SEARCH · PubMed Health

Results for “Multivariate Analysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources

PubMed2003

Experience with over 3,000 open and laparoscopic bariatric procedures: multivariate analysis of factors related to leak and resultant mortality.

BACKGROUND: Intestinal leak is a potentially lethal complication of Roux en-Y gastric bypass (GBP). Identification of patients at high risk for leak may reduce complication rates of surgeons early in the procedure learning curve. METHODS: A total of 3073 patients who underwent GBP were analyzed using univariate and multivariate logistic regression analyses of the following preoperative factors: hypertension (HTN), diabetes mellitus (DM), sleep apnea (SA), age, gender, weight, body mass index (BMI), and surgery type. Multivariate logistic regression analysis was performed for each procedure type. RESULTS: There were 48 (1.5%) deaths. Independent risk factors for death included leak, weight, procedure type, and HTN. A total of 102 (3.2%) leaks were found. Independent factors for leak included age, male gender, SA, and procedure type. CONCLUSION: The data suggests that older, heavier male patients with multiple comorbid conditions are at increased risk for leak and mortality. Surgeons early in their learning curve should avoid these high-risk patients to reduce complications.

Adolescent↗

PubMed1986

Multivariate analysis of risk factors in cadaver donor kidney transplantation.

Data collected prospectively on 3811 kidney transplants performed between June 1977 and July 1982 with follow-up to July 1984 by the 42 member institutions of the South-Eastern Organ Procurement foundation were analyzed to identify factors associated with graft and patient outcome in patients not receiving cyclosporine. Multivariate Cox regression analysis was used to examine the association and relative risk of 24 variables with three actuarial outcomes: overall graft failure, irreversible rejection, and patient death. Factors having no suggested association with any outcome included: recipient sex, history of pregnancy, blood group, and time on dialysis; organ preservation method, time and source; donor race; crossmatch test sensitivity; and annual center transplant rate. In decreasing order of relative risk, the factors most significantly associated with irreversible rejection were: loss of two or more prior grafts, low HLA-A,B match, lack of pretransplant blood transfusion, high (greater than 60%) pretransplant sensitization to leukocyte (HLA) antigens, and delayed graft function. Splenectomy, insulin-dependent diabetes, and antilymphocyte serum therapy provided the greatest risk of patient death. Factors such as recipient age, race, and native nephrectomy had suggested associations with outcome. By adding each center as a separate covariate in the analysis, other center-dependent factors were quantitated and found in some cases to have a highly significant association with graft and patient outcome. These results provide a basis for evaluating the potential risk of graft loss or patient death for those prospective cadaver kidney transplant recipients not being considered for cyclosporine therapy.

Cadaver↗

PubMed2003

Distal intramural spread is an independent prognostic factor for distant metastasis and poor outcome in patients with rectal cancer: a multivariate analysis.

BACKGROUND: The aim of this study was to clarify the prognostic value of distal intramural spread of tumor for survival and recurrence in patients with rectal cancer. METHODS: Microscopic distal intramural spread was examined in 134 consecutive specimens of resected rectal cancer. Correlations among distal intramural spread, established clinicopathologic factors, and patients' prognoses were examined by univariate and multivariate analyses. American Joint Committee on Cancer classification and stage groupings were used for tumor assessment. RESULTS: Thirty-three patients (24.6%) had distal intramural spread. Multivariate logistical regression analysis revealed that T3/T4 and M1 were independent predictive variables for the presence of distal intramural spread. Patients with distal intramural spread had a shorter disease-specific or disease-free survival time after curative surgery than those without distal intramural spread (P =.0003 and P =.0006, respectively). Most patients with distal intramural spread developed distant recurrence. Cox's regression with multiple covariates showed that distal intramural spread is an independent factor in predicting distant recurrence and worse outcomes after curative surgery in patients with rectal cancer. CONCLUSIONS: Distal intramural spread is an independent risk factor for distant metastasis and poor prognosis in patients with rectal cancer.

