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PubMed2006

Validation of a nomogram predicting the probability of lymph node invasion among patients undergoing radical prostatectomy and an extended pelvic lymphadenectomy.

INTRODUCTION: Our goal was to develop and internally validate a nomogram for prediction of lymph node invasion (LNI) in patients with clinically localized prostate cancer undergoing extended pelvic lymphadenectomy (ePLND). METHODS: 602 consecutive patients (mean age 65.8 years) underwent an ePLND, where 10 or more nodes were removed. PSA was 1.1-49.9 (median 7.2). Clinical stages were: T1c in 55.6%, T2 in 41.4% and T3 in 3%. Biopsy Gleason sums were: 6 or less in 66%, 7 in 25.4%, 8-10 in 8.6%. Multivariate logistic regression models tested the association between all of the above predictors and LNI. Regression-based coefficients were used to develop a nomogram predicting LNI and 200 bootstrap resamples were used for internal validation. RESULTS: Mean number of lymph nodes removed was 17.1 (range 10-40). LNI was detected in 66 patients (11.0%). Univariate predictive accuracy for total PSA, clinical stage and biopsy Gleason sum was 63%, 58% and 73%, respectively. A nomogram based on clinical stage, PSA and Biopsy Gleason sum demonstrated bootstrap-corrected predictive accuracy of 76%. CONCLUSIONS: A nomogram based on pre-treatment PSA, clinical stage and biopsy Gleason sum can highly accurately predict LNI at ePLND.

Aged↗
PubMed2006

Evaluation of an existing nomogram for predicting the response to clomiphene citrate.

OBJECTIVE: To evaluate the ability of an existing nomogram to predict response to clomiphene citrate (CC) in infertile couples with World Health Organization group II ovulatory disorders, using the free androgen index, body mass index, and menstrual-cycle history. DESIGN: Retrospective case-notes study. SETTING: Reproductive medicine and fertility center at a university teaching hospital in the United Kingdom. PATIENT(S): One hundred four anovulatory women. INTERVENTION(S): One hundred four anovulatory women who had been treated with CC were studied retrospectively. Age, body mass index, free androgen index, and cycle history were used to assign a likelihood of response for each patient on the basis of a published nomogram. Predicted and observed responses were compared. MAIN OUTCOME MEASURE(S): Ovulation rate. RESULT(S): The diagnostic characteristics of the model on the basis of the optimal cutoff points were as follows: sensitivity, 96% (95% confidence interval [CI]: 90%-99%); specificity, 33% (95% CI: 18%-49%); positive predictive value, 73% (95% CI: 63%-82%); negative predictive value, 80% (95% CI: 60%-99%); likelihood ratio for ovulation, 1.34 (95% CI: 1.1-1.8); likelihood ratio for resistance, 0.13 (95% CI: 0.04-0.43); kappa, 0. 26 (95% CI: 0.09-0.44). CONCLUSION(S): The accurate prediction of response to CC would allow more rapid transfer of nonresponders to alternative treatments and may shorten the treatment to pregnancy interval. Although the current nomogram could identify 80% of nonresponders to CC, it was insufficiently accurate for use in the present clinical setting. Moreover, the nomogram could not identify the most appropriate dose to achieve ovulation. This nomogram should be tested on patients in other clinical settings, where it may perform better.

Body Mass Index↗
PubMed2006

Development and internal validation of preoperative transition zone prostate cancer nomogram.

