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Results for “Regression Analysis”

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PubMed1996

High-dose administration of nonionic contrast media: a retrospective review.

PURPOSE: To assess the safety of high-dose nonionic contrast media (CM) during a single radiologic procedure. MATERIALS AND METHODS: From November 1991 to August 1995, 255 high-dose angiographic procedures were performed in 228 patients with normal serum creatinine (SCr) levels (< or = 1.6 mg/dL [141 mumol/L]). All patients received 250-800 mL low-osmolarity CM (300 mg iodine per milliliter). Pre- and postprocedure SCr levels were assessed. Urine output was measured daily in the 75 patients who received more than 400 mL CM. With linear regression analysis, a dose-related elevation in SCr levels was calculated. RESULTS: No patient developed abnormal SCr levels (> 1.6 mg/dL [141 mumol/L]) as a result of the CM. Among the patients who received more than 400 mL, none developed oliguria over the first 36 hours. With follow-up up to 3 years, no patient experienced delayed clinical renal failure. In 11 (4.3%) patients, the SCr levels increased more than 25%, but all increases were within expected limits (chi 2 analysis). Linear regression analysis revealed a 0.015 mg/dL (1 mumol/L) increase in SCr levels per 100 mL CM. CONCLUSION: Intravenous administration of high-dose low-osmolarity iodinated CM appears safe in patients without renal dysfunction or other underlying risk factors, in doses as large as 800 mL (300 mg iodine per milliliter).

Adolescent↗

PubMed2006

Effects of a combined therapy of erythropoietin, iron, folate, and vitamin B12 on the transfusion requirements of extremely low birth weight infants.

OBJECTIVES: Erythropoietin is frequently administered to premature infants to stimulate erythropoiesis. The primary goal of erythropoietin therapy is to reduce transfusions, but the efficacy of erythropoietin has not been convincingly demonstrated in this regard. The aim of this trial was to investigate whether combined administration of vitamin B12, folic acid, iron, and erythropoietin could decrease transfusion requirements in extremely low birth weight infants. PATIENTS AND METHODS: In a randomized, controlled trial, extremely low birth weight infants with a birth weight < or = 800 g and a gestational age < or = 32 weeks were randomly assigned to a group receiving combination treatment or a control arm. RESULTS: The treatment increased levels of folate in red blood cells, vitamin B12, ferritin, transferrin receptor levels in plasma, and reticulocyte counts. The proportion of infants requiring no transfusions was lower in the treatment group (38%) as compared with controls (5%). The treatment group and the need for mechanical ventilation were independent predictors of the number of transfusions in multiple regression analysis. Cox regression analysis indicated that combined therapy resulted in a 79% risk reduction for any transfusion. CONCLUSION: Combined treatment with erythropoietin, intravenous iron, folate, and vitamin B12 during the first weeks reduces the need for transfusion in extremely low birth weight infants.

Blood Transfusion↗

PubMedDate not supplied

Factors predictive of LASIK flap thickness with the Hansatome zero compression microkeratome.

PURPOSE: To determine the explanatory power of preoperative variables and comeal flap thickness in laser in situ keratomileusis (LASIK) using the Hansatome zero compression microkeratome (Bausch & Lomb, Rochester, NY). METHODS: A prospective, nonrandomized, comparative interventional case study was performed on 250 eyes of 129 consecutive patients who underwent LASIK surgery using the Hansatome zero compression microkeratome. A 160-microm or 180-microm microkeratome head and an 8.5- or 9.5-mm suction ring were used in the procedures. Preoperative measurements included refraction, spherical equivalent, keratometry, intraocular pressure, corneal white-to-white, anterior chamber depth, and corneal eccentricity. Corneal thickness was measured intraoperatively using ultrasonic pachymetry before and after flap creation, and the difference was taken as flap thickness. Flap diameter was measured with a corneal gauge. Data were analyzed using simple, multiple, stepwise linear and non-linear regression analyses and two-tailed t tests. RESULTS: The mean flap thickness was 124 +/- 17 microm with the nominal 160-microm head and 142 +/- 20 microm with the nominal 180-microm head. One third (33%) of the total variation in flap thickness could be accounted for by three preoperative variables: average corneal thickness, spherical equivalent refraction, and choice of 160- or 180-microm microkeratome head. A simple correlation of 0.114 was noted between corneal eccentricity and flap thickness, but this variable did not add significant explanatory power on multiple regression analysis. Linear regression analysis allowed determination of a flap thickness nomogram with a standard error of the estimate of 16.9 microm and a 95% confidence interval of +/- 33.1. CONCLUSIONS: Comeal thickness is the most systematic predictor of corneal flap thickness using the Hansatome microkeratome. Because three preoperative variables account for only 33% of the range in flap thickness, future studies should focus on variations in blade extension and corneal biomechanical factors, which may also play an important role in determining flap thickness.

