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Results for “multivariate analysis”

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PubMed1999

Open biliary tract surgery: multivariate analysis of factors affecting mortality.

BACKGROUND/AIM: The overall mortality rate in patients undergoing supraduodenal choledochotomy for benign biliary tract disease is around 3%. The aim of this study is to identify and quantify factors affecting the mortality in a group of patients undergoing open common bile duct exploration for benign biliary disease. METHODS: Patients (n = 158) who underwent common bile duct exploration during a 5-year period in a teaching hospital were retrospectively reviewed. RESULTS: Univariate and multivariate statistical analyses were performed. The former identified four statistically significant variables: age (p < 0.001), acute cholangitis on admission (p < 0. 001), heart disease (p < 0.05), and a dilated common bile duct on preoperative ultrasound scan (p < 0.05). Multivariate analysis identified three variables which independently increased operative mortality: age (p = 0.05), heart disease (p = 0.03), and cholangitis (p = 0.008). The latter was associated with the greatest operative mortality, since it increased almost eight times the risk to die after surgical intervention. CONCLUSION: We conclude that an adequate perioperative cardiovascular management may be important in order to improve surgical outcome. Appropriate antibiotic prophylaxis and subsequent treatment after routine operative bile cultures may reduce septic complications and mortality. Finally, an alternative procedure, such as endoscopic sphincterotomy, may be indicated in high-risk patients in order to drain the common bile duct preoperatively and to decrease the risk of unresponsive biliary sepsis.

Acute Disease↗

PubMed2003

Endovascular treatment of basilar tip aneurysms with Guglielmi detachable coils: predictors of immediate and long-term results with multivariate analysis 6-year experience.

PURPOSE: To analyze anatomic and clinical results and factors predictive of outcome in treatment of basilar tip aneurysms with Guglielmi detachable coils (GDCs). MATERIALS AND METHODS: During 6 years, 55 unselected consecutive saccular aneurysms in 53 patients (mean age, 47 years) were treated with GDC occlusion. Forty-one (75%) aneurysms were ruptured (Hunt-Hess and Fisher grades were assigned in patients); 14 (25%), unruptured. Clinical and angiographic evaluations were performed 6 months after treatment and during follow-up (mean follow-up, 2 years). Multivariate analysis was used to determine factors predictive of outcome. RESULTS: GDC occlusion was a success in 52 (95%) aneurysms, a failure in two (4%), and not attempted in one (2%). Occlusion at final follow-up, evaluated in 44 aneurysms, was complete in 34 (77%), near complete in four (9%), and incomplete in six (14%). At 6-12 months, mean aneurysmal occlusion rate significantly worsened because of revascularization (P <.001) but improved at final follow-up because of reembolization in 10 aneurysms (P =.009); it remained stable (P =.351) between initial and final follow-up. Multivariate binary logistic regression indicated that before treatment started, aneurysmal neck size was the only independent predictor of initial occlusion rate (P =.002) and revascularization (P =.004). After the initial procedure, sac size and initial occlusion rate were independent predictors of revascularization (P =.004 and.008, respectively), irrespective of neck size. Occlusion rate at 6-12-month follow-up was the only independent predictor of that at final follow-up (P =.021), regardless of shape of aneurysm. Overall morbidity was 2% (one of 51); mortality, 6% (three of 51). Mortality correlated significantly with Hunt-Hess grade 4 at admission (P =.003) and incidence of vasospasm (P =.058). CONCLUSION: GDC occlusion proved to be a safe effective therapeutic alternative to surgery in patients with ruptured or unruptured basilar tip aneurysms. Morphologic and clinical factors were respectively identified as predictors of the optimal anatomic and clinical outcomes.

Adolescent↗

PubMedDate not supplied

Lymph node involvement as the only prognostic factor in curative resected gastric carcinoma: a multivariate analysis.

