SEARCH · Search PubMed

Results for “External validity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,279 records · Page 71Linked to original sources

PubMed2006

A protocol to diagnose intimate partner violence in the emergency department.

BACKGROUND: To better identify women at risk for intimate partner violence (IPV), we developed a diagnostic protocol composed of injury location and response to a verbal questionnaire to identify women at high risk for reporting an IPV-related injury etiology. The purpose of this study was to test the external validity of the protocol when applied at two institutions that differ considerably in terms of geography and socioeconomic measures. METHODS: A cross-sectional design was used at two demographically and geographically different hospitals, designated H1 and H2. The sample was composed of adult females age >or=18 years presenting to the emergency department (ED) for evaluation and management of nonverifiable traumatic injuries. The predictor variable was risk for reporting an IPV-related injury. Risk was categorized per the protocol as high or low. High-risk subjects had visible head, neck, or face (HNF) injuries and positive responses to the questionnaires. Low-risk subject had non-HNF injuries or negative responses to the screening questionnaires. The outcome variable was self-reported injury etiology classified as IPV-related or other. Descriptive and bivariate statistics and standard measurements for a diagnostic test were computed. RESULTS: The sample was composed of 400 subjects, with 200 subjects enrolled at each institution. Self-reported IPV was 34% and 9.5% at H1 and H2, respectively. The protocol classified 33% (H1) and 18% (H2) of subjects as high risk. Sensitivities were 90% (H1) and 74% (H2). Specificities were 96% (H1) and 88% (H2). Subjects classified per protocol as high-risk had an 18-fold (p < 0.01, H1) and 13-fold (p < 0.01, H2) increased risk for reporting IPV-related injuries. CONCLUSIONS: Despite significant geographic and socioeconomic differences between the two hospitals, the results suggest that our protocol may be applicable in disparate clinical settings.

Adolescent↗

PubMed2006

An economic evaluation of pediatric small bowel transplantation in the United Kingdom.

BACKGROUND: Small bowel transplantation (SBTx) offers an alternative to parenteral nutrition (PN) for the treatment of chronic intestinal failure in children: this study estimated its cost-effectiveness in the early phase of a U.K. program. METHODS: Children assessed for SBTx were categorized as: 1) requiring SBTx following PN-related complications (n=23), 2) stable at home not requiring SBTx (n=24), and 3) terminally ill and unsuitable for SBTx (n=6). Costs were estimated from detailed resource-use data. Two comparisons were used for effectiveness: actual survival following transplantation (n=14) compared to: 1) estimated survival without transplantation using a prognostic model, and 2) the waiting list experiences of all patients listed for SBTx (n=23). RESULTS: Mean costs up to 30 months were pounds sterling 207,000 for those transplanted or on the waiting list, pounds sterling 159,000 for those stable on home PN, and pounds sterling 56,000 for those terminally ill. The prognostic model estimated a mean survival gain from transplantation of 0.12 years over 30 months, and suggested that transplantation was cost-saving. The second approach suggested that transplantation reduced survival by 0.24 years at an additional cost of pounds sterling 131,000. CONCLUSIONS: Firm conclusions on cost-effectiveness of SBTx are not possible given the two different estimates. The prognostic model approach (suggesting that pediatric SBTx may provide a small survival benefit at a small reduction in costs) should be less subject to bias, but the model requires external validation. Meanwhile, children at risk of fatal PN-complications should be given the opportunity to receive a SBTx only within a continuing formal assessment of the technology.

Child↗

PubMed2006

Evaluation of the subjects' response to antipsychotics questionnaire.

The present study reports on the development of a new self-administered instrument to assess patients' responses to antipsychotic medication. The Subjects' Response to Antipsychotics (SRA) Questionnaire is a 74-item instrument with eight scales (Recovery, Weight Gain, Sexual Anhedonia, Sedation, Affective Flattening, Extrapyramidal Side-Effects, Diminished Sociability and Increased Sleep), and a total adverse responses score including additional items. Psychometric aspects were examined in a study of 320 inpatients and outpatients showing good internal consistency, reproducibility and external validity. Concordance with other instruments claiming to measure the subjective response is low, suggesting that the instruments measure different concepts. The SRA Questionnaire appears to be a reliable and efficient way of measuring patients' subjective responses to antipsychotic medication.

