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Results for “External validity”

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At least 1,351 records · Page 75Linked to original sources
PubMed2001

Towards a national system for monitoring the quality of hospital-based stroke services.

BACKGROUND AND PURPOSE: We sought to evaluate a system for monitoring the quality of hospital-based stroke services that uses routinely collected case fatality data, adjusted for case mix, as well as simple measures of the process of stroke care. METHODS: We compared the process of care and case fatality after stroke between 5 Scottish hospitals (A through E) during 1995-1997. We retrospectively identified 2724 patients with acute stroke using routine discharge data and obtained case mix and process of care data from the medical record. We ascertained case fatality by record linkage and adjusted for case mix using a simple, externally validated regression model. RESULTS: Crude case fatality varied by 21 deaths per 100 admissions between the 5 hospitals. After adjustment, case fatality still differed significantly (P=0.047), with 5 to 7 more deaths per 100 admissions at Hospital A than at Hospitals B through E. There were major shortcomings in the specialization and organization of care, the use of CT scanning, and the completeness of documentation at Hospital A compared with the other hospitals. There were smaller, but clinically important, differences in care between Hospitals B through E but no significant differences in adjusted case fatality. CONCLUSIONS: Once adjusted for important prognostic variables, routinely collected case fatality data might identify hospitals with major shortcomings in the processes of stroke care. More moderate, but still clinically important, variations in stroke care can only be identified by monitoring the process of care directly.

Aged↗
PubMed2003

Monocyte chemoattractant protein-4 core promoter genetic variants: influence on YY-1 affinity and plasma levels.

Monocyte chemoattractant protein-4 (MCP-4) is a CC chemokine implicated in the recruitment of eosinophils, monocytes, and T-lymphocytes in diseases of mucosal inflammation, including asthma. We tested the hypothesis that there is a genetic basis for differences in MCP-4 expression among individuals by evaluating the effects of core promoter variants on MCP-4 expression. We identified two single-nucleotide T-to-C polymorphisms in the MCP-4 core promoter that occur 896 and 887 base pairs preceding the transcription initiation site. The -887 variant alters a consensus binding motif for the transcription factor YY-1. Electrophoretic mobility shift assay demonstrated that YY-1 containing nuclear extracts from tumor necrosis factor-alpha-stimulated peripheral blood mononuclear cells had greater avidity for the wild-type (YY-1 motif intact) sequence than for the variant sequence. Increasing doses of a YY-1 expression vector induced significantly greater reporter activity from MCP-4 core promoter expression constructs of the wild-type compared with the variant sequence in transient transfection experiments. The external validity of these observations was demonstrated by measuring plasma levels of MCP-4 from individuals with the alternative forms of the gene. Individuals bearing haplotypic variants of the MCP-4 core promoter that avidly bind the transcription factor YY-1 had higher plasma levels of MCP-4 than did individuals with variants with lower binding avidity (490, 360, and 360 pg/ml; P < 0.01). Our findings suggest that the MCP-4 core promoter YY-1 binding motif is functional, modulates the transcriptional regulation of the MCP-4 gene, and that part of the variance in the systemic expression of MCP-4 is determined by core promoter genetic variants.

Erythroid-Specific DNA-Binding Factors↗
PubMed2026

Pulmonary fibrosis after COVID-19 is characterized by airway abnormalities and elevated club cell secretory protein-16.