The aim of this study was to evaluate the independent influence of clinical and pathological variables on survival of patients with gastric carcinoma using the Cox regression proportional hazard model. Of 156 patients operated on for gastric carcinoma, 46 (29.5%) underwent palliative operation, 24 (15.5%) had a palliative resection, and 86 (55%) had a curative resection. The overall 5-year survival rate was 25 +/- 4%. After curative resection, the 5-year survival rate was 44 +/- 6%. Univariate analysis applied to these patients showed that poor survival was related (p less than 0.01) to: age (over 80 years), absence of epigastric pain, vomiting and dysphagia, total gastrectomy, tumor size (more than 4 cm), lymph node involvement (LNI), invasion through the muscularis propria, absence of intestinal metaplasia near the tumor, and linitis plastica. In multivariate analysis, lymph node involvement was found to be the only independent prognostic factor. The 5-year survival rate was 75.5 +/- 8% without LNI, 28 +/- 10% with proximal LNI, and 7 +/- 6% with distal LNI. Our results suggest that classification into 3 LNI groups is the best staging system for curative resection in gastric carcinoma.

Adenocarcinoma↗

PubMed1978

Defects of the central nervous system in Finland: V. Multivariate analysis of risk indicators.

Based on the Finnish Register of Congenital Malformations a search was undertaken for associations between defects of the central nervous system [CNS] and various selected risk indicators. The study material consisted of 710 cases of CNS defects and their time-area matched pair controls. 259 cases of polydactyly and their controls were also compared with a view of demonstrating the possible biases introduced by the case-control method. The present report is a multivariate analysis of previously observed associations, and the linear logistic regression model was used for the elimination of confounding factors. Risk indicators remaining after the analysis were high maternal age, multipara with previous stillbirths and defective children, especially defects of the CNS. Maternal influenza, especially in combination with the intake of salicylates, was also associated with an increased risk.

Central Nervous System↗

PubMed1991

Multivariate analysis of spect images with illustrations in Alzheimer's disease.

Modern neuroimaging techniques such as positron emission tomography and single photon emission computed tomography (SPECT) often generate datasets consisting of a large number of variables measured on a small number of subjects. In addition, the data contain large 'subject effects' which must be adjusted for in any statistical analysis. This paper illustrates the dangers inherent in naive univariate analysis and proceeds to demonstrate the application of multivariate methods such as Hotellings T2-test, canonical correlation analysis and discriminant analysis. The issues and statistical methods are illustrated using a dataset from a SPECT study of groups of normal control subjects and subjects with a clinical diagnosis of Alzheimer's disease.

Alzheimer Disease↗

PubMed1986

Bivariate and multivariate analysis of the skin ridge pattern intensities.

Bivariate correlations and multivariate (factor) analysis of pattern intensities on individual fingers and all specified areas of palms and soles were performed in a large sample of 834 individuals from two rural districts of Poland, and in a sample of 383 school children from the city of Warsaw, with males and females considered separately. Eleven factors were extracted in all samples, including two for finger pattern intensities, and the remaining nine for palmar or sole individual areas, or some of their combinations. Patterns of intercorrelation between variables and the factor structure matrices were essentially similar in all subsamples, but several factors differed in the amount of variance they contributed to individual variables, or the factors occupied somewhat different positions when ranked in respect of the contribution to the total variance. Orthogonal and oblique rotation were applied to the data, but only the results of the latter were tabulated and fully discussed. In contrast with finger patterns, separate and independent factors have mainly been extracted for individual pattern intensities on palms or soles. Nevertheless the obtained factor solution on the whole is not incompatible with the concept of developmental induction fields. It is postulated that the factor structure may be susceptible to natural selection acting through functional preferences in man, and that epistatic interaction may account for some common factors.

Dermatoglyphics↗

PubMed1986

Recurrence-free survival time for surgically treated soft tissue sarcoma patients. Multivariate analysis of five prognostic factors.