OBJECTIVES: Up to 20% of men may harbor a transition zone (TZ) prostate cancer (PCa) at radical prostatectomy (RP). TZ PCa may be associated with more favorable RP pathologic findings than peripheral zone (PZ) PCa. To identify these men, we developed a model capable of predicting the probability of TZ PCa at RP. METHODS: The study cohort consisted of 945 consecutive men treated with RP, with clinical stage, prostate-specific antigen (PSA) level, and detailed biopsy and RP pathology data available. The preoperative variables were used as predictors in the multivariate logistic regression models to predict the rate of TZ PCa at RP. PCa was defined as a TZ tumor when more than 50% of the planimetrically measured tumor volume was situated within the TZ. Regression coefficients were used to develop nomograms, which were subjected to 200 bootstrap resamples to reduce overfit bias. RESULTS: TZ PCa at the final pathologic examination was recorded in 110 patients (11.6%). After 200 bootstraps, the most parsimonious and most accurate nomogram was 77.3% accurate in predicting the probability of TZ PCa. CONCLUSIONS: This nomogram is ideally suited to identify patients with markedly elevated, nearly metastatic serum PSA levels who harbor a TZ tumor that is highly treatable by RP.

Adult↗
PubMed2026

Kynurenine metabolism-related gene signature for prognostic stratification in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) remains a major global health burden with high mortality rates and limited therapeutic options. The identification of reliable biomarkers for early diagnosis and prognosis prediction is urgently needed. Kynurenine metabolism, a critical pathway in immune regulation and tumor progression, has been implicated in various cancers. However, its prognostic value in HCC has not been fully elucidated. This study aimed to develop a prognostic risk model based on kynurenine metabolism-related genes (KMRGs) for HCC patients. METHODS: Transcriptomic and clinical data of HCC patients were retrieved from The Cancer Genome Atlas (TCGA) and the International Cancer Genome Consortium (ICGC) databases. A prognostic risk model was established using least absolute shrinkage and selection operator (LASSO) and Cox regression analyses. Survival analysis and functional enrichment analysis were conducted to validate the predictive performance of the model and to investigate the underlying mechanisms. ALDH8A1 was ultimately identified as a target gene based on survival analysis, and its impact on tumor cell migration was assessed using the HCC cell line. RESULTS: A prognostic model based on seven KMRGs was established. The high-risk group exhibited significantly worse overall survival compared to the low-risk group. Functional enrichment analysis in high-risk patients highlighted significant enrichment in core biological processes, including spliceosome assembly and ribonucleoprotein complex biogenesis. Furthermore, a nomogram integrating the risk score and clinical pathological features was developed, demonstrating moderate predictive performance for HCC prognosis. CONCLUSIONS: This study successfully constructed a prognostic risk model based on seven KMRGs, providing a valuable tool for predicting clinical outcomes in HCC patients. These findings highlight the potential role of kynurenine metabolism in HCC progression and offer new insights for future therapeutic strategies.

ALDH8A1↗
PubMedDate not supplied

Laser in situ keratomileusis nomogram development.

BACKGROUND: There is no standard laser in situ keratomileusis (LASIK) nomogram for the Nidek EC-5000 excimer laser when used with current software versions 2.23 or 2.25. Nomogram tables developed by various EC-5000 users differ significantly from one another. METHODS: We analyzed the results of our first 138 eyes treated for myopia and myopic astigmatism with the Nidek EC-5000 excimer laser, model 2b, long working distance. In addition to analyzing standard clinical outcomes, the correction values entered into the laser were compared to the achieved change in refraction for these eyes. A global nomogram parameter was created, incorporating the effect of optical zone size and patient age. After observing initial overcorrections, we elected to treat most of the eyes using a 20% reduction of the attempted spherical correction. RESULTS: The mean value for the attempted change in spherical equivalent refraction was -6.85 D. This correction was achieved with a standard deviation of -0.04 D at 1 month, -0.08 D at 3 months, and -0.09 D at 6 months after LASIK. The postoperative values for the uncorrected and spectacle-corrected visual acuity were similar to other published studies. However, scatterplots comparing the laser settings to achieved postoperative refractions showed a clear 20% trend toward overcorrection. This trend increased with patient age and optical zone diameter. CONCLUSIONS: The basic calibration values (factory standard) for software versions 2.23 and 2.25 are too aggressive for LASIK treatments. When using optical zone diameters of 6 mm and above, the spherical refraction values entered into the laser must be reduced by at least 20%. LASIK nomograms for the Nidek EC-5000 excimer laser should be specific for optical zone diameter and patient age.