Adenocarcinoma↗

PubMed1984

Factors affecting sensitivity and specificity of exercise electrocardiography. Multivariable analysis.

Unlike the predictive value of a diagnostic test, which depends on the prevalence of disease in the population tested, its sensitivity and specificity have been assumed to be constants. This assumption was examined in patients who had both exercise electrocardiography and cardiac catheterization. The effects on sensitivity of factors from clinical history, catheterization, and exercise performance were defined by multivariable logistic regression analysis in 1,401 patients with coronary disease; effects on specificity were defined by a similar analysis in 868 patients without coronary disease. Five factors had significant, independent effects on exercise electrocardiographic sensitivity: maximal exercise heart rate, number of diseased coronary arteries, type of angina, and the patient's age and sex. Only maximal exercise heart rate had a significant, independent effect on exercise electrocardiographic specificity. Thus, the sensitivity and specificity of exercise electrocardiography vary with clinical history, extent of disease, and treadmill performance; the sensitivity and specificity of other diagnostic tests may also vary.

Adult↗

PubMedDate not supplied

Concussions in college football. A multivariate analysis.

The purpose of this investigation was to examine risk patterns of concussion in college football. Multivariate models were used to interpret the data. Specifically, log-linear modeling and analysis techniques were incorporated into the investigation. An average of 49 college teams were studied over the 8 year period 1975 to 1982. This represented over 36,000 athlete-seasons and 395 team-seasons. The data selected were limited to 1,005 game-related concussions. The general hypotheses tested were the null hypothesis that the variables of team (offense and defense), player position, situation (rushing and passing), and activity (block and tackle) had no effect on the occurrence of these game-related concussions. It was found that concussions were a persistent and regular but relatively infrequent type of injury in college football. Concussions accounted for 75% of the total number of injuries on or about the head. The injuries were examined relative to player position, situation, and activity using a log-linear modeling technique, with interactions among the variables also established. The contribution of each variable was not always equal or completely interactive. Generally, the highest risk of concussion was associated with offensive and defensive players involved in a block on a rushing play. Specifically, running backs demonstrated the highest risk of concussion, regardless of activity. The lowest risk was for offensive linemen and quarterbacks while blocking on any type of play. On defense, the secondary exhibited the highest risk of concussion while being blocked on a running play. Similarly, linemen experienced their greatest risk while being blocked on plays run inside the tackle.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed2000

Characterization of commercial soybean products by conventional and perfusion reversed-phase high-performance liquid chromatography and multivariate analysis.

Conventional and perfusion reversed-phase high-performance liquid chromatography are used to characterize commercial soybean products for human consumption. For this purpose, previously optimized methods of conventional and perfusion chromatography applied to the separation of soybean proteins are employed. Sixty different samples corresponding to 26 different trademarks of soybean products [soybean protein isolate, soybean flour, textured soybean, soybean milks (liquid and powdered), and soybean infant formulas] are analyzed. Characterization of soybean products is carried out on the basis of their protein profiles obtained by both chromatographic methods. Data obtained are processed using multivariate methods such as principal components and discriminant analysis. Perfusion chromatography enables a further and faster characterization of commercial soybean products than conventional chromatography, of great value in the quality control of this kind of product.

Chromatography, High Pressure Liquid↗

PubMed1999

Prognostic significance of Ki-67 and topoisomerase IIalpha expression in infiltrating ductal carcinoma of the breast. A multivariate analysis of 863 cases.

