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PubMed2003

Acute pain after endoscopic totally extraperitoneal (TEP) inguinal hernioplasty: multivariate analysis of predictive factors.

BACKGROUND: Pain is the most common complaint after inguinal hernia surgery. The present study was undertaken to evaluate the significance of various perioperative clinical factors on the severity of postoperative pain following endoscopic totally extraperitoneal (TEP) inguinal hernioplasty. METHODS: Between November 1999 and December 2002, 509 patients who underwent unilateral ( n = 389) and bilateral ( n = 120) TEP were recruited for this study. There were 491 men and 18 women. Severity of postoperative pain at rest and on coughing was assessed by a linear analogue pain score (scale, 0-10) on a daily basis after operation. Univariate and multivariate analyses were performed to identify the significant independent factors affecting pain. RESULTS: By univariate analysis, pain scores at rest were significantly higher in young (< or =65 years) female patients, as well as patients who underwent unilateral and day case TEP. Clinical factors associated with a significantly higher pain score on coughing included mesh fixation by stapling, female sex, and age (< or =65 years). Other factors, including unilateral vs bilateral TEP, seroma formation, direct vs indirect hernia, primary vs recurrent hernia, and operative time, had no impact on postoperative pain. On multiple regression analysis, age and sex were found to be independent predictive factors for mean daily pain score at rest. Independent factors influencing mean pain score on coughing included age, sex, and prosthetic stapling. CONCLUSIONS: Patient age and sex are the most significant factors determining the degree of pain after TEP. Analgesic therapy should therefore be adjusted in accordance with the age of the patient. With regard to operative factors, avoidance of prosthetic stapling might help to reduce the severity of pain on coughing.

Acute Disease↗

PubMed1984

A multivariate analysis of factors affecting survival in patients with high-grade histology non-Hodgkin's lymphoma.

One hundred and eleven patients with advanced-stage, high-grade histology non-Hodgkin's lymphoma were studied over a 7-yr period and were treated with one form of chemotherapy and radiotherapy. Multivariate analyses were carried out to identify factors which could predict a favourable prognosis. A complete response, low serum LDH and absence of clinical evidence of liver involvement were associated with long-term survival. The presence of 'B' symptoms, bone marrow involvement, low serum albumin and male sex predicted a reduced chance of achieving a complete remission. For those patients who achieved a complete response, the subdivision of histologies, particularly according to the Kiel classification, was the only significant factor predictive of prolonged relapse-free and overall survival. This confirms the importance of identifying different histological subgroups of lymphoma when considering treatment planning.

Aged↗

PubMed2005

Multivariate analysis of single-molecule spectra: surpassing spectral diffusion.

The full exploitation of single-molecule spectroscopy in disordered systems is often hampered by spectral diffusion processes of the optical transitions due to structural fluctuations in the local environment of the probe molecule which leads to temporal averaging of the signal. Multivariate statistical pattern recognition techniques, originally developed for single-molecule cryoelectron microscopy, allow us to retrieve detailed information from optical single-molecule spectra. As an example, we present the phonon side band of the B800 excitations of the light-harvesting 2 (LH2) complex from Rhodospirillum molischianum, revealing the electron-phonon coupling strength for these transitions. The measured Debye-Waller factors, ranging from 0.4 to 0.9, fall in the regime of weak electron-phonon coupling.

Journal Article↗

PubMed1988

Morphological clues to genetic species: multivariate analysis of greater Galago sibling species.

Several studies conducted in diverse fields indicate the presence of a genetic discontinuity within the taxon Galago crassicaudatus E. Geoffroy--the thick-tailed bushbaby. One of these areas is morphology. This contribution details a statistical analysis of skull material classified under this taxon in order 1) to confirm the objective existence of two morphotypes, and 2) to investigate the characters that allow the skull types to be distinguished. Emphasis is placed on multivariate techniques, although univariate and bivariate techniques are included where they are felt to be appropriate. All statistical analyses point to the reality of the morphological discontinuity between the groups. This is true even when size considerations have been reduced by rescaling the data. The results support separation of the populations at a specific level: G. crassicaudatus and G. garnettii. In addition, the structural changes observed in the two taxa--including an increase in overall size in G. crassicaudatus--are indicative of a divergence in preferred habitats: G. garnettii is adapted to more mesic environmental conditions, and to a softer, less fibrous diet than is its more robust sibling.

