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PubMed1995

[Subjective assessment of quality of life, pain and surgical success after laparotomy for Crohn disease].

239 patients following major surgery for Crohn's disease (mean 8 years after first operation) were interviewed by mailed questionnaire. Main target parameters included reduction of quality of life, intensity/frequency of abdominal pain, and grading of success of the most recent operation for Crohn's disease. These targets were correlated in univariate as well as multivariate statistics with 28 different parameters of general medical history, surgical pretreatment, actual somatic and psychosocial findings. Reduction of quality of life correlated with stool frequency, employment status, rectal involvement, hematochezia, liquid stools, extraintestinal manifestations and time since first operation (all with p < 0.05 in multivariate analysis; listed in decreasing levels of significance). Abdominal pain at time of interview was significantly associated with actual intake of corticosteroids, stool frequency, employment status, extraintestinal manifestations, dietary restrictions, and number of previous operations (other than laparotomies). Regarding success of most recent laparotomy important parameters included stool frequency, intake of corticosteroids, number of previous laparotomies, hematochezia, and history of enterostomy. Overall, parameters of disease activity were found to be more important than characteristics of medical history or previous surgery. Despite marked symptoms in many cases 92% of the patients regarded the most recent laparotomy to be fully or partially successful. The results provide direct and indirect evidence that besides momentary disease activity the individual personality profile may be far more important than type and number of previous surgery in coping with this chronic disease.

Activities of Daily Living↗
PubMed1985

Sandhoff disease heterozygote detection: a component of population screening for Tay-Sachs disease carriers. I. Statistical methods.

Serum and leukocyte hexosaminidase profiles (total activity and percent heat-labile activity levels) in obligate Sandhoff disease (SHD) heterozygotes differ from those of obligate Tay-Sachs disease (TSD) heterozygotes and noncarrier individuals. We have developed a procedure to identify, with 95% sensitivity, carriers of the allele(s) for SHD among individuals screened in a TSD heterozygote identification program. Using multivariate statistical methods of cluster analysis and discriminant analysis on serum and leukocyte hexosaminidase profiles from 102 potential SHD carriers, a linear discriminant function to classify individuals as SHD carriers or SHD noncarriers was constructed. This function classifies the serum and leukocyte profiles from all 15 obligate SHD heterozygotes studied, as those of SHD carriers. A 95% isodensity ellipse derived from only the serum hexosaminidase profiles of the 15 SHD obligate carriers has been applied to a TSD screened sample of 37,843 Jewish and non-Jewish individuals. A potential recall rate of screened individuals for serum retests and leukocyte assays of 2.01% has been estimated. These statistical methods enhance the TSD heterozygote screening program by permitting one to detect SHD heterozygotes within the screened population.

Genetic Carrier Screening↗
PubMed2001

Conversion of laparoscopic cholecystectomy to open cholecystectomy in acute cholecystitis: artificial neural networks improve the prediction of conversion.

Laparoscopic cholecystectomy is now also performed for acute cholecystitis. In the presence of inflammatory conditions, technical difficulties leading to conversion to open cholecystectomy may occur and overshadow the advantages of the laparoscopic approach. Factors associated with these undue events combined with techniques capable of learning from them may help in determining when to completely avoid the laparoscopic procedure. In this study we determined predictors of conversion in acute cholecystitis and tested their predictive ability by means of statistical multivariate analysis and artificial neural networks. Between January 1994 and February 1997, 225 patients underwent laparoscopic cholecystectomy for acute cholecystitis. Preoperative and operative data were prospectively collected on standardized forms. The first 180 laparoscopically approached cases entered the training set, which was learned by both the statistical and the artificial neural networks methods. Conversion was first studied in relation to a set of preoperative data. Prediction models were then fitted by both of these methods. The last 45 operated cases, which remained unknown to the learning systems, served for testing the fitted models. The forward stepwise logistic regression technique, the forward stepwise linear discriminant analysis, and the artificial neural networks method enabled positive prediction of conversion in 0%, 27%, and 100% of the cases, and a negative prediction in 80%, 85.5%, and 97% respectively, in the training set. A positive prediction of conversion in 0%, 25%, and 67% of the cases, and a negative prediction in 82%, 88%, and 94%, respectively, in the untrained, validation set of patients. An artificial neural networks based model provides a practical tool for the prediction of successful laparoscopic cholecystectomies and their conversion. The high degree of certainty of prediction in untrained cases reveals its potential, and justifies, under appropriate conditions, the complete avoidance of laparoscopy and turning directly to open cholecystectomy.

