SEARCH · PubMed Health

Results for “multiple linear regression”

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

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

At least 271 records · Page 15Linked to original sources

PubMed2006

Renal function and 25-hydroxyvitamin D concentrations predict parathyroid hormone levels in renal transplant patients.

BACKGROUND: Recent guidelines suggest supplementation with ergocalciferol (vitamin D(2)) in chronic kidney disease stages 3 and 4 patients with elevated parathyroid hormone (PTH) levels and 25-hydroxyvitamin D (25OHD) levels <75 nmol/l. These guidelines are also applied to renal transplant patients. However, the prevalence rates of 25OHD deficiency and its association with PTH levels in renal transplant populations have not been extensively examined. We aimed to document the prevalence rates of 25OHD deficiency [defined by serum levels <40 nmol/l (<16 ng/ml)] and insufficiency [<75 nmol/l (<30 ng/ml)] in a single renal transplant centre, and examine its relationship with PTH levels. METHODS: Serum 25OHD and PTH concentrations were measured in 419 transplant patients attending a single renal transplant clinic over a 4-month period. Demographic and biochemical data were also collected, including serum creatinine, calcium, phosphate and albumin. Simple and multiple linear regression analysis were performed. RESULTS: In 27.3% of the patients, 25OHD deficiency was present, and 75.5% had insufficiency. On univariate analysis, 25OHD, serum albumin and estimated glomerular filtration rate (eGFR) were significantly associated with PTH levels (P < 0.0001, P = 0.004 and P < 0.0001, respectively). Multiple linear regression demonstrated that only 25OHD, eGFR and serum phosphate were significantly predictive of PTH levels (R(2) = 0.19, P < 0.0001). In this model, a 75 nmol/l increase in 25OHD will only result in a maximal reduction in PTH of 2.0 pmol/l. CONCLUSIONS: We conclude that 25OHD deficiency and insufficiency are common in renal transplant patients and may exacerbate secondary hyperparathyroidism. However, 25OHD, eGFR and phosphate only account for 19% of the variability in PTH levels. In addition, even a large increase in serum 25OHD levels is likely to result in only a small reduction in PTH. Therefore, alternative approaches to managing hyperparathyroidism in renal transplant recipients rather than supplementation with ergocalciferol are warranted.

Biomarkers↗

PubMed2006

An ecological study on the association of public dental health activities and sociodemographic characteristics with caries prevalence in Japanese 3-year-old children.

The aim of this ecological study was to determine the association of the frequency of dental health activities conducted as public health service and sociodemographic characteristics with caries prevalence in Japanese 3-year-old children using data for each municipality as one unit. Data on caries prevalence in 3-year-old children in 2000 were obtained from 3,251 municipalities (almost all municipalities in Japan). Caries prevalence for each municipality was recalculated using the empirical Bayes estimation model to make adjustments for variations in municipalities with small numbers of children. Explanatory factors included annual frequency of dental health activities such as dental health education and topical fluoride application programs and various sociodemographic characteristics. Multiple linear regression analysis was applied to examine the associations between caries prevalence and annual frequency of dental health activities with adjustment of other sociodemographic variables. Variations in caries prevalence in municipalities with small populations became smaller after being adjusted by the empirical Bayes estimation model. Multiple linear regression analysis showed significant associations of caries prevalence with sociodemographic characteristics such as the proportion of residents with university degrees, total fertility rate, and the proportion of workers in the manufacturing industry (p < 0.001). Annual frequency of topical fluoride application showed a significant but relatively weak association with caries prevalence (p < 0.001), explaining only 0.8% of the total variation in caries prevalence, whereas no correlation was found between caries prevalence and annual frequency of dental health education. It was concluded that the effect of the fluoride application service on caries prevalence in 3-year-old children, although statistically significant, was of far lower clinical significance than sociodemographic characteristics.

Cariostatic Agents↗

PubMed2004

Fibroblast growth factor (FGF)-23 in patients with primary hyperparathyroidism.