A staging system, based upon the experience of 1215 patients, was published by the American Joint Committee Task Force on Soft Tissue Sarcoma in 1977. A subset of these patients, 594, was selected to study recurrence-free survival time. The authors found 331 patients with a recurrence within 5 years (100 local only, 123 metastatic only, and 108 local + metastatic); median months to recurrence was 9.7. Within 5 years, recurrence was clearly associated with mortality: among the 331 patients who experienced a recurrence, 245 died, whereas only 31 died among the 263 who had no recurrence. To further evaluate the utility of the published staging system, a multivariate analysis of five factors was carried out for 297 of the 594 patients (patients with unknown information for any one of these factors were excluded). Factors in addition to grade that exerted a significant influence on recurrence were: direct extension, symptoms, and location of tumor when survival was measured to the first of any recurrence, and tumor size, measuring survival to the first metastatic recurrence. It is therefore recommended that these factors be taken into account in staging this disease. Estimates of probable recurrence-free survival time based upon the multivariate model (Weibull) are also presented.

Analysis of Variance↗

PubMed1988

Prognostic factors in gestational trophoblastic tumors. A multivariate analysis.

One hundred sixty-two gestational trophoblastic tumors (GTT) were treated at the Institute Gustave-Roussy, Villejuif, France, from 1975 to 1985. Sustained complete remission (CR) was obtained in 146 patients (90%). All 97 patients with no histologic diagnosis of choriocarcinoma were cured, including 19 patients considered at high risk initially. Among 65 histologic chariocarcinoma patients, 16 died (CR, 75.5%) including seven initially nonmetastatic patients. Using a univariate analysis, all factors tested in the whole group of patients were more or less significant except for age and parity. However, when the same variables were tested in patients considered at high risk initially, only three factors were statistically significant. Those three factors were the only ones associated with a statistically significant higher relative death risk (RR) on multivariate analysis and are as follows: an antecedent nonmolar pregnancy (RR = 4.3; P less than 0.01); initial presentation with more than one metastatic organ (RR = 7.4; P less than 0.01); and primary resistance to single agent (RR = 18.8; P less than 0.0001) or multi-agent chemotherapy (RR = 26.1; P less than 0.0001). It seems that those three factors, together with a histologic diagnosis of choriocarcinoma, are the prognostic factors that discriminate patients with unfavorable outcomes among the high-risk group.

Choriocarcinoma↗

PubMed1982

A multivariate analysis of the prognosis after surgical treatment of malignant soft-tissue tumors.

Ninety-seven patients who had received their primary and definitive surgical treatment for a soft-tissue sarcoma during the years 1956--1976 were studied with respect to local recurrence, metastasis, and survival. The aim of the treatment was to eradicate the tumor while preserving good function. The influence of host and tumor properties and different diagnostic and surgical procedures on the prognosis was studied by means of nonparametric multivariate analysis. Ninety-four percent of the tumors were located in the extremities. Malignant fibrous histiocytoma was the most common histologic type. A four-grade scale of histologic malignancy was used. Eighty-eight percent of the tumors were Grade III or IV. In 85% of the patients with an extremity lesion, local extirpation was carried out. The overall local recurrence rate was 21.7% and in 76 patients who underwent an adequate surgical procedure it was 6.6%. The overall five-year survival rate was 59%. The survival depended on the local control of the primary tumor, which was related to the adequacy of the surgical procedure and to the histologic grade of malignancy. No patient with a Grade I or II tumor died. The five-year survival rate for patients with Grade III tumors was 68% and for patients with Grade IV tumors 47%.

Adolescent↗

PubMed1989

Prognostic factors in squamous cell carcinoma of the vulva: a multivariate analysis.

Based on 124 patients with squamous cell carcinoma of the vulva treated at the 1. Frauenklinik der Universität München from 1971 to 1980, the influence of pretreatment characteristics on survival was assessed. The patients underwent a simple vulvectomy with local and inguinal irradiation. All histologic specimens were worked up in the same manner, and all available specimens were reverified. Follow-up lasted from at least 2 up to 12 years post-treatment, with no dropouts. Using the Cox model of multivariate analysis, five pretreatment characteristics were found to most strongly influence survival: age, dissociated tumor growth, lymphatic spread, tumor thickness, and ulceration. These pretreatment characteristics were implemented in an algorithm for survival-oriented prognostic forecasting. Survival data as predicted from this algorithm correlated well with observed survival data. The validity of these prognostic factors needs to be examined in further studies using comparable patient populations and study designs.