Animals↗

PubMed1986

Primary systemic amyloidosis: multivariate analysis for prognostic factors in 168 cases.

One hundred sixty-eight patients with primary systemic amyloidosis (AL) were identified. Median survival after diagnosis was 12 months and ranged from 4 months for patients presenting with congestive heart failure to 50 months for those presenting with peripheral neuropathy only. Utilizing the proportional-hazards model in a stepwise multivariate fashion to evaluate the simultaneous influence of putative risk factors as of diagnosis revealed that congestive heart failure, urine light chain, hepatomegaly, and multiple myeloma were the major factors adversely affecting survival during the first year after diagnosis. Serum creatinine, multiple myeloma, orthostatic hypotension, and monoclonal serum protein were the most important variables adversely affecting survival for patients surviving 1 year. These models were used to categorize patients according to the variables in the models into low-, moderate-, and high-risk groups for the first year after diagnosis and separately for subsequent years. The influence of these variables on survival is important in stratification of patients randomized to prospective clinical trials.

Adult↗

PubMed1999

A Multivariate Analysis on the Sedimentation of Aqueous Silica Suspensions as Studied by Means of Time Domain Dielectric Spectroscopy.

The sedimentation of aqueous silica suspensions has been studied by means of time domain dielectric spectroscopy (TDDS) in the frequency range 20 MHz to 2 GHz. The experiments were designed with a 2(5-1) reduced factorial design and analyzed in terms of multivariate regression models. Five different variables were varied to investigate the corresponding suspension sedimentation. The influence of the different variables on the sedimentation of the silica suspensions is discussed. Copyright 1999 Academic Press.

Journal Article↗

PubMed2002

Serum bilirubin and early mortality after transjugular intrahepatic portosystemic shunts: results of a multivariate analysis.

PURPOSE: To examine the prognostic utility of the serum bilirubin level before transjugular intrahepatic portosystemic shunt (TIPS) creation as an independent predictor of 30-day mortality in patients who underwent TIPS creation for treatment of variceal hemorrhage. MATERIALS AND METHODS: Multiple covariates from a cohort of 220 consecutive patients undergoing TIPS creation were analyzed with use of univariate and multivariate logistic regression. These included pre-TIPS total bilirubin levels, modified Child-Pugh class, APACHE II score, intubation status, etiology of liver disease, and acute versus elective shunting. RESULTS: The mean pre-TIPS serum total bilirubin level was 3.2 mg/dL (range, 0.4-40.3 mg/dL). The bilirubin level was <3 mg/dL in 102 patients, > or = 3.0 mg/dL in 58, > or = 4.0 mg/dL in 34, and > or = 5.0 mg/dL in 27. Each 1.0-mg/dL increase in total bilirubin was associated with 40% greater odds of 30-day mortality (odds ratio = 1.4; 95% CI = 1.2-1.7). Using each threshold as its own referent, bilirubin levels at or greater than 3.0, 4.0, and 5.0 mg/dL stratified patients into increased odds of early death by 5.7, 9.7, and 19.2 times, respectively (all P <.001). A pre-TIPS APACHE II score of >18 increased the odds of early death by a factor of 5.6 (95% CI = 2.4-8.7); modified Child-Pugh class C (vs classes A and B combined) alone increased the odds by a factor of 8.1 (95% CI = 3.6-18.1). Only one of 20 patients (5%) with a pre-TIPS bilirubin level >6.0 mg/dL survived more than 30 days after TIPS creation. In acutely bleeding patients (n = 122) undergoing TIPS creation, bilirubin levels > or = 3.0, > or = 4.0, and > or = 5.0 mg/dL stratified patients into odds ratios of 4.4, 7.1, and 9.8, respectively, compared with 7.1, 13.2, and 9.2 for patients undergoing elective TIPS creation. Combining endotracheal intubation (n = 72) and bilirubin strata yielded mortality odds of 8.3, 12.5, and 20.8 compared with odds of 2.3, 4.6, and 11.2 in nonintubated patients. Combining alcoholic cirrhosis (n = 129) with bilirubin levels yielded mortality odds of 8.0, 10.6, and 18.0 compared with other etiologies of liver disease (odds ratios = 2.9, 7.3, and 22.7). CONCLUSION: An elevated pre-TIPS bilirubin level is a powerful independent predictor of 30-day mortality after TIPS creation with a 40% increased risk of death for each 1-mg/dL increase above 3.0 mg/dL. The predictive value of this criterion is increased in patients who undergo TIPS procedures electively. The magnitude of the effect on mortality is similar to that of APACHE II scores and modified Child-Pugh class but is simpler to ascertain.

