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PubMed2003

Predicting mortality among patients hospitalized for heart failure: derivation and validation of a clinical model.

CONTEXT: A predictive model of mortality in heart failure may be useful for clinicians to improve communication with and care of hospitalized patients. OBJECTIVES: To identify predictors of mortality and to develop and to validate a model using information available at hospital presentation. DESIGN, SETTING, AND PARTICIPANTS: Retrospective study of 4031 community-based patients presenting with heart failure at multiple hospitals in Ontario, Canada (2624 patients in the derivation cohort from 1999-2001 and 1407 patients in the validation cohort from 1997-1999), who had been identified as part of the Enhanced Feedback for Effective Cardiac Treatment (EFFECT) study. MAIN OUTCOME MEASURES: All-cause 30-day and 1-year mortality. RESULTS: The mortality rates for the derivation cohort and validation cohort, respectively, were 8.9% and 8.2% in hospital, 10.7% and 10.4% at 30 days, and 32.9% and 30.5% at 1 year. Multivariable predictors of mortality at both 30 days and 1 year included older age, lower systolic blood pressure, higher respiratory rate, higher urea nitrogen level (all P<.001), and hyponatremia (P<.01). Comorbid conditions associated with mortality included cerebrovascular disease (30-day mortality odds ratio [OR], 1.43; 95% confidence interval [CI], 1.03-1.98; P =.03), chronic obstructive pulmonary disease (OR, 1.66; 95% CI, 1.22-2.27; P =.002), hepatic cirrhosis (OR, 3.22; 95% CI, 1.08-9.65; P =.04), dementia (OR, 2.54; 95% CI, 1.77-3.65; P<.001), and cancer (OR, 1.86; 95% CI, 1.28-2.70; P =.001). A risk index stratified the risk of death and identified low- and high-risk individuals. Patients with very low-risk scores (< or =60) had a mortality rate of 0.4% at 30 days and 7.8% at 1 year. Patients with very high-risk scores (>150) had a mortality rate of 59.0% at 30 days and 78.8% at 1 year. Patients with higher 1-year risk scores had reduced survival at all times up to 1 year (log-rank, P<.001). For the derivation cohort, the area under the receiver operating characteristic curve for the model was 0.80 for 30-day mortality and 0.77 for 1-year mortality. Predicted mortality rates in the validation cohort closely matched observed rates across the entire spectrum of risk. CONCLUSIONS: Among community-based heart failure patients, factors identifiable within hours of hospital presentation predicted mortality risk at 30 days and 1 year. The externally validated predictive index may assist clinicians in estimating heart failure mortality risk and in providing quantitative guidance for decision making in heart failure care.

Aged↗

PubMed2004

Validation of the Composite Laryngeal Recurrence Staging System.

BACKGROUND: The Composite Laryngeal Recurrence Staging System (CLRSS) has been described recently as an improved alternative to the retreatment TNM system (rTNM) for staging patients with recurrent laryngeal squamous cell carcinoma. The objectives of this study were to validate the CLRSS and compare its use with the rTNM system. METHODS: A retrospective chart review was conducted of 67 patients with recurrent laryngeal squamous cell carcinoma who had their initial treatment between 1980 and 1992. The external validity of the CLRSS was assessed, and its ability to stage patients and to predict survival was compared with the rTNM system. RESULTS: The overall 2-year survival rate was 51% (34 of 67 patients). The rTNM system was unable to stage 12 patients (18%), whereas all patients could be staged using the CLRSS. The CLRSS predicted survival better than the rTNM system (c-statistic = 0.79). CONCLUSIONS: The newer CLRSS staging system for recurrent laryngeal carcinoma outperformed the rTNM system in its ability to stage more patients and to predict survival.

Adult↗

PubMed2006

Derivation and validation of a new global method for assessing nutritional status in patients with cirrhosis.