Adult↗

PubMed1990

Quantification of neonatal cerebral ventricular volume by real-time ultrasonography. Derivation and in vitro confirmation of a mathematical model.

The derivation and in vitro confirmation of a method for the calculation of cerebral ventricular volume determined by cranial ultrasonography is described. The derivation depends on use of the cylindrical coordinate method. Confirmation was performed by construction of ultrasound phantoms from latex balloons embedded in a talc/gelatin matrix. Seventeen phantoms of volumes ranging from 10 to 60 mL were measured. The known volume was then compared to the calculated volume by linear regression analysis. The regression analysis indicated a close correlation between the actual volume of the phantoms and the calculated volume with r = 0.96. Various sources of error in the method are discussed. Our results indicate that the cylindrical coordinate mathematical model when applied to cranial ultrasonography images accurately measures cerebral ventricular volumes.

Analysis of Variance↗

PubMed1989

[The correlation of serum IgE and IgE-RAST of mite, egg white, milk, soybean, rice and wheat: a study by analysis of regression curves].

The correlation of variation in serum IgE and IgE-RAST in 364 cases of patients with atopic dermatitis (AD) aged 4 months to 78 years was analysed by comparison with the scatter diagram and fifth dimension regression curve representing the serum IgE and IgE-RAST scores of mite, egg white, milk, soybean, wheat and rice. The antigens indicating a high IgE-RAST score varied according to age. They were egg white and milk in infancy and mite from one to fifteen years of age. Rice and wheat came later. A high value of serum IgE with AD was seen to depend on the production of specific mite IgE antibody and to be influenced by each specific IgE antibody production, which varied according to age. It seemed that egg white and milk were initiators of AD and mite acted as a promotor. Rice and wheat were accelerators in patients with adult type AD. It was confirmed that, for AD patients of all ages, improvement of the environmental antigens and diet therapy was necessary.

Adolescent↗

PubMed1979

MIC determination, disc sensitivity testing, and analysis of regression in cefazedone and cefazolin.

Minimum inhibitory concentrations (MIC) of (6R,7R)-7-(2-[3,5-dichloro-4-oxo-1(4H)-pyridyl-a1-acetamido)-3-([(5-methyl-1,3,4-thiadiazol-2-yl)-thio]methyl)-8-oxo-5-thia-1-azabicyclo[4,2,0]oct-2-ene-2-carboxylic acid (cefazedone, Refosporen)), a new semisynthetic cephalosporin derivative were determined by a broth dilution technique. In comparison with cefazolin 130 gram-positive and gram-negative bacteria, recent clinical isolates, were tested. In parallel, inhibition zones for the same organisms were determined by a standardized disc technique using 30-micrograms discs. According to the calculated regression lines a good correlation was found for cefazedone and cefazolin between the MIC values and the diameters of the inhibition zones (correlation coefficients r = --0.90 and --0.92, respectively). Taking into account the dosages recommended for cefazedone and the mean serum concentrations to which they give rise, appropriate categories of sensitivity (break points) for susceptibility testing are recommended.