APACHE↗

PubMed2003

Application of multivariate analysis and artificial neural networks for the differentiation of red wines from the Canary Islands according to the island of origin.

Eleven metals (K, Na, Ca, Mg, Fe, Cu, Zn, Mn, Sr, Li, and Rb) were determined in 83 red wines from the Canary Islands. The wines presented high concentrations of Na, and the concentrations of Cu and Zn were much lower than the maximum concentrations established by the International Office of Vine and Wine (OIV). Applying principal component analysis, the dimension space was reduced to five principal components that explain 76.4% of the total variance, and the wines tend to separate on the basis of the island of production. Linear discriminant analysis (LDA) allowed a reasonable classification of wines according to the island of production. When artificial neural networks (Kohonen self-organizing maps and back-propagation feed-forward as unsupervised and supervised techniques, respectively) were applied on the matrix of data constituted by the analyzed metals, the results improved in relation to those obtained by other multivariate methods observing a differentiation of wines according to island of production.

Analysis of Variance↗

PubMed1994

Malnutrition as a prognostic factor in lymphoblastic leukaemia: a multivariate analysis.

One hundred and twenty eight Brazilian children with lymphoblastic leukaemia were intensively treated with a Berlin-Frankfurt-Munich based protocol. More children had a white cell count above 50 x 10(9)/l (31%) then observed in developed countries. After a median follow up of 31 months (11-58 months), the estimated probability of relapse free survival was 41% (7%) for the whole group. After adjustment in the Cox's multivariate model, malnutrition was the most significant adverse factor affecting duration of complete remission. Age above 8 years and high peripheral white cell count were also significant adverse factors. Among the nutritional indices, the height for age and weight for age z scores were both significant, whether the cut off points of z-2 or z = -1.28 were chosen to define malnutrition. A strong statistical association between the two indices was found; the contribution of height for age z score to the prediction of relapse free survival was more significant. Children with height for age z score < -2 had a relapse risk of 8.2 (95% confidence interval 3.1 to 21.9) relative to children with z score > -2. The results of this study suggest that socioeconomic and nutritional factors should be considered in the prognostic evaluation of children with leukaemia in developing countries.

Adolescent↗

PubMed1989

Prognostic value of estrogen and progesterone receptors in primary infiltrating ductal breast cancer. A sequential multivariate analysis of 1262 patients.

Nine prognostic variables were evaluated for their significance in predicting the overall survival (OS), the length of disease-free survival (DFS) and the length of metastasis-free survival (MFS) of 1262 patients with primary breast cancer. The variables studied were: UICC clinical stage; menopausal status; histologic grade; number of involved nodes; anatomic tumor size; estrogen and progesterone receptors; local and adjuvant therapies. Three sequential multivariate analyses, at 2, 5 and 10 years, using the Cox proportional hazard regression model, were carried out to identify those variables most highly related to the criteria studied (overall, disease-free, metastasis-free survivals) and especially to fully evaluate the effects of hormonal receptors on prognosis and their stability over time. Our results showed that number of involved nodes and histologic grade were the most significant prognostic factors for all periods of time and whatever the criterion studied; ER had no predictive value while PR was an independent prognostic factor for metastasis-free survival at 2 years (P = 0.01) and 5 years (P = 0.02) but lost its significance at 10 years (P = 0.06). In the subgroup of 261 patients who received prolonged post-operative adjuvant chemotherapies, PR was the main prognostic factor for MFS at 2 years (P = 0.03) and the second at 5 years (P = 0.05) just after number of involved nodes. In the 1001 patients who did not receive prolonged post-operative adjuvant chemotherapies ER was significant for MFS at 5 and 10 years. The present data urge the need for a periodic redefinition of prognostic factors in primary breast cancer.

Adult↗

PubMed1991

Prognostic factors in patients with melanoma metastatic to axillary or inguinal lymph nodes. A multivariate analysis.