Accurate assessments of nutritional status are difficult to obtain in patients with cirrhosis. The aim of this study was to devise and validate a global nutritional assessment scheme for use in this patient population. Measures of body mass index (BMI) and mid-arm muscle circumference (MAMC) were combined with details of dietary intake in a semistructured, algorithmic construct to provide a nutritional assessment scheme for use in patients with cirrhosis; evaluated individuals were classified as adequately nourished, moderately malnourished (or suspected to be), or severely malnourished. There was good interobserver agreement in the nutritional categorization of 50 patients with cirrhosis (34 men, 16 women) using this scheme (kappa = 0.79) and significant associations with the contributing objective variables--namely, BMI (Spearman's correlation r = -0.78; P < .001) and relative MAMC (r = -0.69; P < .001)--confirming its internal validity. There was a significant association between nutritional categorization in 20 patients with cirrhosis (10 men, 10 women) and estimates of total body protein obtained using a four-component model (r = -0.45; P = .046), confirming the external validity of the scheme. Finally, a significant association was found between poor nutritional status in 116 patients with cirrhosis (65 men, 51 women), followed for 14 to 52 months, and shorter subsequent survival (P = .0005), confirming the scheme's predictive validity. In conclusion, a global assessment scheme has been devised that provides a simple, reproducible, valid, and predictive method of assessing nutritional status in patients with cirrhosis.

Adult↗

PubMed2006

Clinical trial-based cost-effectiveness analyses of antipsychotic use.

OBJECTIVE: Second-generation antipsychotics make up one of the fastest growing segments of the rapidly growing pharmaceutical sector. Given limited health care resources, assessment of the value for the cost of second-generation antipsychotics relative to first-generation antipsychotics is critical for resource-allocation decisions. METHOD: With a MEDLINE search, the authors identified eight studies (based on six randomized clinical trials) that analyzed the cost-effectiveness of second-generation antipsychotics relative to first-generation antipsychotics in individuals with schizophrenia disorders. The authors reviewed appropriate methods of measurement, analysis, and design of cost-effectiveness studies in randomized clinical trials and evaluated the validity of economic results derived from the studies in light of appropriate methods. RESULTS: The eight randomized clinical trial-based cost-effectiveness studies of antipsychotic medications faced a variety of threats to validity related to 1) measurement of costs, 2) measurement of effectiveness, 3) analysis of costs, 4) measurement of sampling uncertainty, 5) analysis of incomplete cost data, 6) minimizing loss to follow-up, and 7) threats to external validity. CONCLUSIONS: Economic claims made by the authors of a number of trial-based economic evaluations have generally been favorable to second-generation antipsychotics. However, the methodological issues the authors of the current study identified suggest that there is no clear evidence that atypical antipsychotics generate cost savings or are cost-effective in general use among all schizophrenia patients. Psychiatrists, researchers, and administrators should consider the methodological issues highlighted in interpreting study results. These issues should be addressed in future trial designs.

Antipsychotic Agents↗

PubMed1991

[Validity of a new psychogeriatric behavior observation scale for application in nursing homes and homes for the aged].

In this article we report a study on the validity and discriminating power of the behaviour rating scale OPG - 'Observation Psycho Geriatrics'. The OPG was designed to measure the need of care and the remaining capacities of people with a mild dementia syndrome. To establish the external validity in nursing homes, the OPG was compared with the BOP (Dutch version of the Stockton Geriatric Rating Scale) for 74 residents and in homes for the aged with the BPS, a rating scale for mental and social problems (66 residents). Both scales show a substantial relationship with the OPG and confirm its validity. Assumptions concerning OPG-scales were given for six different levels of residential care (829 residents). The 7 distinguished OPG-scales show differences in mean scores, which are in general plausible in the light of these assumptions. The mean scores for residents in homes for the aged who receive special treatment are best comparable with those of average nursing home residents.

Activities of Daily Living↗

PubMed2004

Validation of a risk score identifying patients with acute pulmonary embolism, who are at low risk of clinical adverse outcome.

