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PubMed1990

Prospective study of late potentials to predict cardiac sudden death and ventricular tachycardias in patients with myocardial infarction surviving over 4 weeks.

We studied, prospectively, the predictive value of late potentials to cardiac sudden death and sustained ventricular tachycardias in 385 patients with myocardial infarction surviving over 4 weeks. Signal averaged electrocardiogram was performed over a 4 week period from the onset of acute myocardial infarction in all patients. Late potentials were observed in 118 of 385 patients. During the mean follow up period of 24.3 months, 17 patients had cardiac sudden death and 15 patients had symptomatic sustained ventricular tachycardias. In 16 of 17 patients with cardiac sudden death and 14 of 15 patients with sustained ventricular tachycardias, late potentials were observed. Sensitivity, specificity, positive predictive value, negative predictive value, and predictive accuracy of late potentials to cardiac sudden death in these 385 patients were 94.1%, 72.3%, 13.6%, 99.6% and 73.2% respectively. Also, these predictive values of late potentials to sustained ventricular tachycardias in the group of patients were 93.3%, 71.9%, 11.9%, 99.6% and 72.7%, respectively. We concluded that the clinical usefulness of late potentials in patients with myocardial infarction surviving over 4 weeks in the negative predictive value to cardiac sudden death and sustained ventricular tachycardias is superior to that of positive predictive value. Sensitivity of late potentials to these events is also higher.

Adult↗

PubMed1998

Blood lead slope factor models for adults: comparisons of observations and predictions.

Here we explore the appropriateness of various parameter values for the Bowers et al. model [Risk Anal 14:183-189, 1994] in the context of predicting the influence of site-related exposure to lead in soil on the blood lead (PbB) levels of women of childbearing age. We outline the parameters prescribed by Bowers et al. as well as those prescribed by the U.S. Environmental Protection Agency (U.S. EPA). Comparison of the PbB levels predicted by the Bowers et al. model to those predicted by the validated O'Flaherty pharmacokinetic model indicates that the Bowers et al. model performs favorably when parameter values prescribed here are used. Use of the U.S. EPA-prescribed parameters yields predicted PbB levels that substantially exceed the validated O'Flaherty model predictions. Finally, both the U.S. EPA-prescribed parameter values and the parameter values recommended herein are used to predict PbB levels among adults living in four Superfund communities. Comparison of predicted PbB levels for these communities indicates that the U.S. EPA parameters overstate the incremental influence of lead in soil on PbB levels. Differences between the parameter values prescribed here and the U.S. EPA-prescribed parameters yield substantially different cleanup criteria for lead in soil, although conservative parameter values may still be appropriate for screening purposes.

Adult↗

PubMed2004

The use of a cognitive battery to predict who will fail an on-road driving test.

OBJECTIVES: There is a growing need to find a valid and reliable neuropsychological battery to screen out those people who are clearly unsafe to drive following brain injury or pathology, and thus alleviate the need to refer for an on-road assessment. DESIGN: A battery of cognitive tests fine-tuned for their relevance to driving was examined in terms of its sensitivity and specificity for predicting who would fail an on-road test following brain injury or pathology. METHOD: Performance on the battery was compared to the results of an on-road driving test in a consecutive series of 142 clients referred to a driving assessment centre following brain injury or pathology. The group represented diverse neurological conditions which affect brain functioning. RESULTS: The overall accuracy rate of the battery in predicting a fail on-road was 92% and in predicting a pass on road was 71%. It was more accurate for those under 70 with 100% accuracy in predicting a fail on-road and 85% accuracy in predicting a pass on-road, but less accurate for those aged 70 or above with 85% accuracy in predicting a fail on-road and 37% accuracy in predicting a pass on-road. CONCLUSION: The battery is a useful tool in helping to determine whether someone is safe to drive following brain injury but needs to be used with far more caution for the older driver.

Adult↗

PubMed1999

Early prediction of persisting post-concussion symptoms following mild and moderate head injuries.