Acute Disease↗
PubMed2002

Patterns of morphological discrimination in selected human tarsal elements.

A suite of measurements was collected from the talus, calcaneus, navicular, and cuboid of humans from Southern China, Victorian Britain, Roman Britain, and Zulu tribes people from the Republic of South Africa. Univariate and multivariate statistical analyses of dimensions of individual foot bones revealed subtle but distinct patterns of morphological discrimination on the basis of sex and size on the one hand, and geographical relationships on the other. These differences are largely expressed in the first three canonical variates of the multivariate analyses: the first axis expresses both sex and size differences, and the second and third, geographical group differences. Confirmation of morphological patterns obtained from individual multivariate analyses was provided by an integrated analysis of the four tarsal elements together. However, the integrated analysis also gave larger separations with discriminations along different axes. Thus the three geographical groups (Zulus, Southern Chinese, and the two British groups together) were separated by first and third variates. The discrimination of sex and size differences was found in the second axis, mirroring what was found in the first axes of the individual studies. This axis reversal implies that in examining all bones together, there is enough redundant information about sex and size in each individual bone that they are relegated to a second axis. It likewise implies that the data referring to geographic discriminations provided by each individual bone are not redundant; they sum in the integrated analysis, and therefore contribute to the overall analysis to a greater extent, with increased clarity.

Anthropology, Physical↗
PubMed2001

Length of stay and procedure utilization are the major determinants of hospital charges for heart failure.

BACKGROUND: Most of the 10 billion dollars spent annually on heart failure (HF) management in this country is attributed to hospital charges. There are widespread efforts to decrease the costs of treating this disorder, both by preventing hospital admissions and reducing lengths of stay (LOS). HYPOTHESIS: The objective of this study was to identify the major determinants of hospital charges for an acute hospitalization for HF among a large, diverse group of patients. METHODS: Administrative information on all 1995 New York State hospital discharges assigned ICD-9-CM codes indicative of HF in the principal diagnosis position were obtained. Bivariate and multivariate statistical analyses were utilized to determine those patient- and hospital-specific characteristics which had the greatest influence on hospital charges. RESULTS: In all, 43,157 patients were identified. Mean hospital charges were $11,507+/-15,995 and mean hospital LOS was 9.6+/-14.5 days. With multivariate analyses, the most significant independent predictors of higher hospital charges were longer LOS, admission to a teaching hospital, treatment in an intensive care unit, and the utilization of cardiac surgery, permanent pacemakers, and mechanical ventilation. Age, gender, race, comorbidity score, and medical insurance, as well as treatment by a cardiologist and death during the index hospitalization were not among the most significant predictors. CONCLUSIONS: We conclude that LOS and procedure utilization are the major determinants of hospital charges for an acute episode of inpatient HF care. Reducing LOS and other initiatives to restructure hospital-based HF care may reduce total health care costs for HF.

Aged↗
PubMed2000

Methylmercury exposure affects motor performance of a riverine population of the Tapajós river, Brazilian Amazon.

Gold mining and deforestation in the Brazilian Amazon are increasing mercury pollution of the extensive water system, exposing riverine populations to organic mercury through fish-eating. The aim of the present study was to evaluate the effect of such exposure on motor performance. This cross-sectional study was carried out in May 1996, in a village located on the banks of the Tapajós river in the Amazonian Basin, Brazil. Information concerning sociodemographics, health, smoking habits, alcohol drinking, dietary habits and work history were collected using an interview-administered questionnaire. Mercury concentrations were measured by cold vapor atomic absorption in blood and hair of each participant, of whom those aged between 15 and 79 years were assessed for motor performance (n = 84). Psychomotor performance was evaluated using the Santa Ana manual dexterity test, the Grooved Pegboard Fine motor test and the fingertapping motor speed test. Motor strength was measured by dynamometry for grip and pinch strength. Following the exclusion of 16 persons for previous head injury, working with mercury in the goldmining sites, or for diabetes, the relationship between performance and bioindicators of mercury was examined using multivariate statistical analyses, taking into account covariables. All participants in the study reported eating fish, which comprised 61.8% of the total meals eaten during the preceding week. The median hair total mercury concentration was 9 microg/g. Organic mercury accounted for 94.4 = 1.9% of the total mercury levels. Multivariate analysis of variance indicated that hair mercury was inversely associated with overall performance on the psychomotor tests, while a tendency was observed with blood mercury. Semipartial regression analyses showed that hair total mercury accounted for 8% to 16% of the variance of psychomotor performance. Neither hair nor blood total mercury was associated with the results of the strength tests in women and men. Although dose-effect relationships were observed in this cross-sectional study, they may reflect higher exposure levels in the past. The findings of this study demonstrated neurobehavioral manifestations of subtle neurotoxic effects on motor functions, associated with low-level methylmercury exposure.