To evaluate the prognostic relevance of Ki-67 and topoisomerase IIalpha expression in relation to tumor stage, grade, and hormone receptor content, 942 ductal infiltrating carcinomas of the breast were examined by means of the monoclonal antibodies Ki-S11 (Ki-67) and Ki-S4 (topoisomerase IIalpha). pS2, c-erbB2, and p53 were additionally considered as prognostic variables. The median follow-up time was 149 months. Eight-hundred-and-sixty-three tumors reacted with Ki-S11 and Ki-S4; the labeling indices of the two antigens were closely associated (r = 0.93). Both correlated positively with the tumor size, c-erbB2, and p53 expression, and negatively with patient age, hormone receptor content, and pS2 immunostaining. In the univariate analysis, Ki-S11 and Ki-S4 scores, nodal status, tumor size, tumor grade, and progesterone receptor content strongly predicted both overall and metastasis-free survival (p < 0.00001). Estrogen receptor status, p53, and c-erbB2 were of minor significance. Concerning overall survival, multivariate Cox regression analysis selected a Ki-S4 score >25% (p < 0.00001) next to the nodal status, and before tumor size, progesterone receptor content, and patient age. Independent predictors of the occurrence of distant metastases were nodal status, Ki-S4, tumor size, grade 1, and progesterone receptor negativity, in that order. The Ki-S11 score was of independent prognostic significance only if examined as a continuous variable. We conclude that topoisomerase IIalpha expression as assessed by monoclonal antibody Ki-S4 may add valuable information to current prognostic models for breast cancer. Its predictive value appears to be essentially related to the proliferative activity of tumor cells.

Adult↗

PubMed1990

Clinical and serologic markers of stage and prognosis in small cell lung cancer. A multivariate analysis.

The respective pretreatment prognostic impacts of the following markers were evaluated in 125 patients with small cell lung cancer (SCLC): lactic dehydrogenase (LDH), serum thymidine kinase (S-TK), carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), and tissue polypeptide antigen (TPA). More traditional clinical and serologic markers were also evaluated. Univariate analysis showed that all of the biochemical markers mentioned above, the Karnofsky index (KI) and the patient's sex were related to both the stage of disease (limited/extensive disease: LD/ED) and to survival. The strongest marker for the clinical stage was S-TK, whereas TPA showed the strongest relationship with survival. Multivariate analyses produced a model consisting of S-TK, CEA, NSE, and the patient's sex for determining the clinical stage. To compare the prognostic capacity of easily determined biochemical and simple clinical variables to the more resource-demanding variable of the clinical stage, three multivariate analyses in relation to survival were performed: (1) biochemical markers and simple clinical variables; (2) LD/ED and simple clinical variables; and (3) all available variables. The model obtained from the first analysis included TPA, KI, age, and the patient's sex; the model from the second analyses included LD/ED, patient's age, and KI; and the model from the third analysis, TPA, KI, age, sex, and LD/ED. Indices based on these three multivariate models were calculated for each patient and the prognostic capacity of these indices was compared. Pretreatment serum marker levels also had the capacity to predict both the grade and the duration of the response to therapy.

Adult↗

PubMed1992

Multivariate analysis of second trimester midfacial morphology in normal and cleft lip and palate human fetal specimens.

To better understand the contribution of congenital dysmorphogenesis to postnatal midfacial dysplasia in individuals with complete cleft lip and palate (CLP), a series of studies were undertaken to investigate age related changes in a number of midfacial components for a sample of 20 normal and 9 complete CLP second trimester fetal specimens. Using data from this sample, the present study assessed the complex multivariate relationships among these variables which represent the fetal normal and CLP midface. Ten variables were standardized relative to crown-rump length and used in Canonical Discriminant Function Analysis (CDFA). CDF analysis revealed that five variables best described the midface and accounted for 72% of the overall variance. These included nasal capsule length, nasal airway volume, premaxillary length, premaxillary volume, and tongue volume. Classification using the CDFA coefficients resulted in correct group membership assignment for 26 of 29 total specimens (89.66%), 8 of 9 cleft (88.9%), and 18 of 20 normal specimens (90.0%). These results suggest that by as early as the second trimester CLP fetuses have a significantly distinct set of midfacial morphological relationships. Some or all of these factors may be responsible for postnatal growth dysplasias noted in CLP individuals.

Cleft Lip↗

PubMed2003

Multivariable analysis of tests for the diagnosis of intrauterine growth restriction.