A clinical predictive model that accurately identifies patients with pulmonary embolism who are at low risk of adverse medical outcomes may be useful for management decisions, such as outpatient treatment. We aimed to externally validate a previously derived prognostic score identifying emergency ward patients with acute pulmonary embolism at low risk of 3-month complications. One hundred and ninety-nine consecutive patients with proven pulmonary embolism were included from the emergency centres of three teaching and general hospitals. Adverse outcomes, such as death, major bleed, or recurrent venous thromboembolism, were recorded during a 3-month follow-up. We retrospectively computed the prognostic score for each patient and determined its predictive accuracy at different threshold values. The overall 3-month risk of adverse event after the diagnosis of pulmonary embolism was 9.5%. At a threshold of 2 points, eight patients with scores at or below the cut-off (5%; 95% CI 2.6-9.6) and 11 patients with scores above this cut-off (27.5%; 95% CI 16.1-42.8) presented a complication. The negative predictive value for an adverse out-come was 95.0% (95% CI 90.4-97.4). The receiver operating characteristic curve derived from the score distribution had an area of 0.77 (95% CI 0.65-0.89). This compared favourably with the characteristics of the derivation study. We conclude that the Geneva risk score has an acceptable predictive accuracy to identify patients with pulmonary embolism at low risk for 3-month adverse outcomes. Whether this score remains accurate and useful in clinical practice should be determined in a prospective multicentre validation study.

Acute Disease↗

PubMed2006

Prediction of germline mutations and cancer risk in the Lynch syndrome.

CONTEXT: Identifying families at high risk for the Lynch syndrome (ie, hereditary nonpolyposis colorectal cancer) is critical for both genetic counseling and cancer prevention. Current clinical guidelines are effective but limited by applicability and cost. OBJECTIVE: To develop and validate a genetic counseling and risk prediction tool that estimates the probability of carrying a deleterious mutation in mismatch repair genes MLH1, MSH2, or MSH6 and the probability of developing colorectal or endometrial cancer. DESIGN, SETTING, AND PATIENTS: External validation of the MMRpro model was conducted on 279 individuals from 226 clinic-based families in the United States, Canada, and Australia (referred between 1993-2005) by comparing model predictions with results of highly sensitive germline mutation detection techniques. MMRpro models the autosomal dominant inheritance of mismatch repair mutations, with parameters based on meta-analyses of the penetrance and prevalence of mutations and of the predictive values of tumor characteristics. The model's prediction is tailored to each individual's detailed family history information on colorectal and endometrial cancer and to tumor characteristics including microsatellite instability. MAIN OUTCOME MEASURE: Ability of MMRpro to correctly predict mutation carrier status, as measured by operating characteristics, calibration, and overall accuracy. RESULTS: In the independent validation, MMRpro provided a concordance index of 0.83 (95% confidence interval, 0.78-0.88) and a ratio of observed to predicted cases of 0.94 (95% confidence interval, 0.84-1.05). This results in higher accuracy than existing alternatives and current clinical guidelines. CONCLUSIONS: MMRpro is a broadly applicable, accurate prediction model that can contribute to current screening and genetic counseling practices in a high-risk population. It is more sensitive and more specific than existing clinical guidelines for identifying individuals who may benefit from MMR germline testing. It is applicable to individuals for whom tumor samples are not available and to individuals in whom germline testing finds no mutation.

Adaptor Proteins, Signal Transducing↗

PubMed2006

QSPR models for the prediction of apparent volume of distribution.

An estimate of volume of distribution (V(d)) is of paramount importance both in drug choice as well as maintenance and loading dose calculations in therapeutics. It can also be used in the prediction of drug biological half life. This study employs quantitative structure-pharmacokinetic relationship (QSPR) techniques for the prediction of volume of distribution. Values of V(d) for 129 drugs were collated from the literature. Structural descriptors consisted of partitioning, quantum mechanical, molecular mechanical, and connectivity parameters calculated by specialized software and pK(a) values obtained from ACD labs/log D database. Genetic algorithm and stepwise regression analyses were used for variable selection and model development. Models were validated using a leave-many-out procedure. QSPR analyses resulted in a number of significant models for acidic and basic drugs separately, and for all the drugs. Validation studies showed that mean fold error of predictions for the selected models were between 1.79 and 2.17. Although separate QSPR models for acids and bases resulted in lower prediction errors than models for all the drugs, the external validation study showed a limited applicability for the equation obtained for acids. Therefore, the universal model that requires only calculated structural descriptors was recommended. The QSPR model is able to predict the volume of distribution of drugs belonging to different chemical classes with a prediction error similar to that of the other more complicated prediction methods including the commonly practiced interspecies scaling. The structural descriptors in the model can be interpreted based on the known mechanisms of distribution and the molecular structures of the drugs.