Adolescent↗
PubMed2005

A new predictor of toxicity following acetaminophen overdose based on pretreatment exposure.

INTRODUCTION: Despite extensive clinical experience, no dose-response curve exists for acetaminophen toxicity in man. The absence of accurate toxicodynamics has hampered efforts to optimize patient therapy and to identify risk modifiers following overdose. We set out to parameterize both the degree and duration of pretreatment exposure into a single, continuous measure of exposure, which will serve as the x-axis of an eventual dose-response curve. METHODS: The model was constructed from pharmacokinetic first principles, using as inputs the vertical distance above the Rumack-Matthew nomogram line (expressed as the equivalent serum acetaminophen concentration 4 h after ingestion) and the delay to antidote therapy (tNAC). A no-effect dose ([APAP]threshold) and lag time (ti) were assumed. RESULTS: The area under the serum acetaminophen concentration vs. time curve bounded by [APAP]threshold, ti and tNAC represents our proposed time-weighted measure of exposure. We demonstrate that this non-negative area estimates the cellular burden of toxic adducts formed following overdose. This measure is also easily calculated at patient presentation using clinical data and allows for both declining serum acetaminophen concentrations and variable delays to antidote therapy. DISCUSSION: We describe a new, pharmacokinetically based measure of exposure following acute acetaminophen overdose treated with N-acetylcysteine. Using this measure should enhance the analysis of nonexperimental clinical data and permit more accurate characterization of acetaminophen toxicodynamics. Ultimately, this approach may facilitate progress on many of the long-standing controversies regarding acetaminophen toxicity in man.

Acetaminophen↗
PubMedDate not supplied

A microcomputer program for tobramycin consult services, based on the two-compartment pharmacokinetic model.

A microcomputer program has been developed to provide assistance to tobramycin clinical pharmacokinetic consult services. Written for the Apple II Plus computer with 64 K memory, one-disk drive, and a dot matrix graphics printer, this software is user-oriented and simple to operate. The program disk contains complete documentation and referenced instructions. Major sections provide empiric dosing recommendations based on population data and allow determination of dosage from measured serum concentrations. The program keeps a record of previous regimens, allows for the entry of the user's own recommendation, and provides complete flexibility for up to 15 dosage and interval changes. In addition to its dosing information and file management capabilities, the program simulates serum concentration profiles based on user-selected one-compartment, two-compartment, or two-compartment prenephrotoxic models. The program prints a consult sheet with concentration vs. time simulation, patient demographic data, and user-entered recommendations and comments. The program provides extensive disk storage capabilities for patient files, with immediate access to facilitate updating and dosing regimen changes as they occur. In addition to providing improvements in empiric dosing capabilities, pharmacokinetic modeling, and data handling, this computer software has been designed to incorporate pharmacokinetic data derived from important subpopulations into the empiric dosing algorithms. This unique aspect enables the program to provide improved empiric dosing regimens for patients who do not fall under the guidelines for any of the conventional aminoglycoside dosing nomograms.

Aging↗
PubMed1995

Pharmacokinetic optimisation of vancomycin therapy.

