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PubMed2000

Basal follicle-stimulating hormone levels are of limited value in predicting ongoing pregnancy rates after in vitro fertilization.

OBJECTIVE: To evaluate whether basal FSH (bFSH; measured on menstrual day 1-4) adds relevant clinical information to the prediction of ongoing pregnancy rates (OPRs) after IVF, once age and diagnostic characteristics have been taken into account. DESIGN: Retrospective. SETTING: Academic fertility center. PATIENT(S): 435 women undergoing their first IVF cycle. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Ongoing pregnancy rate. RESULT(S): The likelihood ratio of bFSH as a single prognosticator for treatment failure at a cutoff level of 15 IU/L was 3.87. The proportion of patients with such a bFSH level was 5%. Multivariate logistic regression analysis selected age, bFSH level, and infertility diagnosis as relevant predictors of ongoing pregnancy. When compared to a predictive model for OPRs based on age and infertility diagnosis, the inclusion of bFSH into this model helped to identify more patients (22 vs. 1) whose predicted OPR decreased from a low level (5%-12%) towards an extremely low level (<5%). CONCLUSION(S): An acceptable performance of bFSH as a single test to predict treatment failure is only obtained above a high cutoff level. Thus, the number of patients for whom bFSH provides relevant information is small. The predictive model including bFSH identified significantly more patients with an extremely poor prognosis than did the predictive model without bFSH. However, predictions based solely on age and infertility diagnosis usually were already poor in these patients. Measurement of bFSH adds little in only a few patients and is, therefore, debatable.

Adult↗
PubMed1995

Resting energy expenditure in clinical pediatrics: measured versus prediction equations.

OBJECTIVE: To evaluate the use of resting energy expenditure (REE) prediction equations compared with measured REE in children referred for REE to aid clinical care. SUBJECTS: One hundred two patients, aged 0.2 to 20.5 years, 55% female, with a nutritional diagnosis of failure to thrive (76%), obesity (19%), or other (5%). METHODS: We measured REE by indirect calorimetry and compared with prediction equations: Food and Agriculture/World Health Organization/United Nations University (FAO/WHO/UNU) equation, Harris-Benedict (H-B) equation, and two equations from Schofield, one using weight (SCHO-WT) and one using weight and height (SCHO-HTWT). RESULTS: The SCHO-HTWT equation more closely predicted measured REE (100% +/- 19%), compared with the WHO equation (99% +/- 22%), the SCHO-WT equation, (99% +/- 21%), and the H-B equation (92% +/- 25%). The SCHO-HTWT equation was the best at predicting REE for obese subjects (95% +/- 17%), for those with failure to thrive (101% +/- 20%), and for children from birth to 3 years of age (101% +/- 23%). Nevertheless, the prediction equations closely predicted REE in only about 40% of subjects. CONCLUSION: These findings suggest that the SCHO-HTWT equation predicts REE in children with clinical nutritional problems better than equations that use weight alone. In view of the wide variability in REE measurements, however, we believe that REE should be measured in patients for whom knowledge of caloric expenditure is required for clinical care.

Basal Metabolism↗
PubMed2006

Neuro-fuzzy modeling: an accurate and interpretable method for predicting bladder cancer progression.

PURPOSE: New methods are required to improve the prediction of cancer progression as traditional statistical tests have limited accuracy. Accurate predictions would allow physicians to offer specific treatment according to individual patient risk. While predictive improvements are obtained using ANN, the hidden nature of these networks prevents insight and has hindered their widespread implementation. NFM is an alternate form of artificial intelligence using fuzzy logic (which is a multivalued logic which provides reasoning under uncertainty). By defuzzification the NFM rule base becomes transparent to overcome the black box nature of ANN. MATERIALS AND METHODS: Combinations of clinicopathological (tumor stage and grade, patient age, gender, and smoking status) and molecular (immunohistochemical expression of p53 and methylation status of 11 loci) data from 117 patients were used to develop and compare predictive models of tumor progression using NFM, ANN and LR. RESULTS: NFM (88% to 100% sensitivity, 97% to 100% specificity and 94% to 100% accuracy) predicted the presence and timing of cancer progression more accurately than ANN (81% to 87%, 95% to 100% and 89% to 90%, p = 0.002) and LR 3%, 61% to 72% and 47% to 53%, p = 0.00005). NFM was able to interrogate the clinicopathological and molecular data, and select the most important parameters (age, grade, stage, smoking, methylation) for progression prediction. CONCLUSIONS: Intelligent systems and molecular biomarkers improved the accuracy of cancer progression predictions. NFM appeared superior to ANN in terms of accuracy, sensitivity, specificity and transparency. The use of NFM in routine clinical practice warrants further validation.

