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Results for “external validation”

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PubMed2002

External validation of a prognostic model for predicting survival of cirrhotic patients with refractory ascites.

OBJECTIVE: Cirrhotic patients with refractory ascites (RA) have a poor prognosis, although individual survival varies greatly. A model that could predict survival for patients with RA would be helpful in planning treatment. Moreover, in cases of potential liver transplantation, a model of these characteristics would provide the bases for establishing priorities of organ allocation and the selection of patients for a living donor graft. Recently, we developed a model to predict survival of patients with RA. The aim of this study was to establish its generalizability for predicting the survival of patients with RA. METHODS: The model was validated by assessing its performance in an external cohort of patients with RA included in a multicenter, randomized, controlled trial that compared large-volume paracentesis and peritoneovenous shunt. The values for actual and model-predicted survival of three risk groups of patients, established according to the model, were compared graphically and by means of the one-sample log-rank test. RESULTS: The model provided a very good fit to the survival data of the three risk groups in the validation cohort. We also found good agreement between the survival predicted from the model and the observed survival when patients treated with peritoneovenous shunt and with paracentesis were considered separately. CONCLUSION: Our survival model can be used to predict the survival of patients with RA and may be a useful tool in clinical decision making, especially in deciding priority for liver transplantation.

Actuarial Analysis↗
PubMed2025

Identification and external validation of a prognostic signature based on myeloid-derived suppressor cells-related LncRNAs to evaluate survival prognosis and treatment efficacy in invasive breast carcinoma.

BACKGROUND: Originating in the hematopoietic tissue, myeloid-derived suppressor cells (MDSCs) significantly contribute to tumor-related immunological processes. However, their relationship with long noncoding RNAs (lncRNAs) and breast cancer remains incompletely understood. In this study, we introduced MDSCs-associated lncRNAs as novel prognostic biomarkers to assess outcomes in patients with invasive breast carcinoma (BRCA). METHODS: Information regarding BRCA cases, including clinical and genomic details, was obtained from the TCGA repository. Predictive indicators were discovered, and their reliability underwent thorough verification. A clinically useful nomogram was developed following application-based validation. Additional investigations encompassed functional analysis, TMB assessment, TME profiling, immunotherapy efficacy forecasting, and drug sensitivity testing along with target identification. Long non-coding RNA expression was measured using reverse transcription quantitative PCR. RESULTS: A risk stratification model incorporating eight MDSCs-related lncRNAs effectively predicted patient outcomes. Kaplan-Meier (K-M) survival analysis clearly indicated a much worse prognosis among patients classified as high-risk (p&#xa0;<&#xa0;0.001). The nomogram accurately forecasted overall survival (OS). Analysis of functional enrichment revealed that pathways associated with epithelial cells showed activity among patients at higher risk. Characterization of the tumor microenvironment showed increased immune cell presence in those classified as low-risk. Conversely, individuals with greater risk displayed higher tumor mutational burden. TIDE and IPS analyses indicated superior immunotherapy responsiveness in the low-risk BRCA subgroup. Among 47 drugs with notable IC50 variations, Ribociclib, PD173074, KU-55933, NU7441, and nutlin-3a exhibited lower IC50 values within the low-risk group, whereas Lapatinib demonstrated greater efficacy among the high-risk group. Moreover, 10 potential therapeutic agents and their targets were predicted for high-risk patients. RT-qPCR validation confirmed the robustness of the model. CONCLUSIONS: We successfully verified a new model of molecular markers of MDSCs-related lncRNAs, offering critical insights for predicting outcomes and guiding therapeutic decisions in BRCA cases.

Bioinformatics↗
PubMed1980

Psychosocial problems and outcome: an external validity study.

Six acute-care teaching hospitals participated in a study to determine the validity of a problem-outcome classification system. Three hundred and forty-three randomly selected clients of 152 social workers served as external sources to determine the validity of the instrument. In 77 percent of the problems, social workers and clients agreed on the nature of the problem dealt with during intervention. However, workers tended to give more negative values to their assessments of outcome of intervention than did their clients.