Adolescent↗
PubMed2003

Determination of the enantiomeric composition of guest molecules by chemometric analysis of the UV-visible spectra of cyclodextrin guest-host complexes.

Multivariate statistical techniques were applied to the UV spectra of a series of solutions at pH 12 containing a fixed concentration (30 mM) of beta-cyclodextrin (beta-CD) and a fixed concentration (15 mM) of 2-phenylglycine (phi-Gly) with various known enantiomeric compositions. Multivariate correlation of the spectral data for the solutions containing the phi-Gly/beta-CD guest-host complexes with the known enantiomeric composition of the phi-Gly samples was accomplished by partial-least-squares regression. When the multivariate model was used to predict the enantiomeric purity of a test set of samples over the mol fraction range of 0.5-0.9 R-phi-Gly, the average magnitude of the relative errors in the mol fraction determination of enantiomeric composition was 3%. A plot of the enantiomeric composition predicted by the model versus the known enantiomeric composition of the calibration set gave a straight line with a correlation coefficient of 0.955, a slope of 1.05, and an offset of 5.61 x 10-4.

Cyclodextrins↗
PubMed2001

Distribution of chlorinated organic pollutants in harbor sediments of Livorno (Italy): a multivariate approach to evaluate dredging sediments.

Dredging is a very important procedure for harbor management. In Italy the guidelines for the offshore dumping of dredged materials are issued by the Ministry of Environment. They described a few steps of dredging activities, such as the sampling strategy, but do not deal with limits or guide-values for the chemical, physical and biological composition of the resulting sediments. The quality of dredged materials is mainly dependent on the presence of inorganic and organic pollutants. In particular, polychlorinated biphenyls (PCBs) and organo-chlorinated pesticides are seen as a high priority in marine environment by international organizations because of their persistence, toxicity and bioaccumulation capacity. In this article the presence of some PCBs and organo-chlorinated pesticides in sediment samples collected from the harbor of Livorno (Northern Tyrrhenian Sea) was investigated. The concentration of HCHs, Aldrin, Chlordanes, DDEs, DDTs, and PCBs in 12 representative sites ranged between <1 microg kg(-1) and 95, 19, 32, 35, 107, and 111 microg kg(-1), respectively. The application of univariate and multivariate statistical techniques, such as linear regression analysis and principal component analysis, to the experimental data showed a different distribution of PCBs in the two sediment layers. On the contrary, the vertical distribution of the other investigated pollutants was more homogeneous and affected by random variability. The multivariate approach was an important tool to establish more rational criteria for the management of dredged materials.

Conservation of Natural Resources↗
PubMedDate not supplied

Plasma triglyceride and coronary heart disease.

Although the literature on epidemiological associations between plasma triglyceride and CHD is not completely consistent, trends do emerge from the studies described here. First, the majority of observational studies demonstrate a significant univariate relation, although the results of case-control and cross-sectional studies are more uniform than those from prospective study designs. In many but not all studies, triglyceride remains a significant predictor of CHD in multivariate statistical analyses after controlling for TC or LDL-C. Perhaps the least consistent result is that the triglyceride association does not persist in some analyses controlling for HDL-C, while in other studies, the association remains significant. Although most studies have been conducted in men, the studies providing data on women, normocholesterolemic subjects, and diabetic subjects have generally found triglyceride to be, at the very least, a univariate risk factor. The results of intervention trials differ considerably, but no such study to date has been specifically designed to evaluate triglyceride-lowering effects on primary prevention of CHD. Important statistical properties must be taken into consideration in evaluating triglyceride as a risk factor for CHD. The large variability of triglyceride measurements and the correlation of triglyceride values with other lipid measures appears to result in the underestimation of the association between triglyceride and disease in multivariate analyses. Finally, individual genetic susceptibility may play an important role in the relation between plasma triglyceride levels and CHD. For example, risk of CHD clearly varies among the well-established familial forms of hypertriglyceridemia. A predominance of small, dense, LDL particles (LDL subclass pattern B) also appears to be a genetic trait associated with both increased risk of MI and increases in plasma triglyceride levels.

