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Results for “Regression Analysis”

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At least 865 records · Page 48Linked to original sources

PubMed1988

[Correlation-regression analysis of the influence of psychiatric service resources on the dynamics of detected morbidity in the populations of Siberia and the Far East].

The authors have demonstrated the existence of linear correlation between the complex of three factors (the number of beds and psychiatrists in hospitals and outpatient clinics) and incidence rate (over a period of 16 years) of neuroses in 11 administrative areas, epilepsy, in 12 areas, psychoses, in 15, oligophrenia, in 17, alcoholism and schizophrenia in all 18 areas of Siberia and the Far East. Correlations of each of the three factors with the morbidity rate varied within a wide range in relation to both administrative areas and individual diseases. The authors draw attention to the importance of supplementing the growth of resources of psychiatric service with new forms and methods of work.

Ambulatory Care↗

PubMed2001

Monitoring of nonlinear respiratory elastance using a multiple linear regression analysis.

The elastic pressure/volume (P/V) curve obtained by the multiple linear regression (MLR) technique using a new model, was compared with the quasi-static P/V points obtained by the rapid airway occlusion technique. Seven infants were studied during mechanical ventilation using a pressure controlled mode. The resistive pressure was subtracted from airway opening pressure, thus determining the elastance related pressure, which was then plotted against the volume to make an MLR-elastance curve. Quasi-static P/V curves of the rapid occlusion technique were constructed by plotting the different inspiratory and expiratory volumes against the corresponding values of the quasi-static airway pressure. The calculated MLR-elastance curves closely fit the experimental quasi-static P/V points obtained by the occlusion technique. There were, however, some discrepancies due to the viscoelastic behaviour of the respiratory system. Although slightly altered by these discrepancies, the multiple linear regression-elastance curves did fit the observed quasi-static pressure/volume characteristics for use in clinical practice. The multiple linear regression technique may prove to be clinically useful by continuous monitoring of respiratory system mechanics during mechanical ventilation.

Airway Resistance↗

PubMed1990

[Effect of psychiatric service resources on detection of mentally ill patients in Siberia and Far East (correlation-regression analysis)].

Analysis of the character of the linear relation between the totality and some factors (the number of beds, psychiatrists working at hospitals and on an outpatient basis) that characterize the psychiatric services in 18 regions of Siberia and the Far East over 16 years as well as between the identification of new cases of schizophrenia, epilepsy, alcoholism, neuroses, psychoses and oligophrenia has demonstrated a high efficacy of the totality of factors. The differences have been shown between the regions in respect to the relation of the factors to the disease incidence, explained by the authors by the specificity of the organizational structure of the psychiatric services and by a number of other factors.

Community Mental Health Services↗

PubMed1993

A computer program for regression analysis of repeated measures using generalized estimating equations.

RMGEE is an easy-to-use FORTRAN program for the analysis of repeated binary, count, and normally-distributed response variables using the generalized estimating equations approach of Liang and Zeger [1]. The program can be used when measurements are obtained at multiple time points from each subject or experimental unit, and also when the basic sampling unit is a group or cluster of subjects, and the response variable of interest is obtained from each subject within the cluster. It is not necessary for the number of repeated measurements to be the same for every experimental unit and missing data are easily accommodated. Both time-independent (cluster-specific) and time-dependent (occasion- or subject-specific) covariates are permitted. The program can be run on microcomputers, workstations, and mainframe computers. Three examples illustrating the usage and features of RMGEE are provided.

Algorithms↗

PubMed1986

The efficacy of intraoperative autologous transfusion in major orthopedic surgery: a regression analysis.