Although pathologic nodal status is a major determinant of outcome in melanoma, there is substantial prognostic heterogeneity among node-positive patients. This study was undertaken to further clarify significant variables predicting survival in patients with melanoma metastatic to axillary or groin nodes. From 1019 patients with melanoma undergoing axillary or groin dissection between 1974 and 1984, the authors identified 449 patients with histologically positive nodes. Both univariate and multivariate analyses were performed using the Kaplan-Meier product limit method and the Cox model of proportional hazard regression. The major determinant of survival was pathologic stage (PS) according to the 1983 AJCC staging system. Three hundred fifty patients (78%) were classified PS-III (one nodal group involved), with a survival of 39% at 5 years and 32% at 10 years. Factors independently predictive of a favorable outcome in these patients were nontruncal primary site (p = 0.0002), microscopic nodal involvement (p = 0.001), number of positive nodes less than three (p = 0.003), and absence of extranodal disease (p = 0.01). Ninety-nine patients (22%) were classified PS-IV, 51 with two nodal stations involved (N2), 25 with intransit disease and one nodal station involved (N2), 7 with extraregional soft tissue metastases (M1), and 16 with visceral metastases (M2). Survival for PS-IV patients was 9% at 5 and 10 years, respectively. Within PS-IV, factors independently predictive of a more favorable outcome were the absence of extranodal disease (p = 0.0001), female sex (p = 0.03), and a long interval from diagnosis to lymph node dissection (p = 0.04). These factors were incorporated into a model predicting relative risk of death from disease for both PS-III and PS-IV patients, separating patients into groups at high, intermediate, and low risk of recurrence after lymphadenectomy.

Adolescent↗

PubMed1988

The social and economic correlates of pregnancy resolution among adolescents in New York City, by race and ethnicity: a multivariate analysis.

This study utilizes a data set combining vital records from live birth and induced abortion certificates in New York City in 1984 to examine the correlates of the two outcomes among pregnant adolescents. Four groups totaling 31,207 teenagers were examined: Black non-Latinos (51 per cent), White non-Latinos (17 per cent), Puerto Ricans (25 per cent), and non-Puerto Rican Latinos (8 per cent). Multivariate regressions were fit for each group. Simulations based on the regressions reveal that the proportion of live births plus induced abortions among unmarried 18-year-olds, on Medicaid, with a previous live birth, no previous induced abortions, and nine years of completed schooling was .55 in the case of Puerto Ricans, .34 for non-Puerto Rican Latinos, .60 for Blacks, and .51 for Whites. For nulliparous adolescents of the same age and marital status, with an additional year of schooling, but not on Medicaid, and with a previous induced abortion, the fraction of pregnancies that were terminated rose to .84 in the case of Puerto Ricans, .81 for non-Puerto Rican Latinos, .87 for Blacks, and .96 for Whites. The results suggest that attitudes toward abortion as proxied by previous induced terminations substantially increase the likelihood of aborting as well as narrow the racial and ethnic differences with respect to pregnancy resolution.

Adolescent↗

PubMed1989

Prognosis in equine colic patients using multivariable analysis.

Multiple logistic regression was used to investigate prognosis in 308 horses referred to the University of Minnesota veterinary teaching hospital with colic. Bivariate results identified the following significant individual parameters: absent or hypomotile abdominal sounds, medical or surgical classification, peritoneal fluid total protein, anion gap, serum glucose, capillary refill time, blood pH, heart rate, packed cell volume, base excess, serum chloride, plasma bicarbonate, serum urinary nitrogen and age. Two multivariable prognostic models were developed using logistic regression. Model I (based on 257 cases with a mortality rate of 39%) included age, sex, medical or surgical classification, capillary refill time, packed cell volume and heart rate. Model II (based on 138 cases with a mortality rate of 48%) included age, sex, medical or surgical classification, capillary refill time, serum bicarbonate, serum chloride and respiratory rate. Predictive performance of the models was evaluated by treating the calculated probability of death for each horse as a continuous test result. The influence of varying the probability cutoff point for death on test characteristics (sensitivity, specificity and positive and negative predictive values) was determined. These models have not been validated and thus their performance in a different population is uncertain.

Animals↗

PubMedDate not supplied

A multivariable analysis of factors governing the steady-state pharmacokinetics of valproic acid in 52 young epileptics.

A number of factors have been implicated in the interpatient variability of valproic acid (VPA) pharmacokinetics. These include patient age, concurrent anticonvulsant therapy, and dosage of VPA. In the clinical setting, it is important to determine which of these variables exert a major effect on the observed differences in VPA disposition. Accordingly, we analyzed the data from 52 young epileptic patients using multivariate statistical methods. Concurrent anticonvulsant therapy was the major determinant of VPA clearance in this patient population. The half-life of VPA was significantly related to age, but volume of distribution and clearance were not. The dosage of VPA affected the volume of distribution of VPA but not the half-life or clearance of this drug. These results provide a more rational understanding of VPA pharmacokinetics in the clinical setting and have implications for the monitoring and manipulation of VPA therapy in the epileptic population.