Renewed interest in vancomycin over the past decade has led to an abundance of data concerning the pharmacokinetics of vancomycin, and its dosage selection and concentration-response relationships. No definitive data exist that correlate vancomycin serum concentrations with clinical outcomes. However, inconsistencies in sampling times for peak serum concentrations and differences in infusion times make interpreting vancomycin serum concentrations difficult. Furthermore, the evidence implicating vancomycin as a cause of oto- or nephrotoxicity is circumstantial, and these adverse effects may occur only in high-risk populations. Owing to the variability in its dose-serum concentration relationship and multicompartmental pharmacokinetics, several methodologies have been developed for instituting and adjusting vancomycin dosages. Nomograms rely on a fixed volume of distribution and the relationship between vancomycin clearance and creatinine clearance. Since both of these factors may be altered in certain populations, dosage methodologies (both traditional and Bayesian) that use population- or patient-specific pharmacokinetic data perform better than standard nomograms for initiating vancomycin therapy. Controversy still exists as to whether a 1- or a 2-compartment model is more appropriate for making dosage adjustments; however, steady-state rather than non-steady-state vancomycin serum concentrations should be used for dosage adjustments. Certain pathophysiological states such as age, bodyweight and renal function contribute to altered pharmacokinetics and may alter the design of the dosage regimen. Since no definitive relationship exists between vancomycin serum concentrations and either clinical outcome or adverse effects, considerable controversy surrounds the utility of monitoring serum vancomycin concentrations. Therefore, routine vancomycin serum concentration monitoring may be warranted only in specific populations, such as patients receiving concurrent aminoglycoside therapy or those receiving higher than usual dosages of vancomycin, patients undergoing haemodialysis and patients with rapidly changing renal function.

Dose-Response Relationship, Drug↗
PubMed1981

Prediction of phenytoin dosage in relation to the variability of phenytoin plasma concentration.

1 In a model study the influence of some variables on the accuracy of predictions of phenytoin doses which should produce desired plasma concentrations were studied. All predictions were extrapolations from low test doses with concurrent observations of plasma concentrations. 2 The variables in introduced were:--Variability in observed plasma concentration;--Variability in applied test doses;--Variability in patient characteristics as expressed in Km and Vmax values. 3 The model study generated the same sort of result as a previous one, executed in practice (Driessen. Van der Velde + Höppener, 1980), i.e. predictions are often inaccurate and of the method tested (Richens & Dunlop, 1975; Ludden, Hawkins, Allen & Hoffman, 1976; Martin, Tozer, Sheiner & Riegelman, 1977; Rambeck, Boenigk, Dunlop, Mullen, Wadsworth & Richens, 1980), Richens' first nomogram (Richens & Dunlop, 1975) is to be preferred.

Humans↗
PubMed2002

Application of pharmacokinetic modelling to the routine therapeutic drug monitoring of anticancer drugs.

Over the last 10 years, proofs of the clinical interest of therapeutic drug monitoring (TDM) of certain anticancer drugs have been established. Numerous studies have shown that TDM is an efficient tool for controlling the toxicity of therapeutic drugs, and a few trials have even demonstrated that it can improve their efficacy. This article critically reviews TDM tools based on pharmacokinetic modelling of anticancer drugs. The administered dose of anticancer drugs is sometimes adjusted individually using either a priori or a posteriori methods. The most frequent clinical application of a priori formulae concerns carboplatin and allows the computation of the first dose based on biometrical and biological data such as weight, age, gender, creatinine clearance and glomerular filtration rate. A posteriori methods use drug plasma concentrations to adjust the subsequent dose(s). Thus, nomograms allowing dose adjustment on the basis of blood concentration are routinely used for 5-fluorouracil given as long continuous infusions. Multilinear regression models have been developed, for example for etoposide, doxorubicin. carboplatin, cyclophosphamide and irinotecan, to predict a single exposure variable [such as area under concentration-time curve (AUC)] from a small number of plasma concentrations obtained at predetermined times after a standard dose. These models can only be applied by using the same dose and schedule as the original study. Bayesian estimation offers more flexibility in blood sampling times and, owing to its precision and to the amount of information provided, is the method of choice for ensuring that a given patient benefits from the desired systemic exposure. Unlike the other a posteriori methods, Bayesian estimation is based on population pharmacokinetic studies and can take into account the effects of different individual factors on the pharmacokinetics of the drug. Bayesian estimators have been used to determine maximum tolerated systemic exposure thresholds (e.g. for topotecan or teniposide) as well as for the routine monitoring of drugs characterized by a very high interindividual pharmacokinetic variability such as methotrexate or carboplatin. The development of these methods has contributed to improving cancer chemotherapy in terms of patient outcome and survival and should be pursued.