Perioperative blood loss associated with 89 cases of major orthopedic surgery was compared with that of a control group of 89 to determine the effectiveness of intraoperative autologous transfusion. Volume of banked blood transfused and hematocrit change were used to determine total blood loss. The orthopedic cases consisted of cemented "virgin" total hip replacement, cemented virgin tricompartmental knee replacement, and spine fusion. Use of an autotransfusion device (Cell Saver) intraoperatively was associated with significantly smaller volumes of transfused banked blood and significantly smaller hematocrit drops in the groups of patients who underwent total hip replacement or spine fusion, but not in the group of patients who underwent total knee replacement. One potential source of bias in the study stems from the fact that four days were allotted for equilibrium from perioperative blood loss in the hip and knee replacement groups, while, for reasons of data availability, equilibrium time in the spine fusion groups was two days.

Adult↗

PubMed1990

Clinical significance of a multiple biomarker assay in patients with lung cancer. A study with logistic regression analysis.

The relative usefulness of a combination of some tumor markers, such as CEA, AFP, ferritin and NSE for the diagnosis of lung cancer was assessed by multiple logistic analysis. Serum concentration of these markers was determined in 68 patients with lung cancer (50 with NSCLC and 18 with SCLC, in 68 patients with benign lung disease and 75 normal control subjects. Ferritin proved to be the most useful in diagnosing both NSCLC and SCLC, while NSE was found to be of some help in diagnosing SCLC only. The multiple marker panel proved to be more sensitive and specific than any single marker in discriminating lung cancer from normal control tissue, but it was of limited value in discriminating malignant from benign lung disease. The results of the present study would suggest that the panel of investigated tumor markers is not of great help for the early diagnosis of lung cancer.

Biomarkers, Tumor↗

PubMedDate not supplied

Factors affecting alkalinity generation by successive alkalinity-producing systems: regression analysis.

Use of successive alkalinity-producing systems (SAPS) for treatment of acidic mine drainage (AMD) has grown in recent years. However, inconsistent performance has hampered widespread acceptance of this technology. This research was conducted to determine the influence of system design and influent AMD chemistry on net alkalinity generation by SAPS. Monthly observations were obtained from eight SAPS cells in southern West Virginia and southwestern Virginia. Analysis of these data revealed strong, positive correlations between net alkalinity generation and three variables: the natural log of limestone residence time, influent dissolved Fe concentration, and influent non-Mn acidity. A statistical model was constructed to describe SAPS performance. Subsequent analysis of data obtained from five systems in western Pennsylvania (calibration data set) was used to reevaluate the model form, and the statistical model was adjusted using the combined data sets. Limestone residence time exhibited a strong, positive logarithmic correlation with net alkalinity generation, indicating net alkalinity generation occurs most rapidly within the first few hours of AMD-limestone contact and additional residence time yields diminishing gains in treatment. Influent Fe and non-Mn acidity concentrations both show strong positive linear relationships with net alkalinity generation, reflecting the increased solubility of limestone under acidic conditions. These relationships were present in the original and the calibration data sets, separately, and in the statistical model derived from the combined data set. In the combined data set, these three factors accounted for 68% of the variability in SAPS systems performance.

Calibration↗

PubMed1995

Prognostic factors in patients with cervix cancer treated by radiation therapy: results of a multiple regression analysis.

A retrospective analysis of 965 patients with invasive cervix cancer treated by radiation therapy between 1976 and 1981 was performed in order to evaluate prognostic factors for disease-free survival (DFS) and pelvic control. FIGO stage was the most powerful prognostic factor followed by radiation dose and treatment duration (P values = 0.0001). If the analysis was limited to patients treated with radical doses of 75 Gy or more, dose was no longer significant. Young age at diagnosis, non-squamous histology and transfusion during treatment were also adverse prognostic factors for survival and control. Para-aortic nodal involvement on lymphogram was associated with a reduction in DFS (P = 0.0027), whereas pelvic lymph node involvement alone was not. In patients with Stage I and IIA disease, tumour size was the most powerful prognostic factor for survival (P = 0.0001) and the extent of pelvic sidewall involvement was significant in patients with Stage III tumours (P = 0.007). Histological grade appeared to be a predictive factor but was only recorded in 712 patients. These features should be considered in the staging of patients and in the design of clinical trials.