OBJECTIVE: We aimed to determine the serum level of fibroblast growth factor-23 (FGF-23) in patients with primary hyperparathyroidism (pHPT) to understand its physiological role in the disorder. PATIENTS AND METHODS: Ninety-eight patients with pHPT who underwent parathyroidectomy formed the study group. We also measured serum FGF-23 in 11 of these patients on postoperative day 6. RESULTS: Serum FGF-23 levels was significantly higher in pHPT patients than in healthy controls (35.6+/-17.8 ng/l vs 28.9+/-11.2 ng/l (mean+/-s.d.); P<0.001 (Pearson's correlation coefficient)), but there was no significant difference in the serum FGF-23 level between pHPT patients with normal renal function (creatinine clearance (Ccr) of >or=70 ml/min) and healthy controls. Serum FGF-23 correlated positively with serum calcium (P<0.0001) and intact parathyroid hormone (PTH) (P<0.01), and negatively with Ccr (P<0.001), serum phosphate (P<0.05), and serum 1,25-dihydroxyvitamin D (1,25(OH)(2)D) (P<0.05). Multiple linear regression analysis of factors potentially determining serum FGF-23 levels in pHPT patients showed serum calcium (P<0.01) and Ccr (P<0.001) to be significant predictors. The serum levels of FGF-23 did not change after parathyroidectomy despite the normalization of serum calcium values. Multiple linear regression analysis revealed that serum FGF-23 was not a significant predictor of serum phosphate or 1,25(OH)(2)D in pHPT patients. CONCLUSIONS: FGF-23 may not play a significant role in regulating phosphate or 1,25(OH)(2)D in pHPT patients, especially in those with normal renal function. Further studies are warranted to determine the role of FGF-23 in renal insufficiency or failure.

Adult↗

PubMed2004

The Bambui health and aging study: is calibration of dietary intake necessary among older adults?

Accurate measurements of food intake in surveys are difficult to be obtained especially in the older adults. Calibration, using two instruments, has been adopted in order to improve the information. This study was carried out in a random sample of older adults (> or =60) living in a Brazilian town. Food intake was obtained by the semi-quantitative food frequency questionnaire associated with photos (SFFQ-P) and the 24 hours recall (R24) with or without food models. Statistical analysis included tests to compare averages, Pearson's correlation coefficient and multiple linear regression. For all nutrients, the average intake obtained through SFFQ-P was significantly higher compared to the obtained by the R24 (p < or =0.05). SFFQ-P correlated better with R24 with food models, which was chosen as the reference method. In the multiple linear regression, vitamin C, fatty acid, protein and zinc intakes were influenced by age, especially when such nutrients were more concentrated in food not frequently reported. For protein and zinc, the significantly interaction between age with the 24 hours recall may have happened because of a differential selection of food sources as a function of age. This fact is probable related to chewing difficulties, reduction in the income and, a diet simplification associated with less complicated preparations, such as meat. This study reinforces the need for calibration of SFFQ in nutritional surveys among older adults, especially in etiological studies where the exposure assessment has to be accurate. In this case, R24 with food models should be used as a reference method to best estimate the true intake.

Adult↗

PubMed1998

Estimating urea clearance in patients on continuous ambulatory peritoneal dialysis: a multivariate analysis.

The purpose of this study was to determine if Kt/V urea in continuous ambulatory peritoneal dialysis (CAPD) could be estimated by a multivariate model based upon simple clinical observations. The study included 439 clearance studies in 301 CAPD patients followed in 8 dialysis centers. Weekly urea clearance, 24 h urine volume and 24 h drain volume were normalized to body water by the formulae of Watson (Kt/V, UV/V and DV/V respectively). Adequate dialysis was defined as Kt/V > or = 2.0 weekly. Subjects at 2 units were used to derive the models, while others were used for model validation. Stepwise multiple linear regression was performed on the derivation set (DS) to identify the clinical variables that correlated with Kt/V. The model was then used to estimate Kt/V for the validation set (VS). In the DS, 110 clearance studies were performed in subjects with residual renal function. Multiple linear regression showed that weekly Kt/V was defined by the expression: Kt/V=1.48 + 24.1 (UV/V) + 2.92(DV/V) - 0.049 (serum creatinine) (r=0.750, p<0.001). In 204 VS studies, the correlation between estimated and measured Kt/V was 0.633. There were marked differences in the proportion of adequately dialyzed patients when Kt/V estimated from the formula shown was <2.0, between 2.0 and 2.3, and >2.3 weekly (7.9%, 54.7% and 79.7%, respectively; p 2.3 weekly (8.1%, 68.8%, and 100%, respectively; p<0.001). The risk of low Kt/V can be estimated by multivariate linear models requiring only simple clinical measurements.