BACKGROUNDThere are no known serum biomarkers that provide mechanistic insight or prognostic enrichment for post-COVID-19 pulmonary fibrosis.METHODSWe tested associations of serum biomarkers with radiographic fibrosis-like abnormalities (reticulation, traction bronchiectasis, or honeycombing) on thoracic computed tomography (CT) scans 4 months, 15 months, and 3 years after hospitalization in an American discovery cohort of severe-to-critical COVID-19 survivors, and externally validated findings in 2 Canadian cohorts of moderate-to-critical COVID-19 survivors. In the discovery cohort, we investigated the dose-response relationship of the biomarker with CT-derived airway-to-lung ratio. We performed single-cell RNA sequencing (scRNA-seq) of transbronchial lung biopsies from COVID-19 survivors obtained 3 years after COVID-19 hospitalization and conducted immunofluorescence analysis of COVID-19 lung explants.RESULTSAmong 150 discovery cohort participants, only higher levels of circulating club cell secretory protein-16 (CC16, encoded by the SCGB1A1 gene) at hospital discharge, 4 months, 15 months, and 3 years were associated with thoracic CT fibrosis-like abnormalities in cross-sectional and longitudinal analyses. Higher CC16 levels were associated with thoracic CT fibrosis-like abnormalities in 2 validation cohorts (n = 56 and n = 37). CC16 levels were linearly associated with increased airway-to-lung ratio. scRNA-seq revealed increased proportions of epithelial cells expressing SCGB1A1 and SCGB1A1/MUC5B in COVID-19 survivors with fibrosis. Immunofluorescence analysis of COVID-19 lung explants demonstrated increased numbers of SCGB1A1-expressing epithelial cells only in small (<100 &#x3bc;m) airways, with 3-fold more CC16/MUC5B-coexpressing cells in respiratory bronchioles..CONCLUSION. Higher CC16 levels are associated with CT fibrosis-like abnormalities for up to 3 years following moderate-to-critical COVID-19. Increased CC16 reflects dysregulated small airway epithelial progenitor cell remodeling and increased expansion of CC16+MUC5B+ epithelial cells in respiratory bronchioles after COVID-19.TRIAL REGISTRATIONNot applicable.FUNDINGDepartment of Defense, NIH, and Japan Society for the Promotion of Science for Young Scientists.

Humans↗
PubMed1993

Diagnostic decision making in psychiatry.

The purpose of this article is to examine the consequences of and possible responses to uncertainty in psychiatric diagnosis. Uncertainty is inevitable because of the overlap in characteristics, or test results, between populations with and without a psychiatric disorder. As a result, there is never one correct method of identifying cases and noncases (i.e., case definition). In this paper principles of decision analysis and clinical epidemiology are used to develop a framework for thinking about the consequences of different diagnostic schema and for choosing among them. The framework illustrated here involves choosing an external validator, choosing a separator, and choosing a cutoff. This framework is applied to the problems facing three hypothetical researchers, and the consequences for their research of different diagnostic choices are explored. It is demonstrated how the relevance of research to clinicians and policy makers rests on the choice of the case definition process. The prevalent use of structured psychiatric interviews has not been accompanied by adequate attention to the problem of determining a diagnosis once the information is obtained. It is argued that more attention must be given to this process if we are to make optimal use of available resources for research and treatment.

Decision Making↗
PubMed1994

Typology of patient-patient assaults detected by videocameras.

OBJECTIVE: Previous studies of inpatient assault have relied on reports by ward staff, data from which are often incomplete. The authors observed patient-patient assaults with videocameras, obtaining previously unavailable data. In this article they report a systematic method for assault description and classification. METHOD: Assault was defined by behaviors such as hitting, kicking, and choking, with physical contact. Raters reviewed videotapes to make a global judgment of assailant intent to hurt; assault class was based on this judgment. At the same time the raters chose descriptors to better define classes. For external validation, the authors compared classes for resulting injuries, detection by incident reports, and patients' accounts of their motivations. RESULTS: Of 155 assaults detected, 21 were classified as least serious, 57 were in an intermediate group, and 76 were classified as most potentially hurtful. One assault could not be classified. Descriptor variables each made independent significant contributions to assault classification. Almost all assaults detected by incident report or resulting in injuries were in the most serious class. Assailants' claims that they were playing were significantly associated with the least serious class. CONCLUSIONS: With videocameras a variety of interactions between patients involving hitting, slapping, etc., were detected and documented. Some events seemed playful, others seemed intended to hurt, and some were of an intermediate type. This basic, descriptive work can lead to advances in the study of assault predictors.

Adolescent↗
PubMed2005

Generalizability of studies on mental health treatment and outcomes, 1981 to 1996.