Coronary Disease↗
PubMedDate not supplied

[Quality control in carotid surgery. Results from the carotid surgery records in Central region of Spain (1999-2000)].

OBJECTIVE: Evaluation of technique and results of carotid endarterectomy (CEA) in the central region in Spain and possible differences among the hospitals included. Study of factors predictors of complications. PATIENTS AND METHODS: All CEAs performed in 9 hospitals in the central region in Spain (1999 2000). Registry design by a specific commission and contents selected by consensus. Voluntary participation. Ambispective study. Uni and multivariate statistical analysis (logistic regression). RESULTS: 576 procedures registered. Global mortality: 1.9%. 15 (2.7%) patients died or were severely handicapped. The selection of patients adjusted to expert s recommendations in 98%. Significant differences in technique and results were found among the hospital centres (>0,25). In the multivariate analysis, the risk factors associated with complications were: presence of preoperative symptoms (p= 0.006) small number of annual CEAs (p= 0.01), contralateral occlusion (RR= 4.7, p= 0.02) and use of shunt (RR= 6.1, p= 0.01). CONCLUSIONS: Globally, both the selection of patients and the results obtained adjust to the accepted standards for this type of surgery. The patient s risk profile has had a greater influence on the results than the technique used. The mortality rate has been influenced by the low volume hospitals

Carotid Arteries↗
PubMed1991

Short-term in vitro drug testing of mamma tumors: relation to estrogen and progesterone receptor levels, age, and proliferation rate.

The correlation between age, proliferation rate of tumors, estrogen and progesterone receptors, and in vitro chemosensitivity to Adriamycin was studied on 43 primary mamma tumors. From an univariate statistical analysis of the results, it appeared that sensitive tumors, unlike resistant tumors, have fewer estrogen receptors and show a higher proliferation rate. And in addition, they are blocked to a greater extent by Adriamycin. In both groups age and progesterone receptors were not significantly different. A multivariate statistical analysis showed that in the classification into sensitive and resistant tumors, the percentage remaining incorporation after addition of Adriamycin and the proliferation rate contributed 94 and 5%, respectively. The first variable was the best measure for in vitro chemosensitivity. The classification of the tumors with the aid of a discriminant function proved to be successful in 91% of all the cases. No significant difference was observed between the in vitro sensitivity to Adriamycin when patients were divided into two groups according to age (less than or equal to 50 and greater than 50 years; 64 and 45% sensitive, respectively). This indicates that all patients benefit from the treatment. It also appeared that 85% of the estrogen negative tumors were sensitive to Adriamycin. So a chemotherapeutic instead of a hormonal therapy has to be considered for all ages, particularly in the case of estrogen negative receptors.

Age Factors↗
PubMed1991

Long-term prognosis of schizophrenia.

The question of determining prognostically relevant features for schizophrenia was approached with multivariate statistical methods applied to the data from the Bonn longitudinal study of 502 schizophrenic patients. In this study, personal interviews according to a clinical classification scheme allowed every patient to be ranked within each of three different outcome classes: psychopathological remission, occupational remission, and course type. Our multivariate analysis encompassed a total of 50 items pertinent to the time up to and including the first 6 months after the first psychotic manifestation. Despite the introduction of mathematical methods considerably more sophisticated than those employed in earlier studies, no satisfactory solution could be found to the problem of predicting end states of schizophrenia. Reliable predictions could be made only for 'extreme' end states (i.e. full remission versus (1) characteristic residues in the narrower sense; (2) total unemployment, or (3) surging or simple courses to mixed residues or to typical schizophrenic defect psychoses). Accordingly, sufficiently reliable assertions applied only to a minority of about 1/3 of patients, whereas for the majority of 2/3, no generalizable prognostication was possible (67-71% true-positive predictions on 36-63% of total population in extreme states). By contrast, our analyses have clearly uncovered a fundamental problem of investigations into the long-term prognosis of schizophrenia: the extreme dependence of results on the clinical definition of end states. The further the phenomenon 'end state' is qualitatively subdivided, the poorer and less reproducible is the mutual discrimination between intermediate states and the less reliable are allocations of patients to these intermediate states by means of multivariate classifiers. Furthermore, our analyses have also demonstrated the usefulness of multivariate, adaptive procedures for investigations into the structural properties of long-term courses, so that predictions might be considerably improved if more reliable definitions of schizophrenic end states are available.