Bacteria↗

PubMedDate not supplied

[Development and contribution to the validation of a brief French version of the Yesavage Geriatric Depression Scale].

Depression in old age is underdiagnosed. In order to help detection, Yesavage et al. (1983) developed the Geriatric Depression Scale in a 30 items original version, with good reliability and validity. To abbreviate duration of examination, a shortened 15 items version was proposed (Sheikh et al., 1986) and a 4 items GDS for primary care attenders was also developed (D'Ath et al., 1994) with satisfactory metrological characteristics. The aim of this study is to develop a short French version and to contribute to its validation. French elderly depressives (181) and controls (66) were asked to complete the 30 items GDS (french version) and an other french self-rating scale, the QD2A (Pichot, 1986). In an attempt to devise the short scale, data were subjected to logistic regression analysis, multiple regression analysis, item-total Spearman's rank correlation coefficients and finally to mean choice ranks combination method. The generated 4 items version (mini-GDS) was found to be highly correlated with GDS 30 (r = 0.84, p < 0.0001) and with QD2A (r = 0.64, p < 0.0001) and had a high level of internal consistency (KR20 = 0.66). The sensitivity and specificity of the GDS 4 were 69% and 80% (cut-off 0/1) and against QD2A were 75% and 75% (cut-off 0/1). Out of the four items, two were common with the D'Ath's 4 items version. Method with its different statistical developments was discussed and the 4 selected items of the mini-GDS were compared with data from several authors who evaluated, discussed or examined factor structures of the 30 items GDS. Conclusion is that mini-GDS is reliable to easily detect a depressive symptomatology in the elderly, in different circumstances.

Aged↗

PubMed1986

Survival analysis (or time to an event analysis), and the Cox regression model--methods for longitudinal psychiatric research.

A multivariate statistical instrument is presented, which combines the life table with regression analysis: the Cox proportional hazards regression model. It is suitable for analyzing longitudinal clinical data, and to find predictors of different outcomes in psychiatric research such as death, relapse or cure. All patient information can be used, since the time to the outcome event is included in the model. Treatments can be compared, and prognostic indices created.

Actuarial Analysis↗

PubMed2000

Procollagen IIC-peptide as a marker for assessing mechanical risk factors of knee osteoarthritis: effect of obesity and varus alignment.

OBJECTIVE: To ascertain by cross sectional examination whether the concentration of procollagen IIC-peptide in joint fluid significantly correlates with mechanical risk factors of knee osteoarthritis (OA), such as obesity (body mass index) and varus alignment (lateral femorotibial angle). METHODS: The concentrations of procollagen IIC-propeptide in synovial fluid were measured by a sandwich enzyme immunoassay of 65 patients with the same radiological stage of primary knee OA-that is, Ahlbäk stage I. The relations between procollagen IIC-peptide and body mass index and lateral femorotibial angle were examined using simple regression analysis and multiple regression analysis. RESULTS: Significant positive correlations were found between procollagen IIC-propeptide concentrations and body mass index (r=0.479, p<0.0001), and between procollagen IIC-propeptide concentrations and lateral femorotibial angle (r=0.375, p=0.0021). Significant correlations were also found by multiple regression analysis. The multiple correlation coefficient of body mass index and femorotibial lateral angle to the procollagen IIC-propeptide concentrations was 0.547 (p<0.0001). CONCLUSIONS: The findings suggest that synthesis of type II collagen by chondrocytes is enhanced by abnormal mechanical stress, in this case obesity and varus alignment. It is concluded that procollagen IIC-propeptide concentrations in joint fluid are a useful marker of early OA.

Biomarkers↗

PubMed1985

A model for the evaluation of respiratory therapy program admissions criteria.

