Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “nomogram model”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 379 records · Page 21Linked to original sources
PubMed1987

Deciding the optimum interval between specimen collections: theory and nomograms.

The time interval between collection of specimens from an individual patient is usually determined empirically. For analytes whose values decline according to first-order kinetics--for example, enzyme activities in serum after an acute myocardial infarction, tumor markers in serum after excision of the tumor, and drugs in serum after an overdose--the minimum time between collections (delta T) depends on the elimination half-life (t) and the analytical precision (CVA), according to the equation: delta T = (1/log2) X t X log (2.33 CVA/100 + 1). Nomograms showing this relationship graphically have been generated.

Antigens, Neoplasm↗
PubMed2007

Nomograms of the axial fetal cerebellar hemisphere circumference and area throughout gestation.

OBJECTIVE: The widely applied transcerebellar diameter (TCD) obtained at axial cranial imaging, measures the distance between the lateral aspects of the cerebellum and incorporates the width of the cerebellar vermis. Our objective was to create reference ranges of axial fetal cerebellar hemisphere circumference (CHC) and area (CHA), independent of the cerebellar vermis, throughout gestation. METHODS: This cross-sectional study involved pregnant patients between 14 and 41 weeks of gestation. Inclusion criteria consisted of well-established dates (confirmed by early ultrasound), non-anomalous singleton fetuses and intact amniotic membranes. Sonographic measurements included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), humerus length (HL), TCD, and estimated fetal weight (EFW). Values of axial fetal CHC and CHA were each calculated as the mean of three separate measurements. The 5th, 50th and 95th centiles were estimated at each week of gestational age (GA) by least-squares regression for the mean and standard deviation (SD) of the CHC and CHA as functions of GA. r2 and associated P-values for the relationships of CHC and CHA with other sonographic biometric measurements were calculated. RESULTS: The study included 651 consecutive patients. All attempts at obtaining axial fetal CHC and CHA were successful. Mean maternal age was 27.3+/-6.7 years, median gravidity was 1 (range 1-16), and median parity was 1 (range 0-6). Mean CHC (cm) throughout gestation was modeled as -2.091+0.2563xGA (weeks) (SD=-0.075+0.0164xGA), and mean CHA (cm2) was modeled as 0.245-0.0765xGA+0.00506xGA2 (SD=1.167-0.1565xGA+0.006785xGA(2)-0.00008028xGA3). Fetal axial CHC and CHA correlated significantly and strongly with BPD, HC, AC, HL, FL, TCD and EFW (all R2 values were >or=0.95, and all P-values were <0.001). CONCLUSION: Nomograms of axial fetal cerebellar hemisphere circumference and area throughout gestation, independent of the cerebellar vermis, have been provided.

Abdomen↗
PubMed2003

Is intraoperative nomogram-based overplanning of prostate implants necessary?

PURPOSE: Several investigators have described intraoperative planning of prostate implants based on a nomogram. The aim of this work was to investigate the adequacy of the nomogram in predicting the total activity necessary for optimal dosimetry. METHODS AND MATERIALS: Eighty CT-based postimplant treatment plans were performed for patients who underwent ultrasound guided I-125 permanent implants alone between April 2000 and March 2001. The cohort of 40 patients had early stage (T1-T2) prostatic carcinoma and pre-treatment prostate volumes of 19-50 cc. I-125 seeds (0.391 mCi/seed) were implanted to achieve a distribution of 75% of the activity peripherally and 25% centrally. The CT studies were obtained on the day of (CT1) and at 1 month (CT2) after implant. All patients were catheterized at CT1, and 28 patients were catheterized at CT2 to visualize the urethra. For each patient, the percentage difference (dA) between the total implanted and nomogram predicted activity for a known prostate volume was calculated. The V200 (volume receiving 200% of the prescribed dose), V150, V100, V90, D100 (maximum dose received by 100% of the volume), D90, and D80 were measured for the prostate at CT1 and CT2. For the urethra, V275, V250, V200, and V150 were evaluated, and V100 and V70 were evaluated for the rectum. The Pearson test was used to correlate the dosimetric parameters with dA. Linear regression was used to fit the correlation of the volume and dose parameters with dA. RESULTS: The median V100 at CT1 and CT2 was 91.8% and 94.2%, respectively. The Pearson test was significant for the prostate V100 and dA measured at CT1 (p = 0.005) but not at CT2 (p = 0.106). A similar correlation was found for the prostate D90 at CT1 (p = 0.002), but not at CT2 (p = 0.076). D100 (maximum dose received by 100% of volume) for prostate did not correlate with dA at CT1 (p = 0.094) and CT2 (p = 0.148). The volume of the prostate receiving higher doses (greater than 150% and 200% of the prescribed dose) correlated with dA. There were no significant correlations between V275, V250, V200, and V150 at CT1 and CT2 as a function of dA for the urethra. V100 and V70 for the rectum correlated significantly with dA; for V100, p = 0.041 at CT1 and p = 0.014 at CT2 and for V70, p = 0.041 at CT1 and p = 0.026 at CT2. A linear regression model fitted to the prostate data obtained from CT1 with the goal of achieving a V100 of 90% and D90 of 145 Gy suggests that no increase in the number of seeds may be warranted using intraoperative planning. The implants examined showed no concomitant increase of urethral doses with increase in activity relative to the nomogram, but showed an increase in the rectal doses for the same increase in activity. CONCLUSION: The doses evaluated at CT1 represent an underestimate, whereas those obtained at CT2 represent an overestimate of the actual delivered protracted permanent implant dose. Based on these results and consideration of the dynamic nature of the dose distribution, target coverage obtained with intraoperative planning using the nomogram predicted activity is consistent with published guidelines for a quality implant and critical structure doses are within tolerance.