Adolescent↗

PubMed1987

Maternal age and primary cesarean section rates: a multivariate analysis.

To study the effect of maternal age on primary cesarean section rates, 3458 consecutive deliveries were analyzed. The cesarean section rates in primiparous women less than 25, 25 to 34, and over 34 years of age were 13.1%, 18.5%, and 28.2%, respectively. A similarly dramatic rise with advancing maternal age was seen in multiparous women with rates of 3.4%, 4.7%, and 10.1%, respectively, in the three age groups. The strong association between cesarean section and maternal age persisted after multivariate adjustment for induction of labor, epidural anesthesia, meconium-stained amniotic fluid, and fetal distress, and thus these factors do not explain the relationship.

Abruptio Placentae↗

PubMed1987

Pyramidal cortical cell morphology studied by multivariate analysis: effects of neonatal thyroidectomy, ageing and thyroxine-substitution therapy.

The changes produced on the whole dendritic morphology of layer III cortical pyramidal neurons by neonatal hypothyroidism, induced in rats by thyroidectomy at 10 days of age (T), as well as those changes related to ageing, have been studied in rats at 40 and 80 days of age. For these purposes, the dendritic structure of these neurons was defined by a set of 10 variables whose measurements were analyzed using multivariate methods. The effect of tyroxine (T4) substitution therapies applied to T rats between 12-40 and 30-80 days of age has been further investigated with the same mathematical methodology. The results obtained from the analyses performed show that hypothyroidism affects both the apical tuft and the basal dendritic arborization of these neurons. The observed damage was similar: a decrease of the total length of the dendritic segments of the apical tuft and the basal arborization. This change, however, was detected in these two different subregions with a different timing. These results seem to reinforce our findings concerning the selective effect of T on different sites of these neurons. On the other hand, 3 morphological changes have been revealed regarding the development of the pyramidal neuron studied: (1) the total length of the apical tuft dendritic segments increases from 40 to 80 days of age; (2) the total length of the basal dendritic segments decreases from 40 to 80 days of age; and (3) the perimeter of the cell body decreases from 40 to 80 days of age. Finally, the results obtained did not allow us to detect any recovery of the damage induced by T, as a consequence of the T4 substitution therapies applied.

Aging↗

PubMed1986

Similarities and differences in acute cardiovascular responses to alcohol among normal men of European, Japanese, and Chinese ancestry: a univariate and multivariate analysis.

Normal young adult males residing in Hawaii (46 of European ancestry, 30 Japanese, 27 Chinese) were tested for changes in heart rate and blood pressure following a dose of 0.59 g of ethanol/kg. The two Oriental groups did not differ in mean changes but, when pooled, differed from Europeans, having increased heart rate and decreased blood pressure. Within-race analyses showed that, contrary to the literature, all three groups have great interindividual differences in cardiovascular responses. In addition, the three races show a basically similar multivariate response: blood pressure more variable than heart rate and blood pressure changes uncorrelated with heart rate changes.

Adult↗

PubMed1988

An ordinal multivariate analysis of accident counts as functions of traffic approach volumes at intersections.

This research is concerned with the statistical analysis of accident counts at nonsignalized intersections. The objective is to develop a method for determining general (nonlinear) relationships between approach volumes and accident counts. The method must accommodate the testing of whether intersections of differing physical designs have higher or lower rates of accidents than predicted by traffic levels. It is assumed that only aggregate data are available: (1) counts of total accidents by type (e.g., injury versus property damage) without details concerning the locational position(s) of the vehicle(s) involved; and (2) aggregate traffic intensity on each intersection entry without details concerning turning volumes. The method involves the application of nonlinear multivariate methods to variables treated as ordinal scales. A case study application involving four-leg and three-leg ("T") nonsignalized major arterial intersections in the Netherlands is described. The effect of bicycle traffic on accident rates is included in the case study analysis. The results indicate that there are three groups of each of the two types of intersections based on traffic flow patterns. For each group, a different functional form was found to relate accident rates and specific variables measuring traffic volumes. There were no significant differences among the physical design categories of the intersections in each group that were not accounted for by differences in traffic intensities.

Accidents, Traffic↗