OBJECTIVES: King (1996) reported that a combination of emotional, organic and neuropsychological measures taken at 7-10 days following mild and moderate head injury may significantly help predict patients most likely to suffer persisting post-concussion symptoms (PCS) at three months post-injury. This study investigated a cross-validation sample (N = 57) to determine whether the results would be replicated for the early prediction of longer-term sufferers (i.e. those with persisting symptoms at 6 months post-injury). DESIGN: Multiple regression analyses were used in which scores on the Hospital Anxiety and Depression Scale, Impact of Event Scale, Short Orientation Memory and Concentration Test, Rivermead Post-Concussion Symptoms Questionnaire and Post-Traumatic Amnesia taken at 7-10 days post-injury were the independent measures. Scoring on the Rivermead Post-Concussion Symptoms Questionnaire taken at 6 months post-injury was the dependent measure. METHODS: Sixty-six consecutive patients admitted to any trauma ward in Oxfordshire with a mild or moderate head injury were recruited from a largescale randomized controlled sample. The assessment measures were administered at 7-10 days post-injury and the Rivermead Post-Concussion Symptoms Questionnaire at 6 months post-injury. Nine patients were unable to be followed up, leaving an active sample of 57. RESULTS: The cross-validation data confirmed that a similar combination of measures to that found in the original study best predicted persisting PCS but that the strength of prediction diminished for the longer term prediction (i.e. 6 months post-injury). CONCLUSIONS: The Hospital Anxiety and Depression Scale, Impact of Even Scale and Post-Traumatic Amnesia in combination are recommended as useful prognostic screening instruments for predicting persisting PCS, but great caution is required if they are used to aid predictions beyond 3 months post-injury.

Adolescent↗

PubMed2005

Predictive markers in breast and other cancers: a review.

BACKGROUND: Unpredictable efficacy and toxicity are hallmarks of most anticancer therapies. Predictive markers are factors that are associated with response or resistance to a particular therapy. METHODS: The English literature relating to predictive markers in oncology was reviewed. Particular attention was paid to metaanalyses, systematic reviews, prospective trials, and guidelines issued by expert panels. RESULTS: The prototype predictive tests in oncology are the estrogen receptor (ER) and progesterone receptor (PR), which are used to select patients with breast cancer likely to respond to hormone therapy. A more recently introduced predictive marker is HER-2 for selecting patients with advanced breast cancer for treatment with the therapeutic antibody trastuzumab (Herceptin). In adjuvant breast cancer, overproduction of HER-2 may also indicate an enhanced sensitivity to high-dose anthracycline-based regimens. On the other hand, in both early and advanced breast cancer, high concentrations of HER-2 appear to correlate with a lower probability of response to hormone therapy. Although many different anticancer drugs appear to mediate tumor regression by inducing apoptosis, there is currently no consistent evidence that any of the molecules implicated in this process can be used as predictive markers. CONCLUSIONS: Currently, the only recommended predictive markers in oncology are ER and PR for selecting endocrine-sensitive breast cancers and HER-2 for identifying breast cancer patients with metastatic disease who may benefit from trastuzumab. For malignancies other than breast cancers, validated predictive markers do not exist at present.

ATP-Binding Cassette Transporters↗

PubMed1996

Predicting eventual success or failure to wean in patients receiving long-term mechanical ventilation.