Brachytherapy↗
PubMed2026

Non-small cell lung cancer and tumor-educated platelets: screening of biomarkers and construction of a prognostic model.

BACKGROUND: Lung cancer is a leading cause of cancer-related mortality worldwide, emphasizing the urgent need for effective early detection strategies. Traditional Chinese medicine (TCM) provides a unique perspective on tumor pathogenesis, focusing on concepts such as "long-term stasis leading to accumulation". Tumor-educated platelets (TEPs) offer potential as biomarkers due to their ability to reflect cancer heterogeneity and facilitate less invasive diagnostic approaches. This study aims to identify TEP-related prognostic biomarkers for non-small cell lung cancer (NSCLC) and to construct and validate a multigene prognostic model by integrating platelet transcriptomic data with tumor tissue datasets. METHODS: We performed comprehensive analysis of gene expression datasets obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) repositories to characterize transcriptomic differences among lung cancer specimens, normal tissue samples, and TEPs. Using R software, we identified Differentially expressed genes (DEGs) and subsequently applied a multi-stage analytical pipeline to TEP-associated DEGs, incorporating univariate Cox proportional hazards regression, least absolute shrinkage and selection operator (LASSO) regression, multivariate Cox regression, and stepwise regression modeling to pinpoint genes with prognostic significance. These prognostically relevant genes served as the foundation for developing a risk stratification model. We computed individual risk scores across both training and validation cohorts, enabling patient stratification into high- and low-risk categories. Model robustness was assessed through internal cross-validation and external validation procedures, while predictive performance was quantified using risk calibration metrics and receiver operating characteristic (ROC) curve analysis. RESULTS: Through systematic bioinformatics screening, we identified a four-gene prognostic signature comprising NELL2, C4orf48, PRAM1, and KLHL35, which served as the foundation for developing our risk stratification algorithm. Rigorous internal cross-validation and external cohort validation substantiated the moderate predictive performance of this signature. Comprehensive clinicopathological correlation analysis revealed that elevated risk indices, advanced pathological staging (stage III-IV), increased primary tumor dimensions, regional lymph node metastasis, and distant organ dissemination each demonstrated statistically significant associations with diminished overall survival (OS) outcomes in lung cancer patients. The clinical nomogram exhibited acceptable calibration, with calibration plots showing reasonable concordance between predicted and observed survival probabilities across all time points. Discriminative capacity assessment via time-dependent ROC analysis yielded area under the curve (AUC) values consistently surpassing 0.6, confirming moderate prognostic discrimination. Furthermore, decision curve analysis (DCA) demonstrated that our integrated multi-gene model conferred potential net clinical benefit compared to individual prognostic variables across the full spectrum of clinically relevant threshold probabilities (0-1 range), thereby establishing its potential utility for risk-informed clinical decision-making. CONCLUSIONS: This study identified NELL2, C4orf48, PRAM1, and KLHL35 as candidate TEP-related prognostic biomarkers for non-small cell lung cancer (NSCLC). The developed prognostic model shows preliminary potential for patient stratification, but its clinical application, particularly as a platelet-based liquid biopsy tool, requires further validation in independent TEP-based cohorts.