Algorithms↗

PubMed2006

Development of a novel CASA system based on open source software for characterization of zebrafish sperm motility parameters.

Although computer-assisted sperm analysis (CASA) outperforms manual techniques, many investigators rely on non-automated analysis due to the high cost of commercial options. In this study, we have written and validated a free CASA software primarily for analysis of fish sperm. This software is a plugin for the free National Institutes of Health software ImageJ and is available with documentation at . That it is open source makes possible external validation, should improve quality control and enhance the comparative value of data obtained among laboratories. In addition, we have improved upon the traditional velocity straight line (VSL) algorithm, eliminating inaccurate characterization of highly curved fish sperm paths. Using this system, the motion of zebrafish (Danio rerio) sperm was characterized relative to time post-activation and the impact of acquisition conditions upon data analysis determined. There were decreases in velocity and path straightness (STR), but not linearity (LIN), relative to time. From 30 to 300 frames/s, frame rate significantly affected curvilinear velocity (VCL) and STR measurements. Sperm density in the field of view did not affect any measured parameter. There was significant inter-male variation for VCL, VSL, velocity average path (VAP), percent motility, path character (STR, LIN), and duration of motility. Furthermore, relative sperm output (a measure reflecting both semen volume and concentration) was positively correlated to percent motility. For all motion parameters measured (except duration), the average CV was < or =10%, comparable to values obtained using commercial systems.

Algorithms↗

PubMed2026

Artificial intelligence-based tumour infiltrating lymphocyte quantification in patients with triple-negative breast cancer: an independent validation study.

BACKGROUND: Tumour-infiltrating lymphocytes (TILs) are a robust prognostic marker in patients with triple-negative breast cancer. Artificial intelligence (AI)-derived computational tools assessing TILs could improve efficiency, but require independent validation against clinical outcomes. We aimed to compare the prognostic performance of AI-derived TIL scores with pathologist-scored TILs in a large, prospectively collected dataset pooled from randomised controlled trials. METHODS: CATALINA was an independent, external validation study using prospectively collected long-term clinical outcome data pooled from seven randomised clinical trials conducted at multiple sites. We independently evaluated two previously validated AI pipelines that generate five computationally assessed tumour-infiltrating lymphocyte (cTIL) scores by masked, independent deployment of locked models. cTIL scores were correlated with the mean of the pathologist-scored stromal TILs (sTILs) in 220 digitised haematoxylin and eosin whole slide images in a cohort of patients with early-stage triple-negative or HER-2 positive breast cancer, previously scored by trained pathologists in a TIL-reproducibility study. Prognostic performance was assessed in a separate cohort of patients with early triple-negative breast cancer pooled from seven prospective, randomised adjuvant trials. Multivariable Cox regression models adjusted for clinicopathological factors and study heterogeneity assessed associations of cTIL score and sTIL score with invasive disease-free survival, distant disease-free survival, and overall survival. 5-year discrimination was estimated using time-dependent area under the receiver operating characteristic curve (AUC). FINDINGS: Individual data were collated from 1759 patients, of whom 1356 had complete clinicopathological data, pathologist sTIL scores, and cTIL scores available. Modest correlation (r 0·375-0·473) was observed between cTIL scores and the mean pathologist sTIL score. Both sTIL and cTIL were independently associated with 5-year invasive disease-free survival, distant disease-free survival, and overall survival after adjustment for clinicopathological factors (hazard ratio for invasive disease-free survival was 0·73 [95% CI 0·66-0·82]; q<0·0001, distant disease-free survival was 0·70 [0·61-0·79]; q<0·0001, and overall survival was 0·72 [0·63-0·82]; q<0·0001 for sTIL scores and 0·80 [0·73-0·89]; q<0·0001, 0·77 [0·69-0·86]; q<0·0001, and 0·79 [0·70-0·88]; q=0·0002, respectively, for percentage_lymphocyte scores). In models adjusted for clinicopathological variables and sTIL score, cTIL score did not maintain a statistically significant prognostic association. Both sTIL and cTIL scores improved the 5-year AUC over clinicopathological variables alone, while cTIL score did not significantly further improve AUC when combined with clinicopathological variables and sTIL score. INTERPRETATION: Two cTIL models deployed entirely without retraining or modification provided statistically significant prognostic information and improved risk discrimination compared with clinicopathological variables alone in this large, platform-based, independent validation study. Although cTIL score did not incrementally improve prognostication compared with models combining clinicopathological variables with sTIL score, these findings support the application of cTILs as a reproducible prognostic biomarker, particularly in settings where routine or widespread pathologist assessment is unavailable. FUNDING: Breast Cancer Research Foundation (USA).