PURPOSE: To determine if the ultimate ability of a long-term ventilated patient to wean can be predicted at the time of his or her admission to a long-term ventilator unit. DESIGN: Two-phased prospective study. SETTING: Long-term ventilator facility, university-affiliated. SUBJECTS: Adults ventilated for an average of 3 weeks, who did not have sepsis and who did not have chest tubes or progressive neurologic impairment. INTERVENTIONS: On admission to the long-term ventilator unit, historic factors, ventilator history, and the following laboratory and metabolic tests were obtained: electrolytes, serum calcium, magnesium, and phosphorus, WBC, hemoglobin, albumin, total protein, transferrin, oxygen consumption, carbon dioxide production, respiratory quotient, and dead space/tidal volume. The patients were then placed in a weaning protocol utilizing increasing duration of pressure support ventilation during the day with complete rest at night. Forty-two days after enrollment in the study, representing three times the duration of the weaning protocol, the patients who successfully weaned were compared to those who remained ventilator dependent (n = 20). Patients who died or were transferred to another institution were excluded from this phase of the study, because we were trying to develop parameters that would be predictive of successful weaning. A parameter was considered to be predictive, and retained for the scoring system, if it produced at most 15% false-positives and false-negatives. A score of 0 was then assigned to the threshold value that produced no false-positives; 2 to the threshold value that produced no false-negatives and 1 to the intermediate values. The scoring system was then applied to a new prospective group of patients (n = 72). MEASUREMENTS AND MAIN RESULTS: Of all the parameters evaluated, only the following satisfied the false-positive and false-negative requirements; static compliance, airway resistance, dead space to tidal volume ratio, PaCO2, and frequency/tidal volume. Applying these, in the scoring system, to the initial group of patients, demonstrated that a score greater than 3 was associated with failure to wean; a score less than 3 was associated with successful weaning, and a score of 3 was not predictive. Using these thresholds, the data were applied to the new prospective group of patients, which again demonstrated that a score of greater than 3 was associated with failure to wean in all cases. A score less than 3 was again associated with successful weaning but there were two false-positives. The sensitivity, specificity, and positive predictive and negative predictive values for the scoring system were 1.0, 0.91, 0.83, and 1.0, respectively. None of the individual parameters included in the scoring system demonstrated equivalent statistical results. All but two of the patients who died prior to finishing the weaning period had weaning scores, which suggested that they would not be successfully weaned. CONCLUSIONS: Parameters that are generally available, when combined into a scoring system, can predict at the time of admission to a long-term ventilator unit, in most cases, whether a patient will eventually wean. The scoring system resulted in no false-negatives and an acceptable number of false-positives. None of the individual parameters were as reliable as the scoring system as a whole.

Aged↗

PubMed1997

Is the duration of mechanical ventilation predictable?

BACKGROUND: Prolonged mechanical ventilation (MV) is associated with high morbidity, mortality, and cost. However, few and limited data are available on the prediction of duration of MV. We conducted an observational cohort study to seek predictive criteria. METHODS: The study was performed in a surgical ICU (SICU) in a university hospital. One hundred ninety-five consecutive unselected patients and 203 episodes of MV were prospectively analyzed to determine if clinical features, physiologic parameters, or multifactor scoring systems, at the time of admission or intubation, could be used as predictors of MV > or = 15 days. A univariate statistical analysis and a multiple logistic regression were used. A prospective validation study was then conducted to determine the accuracy of the results. RESULTS: (1) Univariate statistical analysis indicated that SICU length of stay, emergent endotracheal intubation as opposed to elective intubation, indication for MV, sepsis score at the time of admission and intubation, lung injury score (LIS) at the time of admission and intubation, number of organ system failures at the time of admission and intubation, and serum albumin concentration were significantly different between the two groups. (2) Only the circumstances (emergency) of endotracheal intubation (odds ratio [OR]=3.5, p=0.02) and the LIS (OR=3.7, p=0.004) independently predicted a duration of endotracheal intubation > or = 15 days. One hundred twenty-eight consecutive patients requiring emergent intubation and MV were included in the prospective validation. The accuracy of the LIS > or = 1 used to predict MV > or = 15 days was as follows: sensitivity=0.88; specificity=0.28; positive predictive value=0.24; negative predictive value=0.91. CONCLUSION: Low incidence of MV > or = 15 days was observed (13% and 20%, respectively, in observational cohort study and validation study) in unselected SICU patients. LIS > or = 1 at the time of intubation provides excellent negative predictive value (0.93 and 0.91) of duration of MV > or = 15 days. These data suggest that tracheotomy should not be considered for patients with LIS < 1.