Adult↗

PubMed1990

Determinants of dissatisfaction with dentures: a multiple regression analysis.

The purpose of this study was to investigate the relationship between satisfaction with complete dentures and several causal factors. One hundred thirty patients who received new dentures were investigated during their treatment. The results showed that 33% of the variance in satisfaction with dentures could be clarified by (1) the attitude toward dentures, (2) the quality of the dentures, (3), the oral conditions (opposite of what was expected), and (4) the number of previous dentures worn. Thus the patient's attitude toward dentures, measured by a questionnaire administered prior to his or her receiving new dentures, and the number of previous dentures worn, are prospective indicators for satisfaction with new dentures. The oral condition and the patient's personality seem to be unimportant factors, as measured by a neurotic lability scale and by a "health locus of control scale." Only 33% of the variance in satisfaction could be clarified by means of the variables used in the study. Thus satisfaction with dentures for most patients is individually determined and, for dentist and patient, is often unpredictable.

Adult↗

PubMedDate not supplied

Investigation of risk factors for porcine Taenia solium cysticercosis: a multiple regression analysis of a cross-sectional study in the Yucatan Peninsula, Mexico.

A cross-sectional survey for seropositivity to cysticercosis of pigs in the Yucatan Peninsula, Mexico, was carried out in 1996 together with a standardized questionnaire on predetermined individual pig and household risk factors for porcine infection. Serum samples from 697 pigs were analysed by immunoblot for antibodies to Taenia solium cysticercosis and questionnaires from 227 households in 18 villages were collected. All the data were analysed using multivariate analytical techniques taking household clustering into account. The overall porcine seroprevalence in the area was found to be 29%. The most important risk factors for seropositivity in pigs were presence versus absence of a toilet (adjusted odds ratio [adj. OR] 2.37, P = 0.005), crowded households (adj. OR 1.75, P = 0.034) and both corralling (adj. OR 2.14, P = 0.017) and letting pigs loose (adj. OR 2.32, P = 0.035) versus tying them up. There was evidence of clustering at household level and that possible risk factors at municipal or village level may also interact with higher risk management practices such as allowing pigs to run loose.

Animal Husbandry↗

PubMed1987

Regression analysis, proposed interpretative zone size standards, and quality control guidelines for a new macrolide antimicrobial agent, A-56268 (TE-031).

A-56268 is a 6-O-methyl derivative of erythromycin A which has a spectrum of activity similar to that of erythromycin and is 1 log2 dilution more potent than erythromycin against most organisms that have been tested. The correlation of zone size diameters and MICs of A-56268 for 461 strains of bacteria isolated from clinical specimens was investigated. Based on anticipated levels in human serum of 2 micrograms/ml, 15-microgram disks have been recommended with zone size standards of greater than or equal to 15 mm for susceptibility (MIC correlate, less than or equal to 2.0 micrograms/ml) and less than or equal to 11 mm for resistance (MIC correlate, greater than or equal to 8 micrograms/ml). Selection of these tentative breakpoints resulted in no very major errors (false susceptible), a major error (false resistant) rate of 0.22%, and an acceptable minor error (intermediate) rate of 2.82%. MIC ranges and zone diameter limits for quality control organisms used in the standardized agar dilution and disk diffusion susceptibility tests with A-56268 are given.

Clarithromycin↗

PubMed1981

Factors influencing survival after therapeutic shunts. Results of a discriminant function and linear logistic regressions analysis.

Data on 100 consecutive patients undergoing portasystemic shunt at three hospitals of the University of California, San Francisco, were analyzed retrospectively to look for variables portending poor immediate and long-term outcome. As a determinant of early mortality after portacaval shunt, the Child's classification of the patient remains the single most important factor. If the patient is in Child's class C and has a hematocrit of less than 32 percent, he is even less likely to survive 30 days. The malnourished male patient who resumes drinking postoperatively is least likely to survive 1 year. Though short- and long-term mortality did not correlate with type of shunt, the prosthetic interposition mesocaval shunt was associated with an unacceptably high thrombosis rate of 20 percent in our institutions, and represented a technical failure to achieve the goal of preventing further variceal bleeding. No matter what type of shunt was performed, however, the 30 day mortality of Child's class C patients exceeded 50 percent. In the latter patients methods of treatment other than portasystemic shunts should be evaluated.