Humans↗

PubMed2001

Validation of decisional balance and situational temptations measures for dietary fat reduction in a large school-based population of adolescents.

Brief, validated, and reliable theory-based measures specifically designed for use in large survey research with adolescent populations are needed to assess attitudes and behaviors about dietary fat consumption. This study validated two transtheoretical model (TTM)-based instruments in 2639 ninth graders from 12 Rhode Island high schools. The Decisional Balance Questionnaire for Adolescent Dietary Fat Reduction (DBQA) measures the importance adolescents assign to the pros and cons of reducing dietary fat consumption, while the Situational Temptations Questionnaire for Adolescents (STQA) measures temptations to eat high-fat foods as both a global construct and across three categories of challenging situations. Four competing models were compared for each instrument. An eight-item, correlated two-factor Pros and Cons model was validated for the decisional balance measure and a nine-item, three-factor hierarchical model was validated for situational temptations. The theoretically predicted relationships between stage of change and the pros and cons, as well as stage and situational temptations were supported. These results demonstrate that both measures have sound psychometric properties and are externally valid.

Journal Article↗

PubMedDate not supplied

Generating new knowledge from existing data: the use of large data sets for nursing research.

BACKGROUND: An unprecedented amount of data from a variety of disciplines containing variables of interest to nursing are available to nurse researchers. In response, the use of large data sets is emerging as a legitimate method that can help facilitate the translation of knowledge to practice. OBJECTIVE: To explore the spectrum of methodological issues and practical applications encountered by three nurse researchers using secondary data analysis of three existing large data sets as a means to ask new questions and generate new nursing knowledge. METHODS: Three research studies using the analysis of three existing large data sets were described. The following are discussed: developing a theoretical framework, selecting an appropriate data set, operationalizing and measuring variables, preparing data for analysis, and identifying threats to validity and reliability. RESULTS: Although the use of existing data may shorten the time from question to answer, the research process remains the same. The three research studies were used to illustrate conceptual congruence, threats to internal and external validity, and threats to reliability and generalizability. DISCUSSION: Data obtained from a variety of disciplines and for a variety of reasons can and should be used to answer nursing practice and research questions. Using existing large data sets offers nurse researchers a unique opportunity to ask and answer questions that can affect how nurses care for patients in a time-effective and cost-efficient manner. Exploring the spectrum of methodological issues and practical applications involved in this work will help guide nurse researchers through the process.

Data Collection↗

PubMed1997

A multivariate study of the Serial Color-Word Test.

Patterns of adaptation to a conflict situation (the Stroop task) were assessed with the Serial Color-Word Test. A cluster analysis was performed on 859 protocols, adopting a six-cluster solution. A subsequent discriminant function analysis cross-validated the usefulness of the test's variables in predicting the cluster assignments. The distribution of 3 different diagnostic groups (psychotic, neurotic-psychosomatic, and general population) showed significant differences across the 6 clusters, thereby contributing to the external validation of the test. The 6 new complex patterns of adaptation described may now be employed in clinical research, alongside the traditional ones.

Adult↗

PubMed1991

Assessment of activities of daily living in the elderly. A study of a population of 76-year-olds in Gothenburg, Sweden.

The cumulative structure of personal daily activities (Katz' Index of ADL) and four well-defined instrumental activities (cooking, transportation, shopping, and cleaning) have been studied in a population of 76-year-olds (N = 659) in Gothenburg, Sweden. Sixty-five percent of the population were independent, 22% were dependent in instrumental activities, and 13% were dependent in both instrumental and personal activities. No person was dependent in personal ADL and independent in instrumental ADL. The internal consistency and the coefficient of scalability were well above the acceptance level, which indicated an internal reliability and validity of the new scale. The frequency of personal and home-assistance care, type of accommodation, self-assessment of self-care and domestic activities were compared with the level of dependence in ADL and indicated external validity. This cumulative instrument of ADL can be used to describe and compare the level of disability in elderly populations and to define the need for personal assistance in home care among disabled persons.