Adolescent↗

PubMed2005

The predictive power of serum kappa/lambda ratios for discrimination between monoclonal gammopathy of undetermined significance and multiple myeloma.

The predictive power of serum kappa/lambda ratios on initial presentation of immunoglobulin G (IgG) or IgA monoclonal component was studied to differentiate between monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patients. The retrospective study involved 145 patients clinically diagnosed with monoclonal gammopathy of undetermined significance or multiple myeloma, who had serum M-protein IgG <35 g/L or IgA <20 g/L at M-protein detection. Serum light chains kappa and lambda were measured by fixed-time nephelometry. Test performance indices, predictive values and likelihood ratios were calculated according to the Weissler recommendation. MM patients were considered as diseased and MGUS patients as non-diseased in order to estimate the performance characteristics of serum kappa/lambda ratios. There was a statistically significant difference in kappa/lambda ratios distribution between both groups of patients, in both M-protein kappa-type (Mann-Whitney U=168, p<0.001) and in M-protein lambda-type (Mann-Whitney U=143, p<0.001). Negative likelihood ratios at threshold levels of 0.6 and 4.2 were 2.17- and 3.32-fold greater, respectively, than positive likelihood ratios, so that the predictive power of a serum kappa/lambda ratio within these limits is better in ruling out (negative predictive power) than ruling in disease (positive predictive power). The post-test characteristics of a serum kappa/lambda ratio interval between 0.6 and 4.2 in discriminating MGUS from MM in our geographic population were: sensitivity 0.96 (0.93-0.99 95% CI); specificity 0.70 (0.63-0.77); positive predictive value 0.68 (0.64-0.73); negative predictive value 0.96 (0.94-0.99); likelihood ratios (+)LR 3.23 (2.68-4.04); and (-)LR 17.16 (11.00-63.00). Thus, serum M-protein with a kappa/lambda ratio between 0.6 and 4.2 increases the posterior probability of MGUS from 0.60 to 0.96 in asymptomatic patients, for whom only monitoring may be suggested when the serum kappa/lambda ratio is within these limits.

Adult↗

PubMed2000

Can absolute oral bioavailability in humans be predicted from animals? A comparison of allometry and different indirect methods.

The objective of this study was to predict absolute bioavailability in humans from animal data using interspecies scaling as well as indirect approaches. Five different methods were used to predict absolute bioavailability in humans: (i) absolute bioavailability vs body weight (allometric approach); (ii) F = CL(IV)/CL(oral); (iii) F = 1-[CL(IV)/Q]; (iv) F = 1-[CL(oral)/Q]; and (v) F = Q/[Q + CL(oral)]. Methods II-V are indirect approaches, where predicted i.v. or oral clearance and hepatic blood flow (Q) (1500 ml/min) were used to predict absolute bioavailability in humans. Fifteen drugs were tested and the results of this study indicate that all five approaches predict absolute bioavailability with different degrees of accuracy, and are therefore unreliable for the accurate prediction of absolute bioavailability in humans from animal data. In conclusion, although the above-mentioned approaches do not accurately predict absolute bioavailability, a rough estimate of absolute bioavailability is possible using these approaches.

Animals↗

PubMed2004

Predicting anaerobic capabilities in 11-13-year-old boys.

Anaerobic exercise is involved in many recreational and competitive sport activities. This study first established regression equations to predict maximal anaerobic power and then cross-validated these prediction equations. Using stepwise multiple regression analysis prediction equations for relative (watts per kilogram of body mass) and absolute (watts) mean and peak anaerobic power using the 30-second Wingate Test as the power measure were determined for 40 boys (age, 11-13 years). Percentage of body fat, free-fat weight, midthigh circumference, and 30-m dash were the independent predictive variables with the generated regression equations subsequently cross-validated using 20 different boys (age, 11-13 years). Significant correlations (Pearson r) were found for the cross-validation subjects between the measured power outputs and predicted power outputs for relative mean power (r = 0.48, p < 0.05), absolute mean power (r = 0.77, p < 0.01), and absolute peak power (r = 0.76, p < 0.01). Using paired t-tests, no significant mean differences (p > 0.05) were found for the same subjects between actual and predicted power outputs for relative mean power, absolute mean power, and absolute peak power. Prediction of maximal anaerobic power from selected anthropometric measurements and 30-m dash appears tenable in 11-13-year-old boys and can be accomplished in a simple cost- and time-effective manner.