OBJECTIVES: To describe how data from antenatal fetal ultrasound biometry, amniotic fluid index and umbilical artery Doppler can be appropriately combined using multivariable models and to investigate how the addition of these ultrasound parameters influences the ability to predict intrauterine growth restriction (IUGR). METHODS: This was a prospective cohort study involving 274 low-risk pregnancies undergoing serial ultrasound examination at predetermined intervals. Standard deviation (Z) scores of the last values for fetal abdominal area (FAA), growth velocity of the FAA, amniotic fluid index (AFI) and umbilical artery Doppler pulsatility index prior to delivery were calculated for 260 fetuses. Customized estimated fetal weight (cEFW) centiles were also calculated using the last EFW before delivery after adjustment for fetal gender, gestational age, birth order and maternal weight, height and ethnic origin. Following delivery the neonatal ponderal index was calculated and centile position obtained. A neonatal ponderal index <25(th) centile served as the main outcome measure for diagnosis of IUGR. Logistic regression analysis was used to delineate the predictive value of the three fetal growth tests FAA, FAA growth velocity and cEFW and the additional values of AFI and pulsatility index of the umbilical artery. RESULTS: The areas under the receiver-operating characteristics (ROC) curves (95% confidence interval) for FAA, FAA growth velocity and cEFW alone were 0.819 (0.748-0.891), 0.784 (0.699-0.869) and 0.74 (0.643-0.837), respectively, in the prediction of a neonatal ponderal index <25(th) centile. The addition of both the AFI and pulsatility index to FAA, FAA growth velocity and cEFW generated small increases in the areas, to 0.831 (0.758-0.904), 0.817 (0.735-0.899) and 0.766 (0.672-0.859), respectively. These improvements in diagnostic prediction were not statistically significant. CONCLUSIONS: The addition of AFI and umbilical artery pulsatility index to the fetal biometry parameters did not significantly increase the ROC areas in the study population. The approach applied in this study is useful in the context of hypothesis generation. Further studies using larger data sets and other predictors should be carried out using the analytical techniques outlined in this paper to determine the contribution of various antenatal tests in the prediction of IUGR.

Amniotic Fluid↗

PubMed1999

Discrimination between benign and malignant melanocytic skin lesions by multivariate analysis, quantitative S-100 immunohistochemistry, nuclear morphometry and DNA cytometry.

OBJECTIVE: To determine whether combined quantitative immunohistochemistry of S-100, nuclear morphometry and DNA image cytometry improves discrimination between benign and malignant melanocytic skin lesions (MSLs). STUDY DESIGN: S-100 protein expression was measured in tissue sections of MSLs using an image cytometry system. Localized areas of high S-100 expression were used to identify regions in sequential, facing sections in which morphometric and cytometric features of nuclei, including DNA ploidy, were also measured. RESULTS: Malignant cases had significantly higher S-100 protein staining intensity, larger nuclei and greater DNA content (P < .05). High staining intensity for S-100 protein weakly correlated with variation in size of the mean nuclear area (P = .04) and DNA content (P = .03). Combining the features of nuclear area and DNA integrated optical density in areas of high-intensity staining for S-100 protein discriminated more accurately between 12 benign and 16 malignant areas than any of the features along (P = .0003). CONCLUSION: Combined multivariate quantitative immunohistochemical, morphometric and DNA cytometric analysis greatly improves discrimination between benign MSLs and malignant melanoma. Larger test sets are required to confirm the promising results of this initial study.

Cell Nucleus↗

PubMed1993

[Who wants to go in early retirement? A multivariate analysis of civil servants' intention to retire early or not].