Adult↗

PubMed2006

Translating research into clinical practice: critical interpretation of clinical trials in schizophrenia.

Translating research into clinical practice has in part been hampered by practitioners' difficulties in interpreting statistical measures. The main part of this article aims to bridge the gap between research and practice by describing frequently occurring problems in the methodology and reporting of clinical trials. Basic methodological concepts and statistical measures, such as different trial designs, randomization, blinding, case numbers, eligibility criteria, internal and external validity, efficacy versus effectiveness, the meaning of rating scales, choice of comparators, effect size versus P-value and the interpretation of risk measures, are explained and their use illustrated. The text further presents the outcome from a workshop on 'Translating Clinical Studies into Practice' held at an international conference on schizophrenia and bipolar disorder in June 2005. The participants suggested more emphasis on additional secondary endpoints in clinical trials such as patients' self assessments and indicators of well-being. Better training of clinicians in the interpretation of scientific results and the use of more meaningful clinical outcomes are both needed to effectively translate research into clinical practice.

Clinical Trials as Topic↗

PubMed2001

Efficacy of sumatriptan in the treatment of migraine: a review of the literature.

Advanced practice nurses treat many patients, including children and adolescents, with migraine headaches. Management of headache episodes requires a delicate balance of prophylactic and abortive therapies. Sumatriptan has been used effectively to treat adult patients with migraine headaches, but its efficacy in children has not been established. Results of a literature review provide strong evidence supporting the use of sumatriptan in treating adults with migraine headaches. Some evidence also exists for using sumatriptan to treat migraines in pediatric patients. Open prospective studies used small convenience samples, thus limiting the external validity of the research findings. Two randomized, double-blind, placebo-controlled, crossover trials found conflicting results for the efficacy of sumatriptan in the treatment of pediatric migraine. Further research is needed to determine its efficacy in children.

Adult↗

PubMed2025

Machine Learning-Based Identification of Survival-Associated CpG Biomarkers in Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is an exceptionally aggressive cancer with a 5-year survival rate of less than 10%, driven by late-stage diagnosis, limited treatment options, and a lack of reliable biomarkers for early detection and prognosis. In this study, we integrated DNA methylation data from TCGA and ICGC cohorts, categorizing samples based on survival time, and identified 684 differentially methylated CpG sites, along with 224 CpG biomarkers significantly associated with patient survival through statistical and machine learning-based analyses. We developed a random forest model to predict patient survival, achieving 85.2% accuracy for short-survival patients and 70.0% for long-survival patients in the validation set. External dataset validation further confirmed the model's robustness and accuracy. De novo motif analysis of genomic regions surrounding the 224 CpG biomarkers identified TWIST1 and FOXA2 as key transcriptional regulators enriched in survival-associated CpG sites, linking their activity to patient survival outcomes. Collectively, our findings highlight valuable epigenetic biomarkers and provide a predictive model to assess PDAC risk levels post-surgery, offering the potential for improved patient stratification and personalized therapeutic strategies.

Journal Article↗

PubMed2026

Protein Biomarkers in Risk and Prognosis of Amyotrophic Lateral Sclerosis.

BACKGROUND: Plasma and cerebrospinal fluid (CSF) protein biomarkers in amyotrophic lateral sclerosis (ALS) may provide insight into disease mechanisms and yield clinically useful biomarkers. METHODS: Overall, 363 proteins in plasma and CSF from 198 patients with ALS and 125 matched controls were profiled using Olink assays. Associations with disease status, survival, and functional decline, as well as longitudinal biomarker stability across the disease course were assessed, together with network and enrichment analyses. ALS risk-associated biomarkers were externally validated in the UK Biobank (UKB). RESULTS: Overall, 125 proteins were significantly associated with at least one outcome (i.e., case status, risk, survival, or functional decline), and 21 were associated with three or more outcomes. NEFL was the most robust biomarker in plasma and CSF, alongside TNFRSF12A in plasma and CSF, EDA2R in plasma, and FABP4 in plasma and CSF. Most biomarkers remained stable longitudinally across the disease course. ALS risk-associated biomarkers were replicated in UKB, in which > 3000 plasma proteins were measured in 52,990 participants, including 298 with ALS. Network and enrichment analyses highlighted their roles in immune response and extracellular-matrix remodeling, and their enrichments in the brain and T-cell subsets. Construction of an ALS risk-prediction model achieved an ROC-AUC of 0.72 in the UKB validation cohort. CONCLUSIONS: These findings suggest candidate protein biomarkers for ALS risk stratification, early detection, and clinical therapeutic monitoring.