OBJECTIVE: This study operationalized and measured the external validity, or generalizability, of studies on mental health treatment and outcomes published in four journals between 1981 and 1996. METHOD: MEDLINE was searched for articles on mental health treatment and outcomes that were published in four leading psychiatry and psychology journals between 1981 and 1996. A 156-item instrument was used to assess generalizability of study findings. RESULTS: Of more than 9,000 citations, 414 eligible studies were identified. Inclusion of community sites and patients from racial or ethnic minority groups were documented in only 12 and 25 percent of studies, respectively. Random or systematic sampling methods were rare (3 percent), and 75 percent of studies did not explicitly address sample representativeness. Studies with funding from the National Institute of Mental Health (NIMH) were more likely than those without NIMH funding to document the inclusion of patients from minority groups (30 percent compared with 20 percent). Randomized studies were more likely than nonrandomized studies to document the inclusion of patients from minority groups (28 percent compared with 17 percent), include patients with comorbid psychiatric conditions (31 percent compared with 19 percent), and attend to sample representativeness (28 percent compared with 15 percent). Modest improvements were seen over time in inclusion of patients from minority groups, inclusion of patients with psychiatric comorbidities, and attention to sample representativeness. CONCLUSIONS: Generalizability of studies on treatments and outcomes, whether experimental or observational, remained low and poorly documented over the 16-year period.

Bibliometrics↗
PubMed1993

Adolescent psychotherapy research: a practical review.

Most of the review studies, including meta-analyses that pay special attention to internal and external validity, support the efficacy of individual psychotherapy for children and adolescent. However, methodological flaws in existing research on outcome of this form of therapy prevents us from getting incontrovertible proof. This paper reviews these studies, emphasizes factors thought to be important to the outcome--variables such as the development process, family and environment, the young person's motivation for therapy, etc.--that have to be taken into consideration by researchers. Special recommendations for the design of future research are offered.

Adolescent↗
PubMed2004

Fear of people with mental illnesses: the role of personal and impersonal contact and exposure to threat or harm.

Vignette and laboratory experiments suggest that negative reactions to people with mental illness are a direct consequence of their symptomatic behavior, but because of their poor external validity, these studies cannot tell us whether widespread negative public reactions to people with mental illness actually result from observation of symptomatic behavior. Focusing on perceived danger, we use a large national survey to test the "behavior hypothesis" in the general population. We reason that, if this hypothesis is correct, contact with people with mental illnesses should be associated with more perceived danger, and exposure to threat or harm should mediate this association. On the contrary, respondents with more personal and impersonal contact perceive people with mental illness to be less dangerous. Exposure to threat is more common among people with more contact, but this exposure explains very little of the variance in perceived danger. These findings do not support the conclusion that public fear of people with mental illness is due to the observation of violent behavior.

Adolescent↗
PubMed1989

Relationship between social perception and peer status in children with learning disabilities.

This study was undertaken to examine the social perceptual skill deficit theory in explaining the low peer acceptance of children with learning disabilities. The quality of tests measuring social perception was also examined. Thirty 9- to 12-year-old children with learning disabilities and a matched control group were given two measures of social perception: a laboratory task and a behavior rating scale. The behavior rating scale was completed by the children's teachers. In addition, the Peer Acceptance Scale (Bruininks, Rynders, & Gross, 1974) was administered to assess peer status. Results showed that the children with learning disabilities differed significantly from their nondisabled peers on each of the three measures-the children with learning disabilities obtained lower social perception and peer acceptance scores. However, the relationships between sociometric status and social perception varied as a function of task. A small but significant correlation wa found between the behavior rating scale and peer status. The laboratory task was not correlated with either the behavior rating scale or peer status. Results are discussed in terms of the psychometric properties of laboratory versus naturalistic measures of social perception and the importance of establishing the external validity of social skill measures by correlating them with outcome measures such as peer status.

Child↗
PubMed2004

How does active parental consent influence the findings of drug-use surveys in schools?

This study examines the impact of passive and active parental consent procedures on the type of adolescents participating in a school-based survey examining substance use. Schools recruited from a random sample of metropolitan schools were assigned to passive or active parental consent condition. Results showed that participation rates in active consent schools were lower than in passive consent schools for junior students (60% vs. 80%) but not senior students. Although consent condition had limited impact on prevalence estimates among older students, among younger students estimates of cannabis use and ecstasy use were higher in the passive consent condition than the active consent condition. Active consent procedures introduce some degree of selection bias into studies of adolescents' substance use and may compromise the external validity of prevalence estimates produced, especially among younger students.