Aged↗
PubMed2006

Preoperative serum prostate specific antigen remains a significant prognostic variable in predicting biochemical failure after radical prostatectomy.

PURPOSE: Multiple investigators have argued that PSA may no longer be an accurate marker of prostate cancer biology. We determined whether the impact of PSA in predicting biochemical failure after radical prostatectomy has changed since the beginning of the PSA era. MATERIALS AND METHODS: A total of 1,246 patients were identified from the Columbia University Comprehensive Urological Oncology Database who underwent radical prostatectomy by 1 of 3 surgeons between 1988 and 2003. Cox proportional hazards models were fit to the data to estimate the impact of PSA (logPSA) in predicting BCF (PSA 0.2 ng/ml or greater). To determine if the predictive impact of PSA changed over time, patients were classified based on year of surgery, and an interaction term between PSA and time was included. Finally concordance indexes were estimated to determine if the predictive ability of PSA has changed over time. RESULTS: In a Cox model including PSA, year of surgery and a year/PSA interaction term, the impact of PSA appears to change over time (p = 0.002). However, when correcting for the effects of stage and grade there was no significant change in the impact of PSA. In addition, concordance analysis indicated that the predictive ability of PSA has remained constant throughout the PSA era (0.65, 0.66 and 0.64 for each period, respectively). CONCLUSIONS: This study demonstrates that the predictive ability of PSA as a cancer outcomes biomarker has not changed significantly since the beginning of the PSA era. Despite suggestions to the contrary, PSA remains an important variable in predicting risk of BCF after RP.

Humans↗
PubMed2000

Prediction of birth weight by ultrasound in the third trimester.

OBJECTIVE: To compare the accuracy of predicted birth weight by the gestation-adjusted projection method using ultrasonographic measurements obtained just before and at term. METHODS: The study group comprised patients with singleton pregnancies who underwent sonograms between 34.0 and 36.9 weeks' gestation (period 1) and at 37 weeks and beyond (period 2). The mean error in birth weight prediction, absolute birth weight error, and signed and absolute percent errors were compared with paired t tests. Thus, each patient served as her own control. RESULTS: The study included 138 patients undergoing 276 sonograms. The mean absolute error of the predicted birth weight was smaller for period 1 than for period 2 (197 +/- 167 g compared with 235 +/- 209 g, P =.019). The mean absolute percent error was 6.2 +/- 5.2% for period 1 compared with 7.4 +/- 6.3% for period 2 (P =.019). These same trends were observed when fetuses with suspected growth abnormalities were examined separately. Averaging data from both gestational periods did not improve the prediction of birth weight. CONCLUSION: Sonograms between 34.0 and 36. 9 weeks' gestation allow for more accurate prediction of birth weight than sonograms later in gestation. Though these differences are small and not clinically significant, this study indicates that serial sonograms in the late third trimester do not improve the ability to predict birth weight, even in abnormally grown fetuses. A single sonogram between 34 and 37 weeks' gestation is recommended for prediction of birth weight.

Adolescent↗
PubMed2000

The application of predictive models in the environmental risk assessment of ECONOR.

Environmental risk assessment of products requires information on the physico-chemical properties, persistence and ecotoxicity of the product, its constituents and possible metabolic and degradation products. Experimental investigations are usually required to generate this information and consequently risk assessment can be costly and time consuming. One possible approach to minimising the amount of experimental testing is to supplement experimental data with data predicted using models such as quantitative structure-activity relationships (QSARs). Using these models, information can be generated based primarily on the knowledge of the chemical structure of the substance(s) under investigation. In this study predictive models were used to assess the environmental risk of the veterinary medicine, ECONOR which contains the active ingredient valnemulin. Available experimental data on the properties, degradability and ecotoxicity of valnemulin was supplemented with predicted data. Where possible, experimental data was used to validate the predicted approaches and this indicated that the predictions were accurate. Information on usage, properties and degradability was input to fate models to predict environmental concentrations (PECs) of valnemulin in soil, pore water and groundwater. Comparison of PECs with experimental and predicted ecotoxicity data for valnemulin indicated that that even under 'worst case' scenarios the environmental risk posed by valnemulin was low.