Activities of Daily Living↗
PubMed1985

Prediction of long-term outcome of tibial osteotomy in medial gonarthrosis.

To predict the long-term outcome after tibial osteotomy for medial gonarthrosis, multivariate statistical techniques were used and prognostic equations were defined. A comparison between different evaluation systems was also performed. Clinical and radiographic data from 81 patients followed up for more than 7 years were used. Twenty-eight preoperative variables were analysed in relation to the outcome at 7 years with the multivariate procedures discriminant analysis and cluster analysis. Among the variables, knee flexion and walking capacity were found to be the most dominant factors. Excluding the undercorrected osteotomies, preoperative walking capacity was now the dominating variable for prediction. Seven years postoperatively only small differences were found between the evaluation criteria of pain relief, London Hospital score, and HSS score. The discriminant functions for the highest ranked evaluation criteria are given in the text, as are dendrograms showing the patterns of interdependence between the evaluation criteria. Thus it was possible to transform clinical entities into factors suitable for determination and calculation of postoperative evaluation. The most commonly used evaluation systems had very similar discriminant functions showing good agreement.

Female↗
PubMed2002

Angioarchitectural factors present in brain arteriovenous malformations associated with hemorrhagic presentation.

BACKGROUND AND PURPOSE: Associations between clinical presentation of brain arteriovenous malformations (AVMs) and their angioarchitecture have been described. This study aims to identify significant factors related to the initial hemorrhagic event through multivariate statistical methodology. METHODS: The authors studied the initial clinical presentation of 390 consecutive patients with brain AVMs at the University of Toronto Vascular Malformation Study Group. Angiographic features present at that time, such as location, size, and blood supply, were recorded following a standard protocol and associated, through multivariate analysis techniques, with type of presentation. RESULTS: Patients had hemorrhagic presentation in 146 cases (37.4%). Hemorrhage was the initial presentation in 59.5% of the deep-seated AVMs (odds ratio [OR]=3.26; 95% CI=1.15 to 9.2; P=0.03). A single draining vein was associated with bleeding at presentation in 57.6% AVMs (OR=1.78; 95% CI=1.12 to 2.82; P=0.01), and 72.8% of the patients with venous ectasia had bleeding as initial evidence (OR=3.9; 95% CI=1.63 to 9.28; P=0.002). Hemorrhage was the initial presentation in 47.6% (111/233) of AVMs <3 cm, 22.5% (32/142) in sizes between 3 and 6 cm, and 20% in malformations >6 cm (3/15), but these differences were not significant in multivariate analyses. CONCLUSIONS: For initial hemorrhagic presentation, a small number of draining veins, deep location, and the presence of venous ectasias were significant associated factors. In contrast with many previous reports, AVM size was not associated with hemorrhage at presentation in adjusted analyses.

Adult↗
PubMed2001

[DNA chip data mining].

DNA chip data routinely contain gene expression levels of thousands of genes and the analysis should be supported by various computational tools. To be brief, the analysis procedure consists of four steps including image scanning, image processing, mathematical interpretation and biological interpretation. In image processing step, we should detect the spots and measure the signals of the spots and the background. In mathematical interpretation step, first of all we should massage the measured signals to make them appropriate for further mathematical analysis. The massaged data could be analyzed by various computational methods especially when the data were generated for multiple samples comparisons. The clustering techniques including hierarchical clustering, k-means clustering, SOTA, SOM are the most popular methods in this step. Various other multivariate statistics and related machine learning techniques are being introduced and applied to DNA chip data analysis recently. And finally the most important step we should tackle is the biological interpretation task. Although the depth of the domain knowledge about the biological situation under which the data were generated is the most important factor to elucidate the biological context, it could be supported by various bioinformatics tools including MEDLINE abstract processing by NLP techniques or genetic network models constructed by Boolean networks algorithms.