Female↗

PubMedDate not supplied

[Factors related to frequency of sexual activity of postmenopausal women].

OBJECTIVE: To identify factors related to the frequency of sexual activity of postmenopausal women METHODS: A cross-section study of 206 postmenopausal women between 45 and 60 years of age was made at a university health care service in the South of Brazil between June and October 2002. Evaluations were made of sexual activity according to the number of sexual intercourses in the previous month and the climacteric symptoms using the Kupperman index. Statistical analysis was performed with multiple linear regression analysis. RESULTS: Of those surveyed 176 (85%) women were sexually active. Although 60.6% reported a decrease in sexual activity after menopause, mostly attributing it to the husband's sexual impotence (41.7%). Approximately 25.7% stated they had no satisfaction with sexual intercourse. By means of multiple linear regression analysis the following aspects were associated to sexual activity: age (p<0.1), degree of sexual satisfaction (p=0.01), and climacteric symptomatology (p=0.02). As age increased the climacteric symptoms were more intense and sexual activity was less frequent with lower sexual satisfaction. The climacteric symptoms correlated with sexual activity were: hot flashes (p=0.05), irritability (p=0.04), melancholy/sadness (p=0.04), arthralgia/myalgia (p<0.01) and weakness/tiredness (p<0.01). CONCLUSION: Findings of this study were similar to those in literature. They agree with the hypothesis that sexuality of climacteric women is not only influenced by factors related to hypoestrogenism, but also by psychosocial and cultural aspects associated with aging itself. Nevertheless, longitudinal studies are necessary to provide more conclusive data. Special attention should be given to the sexual dysfunction of men.

Body Mass Index↗

PubMed1997

Correlation between the visual field indices and Heidelberg retina tomograph parameters.

PURPOSE: We wished to determine whether a relationship exists between Heidelberg retina tomograph (HRT) parameters and the visual field indices. METHODS: One eye was randomly chosen from 59 normal patients [normal visual field and normal optic nerve head (ONH) and intraocular pressure (IOP) < 21 mm Hg], 64 ocular hypertensive patients (normal visual field and normal OHN and IOP > 22 mm Hg), 124 high-tension glaucoma patients (abnormal visual field and/or abnormal optic nerve and IOP > 22 mm Hg) and 47 low-tension glaucoma patients (abnormal visual field and or optic disc and IOP < 21 mm Hg). All the patients were examined with Humphrey Perimeter, program 30-2, and HRT. Findings were assessed by analysis of variance, Pearson's correlation coefficient, and multiple linear regression. RESULTS: Among all subjects, we noted a statistically significant correlation (Pearson's r, p < 0.001) between cup area, cup/disc area ratio, rim area, rim volume, cup shape measure, and retinal nerve fiber layer cross-section area with mean deviation and corrected pattern SD. Multiple linear regression analysis demonstrated that rim area was the most important predictor of mean deviation and corrected pattern SD. CONCLUSIONS: The presence of significant correlations between some HRT parameters, such as rim area and cup shape measure and visual field indices, suggests that these HRT parameters could be good indicators of the degree of glaucomatous ONH damage.

Glaucoma, Open-Angle↗

PubMed2006

Boosting support vector regression in QSAR studies of bioactivities of chemical compounds.