UNLABELLED: Attrition in respiratory therapy programs is a waste of both human and economic resources and may be one cause of the current shortage of qualified personnel. Poor academic performance has been shown to be the leading cause of program attrition. The purposes of this study were to establish the predictive abilities of aptitude and performance measures for classroom and laboratory performance in a respiratory therapy program and to describe a methodology for the development of academic admissions criteria. METHODS: The preprogram college cumulative grade point average (pPGPA), the preprogram science-mathematics grade point average (S-M GPA), the American College Test (ACT) composite, and four ACT subtest scores of 39 graduates of The Ohio State University Respiratory Therapy Division were compared to their program grade point average (PGPA). We applied a multiple regression analysis and derived regression equations. RESULTS: Multiple regression analysis demonstrated that the S-M GPA is the most significant predictor of program academic performance (P less than or equal to 0.05). The derived regression equation was applied to calculate the minimum S-M GPA for admission by using the standard error of the estimate (SEE) of the regression equation and the mean minimum acceptable PGPA at a 95% confidence interval. For those students who have met the minimum S-M GPA, we have experienced no academic attrition. CONCLUSION: Multiple regression analysis of student data and the derived regression equations may be used to determine program-specific admissions criteria.

Educational Measurement↗

PubMed2003

Sensitivity studies for quantitative assays: use of censored data analysis.

Probit regression analysis is frequently used to study the relation between the concentration of an analyte in a sample and the probability that the assay used yields a positive test result. For these analyses only the qualitative classification 'positive' or 'negative' is used, whereas, particularly in the case where the assay is quantitative in nature, the results contain more information. In the current paper, we propose an alternative method, in which the negative test results are treated as being (left) censored. As such, more efficient use is made of the information in the data. The procedures are illustrated using two generations of NucliSens assays (BioMérieux), which are designed to quantify the viral load of HIV-1 in blood samples. Computer simulations are used to illustrate some properties of the estimated parameters.

Blood Banks↗

PubMed1990

Corneal edema recovery dynamics in the rabbit. A useful model?

Open-eye and closed-eye recovery from contact lens-induced corneal edema was measured on the right eyes of 10 New Zealand White rabbits using ultrasound pachometry. Edema was produced by either 2 hours of eye closure (Patch Test) or 2 hours wearing of a thick hydrogel contact lens over the closed eye (Lens Test). The measured corneal edema recovery data were analyzed by both linear-regression analysis and nonlinear-regression analysis based on a previously published exponential open-eye edema recovery model. Linear-regression analysis revealed that the initial rabbit open-eye edema recovery rate of 36.3 +/- 11.9 (standard deviation) micron/hr was not significantly different (P greater than 0.25) from the initial young human open-eye edema recovery rate of 35.6 +/- 3.4 micron/hr. Similarly, the initial rabbit closed-eye edema recovery rate of 14.3 +/- 5.4 micron/hr was found to be not significantly different (P greater than 0.25) from the initial young human closed-eye edema recovery rate of 15.0 +/- 2.2 microns/hr. Corneal edema recovery indices derived using nonlinear-regression analysis also had a strong similarity between rabbit and human corneal edema recovery rates. For example, the calculated percent recovery per hour (PRPH) for rabbit open-eye corneal edema recovery of 41.4 +/- 11.3%/hr agreed well with the reported human open-eye PRPH of 34.2-58.9%/hr. The rabbit closed-eye PRPH of 25.6 +/- 10.7%/hr was also found to lie between the calculated human closed-eye PRPH values of 19.9-30.2%/hr.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Laboratory- and species-specific interpretive breakpoints for disk diffusion tests of chloramphenicol susceptibility of Haemophilus influenzae.