Adolescent↗

PubMed2006

A simplified clinical model to predict pulmonary embolism in patients with acute dyspnea.

UNLABELLED: The objective of the present study was to develop a simple clinical model for predicting pulmonary embolism (PE) in patients with acute dyspnea in the emergency room. PATIENTS AND MEASUREMENTS: We enrolled 56 patients diagnosed with PE, and 92 consecutive patients without PE, all of whom presented with acute dyspnea in the emergency room. Primary emergency-room physicians assessed the initial evaluation and interpretation of various laboratory findings. Some significantly independent predictors of PE were identified and integrated into a clinical model of pretest probability: low (< 30%), intermediate (>or= 30%, 70%). After setting up the model, another 40 patients (16 with PE, 24 without PE) were tested using the pretest model. Clinical variables associated with an increased likelihood of PE were being female and having unilateral low-leg edema, a high alveolar-arterial oxygen gradient, a clear chest x-ray, and electrocardiographic findings of right ventricular strain. Variables associated with a decreased likelihood of PE were cough, chest tightness, and unclear breath sounds. Our clinical model predicted that 95% of patients with PE had a high or low probability of PE. The positive predictive value for high probability was 94.1% and the negative predictive value for low probability was 94.4%. In the tested group, the positive predictive value for high probability was 92.9%. The negative predictive value for low probability was 91.3%. This simple and easily available prediction model was useful for estimating the pretest probability of PE in patients with acute dyspnea.

Acute Disease↗

PubMed2006

Prediction of Lyme meningitis in children from a Lyme disease-endemic region: a logistic-regression model using history, physical, and laboratory findings.

BACKGROUND: Differentiating Lyme meningitis (LM) from other forms of aseptic meningitis (AM) in children is a common diagnostic dilemma in Lyme disease-endemic regions. Prior studies have compared clinical characteristics of patients with LM versus patients with documented enteroviral infections. No large studies have compared patients with LM to all patients presenting with AM and attempted to define a clinical prediction model. OBJECTIVE: To create a statistical model to predict LM versus AM in children based on history, physical, and laboratory findings during the initial presentation of meningitis. METHODS: Children older than 2 years presenting to the Alfred I. duPont Hospital for Children between October 1999 and September 2004 were identified if both Lyme serology and cerebrospinal fluid (CSF) were collected during the same hospital encounter. Patients were considered to have Lyme disease only if they met Centers for Disease Control and Prevention criteria (documented erythema migrans and/or positive Lyme serology). Patients were eligible for study inclusion if they had documented meningitis (CSF white blood cell count: >8 per mm3). Retrospective chart review abstracted duration of headache and cranial neuritis (papilledema or cranial nerve palsy) on physical examination and percent CSF mononuclear cells. Using logistic-regression analysis, the type of meningitis (LM versus AM) was simultaneously regressed on these 3 variables. The Hosmer-Lemeshow test was performed and the area under the receiver operating characteristic curve was calculated. RESULTS: A total of 175 children with meningitis were included in the final statistical model. Logistic-regression analysis included 27 patients with LM and 148 patients classified as having AM. Duration of headache, cranial neuritis, and percent CSF mononuclear cells independently predicted LM. The Hosmer-Lemeshow test revealed a good fit for the model, and the Nagelkerke R2 effect size demonstrated good predictive efficacy. Odds ratios based on the logistic-regression results were calculated for these variables. The final model was transformed into a clinical prediction model that allows practitioners to calculate the probability of a child having LM. CONCLUSIONS: Longer duration of headache, presence of cranial neuritis, and predominance of CSF mononuclear cells are predictive of LM in children presenting with meningitis in a Lyme disease-endemic region. The clinical prediction model can help guide the clinician about the need for parenteral antibiotics while awaiting serology results.