Data Collection↗
PubMed1990

External validity of the new Devereux Adolescent Behavior Rating scales.

The discriminant and concurrent validity of the five new scales for the Devereux Adolescent Behavior Rating Scale (DAB) was explored using a heterogeneous sample of psychiatric and substance abuse patients. Consistent with predictions, the substance abuse patients scored higher on the Acting Out Behaviors (AOB) and Heterosexual Interests (HI) scales, and psychiatric patients scored higher on the Psychotic Behaviors scale. Gender differences also were found, including boys being rated higher on Acting Out Behaviors, and girls higher on Heterosexual Interests. The new DAB scales demonstrated sufficient concurrent validity using a thorough record review and a patient rating scale (the Child Behavior Checklist [CBCL]). The Neurotic/Dependent Behaviors scale (NDB) showed a consistent relationship with substance abuse and several other measures of more externalizing behaviors, in addition to the predicted relationships with anxious, tense, and dependent behaviors. The Withdrawn/Timid Behaviors scale (WTB) proved to be a purer measure of internalizing behaviors in both sexes.

Acting Out↗
PubMed2004

External validation of compliance to perfusion quality indicators.

PURPOSE: There exists a significant gap between the expected and delivered level of quality received in America's hospitals. As a result, clinical outcomes of critical services such as coronary artery bypass graft (CABG) surgery have received unparalleled scrutiny. Medical information technology companies like Solucient and insurance carriers such as Blue Cross of California have identified and published a list of hospitals that demonstrate superior quality and patient outcomes for CABG procedures. These 'benchmark' programs serve as a reminder that closing the quality gap is possible. Unfortunately, none of these rankings (report cards) provide programs that fail to achieve benchmark status with detailed information on the processes or methods necessary to improve performance. METHOD: After identifying hospitals within the Fresenius Medical Care Extracorporeal Alliance (FMCEA) system that were judged as top performers (benchmark programs) by either Solucient ('100 Top Cardiovascular Hospitals', Evanston, IL 60201) or Blue Cross of California ('Centers of Expertise', Newbury Park, CA 91320), 12 months of continuous collection of CPB-related quality indicator data were analyzed for compliance to the FMCEA evidence-based Quality Indicator Program (QIP). A comparison of compliance to the FMCEA CPB indicators was made between the benchmark FMCEA hospitals and the FMCEA peer group hospitals. RESULTS: Seven CPB process indicators were compared: 1) lowest sustained mean arterial pressure, 2) lowest sustained cardiac index, 3) lowest sustained mixed venous oxygen saturation, 4) lowest sustained hematocrit, 5) lowest activated clotting time, 6) highest sustained arterial blood temperature and 7) average sodium bicarbonate administered. Analysis of hospitals in the FMCEA system designated by Blue Cross of California as 'Centers of Expertise' revealed statistically significantly greater compliance (p < 0.05) in all but one CPB indicator. Hospitals in the FMCEA system designated by Solucient's '100 Top Cardiovascular Hospitals' listing revealed statistically significantly greater compliance to all but three CPB quality indicators. CONCLUSIONS: Successful compliance with the majority of FMCEA CPB process indicators correlates with external recognition from two report card systems demonstrating superior hospital performance. Analysis of compliance to process indicators may provide useful guidelines to improve the standard of care in CABG surgery in many hospitals.

Coronary Artery Bypass↗
PubMed2007

External validity of clinical trials in acute myocardial infarction.