Adult↗

PubMed1997

Multivariate analysis to discriminate species of phlebotomine sand flies (Diptera:Psychodidae): Lutzomyia townsendi, L. spinicrassa, and L. youngi.

Multivariate discriminant analysis was employed to discriminate on a morphological basis females of 3 closely related sand fly species, Lutzomyia townsendi (Ortiz), L. spinicrassa Morales, Osorno-Mesa, Osorno & Hoyos, and L. youngi Feliciangeli & Murillo. Principal component and canonical discriminant analysis compared a set of 31 morphological characters measured from known specimens to detect differences among the 3 species. A subset of 6 characters separated the 3 species with a high level of confidence. A simple method is presented to identify an unknown specimen as L. townsendi, L. spinicrassa, or L. youngi using these 6 morphological characters.

Animals↗

PubMed1989

Predictors of foetal and neonatal mortality in Curaçao, Netherlands Antilles. A multivariate analysis.

In Curaçao a systematic and comprehensive investigation of numerous factors, potentially associated with an increased risk of foetal and neonatal mortality, was carried out in a 2-year period (1984-85). The inquiry was restricted to singleton births. Data on 205 women who experienced pregnancy loss were compared with those on 913 women who did not sustain foetal or neonatal loss. Data comprised information on maternal characteristics, clinical course of pregnancy and delivery, and neonatal characteristics. Of 130 factors measured, 14 were entered into a multivariate analysis. From the analysis 5 risk factors emerged as significant predictors of mortality: gestational age, birth weight, sex, foetal presentation and congenital anomalies. Factors such as social class, marital status, maternal age and parity were not associated with an increased risk of foetal and neonatal mortality in Curaçao.

Adult↗

PubMed1984

[Prognostic value of echocardiography in acute myocardial infarct: comparison, by multivariate analysis, between mono- and bidimensional parameters].

A multivariate step-wise analysis with death or heart failure as prognostic end-points was utilized in 62 patients with an acute myocardial infarction (AMI), to evaluate the age related short-term prognostic significance of selected M-Mode and two dimensional echocardiographic parameters, and to identify, among them, the best predictors of the clinical outcome. The echocardiographic examination was performed within 24 hours from the occurrence of cardiac chest pain. After a three months follow-up study, the patients were divided into groups: 9 patients who died (Group A), 53 patients who survived (Group B), subdivided into 41 asymptomatic patients (Group B1) and 12 patients with clinical signs of heart failure (Group B2). The selected parameters were: age, left ventricular end-diastolic and end-systolic diameters (LVEDD, LVESD), left atrial diameter (LAD), the electrocardiographic PR interval minus AC interval from the mitral echogram (PR-AC), the distance between the mitral E point and the septum (EPSS), total aortic excursion (TAE), and two dimensional wall motion score. From the step-wise analysis of groups A and B we classified the parameters as follows, the relative prognostic significance being highest on the left side: score greater than TAE greater than AGE greater than PR-AC greater than LVEDD (LAD, LVESD, EPSS). For groups B1 and B2 the following results were obtained: score greater than PR-AC greater than AGE greater than LVESD greater than EPSS (TAE, LVESD, LAD). In parenthesis are indicated the variables whose prognostic value did not reach any significant level. When a discriminant function was applied to the 5 most significant variables, we could identify 78% of the patients of group A, and 77% of those of the group B; of groups B1 and B2 we identified correctly 83% and 92% of the patients respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2005

Multivariate analysis of nystatin and metronidazole in a semi-solid matrix by means of diffuse reflectance NIR spectroscopy and PLS regression.

A multivariate method of analysis of nystatin and metronidazole in a semi-solid matrix, based on diffuse reflectance NIR measurements and partial least squares regression, is reported. The product, a vaginal cream used in the antifungal and antibacterial treatment, is usually, quantitatively analyzed through microbiological tests (nystatin) and HPLC technique (metronidazole), according to pharmacopeial procedures. However, near infrared spectroscopy has demonstrated to be a valuable tool for content determination, given the rapidity and scope of the method. In the present study, it was successfully applied in the prediction of nystatin (even in low concentrations, ca. 0.3-0.4%, w/w, which is around 100,000 IU/5g) and metronidazole contents, as demonstrated by some figures of merit, namely linearity, precision (mean and repeatability) and accuracy.