Tumor-educated platelets (TEPs)↗
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↗
PubMed2006

[Non-invasive urodynamics in male patient].

PURPOSE: Pressure-flow studies are currently recognized as the criterion standard to quantify urethral obstruction and its consequence on detrusor contractility. These tests have some disadvantages: they are invasive, time-consuming and expensive and entail risk of disease for the patient. Less invasive methods have been proposed to give the same results without the disadvantages. In this study, we conducted a critical analysis of the devices and techniques and their results. METHOD: After a brief reminder of the general behavior of the flow in an obstructed urethra, we describe the main non-invasive techniques: penile urethral compression-release (PCR), cuffs, and condoms. Using the VBN method, we tried to quantify data from these techniques to specify the relation with the usual parameters of bladder outlet obstruction. RESULTS: In the absence of brisk change of the flow rate, the voiding phases are easily analyzed. With minor corrections, recorded external or cuff pressures could be used in the ICS nomogram; unfortunately, these pressures are greatly modified by perturbations of the nervous control. The spike of flow (due to urine storage in the urethra) observed at resumption of flow after each interruption presents mathematical difficulties for quantitative and reliable modeling but could give a consistent empirical interpretation. CONCLUSION: Of the reported non-invasive tests, all except PCR have an important instrumental heaviness and induce strong perturbations of the nervous control. If they cannot allow an accurate quantification of urethral obstruction and detrusor contractility, they could allow for classification of benign prostatic hypertrophy (BPH) patients. Despite the mathematical problems set by the theory of spikes, the empirical use of the spikes amplitude could perhaps be clinically useful.

Diagnostic Techniques, Urological↗
PubMed1983

The surface area and volume of the human fetus.

The surface area and volume of 79 human fetuses (body weight 8-4080 g) were estimated by use of a geometric method. It was found that body surface area increased by a factor of about 70, and body volume by a factor of about 400, during the fetal period. Surface area (S, in cm2) was related to body weight (W, in g) and crown-heel length (L, in cm) according to the equation S = 6.4954 X W0.562 X L0.320 while volume (V, in cm3) was related to the same two variables by the equation V = 0.6065 X W0.752 X L0.638. The former equation was used to construct a nomogram for estimating the surface area of human fetuses and neonates.

Anthropometry↗
PubMed1997

Pharmacokinetics of gentamicin at traditional versus high doses: implications for once-daily aminoglycoside dosing.

Two doses of gentamicin (2 and 7 mg/kg of body weight) were administered to 11 healthy volunteers in a randomized, crossover single-dose study to compare their pharmacokinetics. Doses were infused over 1 h with a syringe infusion pump, and 14 concentrations in sera were obtained over an 8-h period. Concentration in serum versus time data were fitted to a two-compartment pharmacokinetic model. In addition, to mimic the clinical setting, subjects' data were fitted by the Sawchuk-Zaske method. Distributional and postdistributional peak concentrations, along with the last obtained concentration in serum, were utilized to compare the following pharmacokinetic variables: volume of distribution at steady state (Vss), half-life, clearance (CL), and maximum concentration in serum (Cmax). With two-compartment pharmacokinetic fitting, significant differences in distribution half-life (average, 21.8 and 41.6 min [P < or = 0.05]) and gentamicin CL (76.6 +/- 6.6 and 67.2 +/- 4.2 ml/min/1.73 m2 [P < or = 0.001]) were found between traditional-dose and high-dose groups, respectively. When the data for concentrations in sera were fitted to a one-compartment pharmacokinetic model by using either the distributional or the postdistributional Cmax, statistically significant differences (P < or = 0.001) were found between Vss, half-life, CL, and Cmax values for both dosage groups. The results show that the pharmacokinetics of gentamicin at a large dose differ significantly from those at the traditional dose. This information has direct implications for once-daily aminoglycoside (ODA) literature when the Cmax values reported are distributional and therefore show falsely high Cmax/MIC ratio estimates. In addition, ODA nomogram dosing tools developed with distributional Cmax values are probably inaccurate.