Despite the popularity of early retirement schemes in the Netherlands, little attention has been paid to the factors underlying this phenomenon. In this article an initial step is taken towards a multivariate modelling of plans for taking voluntary early retirement of older employees. Data for this have been obtained from a survey conducted among civil servants eligible for early retirement. This analysis includes various aspects which could be related to retirement. It appears that the attitude towards work, health, expectations regarding the consequences of retirement with respect to the loss of income, self-esteem, the perceived (positive or negative) attitude of the partner are the main reasons for civil servants to retire early or not. In the last model, containing all independent variables, 25 percent of the variance can be explained.

Age Factors↗

PubMed1988

Mode of death in idiopathic dilated cardiomyopathy: a multivariate analysis of prognostic determinants.

A total of 110 patients with idiopathic dilated cardiomyopathy were followed prospectively for 53 +/- 8 (range 41 to 69) months to determine prognostic factors identifying patients at risk for sudden death or death from congestive heart failure. During the follow-up period 39 patients died, 14 of congestive heart failure and 25 suddenly. The incidence of cardiac death after 1 year was 18%, after 2 years 35%, and after 4 years 39%. Multivariate logistic regression analysis identified four independent prognostic factors: left ventricular ejection fraction, cardiac index, number of ventricular pairs/24 hours, and atrial rhythm (sinus rhythm or atrial fibrillation). With the final model of logistic regression 77 of 88 patients (88%) could be classified correctly as being at risk for death from chronic heart failure or sudden cardiac death. Patients who were likely to die of congestive heart failure were characterized by a markedly impaired left ventricular function (measured in terms of left ventricular ejection fraction, cardiac index, or both) and a low number of pairs/24 hours. The association between frequent complex ventricular arrhythmias and depressed left ventricular function identifies patients who are at risk for sudden death. The presence of atrial fibrillation significantly increases the risk of sudden death and death from congestive heart failure.

Adult↗

PubMedDate not supplied

[Diagnosis of ischemic cardiopathy in ambulatory care patients. Multivariate analysis of clinical and electrocardiographic data].

This study was done on 113 subjects, 93 men and 20 women, whose ages ranged between 32 and 70 years (average 52.9 years). Males varied between 35 and 70 years (average 53.7) and females between 32 and 67 years (average 49.5). Our objective is: to give an account of the different discriminatory methods with mixed data usually used in medical applications, to apply these methods to all the subjects studied with the purpose of comparing their performance and, to develop a protocol for diagnosing coronary artery disease by noninvasive tests. All the subjects were referred for evaluation of chest pain, and were submitted to an exercise test on an ergometric bicycle, selective coronary angiography and left ventriculography. Patients with prior myocardial infarction, cardiomyopathy, valvular or congenital disease, mitral valve prolapse or intraventricular conduction defect were excluded. Subjects were classified as having coronary artery disease and not having coronary artery disease according to the coronarographic results. We used four clinical variables (age, sex, risk factor and chest pain) and five variables obtained from the stress test (ST depression, appearance of chest pain, appearance of arrhythmias, variations in blood pressure and R wave changes). For the analysis of this set of data we use well known univariate statistical methods, such as chi-squared test, F-test and t-test, and the following multivariate statistical methods: Fisher, Quadratic and Logistic, discriminant methods. To study the relative importance of the different variables in the discrimination of the individuals, we performed a stepwise linear discriminant analysis over the 113 subjects. Of the 9 variables tested R-wave was of little value and excluded.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2003

Fairly processing rare and common species in multivariate analysis of ecological series. Application to macrobenthic communities from Algiers harbour.

Systematic sampling of communities gives rise to large contingency tables summing up possible changes in the assemblages' structure. Such tables are generally analysed by multivariate statistical methods, which are ill-suited for simultaneously analysing rare and common species (Field et al., 1982). In order to separately process species belonging to either of these categories, we propose a statistical method to select common species in a sequence of ecological surveys. It is based on a precise definition of rarity, and depends on a rarity parameter. In this work, this parameter will be optimised so that the sub-table of common species captures the essential features of the complete table as well as possible. In this way we analysed the spatio-temporal evolution of macrobenthic communities from the Algiers harbour to study the pollution influence during a year. The examination of the communities' structuring was done through Principal Components Analysis (PCA) of the species proportions table. Environmental variables were simultaneously sampled. We show that the data structure can be explained by about 25% of the total number of present species. Two environmental gradients were brought to the fore inside the harbour, the first one representing pollution, and the second one representing hydrological instabilities. Since rare species can also convey information, the complete table was also coded according to a generalised presence/absence index and submitted to Correspondence Analysis. The results were consistent with those of PCA, but they depended on more species, and highlighted the influence of sedimentology on the assemblages composition.