BACKGROUND: Patients enrolled in randomized clinical trials (RCTs) may not reflect those seen in real-life practice. Our goal was to compare patients eligible for enrollment but not enrolled in contemporary RCTs of reperfusion therapy with patients who would have been ineligible and also with patients with acute myocardial infarction (AMI) participating in RCTs. METHODS: Consecutive patients with AMI (n = 8469) enrolled in the GRACE registry (Global Registry of Acute Coronary Events) were divided into 3 groups: RCT participants (11%; n = 953), eligible nonenrolled patients (55%; n = 4669), and ineligible patients (34%; n = 2847). Our main outcome measures were hospital mortality rates. RESULTS: Based on baseline characteristics or GRACE risk-score distribution, RCT participants had the lowest a priori risk of death; eligible patients had a higher risk; and ineligible patients had the highest risk. Actual hospital mortality showed a similar gradient (3.6%, 7.1%, and 11.4%, respectively) (P<.001). Multivariable analysis adjusting for baseline risk, use and type of reperfusion therapy, and delay from symptom onset to admission consistently showed a higher mortality rate for eligible nonenrolled patients than for RCT participants (odds ratio, 1.61; 95% confidence interval, 1.06-2.43; and odds ratio, 1.97; 95% confidence interval, 1.24-3.13, respectively). CONCLUSIONS: Patients with AMI participating in RCTs have a lower baseline risk and experience lower mortality than nonenrolled patients, even when they are trial eligible. This difference is not entirely explained by differences in baseline risk, use and type of reperfusion therapy, and/or delays in presentation. Caution is necessary when extending the findings obtained in RCTs to the general population with AMI.

Aged↗
PubMed2005

External validation of the Canadian CT Head Rule and the New Orleans Criteria for CT scanning in patients with minor head injury.

CONTEXT: Two decision rules for indications of computed tomography (CT) in patients with minor head injury, the Canadian CT Head Rule (CCHR) and the New Orleans Criteria (NOC), suggest that CT scanning may be restricted to patients with certain risk factors, which would lead to important reductions in the use of CT scans. OBJECTIVE: To validate and compare these 2 published decision rules in Dutch patients with head injuries. DESIGN, SETTING, AND PATIENTS: A prospective multicenter study conducted between February 11, 2002, and August 31, 2004, in 4 university hospitals in the Netherlands of 3181 consecutive adult patients with minor head injury who presented with a Glasgow Coma Scale (GCS) score of 13 to 14 or with a GCS score of 15 and at least 1 risk factor. MAIN OUTCOME MEASURES: Primary outcome was any neurocranial traumatic finding on CT scan. Secondary outcomes were neurosurgical intervention and clinically important CT findings. Sensitivity and specificity were estimated for each outcome for the CCHR and the NOC, using both rules as originally derived and also as adapted to apply to an expanded patient population. RESULTS: Of 3181 patients with a GCS score of 13 to 15, neurosurgical intervention was performed in 17 patients (0.5%); neurocranial traumatic CT findings were present in 312 patients (9.8%). Sensitivity for neurosurgical intervention was 100% for both the CCHR and the NOC. The NOC had a higher sensitivity for neurocranial traumatic findings and for clinically important findings (97.7%-99.4%) than did the CCHR (83.4%-87.2%). Specificities were very low for the NOC (3.0%-5.6%) and higher for the CCHR (37.2%-39.7%). The estimated potential reduction in CT scans for patients with minor head injury would be 3.0% for the adapted NOC and 37.3% for the adapted CCHR. CONCLUSIONS: For patients with minor head injury and a GCS score of 13 to 15, the CCHR has a lower sensitivity than the NOC for neurocranial traumatic or clinically important CT findings, but would identify all cases requiring neurosurgical intervention, and has greater potential for reducing the use of CT scans.

Adolescent↗
PubMed2003

Prognostic index for patients with parotid carcinoma: external validation using the nationwide 1985-1994 Dutch Head and Neck Oncology Cooperative Group database.