Adolescent↗

PubMed1995

Bivariate logistic regression analysis of childhood psychopathology ratings using multiple informants.

A central issue in studies of risk factors for childhood psychopathology is utilization of the information obtained about the child's mental health status from multiple informants. In this paper, the authors propose a new approach to the analysis of risk factor data when the outcomes are binary ratings (presence/absence of symptoms). This new approach has several attractive features in this setting. The strategy taken is to perform a single analysis using multivariate modeling, in which simultaneous logistic regressions are conducted for the outcomes given by each of several informants. The advantages of this approach include the following: 1) it retains the complete information about case status for each informant; 2) it permits assessment of informant-risk factor interactions as well as "overall" risk factor effects; 3) it provides measures of association between the multiple informants and adjusts for the association between responses in the analysis; and 4) missing data on a subset of respondents can be incorporated in a straightforward way, permitting all subjects with at least one informant to be used in the analysis. To illustrate the methods, the authors present findings on risk factors for measures of "Internalizing" and "Externalizing" behaviors from two surveys using parent and teacher ratings of 6- to 11-year-old children in Connecticut between 1986 and 1989.

Child↗

PubMed1998

Schild regression analysis of antidepressant and bicuculline antagonist effects at the GABAA receptor.

We showed previously that antidepressants inhibit GABA-stimulated 36Cl- uptake in rat cerebral cortex. In this study Schild analysis was used to determine if antidepressants are competitive antagonists or allosteric modulators at GABAA receptors. GABA concentration-response curves for 36Cl- uptake in rat cerebral cortex were generated in the absence or presence of different concentrations of the following antidepressants: amitriptyline, amoxapine, mianserin, and also the GABAA receptor antagonist, bicuculline. The pA2 values for amitriptyline, amoxapine, mianserin, and bicuculline were 4.2 +/- 0.2, 5.5 +/- 0.3, 4.4 +/- 0.1 and 6.2 +/- 0.6, respectively. The respective Schild slope values were 0.7 +/- 0.1, 0.6 +/- 0.03, 0.7 +/- 0.2 and 1.0 +/- 0.3. All slope values for antidepressants differed from unity. The maximum effect produced by GABA to stimulate chloride influx was decreased by both antidepressants and bicuculline. It is concluded that neither the antidepressants studied nor bicuculline are pure competitive GABA antagonists at the GABAA receptor-chloride-ionophore complex in the rat cerebral cortex.

Animals↗

PubMed2006

Regression analysis for comparing protein samples with 16O/18O stable-isotope labeled mass spectrometry.

MOTIVATION: Using stable isotopes in global proteome scans, labeled molecules from one sample are pooled with unlabeled molecules from another sample and subsequently subjected to mass-spectral analysis. Stable-isotope methodologies make use of the fact that identical molecules of different stable-isotope compositions are differentiated in a mass spectrometer and are represented in a mass spectrum as distinct isotopic clusters with a known mass shift. We describe two multivariable linear regression models for (16)O/(18)O stable-isotope labeled data that jointly model pairs of resolved isotopic clusters from the same peptide and quantify the abundance present in each of the two biological samples while concurrently accounting for peptide-specific incorporation rates of the heavy isotope. The abundance measure for each peptide from the two biological samples is then used in down-stream statistical analyses, e.g. differential expression analysis. Because the multivariable regression models are able to correct for the abundance of the labeled peptide that appear as an unlabeled peptide due to the inability to exchange the natural C-terminal oxygen for the heavy isotope, they are particularly advantageous for a two-step digestion/labeling procedure. We discuss how estimates from the regression model are used to quantify the variability of the estimated abundance measures for the paired samples. Although discussed in the context of (16)O/(18)O stable-isotope labeled data, the multivariable regression models are generalizable to other stable-isotope labeled technologies.