Adolescent↗
PubMed1997

Analysis approaches to community evaluation.

Analysis approaches to the evaluation of community interventions must be sensitive to a wide variety of analytic contaminants that may bias the statistical assessment of changes in outcome measures. These contaminants include model misspecifications related to failures to control for community-specific time trends, temporal autocorrelated errors in equations, spatial autocorrelated errors among geographic units, and other failures of unit independence otherwise indexed by estimated intraclass correlations. Although an enormous amount of progress has been made toward the solution of many of these analytic problems over the past years, the contemporary evaluator of community interventions is left with a number of unenviable design and analysis choices; choices that inevitably force an assessment of the relative threats of different sources of error to the internal and external validity of the evaluation. This article describes the choices made for the evaluation of the Community Trial Project outcome data.

Community Health Services↗
PubMed2005

Evaluating clinical decision rules.

Clinical decision rules (CDRs) are decision support tools that synthesize evidence into bedside tools for practice. Before adopting CDRs into practice, nurses must be assured that there is sufficient evidence in the literature that the rule performs as expected, can do so in a variety of settings (especially in settings similar to one's own), and that using it will likely result in improved patient outcomes at no additional cost (or conversely, that it will lower costs with no adverse effect on clinical outcomes). This article provides a framework for clinical nurses to evaluate CDRs. The framework focuses on the processes used to establish the external validity of the rule, and the evidence that using the rule results in improved patient or systems outcomes, including cost-effectiveness. The Braden Scale is used as an example and is evaluated using the framework described.

Cost-Benefit Analysis↗
PubMed1989

Age: a truly confounding variable.

As Hinshaw (1981) has noted, the process of designing research might best be conceptualized as a series of informed decisions that involve constant trade-offs and compromise. With each advantage gained by a particular theoretical or methodological decision, the researcher inherits a certain number of threats to the study's internal and external validity and a potential number of error sources. Because of the nature of the research questions of interest to nurses and because of situational and contextual constraints in the clinical setting, nurse researchers often are required to select samples that contain small or large proportions of elderly subjects. The purpose of this article has been to raise some of the theoretical and methodological issues associated with the selection of both age-heterogeneous samples and age-homogeneous samples. Although in research all possible error sources cannot be controlled, it is possible to reduce the amount of error by a clear understanding of the implications of choices regarding age-related issues and inclusion of design features that reduce the amount of error introduced when research subjects who are relatively young are studied along with research subjects who are elderly.

Adult↗
PubMed1993

Obtaining and evaluating data sets for secondary analysis in nursing research.

Secondary analysis of existing data offers many advantages to the nurse researcher. Data from large-scale studies may be reanalyzed and refined by secondary analysts with a fresh perspective, thus enhancing the original study's contribution to scientific knowledge. High-quality data can be obtained for comparatively little expenditure of time and money. The secondary analyst, however, must exercise care in evaluating and analyzing a data set to maximize the internal and external validity of the reanalysis. Because the secondary analyst's lack of involvement in data collection procedures may decrease insight into the original study's limitations, vigilant skepticism should accompany all phases of the research process in secondary data analysis, just as it should in all other research. Miller (1982) advised, "Begin by assuming the worst and seek out the same kinds of information about sample selection procedures, sample size, response rates, field procedures, and coding conventions that you would insist on if you were collecting your own data" (p. 722). By systematically evaluating potential data sets according to rigorous predetermined criteria, the nurse researcher can minimize the possible pitfalls inherent in secondary analysis. On the other hand, investigators who use secondary sources appropriately can make significant contributions to nursing science at less cost than that engendered by traditional research methods.

Data Collection↗
PubMed1992

Meta-analysis of antibiotics for the treatment of otitis media with effusion.