BACKGROUND: Validation of the prognostic indices for the recurrence-free interval of patients with parotid carcinoma, the development of which was described in a previous report, is needed to be confident of their generalizability and justified prospective use. METHODS: The Dutch Cooperative Group on Head and Neck Cancer database contains 231 patients with parotid carcinoma from six tertiary referral centers who were seen between 1985-1994. This database was used to validate the predictive value of the prognostic indices, PS1 (pretreatment index predicting recurrence) and PS2 (posttreatment index predicting recurrence), in patients with parotid carcinoma. Validation methods included calculation of both indices for each patient, comparison of coefficients, construction of survival curves using the published cutoff points, and calculation of concordance measure C. Wald tests for optimization of scale and weights of the contributing variables, and for possible score improvement by including other variables, were also performed. RESULTS: The 5-year disease-free rate was 62% (standard error = 4%). PS1 was calculated for 183 patients. The previously set cutoff points resulted in 5-year disease-free rates that ranged from 92% (PS1 = 1) to 42% for the least favorable group (PS1 = 4). Concordance measure C was 0.74. The postoperative score, PS2, was calculated for 171 patients. Previous cutoff points resulted in 5-year disease-free rates that ranged from 90% (PS2 = 1) to 40% (PS2 = 4). Concordance measure C was 0.71. Both PS1 and PS2 did not improve using the findings in this independent material. CONCLUSIONS: The prognostic indices performed adequately in this validation sample. This finding demonstrates that the prognosis of a parotid carcinoma patient can be quantified by using a weighted combination of the parameters of age, pain, clinical T (cT) classification, clinical N (cN) classification, skin invasion, facial nerve dysfunction, perineural growth, and involved surgical margins. A quantified prognosis, in terms of the recurrence-free interval, can be used to provide information to the patient, to perform clinical trials, and eventually to make clinical decisions. A user-friendly translation and computerized calculation of the indices should be the next step toward generalized prospective use and repetitive evaluation of the indices.

Adult↗
PubMed1998

External validity and experimental design: the sensitive phase for song learning.

In the past decade there has been widespread acceptance of the idea that the use of live, socially interactive tutors in song learning experiments produces results that differ dramatically from, and are more valid than, results obtained with tape tutors. The influential series of experiments by Baptista & Petrinovich (1984, Animal Behaviour, 32, 172-181, 1986, Animal Behaviour, 34, 1359-1371; Petrinovich & Baptista 1987, Animal Behaviour, 35, 961-974) have promoted this view, and their results have been widely accepted. Baptista & Petrinovich's results have led them and others to question whether there are age-limited sensitive phases for song learning, as Marler's (1970, Journal of Comparative Physiology and Psychology Monographs, 711-25) early studies on the white-crowned sparrow, Zonotrichia leucophrys, suggested, and led them to argue that interactive tutoring produces essentially open-ended learning. I argue here that this view is mistaken, and that the sensitive phase for song learning in the white-crowned sparrow is identical for live and tape tutors and is restricted to the first few months of life. Baptista & Petrinovich presented live and tape tutors for different periods to their subjects. Type of tutor (live versus tape) is confounded with duration of exposure to tutors. As a consequence, their experiments confound two different forms of song learning that occur at different ages, and give the mistaken appearance of an extended sensitive phase when live tutors are used. Copyright 1998 The Association for the Study of Animal Behaviour

Journal Article↗
PubMed1995

External validation of oppositional disorder and attention deficit disorder with hyperactivity.

Validity of the distinction between oppositional disorder (OD) and attention deficit disorder with hyperactivity (ADDH) was examined in a sample of 6- to 12-year-old boys with behavior problems. Problem identification, cognitive/attentional, family context, and behavioral symptom differences were examined among nine boys with OD only, 20 with ADDH, 40 with comorbid OD and ADDH, and 28 with neither disruptive behavior disorder. Systematic comparisons of groups including and excluding the OD and ADDH diagnoses were undertaken to determine the existence of pure OD and pure ADDH disorder effects. The most consistent result was the lack of evidence for either pure OD or pure ADDH effects. Most of the significant findings reflected differences between the nondisruptive (neither) and comorbid groups. The results support the importance of comorbidity, but they provide little support for disorder-specific distinctions between oppositional and attention deficit disorders.

Attention Deficit Disorder with Hyperactivity↗
PubMed1995

A nonparametric subject-specific population method for deconvolution: II. External validation.