Diterpenes↗
PubMed2001

Is physical examination useful in predicting epididymal obstruction?

OBJECTIVES: To evaluate the independent predictive value of subjective epididymal fullness in predicting obstruction in azoospermic men (group 1) and determining preoperatively the need for vasoepididymostomy (VE) in men presenting for vasectomy reversal (group 2). METHODS: All men were evaluated with a medical history and physical examination. During the physical examination, the epididymis was classified as full, if any portion was palpably distended, or normal. Obstruction was confirmed at surgical exploration for group 1 after a biopsy that revealed sufficient spermatogenesis. In group 2, the indications for VE were either no fluid seen from the testicular end of the vas or thick, pasty fluid devoid of sperm. In cases in which VE was required, these units were classified as obstructed. RESULTS: The predictive value of epididymal fullness was evaluated in 51 units (12 in group 1 and 39 in group 2). The sensitivity, specificity, and positive and negative predictive values were 67%, 100%, 100%, and 83%, respectively, in group 1 and 33%, 89%, 20%, and 94%, respectively, in group 2. CONCLUSIONS: Epididymal fullness in azoospermic men is predictive of obstruction, although a normal epididymal examination cannot rule out obstruction. In men presenting for vasectomy reversal, the absence of epididymal fullness is predictive of vasal fluid that allows for vasovasostomy. Epididymal fullness may suggest, but cannot predict, unfavorable vasal fluid that requires VE.

Epididymis↗
PubMed1995

Prediction of prostate cancer volume using prostate-specific antigen levels, transrectal ultrasound, and systematic sextant biopsies.

OBJECTIVES: Prostate-specific antigen (PSA) levels, transrectal ultrasound, and systematic sextant biopsies have each shown limited ability to predict prostate cancer volume. In combination, these studies may allow more accurate estimation of volume and prognosis. METHODS: One hundred twenty-four patients were evaluated prior to radical prostatectomy. Interactive stepwise multiple regression and separate logistic regression analysis were performed for prediction of prostate cancer volume and volume range. RESULTS: The cancer volumes calculated correlated with the volumes in the radical prostatectomy specimens with R2 of 0.76. Cancers were predicted to be in the volume range associated with poor prognosis (more than 12 cc) or clinically insignificant cancer (less than 1.0 cc) with bias corrected error rates of 5.3% and 10%, respectively. CONCLUSIONS: The formula for prediction of cancer volume correlates well with actual cancer volume in 92 patients but is not adequate to predict volume for an individual patient. The formulas for prediction of volume range show promising predictive ability and may be useful if the extent of disease is unclear.

Aged↗
PubMed2002

Prediction of food thermal process evaluation parameters using neural networks.

Two neural networks (ANN) were developed to predict thermal process evaluation parameters g and f(h)/U (the ratio of heating rate index to the sterilizing value), respectively. The temperature change required for the thermal destruction curve to traverse one log cycle (z), cooling lag factor (j(c)) andf(h)/U were input variables for predicting g and z, while j(c) and g were inputs for predicting f(h)/U. The data used to train and verify the ANN were obtained from reported values. Shrinking of input and output variables using natural logarithm function improved the prediction accuracy. The use of "Wardnets" with three slabs of 14 nodes in each slab, with a learning rate of 0.7 and momentum of 0.9 provided the best predictions. The g (unshrunk values) was predicted with a mean relative error of 1.25 +/- 1.77%, and a mean absolute error of 0.11 +/- 0.16 degrees F. The f(h)/U was predicted with a mean relative error of 1.41 +/- 3.40%, and a mean absolute error of 2.43 +/- 15.97, using 10 nodes in each slab. The process time calculated using the g from the ANN models closely followed the time calculated from the tabulated gvalues (RMS=0.612 min, average absolute error=0.466 min with an S.D. of 0.400 min).