Humans↗

PubMed2004

Inference for the proportional hazards model with misclassified discrete-valued covariates.

We consider the Cox proportional hazards model with discrete-valued covariates subject to misclassification. We present a simple estimator of the regression parameter vector for this model. The estimator is based on a weighted least squares analysis of weighted-averaged transformed Kaplan-Meier curves for the different possible configurations of the observed covariate vector. Optimal weighting of the transformed Kaplan-Meier curves is described. The method is designed for the case in which the misclassification rates are known or are estimated from an external validation study. A hybrid estimator for situations with an internal validation study is also described. When there is no misclassification, the regression coefficient vector is small in magnitude, and the censoring distribution does not depend on the covariates, our estimator has the same asymptotic covariance matrix as the Cox partial likelihood estimator. We present results of a finite-sample simulation study under Weibull survival in the setting of a single binary covariate with known misclassification rates. In this simulation study, our estimator performed as well as or, in a few cases, better than the full Weibull maximum likelihood estimator. We illustrate the method on data from a study of the relationship between trans-unsaturated dietary fat consumption and cardiovascular disease incidence.

Biometry↗

PubMed1994

Pharmacological and non-pharmacological smoking motives: a replication and extension.

Cigarette smokers (n = 387) completed a questionnaire measure of smoking motives, and subgroups of this sample provided external validation information. Seven factors emerged from a principal components' analysis: automatic, sedative, addictive, stimulation, psychosocial, indulgent and sensorimotor manipulation. A higher-order principal components analysis revealed the presence of two second-order factors. Inspection of the pattern of correlations between factor scores and criterion variables clearly indicated that the first four factors above and their underlying second-order factor are more closely related to nicotine pharmacology and mood-altering effects of nicotine than the latter three motives and their underlying second-order factor. Moreover, the positive correlations between these pharmacological motives and age, coupled with a negative relationship between age and the non-pharmacological motives, support the description of the smoking career as a progressive transfer of reward from non-pharmacological to pharmacological factors. These findings suggest that self-reported reasons for smoking represent more than bias in verbal report.

Adult↗

PubMed1993

A comparison of the concentration-effect relationships of midazolam for EEG-derived parameters and saccadic peak velocity.

1. Concentration-effect relationships of midazolam were assessed in an open study in six healthy volunteers. Saccadic eye movements and EEG parameters derived by fast Fourier transform (FFT) and aperiodic analysis (AP) were used to quantify drug effects. 2. Midazolam was infused at a rate of 0.6 mg kg-1 h-1 for a maximum of 15 min. Hypnotic effects were avoided by terminating infusions when subjects could no longer perform the eye movement test properly. 3. Wake-sleep transitions could be recognized through frequent observation of eye movements. The dose needed to reach maximum conscious sedation averaged 0.10 mg kg-1, ranging from 0.06 to 0.13 mg kg-1. 4. Sigmoidal concentration-effect relationships were found for EEG beta-amplitudes in five of six subjects, with average EC50 values (+/- s.d.) of 120 +/- 54 ng ml-1 for FFT and 104 +/- 40 ng ml-1 for AP. For the 'total number of waves' in the beta frequency range (AP) an average (n = 6) EC50 of 63 +/- 37 ng ml-1 was found. Changes in EEG alpha-amplitudes were found in three subjects, resulting in an average EC50 value of 55 +/- 32 ng ml-1. 5. For saccadic peak velocity (PV) concentration-effect relationships were linear in five subjects and sigmoidal in one. The maximal measured decrease in PV averaged -44 +/- 9%. 6. The differences in concentration-effect relationships for various effect parameters call for further studies with emphasis on the external validity and reproducibility of data. In such studies the dose needed to reach wake-sleep transition may be used as a relevant clinical end-point.

Adult↗

PubMed2004

Good practices that address continuity during transition from child to adult care: synthesis of the evidence.

BACKGROUND: Effective transition to adult services is required by an increasing number of children with ongoing needs. AIM: To identify practices that promote continuity at transition between child and adult services. METHODS: Systematic examination of the evidence from two search strategies yielding 5319 items. RESULTS: Only three of the 126 appraised items had strong external validity. A large range of different practices, which focused on the service, the young person and the family, were identified. Practices within the service addressed structural, process and outcome components. CONCLUSION: Four transition models are proposed for testing.