Adult↗
PubMed1996

Pharmacokinetics of vancomycin in critically ill infants undergoing extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is a widely used therapy for neonates with respiratory failure. Because of sepsis, many of these infants require antibiotics like vancomycin during ECMO treatment. ECMO transiently alters renal function and increases the circulating blood volume by 75%. Initial vancomycin pharmacokinetics were determined in 12 infants undergoing ECMO to determine an adequate drug administration regimen. Vancomycin dosage was based on current recommendations for weight and gestational age. Pharmacokinetic parameters were determined by fitting the data to a two compartment model. This study yielded a mean steady-state volume of distribution of 1.1 +/- 0.5 (range, 0.6 to 2.1) liters/kg and a mean vancomycin clearance of 0.78 +/- 0.19 (range, 0.49 to 1.07) ml/min/kg. The mean vancomycin half-life was 16.9 +/- 9.5 (range, 8.8 to 42.9) h. Nomogram-calculated creatinine clearance was a significant predictor of vancomycin terminal rate constant and clearance. These data suggest alterations in the pharmacokinetics of vancomycin in infants on ECMO. With the goal of achieving vancomycin concentrations in serum above the MIC for the offending pathogen while using the least amount of the drug necessary, new administration guidelines for term infants without renal impairment undergoing ECMO should be 20 mg of vancomycin per kg at an interval of 24 h. With significant renal impairment, the interval should be extended on the basis of concentrations in serum. In comparison with previously published data, the neonates undergoing ECMO in our study demonstrated a much larger volume of distribution, a lower clearance, and consequently a longer vancomycin half-life.

Anti-Bacterial Agents↗
PubMed1994

A nomogram to predict exercise capacity from a specific activity questionnaire and clinical data.

Recent investigations suggested that clinical exercise testing can be optimized by individualizing the protocol, depending on the purpose of the test and the subject tested. This requires some knowledge of a patient's exercise capacity before beginning the test. The accuracy of a simple physical activity questionnaire and readily available clinical data in predicting subsequent treadmill performance was examined. A brief, self-administered questionnaire (VSAQ) was developed for veterans who were referred to exercise testing for clinical reasons. The VSAQ was designed to determine which specific daily activities were associated with symptoms of cardiovascular disease (fatigue, chest pain and shortness of breath). Two hundred twelve consecutive patients (mean age 62 +/- 8 years) referred for maximal exercise testing were studied. Clinical and demographic variables were added to VSAQ responses in a stepwise regression model to determine their ability to predict treadmill performance. Only metabolic equivalents by VSAQ, and age were significant predictors of treadmill performance; these 2 variables yielded R = 0.82 (SEE 1.43; p < 0.001), and explained 67% of the variance in exercise capacity. The regression equation reflecting the relation between age, VSAQ and exercise capacity was: achieved metabolic equivalents = 4.7 + 0.97 (VSAQ) - 0.06 (age). Using this equation, a nomogram was developed. Incorporating the VSAQ with the nomogram requires only a few minutes, and yields a reasonably accurate estimate of a patient's exercise capacity. Although the present equation is population-specific, a similar approach in different populations may be useful for individualizing protocols for clinical exercise testing.

Activities of Daily Living↗
PubMed1986

Relationships among duration of infusion, dose, dosing interval, and steady-state plasma concentrations during intermittent intravenous infusions: studies with metronidazole.

Relationships among duration of infusion (T), dose, dosing interval (tau), maximum and minimum plasma drug concentrations at steady state (Cmax,ss and Cmin,ss, respectively), and the duration of effective plasma concentrations (tD) during multidose intermittent infusion regimens were studied by computer simulation using metronidazole as a model drug. Pharmacokinetic parameter values for metronidazole were obtained from the literature and the minimum effective plasma concentration (MEC) was taken as 6.0 micrograms/ml. Increasing the infusion period of the dose reduces Cmax,ss, but increases Cmin,ss. If intermittent bolus injection of a given dose of drug results in effective plasma concentrations for the entire dosage interval (i.e., Cmin,ss,bolus greater than MEC), then infusion of that dose over any period (T less than or equal to tau) will also result in effective concentrations for the entire dosage interval. However, if the dosage is such that Cmin,ss,bolus less than MEC, the relationships among duration of infusion, dose, dosage interval, and duration of effective plasma concentrations are complex. Therefore a nomogram was developed to allow selection of dose, dosing interval, and infusion period such that Cmax,ss and Cmin,ss could be maintained within a desired range.