Algorithms↗
PubMed1998

An algorithm for preoperative prediction of reoperation risk after internal fixation of femoral neck fractures.

An algorithm was designed for preoperative prediction of the risk for reoperation, and the mortality risk, after internal fixation of femoral neck fractures. Out of 51 reviewed studies of femoral neck fractures, eight met specified inclusion criteria such as low dropout rates, a minimum of ten surgeons performing the surgery, a minimum of 2 years follow-up, and a standard age, sex, and Garden class distribution. Five of these studies were used for the construction of the algorithm, and the remaining three for testing the specificity and sensitivity of the algorithm. A separate analysis of the influence of age on the reoperation rate was also performed. In the analysis of 399 reviewed cases of femoral neck fractures, the specificity for the algorithm in predicting the risk for reoperation was 96%, and the sensitivity was 51%. The positive predictive value for the algorithm in predicting the risk for reoperation was 77%, which was three times higher compared to the commonly used predictors age and Garden class (positive predictive value 25%). For prediction of the mortality risk the positive predictive value for-the algorithm was 57%.

Aged↗
PubMed1999

Predicting the relative efficacy of shock waveforms for transthoracic defibrillation in dogs.

STUDY OBJECTIVE: Previous work has shown that a passive membrane model using a parallel resistor-capacitor circuit is capable of predicting optimal waveforms for transvenous defibrillation. This study tested the ability of that model to predict optimal waveforms for transthoracic defibrillation. METHODS: This study was divided into 3 parts, each of which determined transthoracic defibrillation thresholds (DFTs) in 6 dogs for several different waveform shapes and durations. For each part, strength-duration relationships were determined from both experimental and model data and then compared with test model predictions. Part 1 DFTs were determined at various durations for 3 different monophasic waveforms-the ascending ramp, descending ramp, and square waveform. Part 2 DFTs were determined for 3 biphasic waveforms. Phase 1 was a 30-ms ascending ramp, and phase 2 was an ascending ramp, a descending ramp, or a square waveform. Part 3 DFTs were determined for 3 biphasic waveforms with very short second-phase durations. Phase 1 was a 30-ms ascending ramp, and phase 2 was a descending ramp. RESULTS: For part 1, the model was able to predict the relative defibrillation efficacy of the 3 monophasic waveforms ( P < .05). For parts 2 and 3, the model was able to predict the biphasic waveforms with the lowest DFTs. These predictions were based on the criterion that the model response at the end of the second phase should return to or slightly pass the model response value at the beginning of the first phase. CONCLUSION: The resistor-capacitor model successfully predicted the relative defibrillation efficacy of several different waveforms delivered transthoracically.

Analysis of Variance↗
PubMed2001

[An index based on the age and free thyroxine rate predicts the likelihood of Graves' disease in hyperthyroidism].

PURPOSE: Graves' disease patients are generally younger and have more severe symptoms than other thyrotoxic patients. We established an index based on the normalized free thyroxine rate and age, capable of predicting Graves' disease in thyrotoxic patients. METHODS: The predictive index was established from a discriminant analysis from a retrospective population of 114 thyrotoxic patients and its predictivity was confirmed by cross-validation on the same population. RESULTS: The index IGD = 41.38 - age + 37.05 x in (normalized free T4) classifies accurately 80.7% of the patients (CI 95%: 72.2-87.5). Sensitivity is 78.5% (CI 95%: 66.5-87.7). Specificity is 83.7% (CI 95%: 70.3-92.7). Predictive positive value is 86.4% (CI 95%: 75.0-94.0). Negative predictive value is 74.5% (CI 95%: 61.0-85.3). Likelihood ratio of Graves' disease in case of prediction by the index is 4.81 (CI 95%: 2.66-9.32). Likelihood ratio of Graves' disease in case of non-prediction by the index is 0.26 (IC 95%: 0.16-0.40). CONCLUSION: A simple index based on the normalized free thyroxine rate and age provides an early diagnosis orientation toward Graves' disease in thyrotoxic patients who are waiting for complementary investigations.