Algeria↗

PubMed1996

A voxel-by-voxel multivariate analysis of cerebral perfusion defects in divers with 'bends'.

Past analysis of dysbaric-induced cerebral perfusion defects, demonstrated by 99Tcm-hexamethylpropylene amine oxime (99Tcm-HMPAO) single photon emission tomography in divers using quantitative and/or univariate techniques, has resulted i considerable controversy regarding the significance of these lesions compared to those seen in control subjects, correlations with clinical findings and the role of 99Tcm-HMPAO as a prognostic indicator in decompression sickness. We tried to address these problems by using a multivariate approach to a voxel-by-voxel analysis, involving the use of principal components, to determine ranges of normality in 50 reference controls. In subsequent images, abnormality was defined as 10 spatially connected voxels at an appropriate significance level of three standard deviations. The images of 50 divers with clinically diagnosed 'bends' were compared with those of a further 40 normal population controls with no previous history of loss of consciousness, head injury or dysbarism. The results showed that 19 of 50 divers with 'bends' and 3 of 40 population controls had significant perfusion defects, representing a significant difference between divers with dysbarism and population controls at the level P < 0.002. It is concluded that dysbarism causes significant cerebral cortical perfusion defects in affected divers both in 'silent' and symptomatic (clinically correlated) areas.

Adolescent↗

PubMed1980

A multivariate analysis of the infrared spectra of drugs of abuse.

The infrared (IR) spectra of 15 drugs of abuse were analyzed for similarity by using techniques of numerical taxonomy. The study included six barbiturates (amobarbital, barbital, butabarbital, phentobarbital, phenobarbital, and secobarbital), four amphetamine-related compounds (amphetamine, ephedrine, methamphetamine, and phentermine), and five other drugs (cocaine, heroin, phencyclidine, phendimetrazine, and diazepam). Three character sets were based on increasing numbers (10, 24, and 36) of IR peaks. The cluster analysis, principal component analysis, and nonmetric multidimensional scaling elements of the program system NT-SYS were used to structure taxonomic distances between drugs. Best results were obtained from the 36-peak data set; ordination diagrams proved to be more visually informative than phenograms. Preliminary results from our analysis of this set of drugs indicate that an expanded multivariate approach to drug classification may be useful.

Amphetamines↗

PubMed2002

Pre-operative prediction of invasive vs intraductal breast cancer type: multivariate analysis of the accuracy of clinical and imaging findings.

Two consecutive series of 107 invasive carcinomas and 108 carcinomas in situ of the breast were considered retrospectively. The main symptomatic, clinical and cytological features were retrieved from clinical records, whereas the features at mammography and/or ultrasonography were reclassified at a blinded review by an expert radiologist. The power of predicting invasion on the basis of these features was then evaluated. The accuracy of such a prediction was compared to that of a mathematical model using the same diagnostic features by multivariate logistic regression analysis. Neither approach reached a satisfactory accuracy, but the radiologist's judgment (sensitivity 97.1%, specificity 81.9%, positive predictive value 98.4%, negative predictive value 71.6%, overall accuracy 95.8%) was slightly superior to the mathematical model (sensitivity 93.2%, specificity 87.9% positive predictive value 98.8%, negative predictive value 53.7%, overall accuracy 92.8%). Although some presentations are significantly associated with invasive or in situ status, diagnostic features alone are not sufficiently accurate to bypass histological confirmation, although they might give useful clinical indications.

Journal Article↗