A total of 601 clinical isolates of Haemophilus influenzae isolated in six different regions of Sweden were tested for chloramphenicol susceptibility by using agar dilution MIC determinations and disk diffusion tests. For seven strains MICs were 4 micrograms/ml or higher, and for one strain the MIC was 2 micrograms/ml. All eight strains produced chloramphenicol acetyltransferase. For the remaining 593 strains, MICs were less than or equal to 1 microgram/ml, and the MICs for 50% and 90% of the strains were both 0.5 microgram/ml. Disk diffusion tests carried out by using revised interpretive criteria introduced in 1984 by the Swedish Reference Group for Antibiotics correctly identified the 593 strains as susceptible and the 8 strains as resistant. Quality assessments were performed in 29 clinical microbiology laboratories. The revised criteria for chloramphenicol disk diffusion testing gave rise to false resistance results in some laboratories. The interpretive accuracy improved when the interlaboratory variation was compensated for by using adjusted breakpoints. Such revision was possible through peak correction, single-strain regression analysis, and standard curve regression analysis. Peak-corrected breakpoints improved the accuracy from an overall incidence of false-resistant isolates of 4.4% to 2.3%. Single-strain regression analysis and standard curve regression analysis provided laboratory- and species-specific breakpoints which reduced false resistance rates of 0.14% and 0%, respectively.

Chloramphenicol↗

PubMed1992

[Effect of chronic smoking on regional cerebral blood flow in asymptomatic individuals].

The chronic effects of cigarette smoking upon regional cerebral blood flow (rCBF) are unclear. The present study investigated the effects of smoking on rCBF assessed by intravenous 133Xe injection in 40 asymptomatic individuals. Analysis was performed using linear regression analysis and multiple regression analysis, creating a model of the rCBF as a function of cerebrovascular risk factor. The risk factors included smoking status, smoking index, age, gender, mean arterial blood pressure, total cholesterol, fasting blood glucose, hematocrit and STT change and left ventricular hypertrophy in electrocardiogram. The male-to-female ratio was higher in the smoking group (18/2) than that in the non-smoking group (2/18). Among the smokers, mean hematocrit was significantly higher than in the non-smokers (p < 0.01). There was no significant difference in rCBF and other variables between the two groups. Linear regression analysis revealed significantly negative correlations between smoking index and CBF in the whole brain (r = -0.33; p < 0.05), right hemisphere (r = -0.34; p < 0.05), right parietal cortex (r = -0.36; p < 0.05), right occipital cortex (r = -0.34; p < 0.05) and left parietal cortex (r = -0.33; p < 0.05). In other variables, age, male sex, hematocrit, left ventricular hypertrophy and STT change showed significantly negative correlations with rCBF. To reduce the effect of confounding variables in our assessment of the dose-related response, a multivariate regression analysis was carried out treating rCBF as a dependent variable and risk factors as independent variables. In the final model, age, hematocrit, male sex and presence of BCG changes remained as independent negative predictors for rCBF.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Critical levels of blood and urinary cadmium, urinary beta 2-microglobulin and retinol-binding protein for monitoring cadmium health effects.

The critical levels for monitoring cadmium health effects in 358 workers engaged in ore crushing/roasting (cadmium concentration in the workplace air 2.5-6.5 mg/m3), dry smelting (10.8-23.3 mg/m3), cadmium melting (0.01-0.16 mg/m3), and ingot making (2.8-4.7 mg/m3), were investigated. Exposure parameters such as blood and urinary cadmium were determined, together with biological parameters such as proteinuria, amino acids, glucose, beta 2-microglobulin, retinol-binding protein, albumin, plasma beta 2-microglobulin, creatinine clearance, tubular reabsorption of beta 2-microglobulin and phosphate, and blood and urinary levels of zinc, copper and lead. Factor analysis and stepwise regression analysis were then applied to the data to classify parameters and to find the main contributing parameter. Blood and urinary cadmium, urinary beta 2-microglobulin, retinol-binding protein and the ratio of urinary beta 2-microglobulin to albumin were also subjected to multiple correlation analysis, multiple regression analysis and the Chi-square test was applied to contingency tables. It is concluded, based on the data, that cadmium health effects may be assessed by using the following critical levels: blood cadmium: 10 micrograms/l, urinary cadmium: 10 micrograms/g creatinine; urinary beta 2-microglobulin: 2000 micrograms/g creatinine, urinary retinol-binding protein: 200 micrograms/g creatinine and a ratio of urinary beta 2-microglobulin to albumin of 0.001.

Adult↗

PubMed2005

Optimization of basal insulin delivery in Type 1 diabetes: a retrospective study on the use of continuous subcutaneous insulin infusion and insulin glargine.