Adult↗
PubMed2001

Prediction of strength of cortical bone in vitro by microcomputed tomography.

OBJECTIVE: The aim of this study was to evaluate the predictive value of bone mineral density and intracortical porosity measured by microcomputed tomography for the strength of cortical bone biopsies. DESIGN: Experimental study comparing the predictive value of bone mineral density and of intracortical porosity determined in vitro by microcomputed tomography for the mechanical properties of cortical bone cylinders. BACKGROUND: The assessment of cortical bone strength might be relevant for the prediction of fracture risk or the choice of suitable therapy strategies in orthopaedic surgery. The predictive value of cortical density for the mechanical properties is discussed controversially. The relevance of intracortical porosity measured by histomorphometry has been established, but the predictive value of porosity determined by microcomputed tomography remains to be explored. METHODS: Femoral cortical bone specimens from the mid diaphysis of 24 patients were harvested during total hip replacement procedure at the location, where a diaphyseal hole (diameter 4.5 mm) was drilled in order to reduce the intramedullary pressure. In vitro intracortical porosity and bone mineral density measurements by microcomputed tomography were compared with strength and elastic modulus assessed by a compression test transverse to the Haversian systems of the same specimens. RESULTS: Significant negative correlations were found between porosity measured by microcomputed tomography scans and yield stress, stiffness and elastic modulus (P<0.001), however, the positive correlations between bone mineral density and mechanical parameters were stronger (P<0.0001). The mechanical parameter best predicted by mineral density as well as by porosity was yield stress (r=0.72,P<0.0001;r=-0.64,P<0.001). CONCLUSIONS: Bone mineral density determined by microcomputed tomography imaging in vitro may be a potent method to predict mechanical properties of cortical bone non-destructively. The application in vivo remains to be explored.

Aged↗
PubMed2001

Fibrillation power, an alternative method of ECG spectral analysis for prediction of countershock success in a porcine model of ventricular fibrillation.

BACKGROUND: Noninvasive prediction of defibrillation success after cardiac arrest and cardiopulmonary resuscitation (CPR) may help in determining the optimal time for a countershock, and thus increase the chance for survival. METHODS: In a porcine model (n=25) of prolonged cardiac arrest, advanced cardiac life support was provided by administration of two or three doses of either vasopressin or epinephrine after 3 or 8 min of basic life support. After 4 min of ventricular fibrillation and 18 min of life support, defibrillation was attempted. The denoised power spectral density of 10 s intervals of the ventricular fibrillation electrocardiogram (ECG) was estimated from averaged and smoothed Fourier transforms. We have eliminated the spectral contribution of artifacts from manual chest compressions and provide a definition for the contribution of ventricular fibrillation to the power spectral density. This contribution is quantified and termed "fibrillation power". RESULTS: We tested fibrillation power and two established methods in their discrimination of survivors (n=16) vs. non-survivors (n=9) in the last minute before the countershock. A fibrillation power > or =79 dB predicted successful defibrillation with sensitivity, specificity, positive predictive value and negative predictive value of 98%, 98%, 99% and 97% while a mean fibrillation frequency > or =7.7 Hz was predictive with 85%, 83%, 90% and 77% and a mean amplitude > or =0.49 mV was predictive with 95%, 90%, 94% and 91%. CONCLUSIONS: We suggest that fibrillation power is an alternative source of information on the status of a fibrillating heart and that it may match the established mean frequency and amplitude analysis of ECG in predicting successful countershock during CPR.

Animals↗
PubMed2004

Prediction of term birth weight in Hispanic women using an equation based on maternal characteristics.

OBJECTIVE: To test the accuracy of a birth weight prediction equation based on maternal characteristics in Hispanic women. STUDY DESIGN: A previously published birth weight prediction equation based on maternal and pregnancy-specific characteristics was used to predict birth weights for 283 normal Caucasian women of Hispanic ethnicity. The accuracy of these birth weight estimates was compared to a similarly selected group of 233 non-Hispanic Caucasian gravidas who were located 2500 miles away. RESULTS: Birth weight predictions for Hispanic women were accurate to within +/- 8.4% (+/- 287 g). The percentages of birth weights predicted to within +/- 15 and +/- 10% of actual values were 84 and 68%, respectively. These results were no different than those that were obtained for non-Hispanic Caucasian gravidas. CONCLUSIONS: A previously derived birth weight prediction equation based on maternal and pregnancy-specific characteristics alone successfully predicts term birth weight in normal Hispanic gravidas to within +/- 8.4% (+/- 287 g).