Algorithms↗
PubMed2005

Determination of osteoporosis risk factors using a multiple logistic regression model in postmenopausal Turkish women.

OBJECTIVE: To determine the risk factors of osteoporosis using a multiple binary logistic regression method and to assess the risk variables for osteoporosis, which is a major and growing health problem in many countries. METHODS: We presented a case-control study, consisting of 126 postmenopausal healthy women as control group and 225 postmenopausal osteoporotic women as the case group. The study was carried out in the Department of Physical Medicine and Rehabilitation, Dicle University, Diyarbakir, Turkey between 1999-2002. The data from the 351 participants were collected using a standard questionnaire that contains 43 variables. A multiple logistic regression model was then used to evaluate the data and to find the best regression model. RESULTS: We classified 80.1% (281/351) of the participants using the regression model. Furthermore, the specificity value of the model was 67% (84/126) of the control group while the sensitivity value was 88% (197/225) of the case group. We found the distribution of residual values standardized for final model to be exponential using the Kolmogorow-Smirnow test (p=0.193). The receiver operating characteristic curve was found successful to predict patients with risk for osteoporosis. This study suggests that low levels of dietary calcium intake, physical activity, education, and longer duration of menopause are independent predictors of the risk of low bone density in our population. CONCLUSION: Adequate dietary calcium intake in combination with maintaining a daily physical activity, increasing educational level, decreasing birth rate, and duration of breast-feeding may contribute to healthy bones and play a role in practical prevention of osteoporosis in Southeast Anatolia. In addition, the findings of the present study indicate that the use of multivariate statistical method as a multiple logistic regression in osteoporosis, which maybe influenced by many variables, is better than univariate statistical evaluation.

Age Distribution↗
PubMed1989

Multivariate analysis of prognostic factors in patients with advanced prostatic cancer: results from 2 European Organization for Research on Treatment of Cancer trials.

The European Organization for Research on Treatment of Cancer Genitourinary Group performed a multivariate statistical analysis of prognostic factors based on 436 patients entered between 1976 and 1981 in 2 randomized prospective trials that compared 4 different hormonal treatment regimens. Only previously untreated patients with advanced (stage T3/T4/M0 or M1) prostatic cancer were eligible. After identification of prognostic factors by means of univariate analyses a multivariate analysis using Cox's proportional hazards regression model was done. This test identified performance status (according to the Eastern Cooperative Oncology Group scale) as the most important factor, followed by acid phosphatase (more than 2 times normal) for stage M0 cancer patients, and alkaline phosphatase, T category and the presence or absence of associated chronic disease for stage M1 cancer patients. Based on these 4 variables nonbedridden patients with metastatic disease can be divided into 2 groups: poor and good risk patients, with median survivals of 1 and 3 years, respectively. This study shows that routine clinical and laboratory data already provide an excellent indication as to the prognosis.

Adult↗
PubMed1999

Subjective versus statistical model assessment of mortality risk in open heart surgical procedures.

BACKGROUND: The aim of this study was to compare the predictive accuracy for open heart surgical mortality between a statistical model based on collection of clinical data and surgeons' subjective risk assessment. METHODS: Predictive discrimination of both risk assessments (surgeons' and model) was compared through the area under the receiver operating characteristic curve. Logistic regression analysis was used to assess the relation between surgeons' and model predictions to actual outcomes. Calibration of the subjective estimates was evaluated with a chi2 test. RESULTS: Overall, the area under the receiver operating characteristic curve was 0.76 for the statistical model and 0.70 for the subjective assessment. Logistic regression analysis showed that the statistical model remained significant after accounting for the subjective assessment. Calibration of subjective mortality predictions was poor. CONCLUSIONS: Surgeons' risk assessment tends to cluster in the middle ranges of risk. Subjective assessment seems accurate in identifying the two extremes of risk but is inaccurate for intermediate risk levels. A multivariate statistical model improves the accuracy of subjective predictions.

Aged↗