In this paper, boosting has been coupled with SVR to develop a new method, boosting support vector regression (BSVR). BSVR is implemented by firstly constructing a series of SVR models on the various weighted versions of the original training set and then combining the predictions from the constructed SVR models to obtain integrative results by weighted median. The proposed BSVR algorithm has been used to predict toxicities of nitrobenzenes and inhibitory potency of 1-phenyl[2H]-tetrahydro-triazine-3-one analogues as inhibitors of 5-lipoxygenase. As comparisons to this method, the multiple linear regression (MLR) and conventional support vector regression (SVR) have also been investigated. Experimental results have shown that the introduction of boosting drastically enhances the generalization performance of individual SVR model and BSVR is a well-performing technique in QSAR studies superior to multiple linear regression.

Algorithms↗

PubMed1997

Serum immunoreactive leptin concentrations in a Canadian aboriginal population with high rates of NIDDM.

OBJECTIVE: To better understand the relationship between leptin and the anthropometric and physiological variables associated with diabetes, we measured this protein in an isolated Canadian aboriginal population with very high rates of NIDDM. RESEARCH DESIGN AND METHODS: There were 728 individuals aged 10-79 years who participated in a population-based survey to determine the prevalence of NIDDM and its associated risk factors. Fasting blood samples for glucose, insulin, triglyceride, and leptin were collected; a 75-g oral glucose tolerance test was administered and a second blood sample drawn after 120 min. Height, weight, and waist and hip circumference were determined, and percent body fat was estimated using biological impedance analysis. Fitness level was assessed in a subsample of individuals using a validated submaximal step test. The relationship between serum leptin and the other variables was assessed using Spearman's correlation coefficients and multiple linear regression. RESULTS: Serum leptin concentration was strongly correlated with adiposity, and levels were substantially higher in female subjects in all age-groups. For male subjects, percent body fat, fasting insulin level, and waist circumference were significant independent predictors of log serum leptin concentration in a multiple linear regression model (R2 = 0.582). For female subjects, these variables plus glucose tolerance status were included in the final model (R2 = 0.633). Fitness level, when included with the main effects of the above models, was a significant predictor for male subjects only. CONCLUSIONS: In an isolated aboriginal community with high rates of diabetes, we found significant independent relationships between leptin and percent body fat and between leptin and fasting insulin. As documented in other populations, the higher leptin concentration among female subjects may reflect differential leptin production from different adipose tissue beds, or leptin resistance. Independent relationships also existed among leptin and glucose tolerance status in female subjects and fitness level in male subjects.

Adolescent↗

PubMed1991

Comparison of three methods for measuring respiratory mechanics in ventilated children.

Continuous measurements of airway pressure, gas flow, and tidal volume were made in 22 mechanically ventilated children, both during steady state conditions and following airway occlusion at end-inflation. For each child, three methods of analyzing the stored data were used to generate values of respiratory system compliance and resistance: 1) end-inspiratory hold technique (Bone: Respir Care 28:597, 1983; Rossi et al. Am Rev Respir Dis 131:672, 1985); 2) constant flow technique (Rossi et al. J Appl Physiol 58:1849, 1985; Suratt et al. J Appl Physiol 49:1116, 1980); and 3) multiple linear regression (Roy et al. Comput Biomed Res 7:21, 1974; Bhutani et al. Pediatr Pulmonol 4:150, 1988). In the absence of an accepted standard, we used the inspiratory hold technique as a reference. All methods gave comparable values for respiratory mechanics over a wide clinical range. However, multiple linear regression was the most convenient of the three: it can be automated and continuously displayed, there is no subjective input, values are taken through the respiratory cycle, and it is completely noninvasive. We also found that respiratory system resistance was largely a measure of endotracheal tube resistance and that respiratory compliance is a more sensitive monitor of lung function in intubated children.

Airway Resistance↗

PubMed2005

White matter anisotropy in childhood medulloblastoma survivors: association with neurotoxicity risk factors.