Antineoplastic Agents↗
PubMedDate not supplied

Nomograms for the sonographic measurement of the fetal philtrum and chin.

OBJECTIVE: To generate nomograms for the sonographic measurement of the fetal philtrum and chin during pregnancy. DESIGN: A prospective, cross-sectional study in normal singleton pregnancies. SUBJECTS: One hundred and fifty-three fetuses between 13 and 42 weeks of gestation were studied. METHODS: The philtrum was measured from the base of the columella to the upper lip. The chin was measured from the tip of the lower lip to the skin under the lower tip of the mandible. Predictive models were evaluated to generate graphic description of the 5th, 50th and 95th centiles for the fetal philtrum and chin. RESULTS: Fetal philtrum length increased with gestational age. The regression equation for the philtrum length (y) according to gestational age in weeks (x) is best predicted by the S-curve (Gompertz) model, as described by the following equation: y = exp(a + b/x), where a = 2.778577, and b = -23.476723 (R(2) = 85.3%, p < 0.0001). The fetal chin length increased with gestational age. The regression equation for the mean chin length (y) according to gestational age in weeks (x) is best predicted by the S-curve model as described in the following equation. y = exp(a + b/x), where a = 3.7922, b = -28.043, (R(2) = 89.0%, p < 0.0001). CONCLUSIONS: The nomograms generated in this study for the fetal philtrum and chin during pregnancy can be used in confirming subjective impression of facial dysmorphism.

Chin↗
PubMed1990

Experimental and theoretical research in archery.

The aim of this study was to introduce certain methods and research techniques and to present the results of experiments on parameters of archery equipment to optimize the interaction of the archer-bow-arrow system's elements. In order to achieve the research requirements, the following were devised: 1. A mathematical model of an arrow's movement during its interaction with a bow. 2. A mechanical model of an archer-bow-arrow system, which constitutes a device for mechanical loosing of an arrow from the bow strings (DMLA). 3. Three series of high-speed filming. The mathematical model and computer simulation were used to describe the arrow's movement for various initial conditions and various parameters of the equipment, based on which a nomogram was constructed of the optimum arrow parameters for bows of various draw forces. The device for the mechanical loosing of arrows from a bow was used to study the influence of selected parameters of the archer-bow-arrow system on the accuracy of shots. The film analysis was used to verify the mathematical and mechanical models constructed.

Arm↗
PubMed2005

Nomograms including nuclear matrix protein 22 for prediction of disease recurrence and progression in patients with Ta, T1 or CIS transitional cell carcinoma of the bladder.

PURPOSE: We developed and validated nomograms that accurately predict disease recurrence and progression in patients with Ta, T1, or CIS transitional cell carcinoma (TCC) of the bladder using a large international cohort. METHODS: Univariate and multivariate logistic regression models targeted histologically confirmed disease recurrence, and focused on 2,542 patients with bladder TCC from 10 participating centers. Variables consisted of pre-cystoscopy voided urine Nuclear Matrix Protein 22 (NMP22) assay, urine cytology, age and gender. Resulting nomograms were internally validated with bootstrapping. Nomogram performance was explored graphically with Loess smoothing plots. RESULTS: Overall 957 patients had recurrent TCC. Tumor grade and stage was available for 898 patients, including 24% grade I, 43% grade II, and 33% grade III; 45% stage Ta, 32% T1 and/or CIS, and 23% T2 or greater. Bootstrap corrected predictive accuracy for any TCC recurrence was 0.842; grade III Ta/T1 or CIS was 0.869; and T2 or higher stage TCC of any grade was 0.858. Virtually perfect performance characteristics were observed for the nomograms predicting any TCC recurrence or grade III Ta/T1 or CIS. The nomogram predicting T2 or higher stage TCC overestimated the observed probability for predicted values greater than 45%. CONCLUSIONS: We developed and internally validated nomograms that incorporate urinary NMP22, cytology, age and gender to predict with high accuracy the probability of disease recurrence and progression in patients with Ta, T1, and/or CIS bladder TCC. These nomograms could provide a means for individualizing followup in patients with Ta, T1, CIS bladder TCC.

