retina.

PURPOSE: There are few data on the effect of serum lipids on microvascular disease. This study assessed the relationships between serum lipid levels and microvascular disease, as seen in the retina, among participants who attended a population-based study in Australia (n=3654, aged 49+years). METHODS: Diameters of retinal arterioles and venules were measured from digitised photographs of each participant to obtain an estimate of generalised arteriolar narrowing. Focal arteriolar narrowing, arteriovenous nicking, and retinopathy lesions (microaneurysms, haemorrhages, hard/soft exudates) were graded using a standard protocol. Fasting blood tests were performed in 89% of subjects. Adjusted means were calculated using general linear models. Logistic regression models were used to determine the odds ratios for retinal microvascular signs. RESULTS: After controlling for age, sex, body mass index, smoking, and mean arterial blood pressure, elevated high-density lipoprotein cholesterol was associated with narrower retinal arterioles (Ptrend=0.002) and venules (Ptrend=0.03) and with increased odds of generalised arteriolar narrowing (odds ratio 1.6, 95% confidence interval 1.1-2.2 for the highest vs the lowest quintile of high-density lipoprotein cholesterol). Serum triglyceride had a U-shaped relationship with venular diameter (Ptrend=0.003). We found no consistent pattern of association between serum total cholesterol or low-density lipoprotein cholesterol and any retinal microvascular signs. CONCLUSIONS: These findings suggest that microvascular disease in the retina may result from processes distinct from dyslipidaemia.

Aged↗
PubMed2001

Risk factors for fatal myocardial infarction after coronary bypass graft surgery.

BACKGROUND AND OBJECTIVE: The incidence and clinical impact of perioperative myocardial infarction during coronary artery bypass graft surgery vary greatly depending upon the diagnostic criteria applied. Fatal perioperative myocardial infarction has a less arguable diagnosis and clinical impact. The aim of this paper is to find out the risk factors for fatal myocardial infarction after coronary surgery. METHODS: Data from 1561 consecutive patients, who underwent coronary revascularization during a 10-month period, have been retrospectively analysed. After an univariate analysis for pre- and intraoperative risk factors, a multivariate model (logistic regression analysis) was settled. RESULTS: Preoperative use of subcutaneous/intravenous heparin, a heparin sensitivity index < 1.3 and need for a thromboendarterectomy of the left anterior descending coronary artery are independent risk factors for fatal myocardial infarction. The relative risk for fatal myocardial infarction was about 2 in the case of preoperative heparin use or heparin sensitivity index < 1.3 and 5.5 in the case of thromboendarterectomy of the left anterior descending coronary artery. CONCLUSIONS: In patients undergoing coronary artery bypass surgery, preoperative anticoagulation management with heparin may represent a risk factor for fatal myocardial infarction. Patterns of heparin resistance, whether or not due to heparin pretreatment, seem to be closely related to fatal myocardial infarction.

Aged↗
PubMed2004

Amyotrophic lateral sclerosis: delayed disease progression in mice by treatment with a cannabinoid.

Effective treatment for amyotrophic lateral sclerosis (ALS) remains elusive. Two of the primary hypotheses underlying motor neuron vulnerability are susceptibility to excitotoxicity and oxidative damage. There is rapidly emerging evidence that the cannabinoid receptor system has the potential to reduce both excitotoxic and oxidative cell damage. Here we report that treatment with Delta(9)-tetrahydrocannabinol (Delta(9)-THC) was effective if administered either before or after onset of signs in the ALS mouse model (hSOD(G93A) transgenic mice). Administration at the onset of tremors delayed motor impairment and prolonged survival in Delta(9)-THC treated mice when compared to vehicle controls. In addition, we present an improved method for the analysis of disease progression in the ALS mouse model. This logistic model provides an estimate of the age at which muscle endurance has declined by 50% with much greater accuracy than could be attained for any other measure of decline. In vitro, Delta(9)-THC was extremely effective at reducing oxidative damage in spinal cord cultures. Additionally, Delta(9)-THC is anti-excitotoxic in vitro. These cellular mechanisms may underlie the presumed neuroprotective effect in ALS. As Delta(9)-THC is well tolerated, it and other cannabinoids may prove to be novel therapeutic targets for the treatment of ALS.

Age Factors↗
PubMed2002

Hatchery and transportation factors associated with early poult mortality in commercial turkey flocks.

A prospective ecologic study, using routinely collected data from commercial turkey companies, was done of 312 turkey flocks placed over a 1-yr period. The objective was to identify hatchery- and transportation-associated risk factors for poult mortality in the first 14 d after placement using statistical models. Logistic regression was used to determine the effects of hatchery-and transportation-related factors on odds of mortality for hen and tom flocks separately. Hatchery and transportation-related risk factors for hen flock mortality included truck, truck temperature, and number of poults dead on arrival at the farm. Hatchery and transportation-related risk factors for tom flock mortality included desnooding, truck, truck temperature, shipping time, and weather conditions at placement.

Animals↗
PubMed2003

Readiness for cessation of drug use among recent attenders and nonattenders of a needle exchange program.

Needle exchange programs (NEPs) represent a bridge to drug abuse treatment. NEP attenders tend to have more severe drug problems, however, and may be less ready to reduce their drug use than other drug users. This study investigated the relationship between NEP attendance and readiness for cessation of drug use. Since the period from 1988 through 1989, a community-based sample of injection drug users (IDUs) in Baltimore has undergone semiannual interview-administered questionnaires and HIV testing. A total of 288 IDUs completed a questionnaire on readiness for cessation of drug use. Readiness for drug use cessation was assessed from a 28-item validated scale of problem drug use and intention to quit, based on the "stages of change" model. Logistic regression was used to determine factors associated with readiness for cessation of drug use, including sociodemographics, drug use behaviors, and NEP attendance. Thirty percent of respondents attended the NEP in the past month. Stage of change in readiness for cessation of drug use did not differ between NEP attenders and nonattenders (OR = 0.9; 95% CI: 0.5-1.6). Similar proportions of persons recently attending and not attending the NEP were classified as ready to stop drug use (about 30%). In multivariate analysis, readiness for cessation of drug use was associated with speedball injection and previous enrollment in drug treatment but not with NEP attendance. NEP attenders, although exhibiting characteristics consistent with more severe drug dependence, were as motivated for cessation of drug use as were nonattenders. These findings suggest that formal collaboration between NEPs and drug treatment programs could increase the proportion of IDUs in treatment.

Adult↗
PubMed2005

Modeling the pressure inactivation dynamics of Escherichia coli.

Escherichia coli, as a model microorganism, was treated in phosphate-buffered saline under high hydrostatic pressure between 100 and 300 MPa, and the inactivation dynamics was investigated from the viewpoint of predictive microbiology. Inactivation data were curve fitted by typical predictive models: logistic, Gompertz and Weibull functions. Weibull function described the inactivation curve the best. Two parameters of Weibull function were calculated for each holding pressure and their dependence on holding pressure was obtained by interpolation. With the interpolated parameters, inactivation curves were simulated and compared with the experimental data sets.

Escherichia coli↗