Child↗

PubMed2002

Early prediction of poor outcome in patients with acute asthma in the emergency room.

Early identification of patients who need hospitalization or patients who should be discharged would be helpful for the management of acute asthma in the emergency room. The objective of the present study was to examine the clinical and pulmonary functional measures used during the first hour of assessment of acute asthma in the emergency room in order to predict the outcome. We evaluated 88 patients. The inclusion criteria were age between 12 and 55 years, forced expiratory volume in the first second below 50% of predicted value, and no history of chronic disease or pregnancy. After baseline evaluation, all patients were treated with 2.5 mg albuterol delivered by nebulization every 20 min in the first hour and 60 mg of intravenous methylprednisolone. Patients were reevaluated after 60 min of treatment. Sixty-five patients (73.9%) were successfully treated and discharged from the emergency room (good responders), and 23 (26.1%) were hospitalized or were treated and discharged with relapse within 10 days (poor responders). A predictive index was developed: peak expiratory flow rates after 1 h < or =0% of predicted values and accessory muscle use after 1 h. The index ranged from 0 to 2. An index of 1 or higher presented a sensitivity of 74.0, a specificity of 69.0, a positive predictive value of 46.0, and a negative predictive value of 88.0. It was possible to predict outcome in the first hour of management of acute asthma in the emergency room when the index score was 0 or 2.

Acute Disease↗

PubMedDate not supplied

Model to predict septicemia in diarrheic calves.

The difficulty in distinguishing between septicemic and nonsepticemic diarrheic calves prompted a study of variables to predict septicemia in diarrheic calves <28 days old that were presented to a referral institution. The prevalence of septicemia in the study population was 31%. Variables whose values were significantly different (P < .10) between septicemic and nonsepticemic diarrheic calves were selected using stepwise, forward, and backward logistic regression. Variables identified as potentially useful predictors were used in the final model-building process. Two final models were selected: 1 based on all possible types of predictors (laboratory model) and 1 based only on demographic data and physical examination results (clinical model). In the laboratory model, 5 variables retained significance: serum creatinine > 5.66 mg/dL (>500 micromol/L) (odds ratio [OR] = 8.63, P = .021), toxic changes in neutrophils > or = 2+ (OR = 2.88, P = .026), failure of passive transfer (OR = 2.72, P = .023), presence of focal infection (OR = 2.68. P = .024), and poor suckle reflex (OR = 4.10, P = .019). Four variables retained significance in the clinical model: age < 5 days (OR = 2.58, P = .006), presence of focal infection (OR = 2.45, P = .006), recumbency (OR = 2.98, P = .011), and absence of a suckling reflex (OR = 3.03, P = .031). The Hosmer-Lemeshow goodness-of-fit chi-square statistics for the laboratory and clinical models had P-values of .72 and .37, respectively, indicating that the models fit the observed data reasonably well. The laboratory model outperformed the clinical model by a small margin at a predictabilty cutoff of 0.5, however, the predictive abilities of the 2 models were quite similar. The low sensitivities (39% and 40%) of both models at a predicted probability cutoff of 0.5 meant many septicemic calves were not being detected by the models. The specificity of both models at a predicted probability cutoff of 0.5 was >90%, indicating that >90% of nonsepticemic calves would be predicted to be nonsepticemic by the 2 models. The positive and negative predictive values of the models were 66-82%, which indicated the proportion of cases for which a predictive result would be correct in a population with a prevalence of septicemia of 31%.

Animals↗

PubMed2000

Multiplier method for predicting limb-length discrepancy.