Anti-Bacterial Agents↗

PubMed1979

Multivariate analysis of the risk of glaucomatous visual field loss.

In a retrospective study, 92 patients with ocular hypertension, ie, intraocular pressure of 21 mm Hg or higher, and no evidence of glaucomatous visual field defects, were observed for five years. Visual field defects developed in one or both eyes of 33 patients during the five-year follow-up period, while none were detected in the remaining 59. Values for suspected risk factors, determined at the outset of the follow-up period, were subjected to a multivariate analysis with use of linear discriminant analysis and a multiple logistic function. Models of risk providing maximum separation of the two patient groups (visual field loss vs no visual field loss) found that the risk factors having the greatest significance for prediction of visual field loss included vertical estimates of cup/disc ratio, mean IOP during the period of observation, a positive family history of glaucoma, and age. Factors having the lowest predictive values included IOP response to topical dexamethasone, plasma cortisol suppression, and a history of systemic hypertension.

Glaucoma↗

PubMedDate not supplied

Prediction of post-operative survival time by multivariate analysis in patients with advanced cancer of the stomach.

In order to give a sound basis to a surgeon for the decision that a cancer should or should not be removed, an attempt was made to produce a regression equation to estimate postoperative survival. The relation between postoperative survival and the intraoperative gross-finding of the cancer, the age and sex of the patients, operative curability, histological types of the cancer and the need for combined resections of the adjacent organs were analyzed by the method of multivariate analysis (Quantification Method) in 111 patients with advanced cancer of the stomach. A statistically significant regression equation was obtained, by which the survival months were predicted for a prospective patient. This equation appears to be useful for surgeons as one way of deciding on an appropriate method of operation. The difference between the actual and the predicted survival months was less than twelve months in seventy-six percent of the internal samples.

Adult↗

PubMed1989

[Spontaneous development and prognostic factors in patients needing heart transplantation. Multivariate analysis of 171 patients].

In an attempt to determine predictive factors of spontaneous death in patients needing heart transplantation, we studied 27 clinical and paraclinical variables in 171 patients aged from 14 to 61 years. Sixty-one of these patients died before transplantation could be performed, 59 were still alive awaiting transplantation and 51 received a heart transplant. The actuarial survival rate with or without transplantation was 65 percent at 1 year and 51 percent at 2 years. Univariate analysis showed that the following factors were associated with a higher mortality rate: age, history or symptoms of right heart failure, poor general condition, end-diastolic left ventricular diameter and ejection fraction. There was no correlation between high mortality rate and type of heart disease, sex, duration of symptoms, NYHA functional class, cardiothoracic ratio and data obtained from electrocardiography and right heart catheterization. At multivariate analysis (Cox's model), no variable could be selected as predictive factor of mortality. The natural outcome of patients needing heart transplantation therefore is globally unfavourable. This means that once has been decided to perform heart transplantation the operation should not be delayed.

Actuarial Analysis↗

PubMed2005

Novel quality control methods in conjunction with chemometrics (multivariate analysis) for detecting honey authenticity.

The importance of honey has been recently upgraded because of its nutrient and therapeutic effect. The adulteration of honey increased exponentially in terms of both geographic and/or botanical origin. Therefore, the need has arisen for more effective quality control methods aiming at detecting adulteration. Various novel, fast, and accurate methods like AAS, HPLC, GC-MS, ES-MS, TLC, HPAED-PAD, NMR, FT-Raman, and NIR have enriched the arsenal of analytical chemist in this direction. However, apart from these novel methods, the application of multivariate analysis and, in particular, PCA, CLA, and CA, proved to be extremely useful for grouping and detecting honey of various origins. Mineral and trace element analysis were repeatedly shown to be a very effective means for the classification purposes of honey of various origins (geographical and botanical).

Amino Acids↗