OBJECTIVE: To reconcile conflicting reports of antibiotic efficacy for otitis media with effusion in children. DATA SOURCES: English-language MEDLINE search ("antibiotics" and "otitis" media with effusion") from January 1980 through December 1990. Current Contents 1990, consultation with experts, and references from review articles, textbook chapters, and retrieved reports. STUDY SELECTION: Randomized clinical trials with concurrent controls (placebo or no drug), and children with at least one ear not violated by tympanocentesis. Ten of the initial 82 articles were selected after blind review of the methods sections. DATA EXTRACTION: We independently evaluated each trial using 20 measures of internal and external validity, then extracted treatment and control responses for an end point of all affected ears free of effusion at the first posttreatment assessment. DATA SYNTHESIS: Pooled analysis of 1325 children yielded a rate difference of 22.8% (95% Cl, 10.5 to 35.1) that was minimally affected by interstudy quality differences, and was unlikely to represent publication bias. Variations in trial outcomes were not attributable to chance, study design, or choice of drug, but were inversely related to the control group natural cure rate. Children with chronic bilateral effusions not related to a recent episode of acute otitis media tended to have lower natural cure rates, and a more favorable response to therapy. CONCLUSIONS: Antibiotics have a clinically and statistically significant impact on the resolution of otitis media with effusion. The association between outcome and natural cure rate has important implications for the design and interpretation of future trials.

Anti-Bacterial Agents↗
PubMedDate not supplied

Mapping the SF-12 to the EuroQol EQ-5D Index in a national US sample.

BACKGROUND: Preference scores for the Medical Outcomes Study (MOS) SF-12 would enable its use in cost-effectiveness analyses. Previous mapping studies of MOS instruments top reference-based instruments have not examined performance in national samples. PARTICIPANTS: 15,000 adults in the 2000 Medical Expenditure Panel Survey annual survey including the SF-12 and EQ-5D Index. METHODS: Regression of the EQ-5D Index scores onto the physical and mental component summary scores of the SF-12, testing 2nd-4th degree polynomial and spline models, including and excluding sociodemographics. RESULTS: A 2nd degree polynomial model explained 63% of the variance in EQ-5D scores, with robust internal and external validation. More complex mod-els explained minimally additional variance. Compared with EQ-5D valuations, prediction models overestimated the lowest health states (6% of the population). CONCLUSIONS: The mapped SF-12 yields usable preference-scaled scores, with some caution for the lowest health states.

Adult↗
PubMedDate not supplied

Data-source effects on the sensitivities and specificities of clinical features in the diagnosis of rheumatoid arthritis: the relevance of multiple sources of knowledge for a decision-support system.

An experimental computer system was developed to support diagnosis of rheumatic disorders by computing diagnostic probabilities using modified likelihood ratios. The authors examined whether the performance of the model was affected by the settings in which the data used to derive the likelihood ratios were collected. The sensitivities and specificities of various clinical features for diagnosing rheumatoid arthritis (RA) were obtained from: 1) a study of 1,570 consecutive outpatients at a rheumatology clinic; 2) a review of the literature; 3) estimates by rheumatologists; and 4) a population study. Considerable variations in sensitivity and specificity but satisfactory agreement in likelihood ratios were found across the four data sets. The likelihood ratios were then used to compute the probabilities of RA in a test series of 570 of the rheumatology clinic outpatients. The model's diagnoses with likelihood ratios from the other sources were adequate. When the likelihood ratios from these sources were combined, discrimination came close to what could be achieved by using the likelihood ratios based on the data from the clinic. The method applied in the study, which makes use of variation of input data instead of variation of test series, and the results are relevant to assessing the external validity and transferability of Bayesian decision-support systems.

Adolescent↗
PubMed2006

Demographic characteristics of participants in studies of risk factors, prevention, and treatment of postpartum depression.

OBJECTIVES: Metaanalyses have found that sociodemographic variables are not strong predictors of postpartum depression. However, no studies have systematically examined the extent to which the samples used in published research on postpartum depression have included sufficiently diverse samples of women to merit this conclusion. The objectives o this study were to examine the demographic characteristics of participants in previously published studies and to document existing gaps in the current literature. METHOD: We extracted age, ethnicity, relationship status, and socioeconomic status of 51 453 participants from 143 studies previously selected for systematic literature reviews. RESULTS: Few studies reported complete demographic data; however, existing data indicate that participants were predominantly aged 25 to 35 years, white, partnered, and of mid- or high-socioeconomic status. CONCLUSIONS: To assess the external validity of the findings, improved reporting of demographic characteristics is required in publications related to postpartum depression. Additional research is needed to understand postpartum depression among understudied populations.

Adult↗