Adult↗
PubMed2002

Estimation of the Doppler ultrasound umbilical maximal waveform envelope: II. Prediction of fetal distress.

Blood flow variables obtained via Doppler ultrasound (US) waveform estimation have been investigated for prediction of fetal distress. The umbilical flow was assessed using a number of waveform summary statistics in addition to the currently used resistance indices. We examined the relationship between umbilical artery waveform patterns and intrauterine growth restriction, preterm delivery and hypertensive disorders. To enhance prediction, we defined waveform skewness profiles based on pivotal points of the umbilical waveform that appeared to be related to the incidence of preterm delivery and that facilitated construction of IUGR prediction models. The data comprised 204 unselected pregnancies with the umbilical artery images recorded at 18 pregnancy weeks. The sample was divided into 114 pregnancies used to estimate model parameters and 90 pregnancies to validate the model. Logistic prediction models for detection of abnormal velocity waveforms associated with intrauterine growth restriction were derived, based on the waveform information. The estimated model sensitivity and specificity on the training data were 74% and 84%, respectively. Validation of the model on independent data yielded a sensitivity of 57% and specificity of 84%. The logistic IUGR prediction model appears to have significant predictive ability and potential for clinical use, even at this early gestational age. Our data suggest that prediction of IUGR at 18 pregnancy weeks can be much improved when the waveform shape is captured with a number of summary statistics in addition to resistance indices.

Algorithms↗
PubMed1995

Prediction of amputation wound healing with skin perfusion pressure.

PURPOSE: The purpose of this study was to determine whether laser Doppler skin perfusion pressure (LD-SPP) could accurately predict amputation wound healing. METHODS: We studied a total of 62 limbs in 52 patients (28 men and 24 women) with a mean age of 62.2 years (range 34 to 93 years). From this, 39 limbs underwent major amputation (15 above-the-knee, 24 below-the-knee), and 23 limbs underwent minor amputations (4 transmetatarsal and 19 toes). There were five postoperative deaths, leaving a total of 57 limbs available for analysis. RESULTS: Three of 13 above-knee amputations failed to heal. Twenty-one of 23 below-knee amputations healed. Three of four transmetatarsal amputations failed to heal and eight of 17 toe amputations failed to heal. Binary table analysis showed that an LD-SPP value of 30 mm Hg or greater had a negative predictive value (healing occurred) of 90%. An LD-SPP value of less than 30 mm Hg at the amputation site had a positive predictive value (healing failure) of 75%, (p < 0.001, chi square analysis). For major amputations, negative predictive value was 100%, and positive predictive value was 83%, (p < 0.001). For minor amputations, negative predictive value was 75% and positive predictive value was 66.7%, (p < 0.09). CONCLUSION: These data support the use of the LD-SPP test in the selection of major amputation level consistent with healing in ischemic limbs. Further study of the value of this parameter in the determination of minor amputation wound healing is necessary.

Adult↗
PubMed1990

Preoperative astigmatic influence on the predictability of intraocular lens power calculation.

The preoperative and postoperative influence of different parameters on the predictability of formulas used for intraocular lens (IOL) power calculation (axial length, corneal dioptric power, IOL malposition, postoperative astigmatism) has been shown by various authors. In this study, we evaluated the preoperative astigmatic influence on the prediction of postoperative refraction in eyes operated on for cataract with IOL implantation. Three hundred and fifty-nine eyes were evaluated after cataract surgery and IOL implantation. We calculated predictive errors of both the Binkhorst and SRK formulas for each eye. Based on the outcome of the predictive errors we divided the eyes into six groups: three of high and three of low predictability. Preoperative astigmatism in these groups was statistically compared (using the Student's t-test). The preoperative astigmatism was always higher in the group with low predictability than in the group with high predictability (P less than .05).

Astigmatism↗