Activities of Daily Living↗

PubMed1994

Patterns of academic competence in adults with epilepsy: a cluster analytic study.

Cluster analysis was used in the attempt to derive a meaningful taxonomy of academic competence in 117 adults with temporal lobe epilepsy. Reading, spelling and arithmetic achievement scores from the Wide Range Achievement Test-Revised were subjected to hierarchical complete linkage cluster analysis, and the stability of the obtained solution was examined by the application of two additional clustering procedures. A six cluster solution was obtained, and tests of internal validity showed membership in four of the clusters to be extremely stable (Moderate and Marked Reading/Spelling Underachievement, Above Average Achievement, Reading/Arithmetic Underachievement), while the remaining two clusters showed some exchange of cases (Arithmetic Underachievement, Average Achievement). Modest evidence of external validity was found through the comparison of specific clusters to the Average Achievement group on measures of neuropsychological function, neurological and demographic characteristics. It is concluded that cluster analysis may be helpful in developing taxonomies of psychosocial impairment in epilepsy, and may facilitate an understanding of the determinants of variable quality of life outcomes associated with epilepsy.

Adult↗

PubMed2006

Gait classification in children with cerebral palsy: a systematic review.

This systematic review of the literature evaluates the validity of existing classifications of gait deviations in children with cerebral palsy (CP). Numerous efforts have been made to develop classification systems for gait in CP to assist in diagnosis, clinical decision-making and communication. The internal and external validity of gait classifications in 18 studies were examined, including their sampling methods, content validity, construct validity, reliability and clinical utility. Half of the studies used qualitative pattern recognition to construct the gait classification and the remainder used statistical techniques such as cluster analysis. Few adequately defined their samples or sampling methods. Most classifications were constructed using only sagittal plane gait data. Many did not provide adequate guidelines or evidence of reliability and validity of the classification system. No single classification addressed the full magnitude or range of gait deviations in children with CP. Although gait classification in CP can be useful in clinical and research settings, the methodological limitations of many classifications restrict their clinical and research applicability.

Cerebral Palsy↗

PubMed2006

A simple and valid tool distinguished efficacy from effectiveness studies.

OBJECTIVE: To propose and test a simple instrument based on seven criteria of study design to distinguish effectiveness (pragmatic) from efficacy (explanatory) trials. STUDY DESIGN: Currently no validated definition of effectiveness studies exists. We asked the directors of 12 Evidence-based Practice Centers to select six studies each: four that they considered to be examples of effectiveness trials and two considered efficacy studies. We then applied our proposed criteria to test the construct validity using the selected studies as if they had been identified by a gold standard. RESULTS: Based on the rationale to identify effectiveness studies reliably with minimal false positives (i.e., a high specificity), a cutoff of six criteria produced the most desirable balance between sensitivity and specificity. This setting produced a specificity of 0.83 and a sensitivity of 0.72. CONCLUSION: When applied in a standardized manner, our proposed criteria can provide a valid and simple tool to distinguish effectiveness from efficacy studies. The applicability of systematic reviews can improve when analysts place more emphasis on the generalizability of included studies. In addition, clinicians can also use our criteria to determine the external validity of individual studies, given an appropriate population of interest.

Drug Therapy↗

PubMed1985

The development and cross-validation of an MMPI typology of murderers.

A sample of 80 male offenders charged with premeditated murder were divided into five personality types using MMPI scores. A hierarchical clustering procedure was used with a subsequent internal cross-validation analysis using a second sample of 80 premeditated murderers. A Discriminant Analysis resulted in a 96.25% correct classification of subjects from the second sample into the five types. Clinical data from a mental status interview schedule supported the external validity of these types. There were significant differences among the five types in hallucinations, disorientation, hostility, depression, and paranoid thinking. Both similarities and differences of the present typology with prior research was discussed. Additional research questions were suggested.

Antisocial Personality Disorder↗