Algorithms↗

PubMed2002

Deviant peer affiliations, crime and substance use: a fixed effects regression analysis.

The present study was designed to assess the influence of deviant peer affiliations on crime and substance use in adolescence/young adulthood. Data were used from a 21-year longitudinal study of health, development, and adjustment of a birth cohort of 1,265 New Zealand children. Annual assessments of deviant peer affiliations were obtained for the period from age 14-21 years, together with measures of psychosocial outcomes including, violent crime, property crime, alcohol abuse, cannabis abuse, and nicotine dependence. Affiliating with deviant peers was found to be significantly associated with each of these outcomes (p < .0001). Statistical control for confounding by both fixed and time dynamic factors reduced the strength of association between deviant peer affiliations and outcome measures. Nevertheless, deviant peer affiliations remained significantly associated (p < .0001) with all outcomes. For violent/property crime, cannabis and alcohol abuse there was significant evidence of age-related variation in the strength of association with deviant peer affiliations, with deviant peer affiliations having greater influence on younger participants (14-15 years) than older participants (20-21 years). These results suggest that deviant peer affiliations are associated with increased rates of a range of adjustment problems in adolescence/young adulthood with deviant peer affiliations being most influential at younger ages.

Adolescent↗

PubMed1984

Fever, leucocytosis and infection after open heart surgery. A log-linear regression analysis of 115 cases.

A prospective investigation was undertaken in adults to assess the specificity and sensitivity of fever (greater than 38 degrees C) and leucocytosis (greater than 10 000/microliters) for the diagnosis of infection after operations with cardiopulmonary bypass. A log-linear model analysis of a multiway frequency table was used for statistical evaluation. The model parameters were separately evaluated for 2 periods: the early one until the 6th day, the late period from the 7th postoperative day until discharge. Seven out of 115 patients suffered infections during their hospital stay: Bacteremia occurred in 3, pneumonia in 2, and deep sternal wound infection in 2 patients, and a superficial wound infection in one. No significant interactions between fever, leucocytosis and/or infection were found in the first period, except an inverse relation between fever and elevated WBC (p = 0.0197). After the 6th postoperative day the model parameters did show significant interactions, fever and leucocytosis being more frequent in infected patients. However, the specificity was low: only 15% of the patients with fever or elevated WBC had an infection. The risk of in-hospital infection was significantly higher after a long duration of cardiopulmonary bypass (p = 0.009), and after transfusion of more than 2500 ml of blood on the day of operation (p = 0.001).

Adolescent↗

PubMed1975

Application of regression analysis to the hypoglycemic activities of a series of substituted benzenesulfonamidopyrimidines.

Quantitative structure-activity relationship studies have been performed on two types of sulfonamides with hypoglycemic activity. In the case of the 2-benzenesulfonamidopyrimidines, substituted in the 5 position of the pyrimidine ring a correlation between hydrophobic forces, expressed as Rm values, and the binding to serum albumin as well as to the heights of the equipotent dose has been found. In the series of 2-benzenesulfonamidopyrimidines additionally substituted in the 4 position of the benzene ring, however, a correlation between electronic parameters, expressed as the chemical shift of the anilide NH-(type IIA) and benzylamide NH-(type IIb) protons and the biological response was observed. This correlation indicated a charge-controlled second fixation of these molecules to the receptor. This is supported by the observation of stereospecificity of the blood-glucose lowering effect and also by the importance of a constant distance between the nitrogen in the side chain and the nitrogen atom in the sulfonamido group. The correlation between the logarithm of the biological response and the electric effects of the substituents is linear as long as one homologous series is considered. If the anilide and benzylamide derivatives are combined, a linear correlation can only be obtained if a dummy parameter is included which may account for differences in conformation within these two series of compounds.

Animals↗