PURPOSE: To prospectively evaluate the relationships between change in white matter (WM) anisotropy and (a) patient age at craniospinal irradiation (CSI), (b) CSI dose, and (c) time of magnetic resonance (MR) imaging since CSI and to determine the effect of these neurotoxicity risk factors on WM anisotropy in posttreatment medulloblastoma survivors. MATERIALS AND METHODS: Informed consent was obtained from the patients, control subjects, or their parents, and the study was approved by the institutional review board. Twenty consecutive medulloblastoma survivors (14 male, six female; mean age, 11.0 years +/- 4.6 [standard deviation]) and 36 control subjects (14 male, 22 female; mean age, 10.7 years +/- 3.5) were examined. Control subjects were divided into four groups according to age: 5.0-7.9 years, 8.0-10.9 years, 11.0-13.9 years, and 14.0-18.9 years. The authors calculated the histogram-derived mean WM fractional anisotropy (FA) value for each patient and compared it with the mean WM FA value for the control subjects in the corresponding age group to evaluate the percentage change in WM FA (DeltaFA) in each patient. Spearman rank correlation analysis was used to analyze the relationships between DeltaFA and (a) age at CSI, (b) CSI dose, and (c) time of MR imaging since CSI. Then, multiple linear regression analysis was performed to study the simultaneous influence of these factors on DeltaFA. RESULTS: There were significant correlations between DeltaFA and both age at CSI (r = 0.631, P = .003) and CSI dose (r = -0.586, P = .007) but not between DeltaFA and time of MR imaging since CSI. Multiple linear regression analysis revealed age at CSI to be the only independent variable that significantly affected DeltaFA (adjusted r2= 0.391, P = .012). CONCLUSION: Loss of WM anisotropy is significantly affected by age at CSI, and there is a trend toward increasing anisotropy loss with larger CSI dose. Both age at CSI and CSI dose are known risk factors of neurotoxicity.

Adolescent↗

PubMed2005

[Spatial analysis of socioeconomic determinants of homicide in Brazil].

OBJECTIVE: To investigate the association between homicide rates and socio-economic variables taking into account the spatial site of the indicators. METHODS: An ecological study was conducted. The dependent variable was the rate of homicides among the male population aged 15 to 49 years, residing in the districts of the State of Pernambuco from 1995 to 1998. The independent variables were an index of the living conditions, per capita family income, Theil inequality index, Gini index, average income of the head of the family, poverty index, rate of illiteracy, and demographic density. The following techniques were used in the analysis: a spatial autocorrelation test determined by the Moran index, multiple linear regression, a spatial regression model (CAR) and a generalized additive model for the detection of spatial trend (LOESS). RESULTS: The illiteracy and the poverty index explained 24.6% of the total variability of the homicide rates and there was an inverse relationship. Moran's I statistics indicated spatial autocorrelation between municipalities. The multiple linear regression model best fitted for the purposes of this study was the Conditional Auto Regressive (CAR) model. The latter confirmed the association between the poverty index, illiteracy and homicide rates. CONCLUSIONS: The inverse association observed between socio-economic indicators and homicides may be expressing a process that propitiates improvement in living conditions and that is linked predominantly to conditions that generate violence, such as drug traffic.

Adolescent↗

PubMed1996

Studies on acid oils and fatty acids for chickens III. Effect of chemical composition on metabolisable energy of by-products of vegetable oil refining.

1. Fourteen by-products of oil refining, selected for their variability in free fatty acid and unsaponifiable contents, were analysed chemically with the objective of relating the determined ME values of the products to chemical composition by means of multiple linear regression analysis. Refined sunflower oil was included as a reference fat. 2. Twenty-one 2-week-old chicks were used to determine fat digestibilities and AMEn values of diets, using the total collection method. Fats were included in a wheat-soyabean meal diet at 100 g/kg. Multiple linear regression analysis was used to express the ME values of fats as functions of the parameters measured (moisture, gross energy, impurities, unsaponifiables, non eluted material, free fatty acid content, unsaturated: saturated ratio, peroxide value, TBA test). 3. The ME of the fat products lay in the range l2.62 to 24.35 MJ/kg, and 29.26 MJ/kg for refined sunflower oil. Free fatty acid content of the fats was shown to be a poor predictor of their ME values, whereas non eluted material (NEM) of the fat products showed a good correlation with their ME. A regression equation could be derived (R2 0.6548; SEE 2.0064) with the unsaturated: saturated ratio (U:S) and NEM. An ME prediction equation based on the U:S, NEM and unsaponifiable content is also proposed (R2= 0.7l68; SEE= 1.9058).