Adolescent↗

PubMed2005

Effects of nurse-initiated telephone follow-up on self-efficacy among patients with chronic obstructive pulmonary disease.

AIM: This paper reports a study to determine whether a nurse-initiated telephone follow-up programme could increase patients' self-efficacy in managing dyspnoea and decrease health care service use. BACKGROUND: Chronic obstructive pulmonary disease is a worldwide health problem and has been labelled a burdensome disease. Because of the fear of activity-induced dyspnoea, patients with chronic obstructive pulmonary disease lack the confidence to perform daily activities. Studies of cardiac and diabetic patients have shown that telephone follow-up care is an effective approach to increasing self-efficacy. However, little such research has been done with patients with chronic obstructive pulmonary disease. METHODS: This was a randomized controlled study. A total of 60 participants (30 telephone follow-up, 30 control) with chronic obstructive pulmonary disease were recruited from an acute care hospital in Hong Kong. The Chinese Self-Efficacy Scale was used to assess self-efficacy. Measures of health care use were numbers of visits to an accident and emergency department, hospitalizations, and unscheduled visits by physicians. FINDINGS: The self-efficacy scores (U = 272.5, P = 0.009) of patients who were followed up by telephone improved significantly compared with those of patients in the control group. Multiple regression analyses showed that telephone follow-up (Beta = 0.33, CI: 0.19-0.48, P = 0.001), the pulmonary rehabilitation programme (Beta = 0.44, CI: 0.16-0.72, P = 0.003), smoking (Beta = 0.34, CI: 0.09-0.57, P = 0.009), and health care use (Beta = -0.27, CI: -0.47-(-0.07), P = 0.008) were significant factors in predicting patient self-efficacy. CONCLUSIONS: Nurse-initiated telephone follow-up care was effective in increasing self-efficacy in managing dyspnoea. The study needs to be replicated in other setting to strengthen its external validity.

Aftercare↗

PubMed2005

Healthy living interventions and schizophrenia: a systematic review.

AIM: This paper reports a systematic review of the published and grey literature which has investigated the efficacy of healthy living interventions for adults with a diagnosis of schizophrenia or schizo-affective disorder. BACKGROUND: Adults with a diagnosis of schizophrenia or schizo-affective disorder have reduced life expectancy when compared with members of the general population, with approximately 59% of excess mortality resulting from natural causes. METHODS: The review was conducted following guidelines provided by the United Kingdom National Health Service Centre for Reviews and Dissemination, and using the Medline, PsycINFO, CINAHL, Embase, Cochrane Library, National Research Register, and System for Info on Grey Literature databases. RESULTS: Sixteen studies were identified, examining four types of healthy living interventions: smoking cessation (n = 7), weight management (n = 5), exercise (n = 3) and nutritional education (n = 1). The smoking cessation, weight management and exercise studies showed positive outcomes in the main. The quality of the studies, however, was generally poor. Only two had control groups, most recruited small self-selected samples, six did not standardize for diagnosis, external validity was generally poor and no studies followed participants for longer than 6 months. The best quality evidence was produced by the smoking cessation and weight management studies, which were more methodologically robust and demonstrated promising outcomes. CONCLUSIONS: Further research is needed to assist the development of effective interventions to help this client group to adopt and maintain healthier lifestyles. Research and practice development in this area may be an important role for nurses in both hospital and community settings.

Health Promotion↗

PubMed2007

A review of the benefits of whole body exercise during and after treatment for breast cancer.