Humans↗
PubMed1982

Prediction of fetal growth deviation by ultrasonic biometry. I. Methodology.

Early information of impaired or accelerated fetal growth is of importance for antenatal care. The present study has produced a mathematical formula which in the 33rd week of pregnancy permits prediction of fetal weight deviation at birth. The prediction was based on two ultrasonic examinations: in the 17th week of pregnancy the biparietal diameter (BPD) was measured to assess the fetal gestational age; in the 33rd week of pregnancy, BPD and the abdominal diameter (AD) of the fetus were measured. Fetal growth deviation was then described by comparing the assessed BPD and AD with the expected mean values for the gestational age on the day of this measurement. For 872 fetuses the growth deviation found in the 33rd week was related to the fetal weight deviation at birth; multiple regression analyses were performed and a mathematical formula developed. For practical purposes this formula is expressed in a nomogram.

Abdomen↗
PubMed2003

[Optimization of an individualized LASIK surgery. Geometric ray tracing model].

PURPOSE: To develop an objective calculation method that is able to provide a customized surgical correction that allows the patient to reach the emmetropia and the maximum visual acuity after the surgery. METHODS: The study included 187 eyes with myopia or myopic astigmatism that underwent LASIK. The optical characterization of each eye was developed by a complete theoretical model based in Le Grand eye, in which the measured values of radii and thicknesses of the different surfaces have been substituted. By means of a geometric ray tracing, the surgery has been simulated by changing the anterior corneal radius and the corneal thickness within the optical zone to obtain its influence in the ocular image and the visual acuity. We considered the surgery to be < > when the residual equivalent refraction was between 0 and +0.5 D. RESULTS: An interval for the final corneal radius is proposed for each eye in order to reach the best visual acuity (optimal interval). The position of the post-surgical radius in this interval has been related with the success of the surgical process. CONCLUSIONS: An objective method for LASIK has been proposed: i) it calculates a personalized surgical plan that allows the patient to reach the best visual quality, and ii) it can be used as a reference by the surgeon to design his nomogram and to decrease his learning curve.

Adult↗
PubMed2004

Volume kinetics of glucose 2.5% solution and insulin resistance after abdominal hysterectomy.

BACKGROUND: We hypothesized that volume kinetics can be used to predict the rate of infusion of glucose 2.5% solution required to yield any predetermined plasma glucose level and degree of plasma dilution during the postoperative period. METHODS: In 15 women, mean age 50 yr (range 37-63), 2 days after an abdominal hysterectomy, a volume kinetic analysis was performed on an i.v. infusion of 12.5 ml kg(-1) ( approximately 900 ml) of glucose 2.5% given over 45 min. The insulin resistance was measured by a glucose clamp, and it was compared with daily bioimpedance analyses, which indicated the hydration of the intra/extracellular body fluid spaces. RESULTS: The clearance of glucose was 0.42 litre min(-1) (0.60 litre min(-1) is normal) while the other five parameters in the kinetic model were similar to those obtained in healthy volunteers. Computer simulations indicated that in a 70-kg female, at steady state, the rate of infusion (ml min(-1)) should be three times the allowed increase in plasma glucose (mmol litre(-1)). To maintain a predetermined plasma dilution the corresponding rate factor was 160. The glucose uptake during clamping was 3.9 mg kg(-1) min(-1) (7.0 is normal), which, during the second day after hysterectomy, correlated with the dehydration of the intracellular space (r=0.77; P<0.002) and with the protein catabolism as indicated by the urinary excretion of 3-methylhistidine (r=-0.76, P<0.002). CONCLUSION: The anaesthetist can prescribe postoperative administration of glucose 2.5% to reach any desired plasma glucose level and dilution by using the two presented nomograms. Insulin resistance correlated with intracellular dehydration and protein catabolism.

Adult↗
PubMed1983

Bayesian approach to bioequivalence assessment: an example.

The statistical methods required for a Bayesian analysis of bioequivalence are outlined and numerically illustrated. The analysis consists of the calculation of the posterior probability, given the experimental results, that the ratio of true means of a new and a standard formulation of a drug with respect to some biological response lies in a given interval. Nomograms helpful for the calculation of these probabilities are provided.

Bayes Theorem↗