Adolescent↗
PubMed1982

Nomogram for 2-deoxyglucose lumped constant for rat brain cortex.

The quantitation of local cerebral metabolic rate of glucose with the 2-deoxyglucose technique of Sokoloff requires the use of a correction factor, or lumped constant. We have shown previously (Pardridge et al., 1982) that a simple model may be formulated to predict changes in the lumped constant that occur due to alterations in the distribution of glucose and 2-deoxyglucose in brain. Given experimentally observed values for brain and plasma glucose concentrations, the 2-deoxyglucose lumped constant may be determined from a nomogram constructed from knowledge of the blood-brain barrier transport constants (KM, Vmax, KD) for glucose and for 2-deoxyglucose. However, the nomogram is constructed from transport constants determined in the barbiturate-anesthetized state. The applicability of the nomogram to other physiologic states was examined in the present studies. Large changes in blood-brain barrier hexose transport constants do not appreciably alter the shape of the nomogram, if the changes in KM or Vmax for glucose or for 2-deoxyglucose are the same. Moreover, glucose and 2-deoxyglucose are both transported by the same hexose carrier, and selective changes in the transport of only one hexose have not been reported. Therefore, it is probable that the nomogram constructed from transport constants measured under barbiturate anesthesia is useful in predicting the lumped constant in a variety of physiologic states.

Animals↗
PubMed1988

The accuracy and stability of Bayesian theophylline predictions.

Pharmacokinetic parameters for theophylline were determined in 33 patients (3 women), mean age 61.2 years and weight 74.6 kg using the following three methods: (a) standard one-compartmental model calculations, assuming 100% bioavailability, after a single dose of theophylline syrup (mean dose 413 mg); (b) drug nomogram; and (c) Bayesian analysis. Patients entered a randomised study of three two-monthly dosage regimens using low, medium, and high theophylline twice daily doses. These doses produced mean (+/- SE) steady-state serum theophylline concentrations of 6.3 (+/- 0.4), 12.1 (+/- 0.3) and 18.3 (+/- 0.5) mg/L, respectively. A fourth period of placebo (2-month duration) was also included. At the end of each treatment period the measured serum theophylline concentration of each patient was compared with those predicted by each of the above three methods. The revised estimates derived from Bayesian analysis produced the least biased [mean prediction error (ME)] and most precise (mean squared prediction error) predictions for all three dosage periods. Statistical analysis of relative performance demonstrated that the difference in precision between the revised estimates and those of the other two methods was significant (p less than 0.05) with the magnitude of the difference increasing with dose. The revised estimates were also found to be less biased (p less than 0.05) than those of the nomogram. The ME (+/- SE) of the revised estimates for the low, medium, and high dosage periods was 0.34 (+/- 0.30), -0.02 (+/- 0.22) and -0.48 (+/- 0.31) mg/L, respectively.

Bayes Theorem↗
PubMed1991

[Multifactorial study of the combined effect of rifampicin and microbial peptidoglycan in experimental plague infection].

The combined effect of rifampicin and a microbial peptidoglycan was studied in multifactorial experiments on noninbred mice with plague infection. The effect of rifampicin and the immunomodulator was shown to be synergistic. The results of the multifactorial experiments provided designing of polynomial statistic models of the second order characterizing the animal survival rate and mean life-span and plotting of nomograms or equal level lines useful in optimization of the combined therapy parameters.

Animals↗