AIMS: To compare the effects on glycaemic control after using continuous subcutaneous insulin infusion (CSII) or insulin glargine. METHODS: Data were obtained from 17 diabetes outpatient clinics in Sweden, employing the same diabetes data management system. Type 1 diabetic patients using multiple dose injections were included prior to starting on either CSII (n = 563) or glargine (n = 513). The median duration of therapy was 25 months for CSII and 6 months for glargine. The comparison between the treatment modalities was carried out by multiple regression analysis and logistic regression analysis in an attempt at reducing the influence of confounding factors. RESULTS: The mean HbA1c decrease was 0.59 +/- 1.19% for CSII and 0.20 +/- 1.07% for glargine (P < 0.001, when assessed by logistic regression). An additional 0.1% lower HbA1c would be expected if glargine had been optimized with basal insulin 40-60% of the daily dose. The more pronounced effect of CSII was achieved with a lower daily dosage of insulin. In a multiple regression analysis with a change of HbA1c as the dependent variable, the following variables were significant: choice of treatment (P < 0.001), HbA1c prior to treatment (P < 0.001) and BMI prior to treatment (P < 0.01). CONCLUSION: Both regimes improved metabolic control, but CSII resulted in significantly higher reduction in HbA1c than after insulin glargine treatment, particularly in those individuals who had higher levels of HbA1c at baseline.

Adult↗

PubMed1998

Changes in lipid peroxide level in retinal pigment epithelial cells in vitro upon addition of linoleic acids or linoleic acid hydroperoxides under varying concentrations of oxygen.

We previously observed the presence of autofluorescent lipofuscin or its like in retinal pigment epithelial (RPE) cells, which were incubated with linoleic acid hydroperoxides (LHP). We studied the effect of oxygen on the level of lipid peroxides in RPE cells in the presence of linoleic acids (LA) or LHP. The level of lipid peroxides in these cells was determined by use of the thiobarbituric acid-reactive substance (TBARS), which responded to oxygen concentrations qualitatively, and a linear regression analysis. Multiple linear regression analysis disclosed that treatment with LA for 24 hr resulted in detectable increase in the level of TBARS in the cells, whereas treatment with LA or LHP for 48 hr caused detectable decrease. Stepwise linear regression analysis showed that the level of TBARS decreased in an oxygen-tension dependent manner in the cells incubated with LA for 48 hr. Thus, it was shown that short-term incubation with LA increased the level of TBARS in the cells and that LA decreased its level in an oxygen-tension dependent manner. For these results, the postulation was made that the prolonged auto-oxidation of LA caused production of lipofuscin-like materials, a complex of lipid peroxides and proteins that were insoluble in SDS and acetic acid solution.

Animals↗

PubMed1994

Viral and host factors that contribute to efficacy of interferon-alpha 2a therapy in patients with chronic hepatitis C.

Using conventional statistical analysis and multiple regression analysis, we investigated the viral and host factors that influence the response to recombinant interferon-alpha 2a therapy in patients with chronic hepatitis C. A total of 36 patients was randomly assigned to three administration schedules, 12 patients in each. Response to treatment was set as the criterion variable. Four variables were statistically significant in the conventional method in predicting a good therapeutic outcome: HCV genotype III and IV, lower histology activity index (HAI) score for liver, higher total dose of interferon administration, and lower serum HCV RNA concentration. In multiple regression analysis, a combination of the above four variables resulted in a higher multiple correlation coefficient (R = 0.84, P < 0.0001) using a stepwise method. Of those four, HCV genotype had the highest absolute value of standard partial regression coefficient (0.51). The HCV RNA concentration was correlated with HCV genotype and HAI score, whereas HCV genotype and HAI score showed no correlation. Thus, HCV RNA concentration was not statistically significant in multiple regression analysis. These findings indicate that HCV genotype, HAI score, and schedule of administration can be important predictors of the response to interferon therapy.

Adult↗