BACKGROUND: In patients with a congenital or developmental limb-length discrepancy, the short limb grows at a rate proportional to that of the normal, long limb. This is the basis of predicting limb-length discrepancy with existing methods, which are complicated and require multiple data points. The purpose of our study was to derive a simple arithmetic formula that can easily and accurately predict limb-length discrepancy at skeletal maturity. METHODS: Using available databases, we divided the femoral and tibial lengths at skeletal maturity by the femoral and tibial lengths at each age for each percentile group. The resultant number was called the multiplier. Using the multiplier, we derived formulae to predict the limb-length discrepancy and the amount of growth remaining. We verified the accuracy of these formulae by evaluating two groups of patients with congenital shortening who were managed with epiphysiodesis or limb-lengthening. We also calculated and compared the multipliers for other databases according to radiographic, clinical, and anthropological lower-limb measurements. RESULTS: The multipliers for the femur and tibia were equivalent in all percentile groups, varying only by age and gender. Because congenital limb-length discrepancy increases at a rate proportional to growth, the discrepancy at maturity can be calculated as the current discrepancy times the multiplier for the current age and the gender. This calculation can be performed with use of a single measurement of limb-length discrepancy. For progressive developmental (noncongenital) discrepancies, the discrepancy at skeletal maturity can be calculated as the current discrepancy plus the growth inhibition times the amount of growth remaining. The timing of the epiphysiodesis can also be calculated with the multiplier. The predictions made with use of the multiplier method correlated well with those made with use of the Moseley method as well as with the actual limb-length discrepancy in both the limb-lengthening and epiphysiodesis groups. The multipliers derived from the radiographic, clinical, and anthropological measurements of femora and tibiae were all similar to each other despite differences in race, ethnicity, and generation. CONCLUSIONS: The multiplier method allows for a quick calculation of the predicted limb-length discrepancy at skeletal maturity, without the need to plot graphs, and is based on as few as one or two measurements. This method is independent of percentile groups and is the same for the prediction of femoral, tibial, and total-limb lengths. The multiplier values are also independent of generation, height, socioeconomic class, ethnicity, and race. We verified the accuracy of this method clinically by evaluating patients who had been managed with limb-lengthening or epiphysiodesis. The method was also comparable with or more accurate than the Moseley method of limb-length prediction.

Adolescent↗

PubMed2004

Validation of a clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children.

BACKGROUND: The differentiation between septic arthritis and transient synovitis of the hip in children can be difficult. The purpose of the present study was to validate a previously published clinical prediction rule for this differentiation in a new patient population. METHODS: We prospectively studied children who presented to a major children's hospital between 1997 and 2002 with an acutely irritable hip. As in the previous study, diagnoses of septic arthritis (fifty-one patients) and transient synovitis (103 patients) were operationally defined on the basis of the white blood-cell count in the joint fluid, the results of cultures of joint fluid and blood, and the clinical course. Univariate analysis and multiple logistic regression were used to compare the two groups. The predicted probability of septic arthritis of the hip from the prediction rule was compared with actual distributions in the current patient population. The area under the receiver operating characteristic curve was determined. RESULTS: The same four independent predictors of septic arthritis of the hip (a history of fever, non-weight-bearing, an erythrocyte sedimentation rate of 40 mm/hr, and a serum white blood-cell count of >12,000 cells/mm(3) (>12.0 x 10(9)/L)) were identified in the current patient population. The predicted probability of septic arthritis of the hip from the prediction rule was similar to the actual distributions in the current patient population. The area under the receiver operating characteristic curve for the current patient population was 0.86, compared with 0.96 in the original population. CONCLUSIONS: Clinical prediction rules typically demonstrate diminished performance in a new patient population because they are optimally modeled to the original data set. The previously published clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children demonstrated diminished, but nevertheless very good, diagnostic performance in a new patient population.

Algorithms↗

PubMed1996

Prediction of blood lactate accumulation from excess CO2 output during constant exercise.