Animal Feed↗

PubMed2005

Prostate cancer volume -- can it be predicted preoperatively?

INTRODUCTION: The prostate cancer volume (PCvol) is described as a significant predictor for tumor progression after radical prostatectomy, but its determination has not become a routine procedure yet due to high demands on technical standards, labor intensity, and costs. The objective of this study is to predict the PCvol by using common preoperative variables. MATERIAL AND METHODS: Between 1996 and 2001, 365 whole-mounted prostatectomy specimens, processed according to the Stanford protocol, were used for computerized reconstruction of the total PCvol. Widely accepted preoperative variables such as prostate-specific antigen (PSA), digital rectal examination findings, and Gleason score and grading (WHO) of the biopsy cores were correlated and analyzed for a relation to the PCvol by Spearman rho method and Mann-Whitney U test. Integrating these parameters in a multiple linear regression model, independent variables predicting the PCvol were determined, multiplied by their risk factors, and used for calculation of the estimated PCvol. In order to evaluate the precision of our results, we correlated measured and estimated tumor volumes. A nomogram was constructed, in order to visualize our results. RESULTS: Multiple linear regression analysis revealed categorized PSA, grading (WHO), and Gleason score to be independent predictors for the PCvol. The estimated PCvol ranged from 0.5 to 9.8 cm(3) and the measured PCvol from 0.02 to 53 cm(3). An identical mean value of 4.1 cm(3) was observed. The Spearman rho method showed a highly significant correlation (coefficient = 0.5) between estimated and measured PCvol (p < 0.001). CONCLUSIONS: The PCvol is regarded as a significant predictive parameter of tumor progression after radical prostatectomy, but due to its time-consuming determination, it has not become a routine procedure yet. Currently used preoperative parameters such as PSA and grading (WHO) and Gleason score of the biopsy cores do predict the total tumor volume. These results were reconfirmed by correlation analysis. Consequently, by use of our nomogram, the labor-intensive measurement of the PCvol becomes unnecessary.

Adult↗

PubMed1980

Mathematical model of mean age, mean arsenic dietary dose and age-specific prevalence rate from endemic chronic arsenic poisoning: a human toxicology study.

The aim of this investigation was to develop a mathematical model of mean age, mean arsenic dietary dose, and age-specific prevalence rate for endemic chronic arsenic poisoning. Data on mean age (years), mean arsenic dietary dose (mg/kg body weight/day), and age-specific prevalence rate per 100,000 population for endemic chronic arsenic poisoning in Antofagasta Commune, northern Chile, for the 1968-1971 period, were collected. Endemic chronic arsenic poisoning means here chronic arsenical dermatosis associated with marked or sever symptoms (or signs) of chronic arsenic poisoning (chronic diarrhoea, hepatic cirrohsis, chronic bronchitis, bronchiectasis, recurrent broncho-pneumonia, cardiomegaly, systemic occlusive arterial disease, cerebral thrombosis, etc.) There was a strong positive correlation between age-specific prevalence rate per 100,000 population and mean arsenic dose (r = + 0.9593) and a negative correlation between prevalence rate and mean age (r = 0.8789). These findings show that the prevalence rate declines with the advancing age and increases with the increase of arsenic dose. A multiple linear regression model E(y) = alpha + beta X1 + gamma X2, where y represents the age-specific prevalence rate per 100,000 population, X1 the mean arsenic dose, and X2 the mean age, was fitted to the data. The estimates of the parameters (alpha, beta, and gamma) were obtained by minimizing the residual sum of squares sigma(y - alpha - beta X1 - gamma X2)2. The following multiple linear regression equation was obtained: Y = 202.161 + 8452.455 X1 - 2.394 X2. Of the total variability in the prevalence rate, 96.22 per cent was accounted for by the multiple regression.

Adolescent↗

PubMed1997

An analysis of the determinants of urinary urea and creatinine clearance in patients on continuous peritoneal dialysis.