AIM: A current critical review of the literature was deemed necessary to evaluate the strength of evidence to inform clinical practice. BACKGROUND: Recently, there has been a noticeable increase in empirical literature surrounding the benefits of exercise for breast cancer patients. METHODS: A systematic search strategy was used to identify relevant literature. Twenty-nine articles were retained for critical review, appraised for quality and synthesized. RESULTS: Many early studies had limited internal and external validity. Recent studies were considerably more rigorous and robust. Consistent support for all types of aerobic exercise was most evident in studies of patients during adjuvant cancer treatments (chemotherapy and radiotherapy), compared with post-treatment studies. The evidence which suggested that aerobic exercise limits cancer-related fatigue was particularly strong. For other patient concerns, the empirical support was less robust, however, the potential for beneficial and measurable patient outcomes was indicated for cardiopulmonary function, overall quality of life, global health, strength, sleep, self-esteem and reduced weight gain, depression, anxiety and tiredness. CONCLUSIONS: Additional studies with higher methodological quality are required in this clinically relevant area to substantiate current indications particularly for patient subgroups (e.g. older people, those with advanced cancer and the disadvantaged). RELEVANCE TO CLINICAL PRACTICE: It is important for all healthcare professionals involved in the care of individuals affected by breast cancer to be aware of the evidence surrounding the benefits of exercise and to encourage patients to increase physical activity and improve their overall health and well-being.

Breast Neoplasms↗

PubMed1995

Playing at research: methodological pluralism and the creative researcher.

In its quest for acceptance by the scientific community, mental health nursing research has developed an unhealthy obsession with methodological rigour. This paper draws on the work of several writers from the philosophy of social science to argue that this focus on methodology stifles individual creativity and acts as a gatekeeper to the profession which excludes many of our brightest and most creative researchers. The author proposes a new approach to doing research that facilitates the creative process by encouraging a playful approach that temporarily abandons the accepted rules and methods of the research process in favour of an 'anarchistic epistemology' and a variety of unusual and not necessarily externally validated methods. It is only at the end of the research process that valid and generalizable methods are introduced, and the author calls for journals to open a creative dialogue by being more willing to publish papers describing the early, exploratory stages of research, based on a judgement of their creativity and innovation.

Creativity↗

PubMed2006

A systematic review of the reliability of frequency-volume charts in urological research and its implications for the optimum chart duration.

OBJECTIVE: To determine how the reliability of frequency-volume charts (FVCs) vary with their duration when used to assess patients with lower urinary tract symptoms (LUTS) and whether the duration influences patient compliance. METHODS: Peer-reviewed studies involving patients with LUTS were searched systematically, with the selected studies assessed for their internal and external validity and statistical quality. Details of the patients and type of FVC used were summarized, and reliability coefficients and levels of compliance were extracted for commonly assessed FVC variables. RESULTS: In all, 13 studies were considered to meet the review criteria; they assessed the reliability of FVCs lasting 1, 2, 3 and 7 days. The reliability coefficients for 3- and 7-day FVCs were generally >0.8; those for shorter charts tended to be lower, but strong conclusions could not be drawn due to study limitations. There was no obvious relationship between the duration of the FVC and the level of compliance. CONCLUSIONS: Strong recommendations cannot be made about what duration of an FVC should be used to assess or monitor patients with LUTS. The current consensus on using FVCs of > or = 3 days seems to be the most defensible policy, but more research of high quality is required, especially into the relationship of FVC duration with compliance.

Adult↗

PubMed1990

Rising incidence of type 1 diabetes in Hungarian children (1978-1987). Hungarian Childhood Diabetes Epidemiology Group.

A retrospective epidemiological study using primary data sources and external validation was conducted to assess the incidence of childhood (0 to 14 years) Type 1 diabetes in Hungary (excluding the Budapest region) over a 10-year period. Hospital records and regional diabetes centres' registries served as primary data sources, and data were validated by using the records of summer camps for diabetic children. The degree of ascertainment was 96.2%. Age-specific incidence rates increased until puberty with peak incidence in girls at 10 yr, and in boys at 13 yr. There was a significant seasonal variation of onset with peaks in autumn and winter. The incidence was slightly lower amongst boys than amongst girls. A statistically significant increase in incidence was evident in the last decade, from 3.8 per 100,000 in 1978 to 8.2 per 100,000 in 1987.

Adolescent↗

PubMed1995

Self-control in boys with attention deficit hyperactivity disorder: effects of added stimulation and time.

Preference for larger-delayed versus more immediate-smaller rewards was studied in 5- and 6-year-old typical boys with Attention Deficit Hyperactivity Disorder (ADHD) in a repeated measure design. The effect of adding stimulation on preference also was studied. Boys with ADHD chose delayed-larger rewards significantly less than did typical boys. Adding stimulation reduced motoric behavior, but did not affect choice. As rates of motoric activity increased in boys with ADHD, their preference for delayed, larger rewards decreased over time. These findings argue for the external validity of choice tasks in the study of ADHD.

Adolescent↗