To determine the predictability of blood lactate accumulation from excess CO2 output derived from bicarbonate buffering of lactic acid during constant exercise, eight normal active volunteers were studied during three stages of constant exercise on a cycle ergometer. Three work rates consisted of 100% (stage I), 120% (stage II) and 150% (stage III) of each subject's anaerobic threshold (AT), each of which was lasted for 4 min. Excess CO2 output (Ex CO2, ml) at each stage of constant exercise was estimated form the integral of difference between total VCO2 and aerobic VCO2 (from regression line for VCO2 and VO2 at exercise intensities below the AT obtained in incremental exercise test). Ex CO2 per body mass (Ex CO2-mass-1) was increased progressively with blood lactate (La) accumulation from rest to each stage of constant exercise. Mean values (+/-SD) in the measured La accumulation (delta La,measured) and predicted La accumulation (delta La,predicted) at three stages of constant exercise were 1.82 +/- 0.83 vs 3.19 +/- 1.70 for stage 1, 5.58 +/- 3.47 vs 7.09 +/- 3.28 for stage II and 12.19 +/- 2.36 vs 12.74 +/- 1.83 mmol.l-1 for stage III, respectively. There was a significant difference between delta La,measured and delta La,predicted at stage I (p < 0.05), but no significant differences between these two variables at stage II and III. The averaged difference from delta La,predicted to delta La,measured at stage III (0.55 mmol.l-1) showed a tendency to be smaller than stage I (1.38 mmol.l-1) and II (1.50 mmol.l-1). On the other hand, delta La,predicted was found to correlate very closely with delta La,measured (r = 0.954, P < 0.001, n = 20). The results of this study suggest that the changes of La accumulation could be predicted from excess CO2 output generated in constant exercises above the AT.

Adolescent↗

PubMed2005

The quantitative prediction of in vivo enzyme-induction caused by drug exposure from in vitro information on human hepatocytes.

There have been no reports of the quantitative prediction of induction for drug-metabolizing enzymes in humans. We have tried to predict such enzyme induction in humans from in vitro data obtained using human hepatocytes. The in vitro and in vivo data on enzyme induction by inducers, such as rifampicin, phenobarbital and omeprazole, were collected from the published literature. The degree of enzyme induction in humans was compared with that predicted from in vitro data on human hepatocytes. Using the in vivo data, we calculated the hepatic intrinsic clearance of typical CYP substrates, such as midazolam and caffeine, before and after inducer treatment and estimated the induction ratios of hepatic intrinsic clearance following treatment. In the in vitro studies, the amount of mRNA or enzyme and enzyme activity in human hepatocytes, with or without an inducer, were compared and the induction ratios were estimated. The unbound mean concentration was taken as an index of drug exposure and the induction ratios in the in vivo and in vitro studies were compared. The unbound mean concentrations of inducers used in the in vitro studies were higher than those in the in vivo studies. The maximum induction ratios by inducers in the in vitro studies were higher than those in the in vivo studies. The induction ratio for rifampicin, omeprazole, troglitazone, dexamethasone and phenobarbital increased as the unbound mean concentration increased to reach a constant value. The induction of CYP3A and 1A was analyzed by the Emax model. The maximum induction ratio (Emax) and the concentration at half maximum induction (EC50) for rifampicin, omeprazole, troglitazone, dexamethasone and phenobarbital were 12.3, 0.847 micromol/L, 2.36, 0.225 micromol/L, 6.86, 0.002 micromol/L, 8.30, 9.32 micromol/L, and 7.62, 58.4 micromol/L, respectively. The Emax and EC50 of omeprazole for CYP1A were 12.02 and 0.075 micromol/L, respectively. The predicted induction ratio of all those inducers, except for omeprazole, based on the Emax and EC50 values obtained from the in vitro data were similar to the observed values. On the whole, a good correlation between the observed and predicted induction ratio of omeprazole was observed (r=0.768, p<0.05), although the predicted induction ratio was higher than the observed value. In conclusion, the present study suggests that it is possible to predict quantitatively the CYP3A enzyme induction from hepatocyte data.

Area Under Curve↗