The relative contribution of urinary volume (UV) and urine-to-plasma concentration ratios for urea (U/PUr) and creatinine (U/PCr) to urinary Kt/V urea (Kt/VU) and urinary uncorrected creatinine clearance (CCrU), respectively, was studied by simple and multiple linear regression analysis in 236 urea kinetic studies and 233 creatinine kinetic studies performed in 135 patients on continuous peritoneal dialysis (CPD). The following simple regressions were obtained: Kt/VU = 0.09 + 0.72 (UV), r = 0.75; Kt/VU = -0.01 + 0.11 (U/PUr), r = 0.55; CCrU = 12.06 + 56.46 + 46.46 (UV), r = 0.62; CCrU = 3.51 + 3.40 (U/PCr), r = 0.58. All r values were significant (p < 0.001). According to these regressions, a loss of 0.2 L/24 hours in UV leads to a loss of 0.15 weekly in Kt/VU and 11.3 L/1.73 m2 weekly in corrected CCrU (approximately 8 L/1.73 m2 weekly in corrected CCrU). By multiple linear regression, (1) Kt/VU = -0.38 + 0.70 (UV) + 0.10 (U/PUr). Standardized coefficients were 0.72 for UV and 0.51 for U/PUr (2) CCrU = -33.36 + 59.83 (UV) + 3.63 (U/PCr). Standardized coefficients were 0.65 for UV and 0.61 for U/PCr. UV is the most important determinant of both urea and creatinine urinary clearances in CPD patients. The contribution of the U/P ratios to the urinary clearances is important, but less than that of UV. The primary dependence of urinary clearances on UV allows the use of UV, which can be easily monitored by patients, as a first approximation index of changing residual renal function in CPD.

Creatinine↗

PubMed1988

Methodologic considerations in measuring glycosylated hemoglobin in epidemiologic studies.

Multiple linear regression was used to predict an incubated glycosylated hemoglobin value from the unincubated value and blood glucose. Hemoglobin A1 (HbA1) was measured by a disposable microcolumn technique in a large, geographically defined population of diabetic persons in southern Wisconsin. During the study, incubation of blood samples to remove pre-A1c was implemented. Multiple linear regression using data from a group of 788 patients yielded the equation: incubated HbA1 = 0.897 (non-incubated HbA1)-0.00332 (blood glucose) + 0.388. This equation was "validated" by substituting the calculated value of incubated HbA1 for the actual value in a multinomial logistic regression with diabetic retinopathy as the dependent variable. Little change in the model resulted from the substitution. Further validation was obtained from an independent sample of diabetic persons. Calculated values of incubated HbA1 were an average of 0.4% lower than the actual values.

Age Factors↗

PubMed1984

The effect of prior cisplatin therapy on the pharmacokinetics of high-dose methotrexate.

The pharmacokinetics of high-dose methotrexate (MTX, 5-15 g/m2) were evaluated in 11 children and adolescents who had previously received two to eight doses of cisplatin (90 mg/m2) in the treatment of malignant solid tumors. The half-life for disappearance of MTX from serum during the first 24 hours after infusion was determined from serum samples obtained at the end of a six-hour infusion and six, 12, and 24 hours after infusion. These values were compared to a mean half-life of 2.83 (+/- 0.34) hours following 489 courses administered to 71 patients who had not received cisplatin. Stepwise multiple linear regression analysis of patient variables revealed cumulative cisplatin dosage and time from last cisplatin dose as the best predictors of MTX half-life (r2 = 65.4%, p less than 0.001). The best predictors of 24-hour serum concentration were cumulative cisplatin dosage and MTX dosage (r2 = 54.2%, p less than 0.001) in the multiple linear regression model. Patients with delayed MTX clearance received additional leucovorin and experienced no severe toxicity. Patients receiving up to 270 mg/m2 of cisplatin appear to have minimal increases in MTX half-life, while the likelihood of delayed clearance increases in patients who have received 360 mg/m2 or more of cisplatin. All patients who have previously received cisplatin should be treated cautiously with high-dose MTX and prospective pharmacokinetic monitoring should be routinely performed.

Adolescent↗