A lot of attention has been given in the past to deconvolution and in particular to its nonparametric variants. In a companion paper (1), we present a fully nonparametric deconvolution method in which subject specificity is explicitly taken into account. To do so we use so-called "longitudinal splines." A longitudinal spline is a nonparametric function composed of a template spline, in common to all subjects, and of a distortion spline representing the difference of the subject's function from the template. In this paper we concentrate on testing and documenting the performance of this nonparametric methodology in terms of the approximation of unknown functions. We simulate population data using parametric functions, and use longitudinal splines to recover the unknown functions. We consider different estimation methods including (1) parametric nonlinear mixed effect, (2) least squares, and (3) two-stage. Methods 2-3 are more robust than Method 1, and obtain reliable estimates of the unknown functions. The lack of robustness of Method 1 appears to be due to the misspecifications of the distribution of the subjects' parameters. Results also suggest that in a data-rich situation nonparametric nonlinear mixed-effect models should be preferred.

Models, Theoretical↗
PubMed1998

[Vertebral deformity as an index of osteoporosis-induced spinal fracture--an external validity construct based on bone density data].

BACKGROUND: In order to test the validity of vertebral morphometry for the assessment of prevalent vertebral osteoporotic fractures, we examined the association between vertebral deformities and bone mineral density (BMD). METHOD: The study population consisted of 595 postmenopausal women and 581 men aged 50 to 82 years who participated in the baseline survey of the European Vertebral Osteoporosis Study (EVOS) in Germany and received BMD measurements by dual-X-ray-absorptiometry (DXA) at the femur and the lumbar spine. RESULTS: In both sexes only vertebral deformities defined by more stringent morphometric criteria (McCloskey; Eastell 4 SD criterion) were significantly and inversely related to BMD (odds ratios 1.42 to 3.21 for a 1 SD [standard deviation] reduction in BMD; p < 0.05). The strength of the association depended on the stringency of the morphometric algorithm applied, and on the site of BMD measurement. The strongest associations were observed with femoral neck BMD in women and with BMD at the lumbar spine in men. In contingency analyses between vertebral deformities and osteoporosis (WHO criteria; European young female BMD reference values), vertebral deformities proved to be highly specific by all methods, even slightly more so in men (87.8 to 97.5%) than in women (86.3 to 96.7%). The predictive value of a positive test with respect to vertebral osteoporosis reached a maximum value of about 50% in both sexes. It further increased up to 72%, when the definition of osteoporosis was based on low BMD values at either the spine or the femoral neck, but only in women. CONCLUSIONS: In conclusion, for both men and women the likelihood of vertebral deformities to be related to osteoporosis increases with the stringency of the morphometric method, with a similar probability of major deformities to represent vertebral osteoporotic fractures in men as in women. Nevertheless, even the most stringent morphometric criteria are not sufficiently valid instruments for the assessment of the prevalence of vertebral osteoporotic fractures in epidemiological studies.

Aged↗
PubMed2003

Italian version of the Epworth sleepiness scale: external validity.

We assessed the validity of an Italian language version of the Epworth sleepiness scale (ESS). The translated ESS was compared to the multiple sleep latency test (MSLT), considered the gold standard for the diagnosis of excessive daytime sleepiness (EDS). Within the context of a multicentric national study on narcolepsy (Gruppo Italiano Narcolessia Studio Epidemiologico Nazionale, GINSEN) involving 17 Italian sleep centres, we compared the two diagnostic tests on 91 prospectively recruited subjects with suspected EDS (34 with narcolepsy, 16 with obstructive sleep apnea syndrome, 19 with idiopathic hypersomnia, and 22 with other sleep, neurologic or psychiatric disorders). ESS scores were inversely correlated with mean sleep latency values, as measured with MSLT (rho = -0.31, p<0.01). ESS cut-off scores with best sensitivity and specificity were 12 and 17. For the 5-min MSLT cut-off, sensitivity was 87% and 47% respectively; specificity 39% and 74%. For the 8-min MSLT cut-off, sensitivity was 84% and 49%; specificity 50% and 88%. The Italian version of the ESS is an easy-to-use form useful for preliminary screening of daytime sleepiness level in specialist settings.

Adolescent↗