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Results for “Internal validation”

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At least 1,189 records · Page 66Linked to original sources

PubMed2000

Epilepsy in rural South African children--prevalence, associated disability and management.

OBJECTIVE: To determine the prevalence of epilepsy and its associated disabilities in rural South African children aged 2-9 years. SETTING: Eight villages in the district of Bushbuckridge, Northern Province, South Africa. DESIGN: A two-phase design was used. The first phase involved screening children on a house-to-house basis by interviewing mothers or caregivers using an internationally validated questionnaire for detecting childhood disability in developing countries. The second phase consisted of a paediatric/neurodevelopmental assessment of the children who screened positive. RESULTS: A total of 6,692 children were screened; 722 (10.8%) had a paediatric evaluation and 49 (0.73%) had epilepsy. The lifetime and active prevalences of epilepsy in these children were 7.3/1,000 and 6.7/1,000 respectively. Associated developmental disability was recorded in 35 affected children (71.4%), including 8 (16.3%) in whom this was moderate to severe. More than a half of the children with epilepsy (57.1%) did not receive anticonvulsant medication. CONCLUSION: The prevalence of epilepsy in the rural childhood population investigated is higher than that recorded in most similar studies from sub-Saharan Africa, and the poor utilisation of appropriate anticonvulsant treatment is cause for concern. This study highlights the paucity of relevant information on the epidemiology of epilepsy in South Africa and that the system available for its management, especially in rural areas, appears to have functional deficiencies. Appropriate research is needed to identify the problems in service delivery and to enable the planning and implementation of an appropriate primary health care-based system for the diagnosis and management of epilepsy in children.

Child↗

PubMedDate not supplied

[A critical review of the specificity of the Wisconsin card sorting test for the assessment of prefrontal function].

INTRODUCTION AND OBJECTIVE: Clinical and experimental research with the Wisconsin Card Sorting Test (WCST) has shown inconsistencies which bring into question the specificity of the test as a marker of frontal dysfunction. The aim of the present review is to evaluate the causes and the consequences of those criticisms for the assessment of both prefrontal function and the executive system of attention. DEVELOPMENT: Clinical evidence confirms that, in its present form, the WCST can not discriminate between lesions in frontal and non frontal brain regions. Moreover, functional neuroimaging studies have shown rapid and widespread activation of frontal and non frontal brain regions during WCST performance. On the one hand, these studies strongly suggest that the concept of anatomically 'pure' tasks is deceptive, but they also provide us with evidence that inconsistencies in WCST research might be motivated by problems with the internal validity and reliability of the original test as a measure of attentional set shifting ability. In contrast, recent studies have successfully employed WCST analogues to link precise cognitive processes with anatomically and functionally well defined prefrontal areas. CONCLUSIONS: It is deemed necessary to apply the new technical and methodological developments to generate more valid and reliable neuropsychological tests, that yield a better correspondence between anatomy and function. This will make possible future progress in the clinical assessment of higher brain functions.

Attention↗

PubMed2000

[Acute low back pain: activity, NSAID's and muscle relaxants effective; bedrest and targeted exercise not effective; results of systematic reviews].

OBJECTIVE: To inventory the current state of the art regarding the effectiveness of conservative treatment of acute low back pain. DESIGN: Systematic reviews. METHOD: The relevant literature from the period January 1966-September 1999 was retrieved via Medline, Embase, Psychlit and the Cochrane Library and via reference lists in the articles found. The methodological quality of the studies was assessed using criteria for internal validity. On the basis of the number of examinations, their quality and the consistency of the findings, conclusions were subdivided into four levels of strength of scientific evidence. RESULTS: Approximately two-thirds of the randomised trials in the field of back pain were of poor methodological quality. There was strong evidence that advice to stay active, non-steroidal anti-inflammatory drugs (NSAIDs) and muscle relaxants were effective in acute low back pain. There was also strong evidence that bed rest and specific exercises were not effective in acute low back pain. Strong evidence for effectiveness of many other commonly used interventions was lacking.

Acute Disease↗

PubMed2000

[Chronic low back pain: exercise therapy, multidisciplinary programs, NSAID's, back schools and behavioral therapy effective; traction not effective; results of systematic reviews].

OBJECTIVE: To inventory the current state of the art regarding the effectiveness of conservative treatment of chronic low back pain. DESIGN: Systematic reviews. METHOD: The relevant literature from the period January 1966-September 1999 was retrieved via Medline, Embase, PsychLit and the Cochrane Library and via reference lists in the articles found. The methodological quality of the studies was assessed using criteria for internal validity. On the basis of the number of examinations, their quality and the consistency of the findings, conclusions were subdivided into four levels of strength of scientific evidence. RESULTS: There was strong evidence that exercise therapy and multidisciplinary treatment programmes were effective in chronic low back pain, and moderate evidence that non-steroidal anti-inflammatory drugs (NSAIDs), back schools and behavioural therapy were effective in chronic low back pain. There was also strong evidence that traction was not effective in chronic low back pain. Strong evidence for effectiveness of many other commonly used interventions was lacking.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMedDate not supplied

Determination of polydextrose as dietary fiber in foods.

Polydextrose (Litesse) provides physiological effects consistent with dietary fiber. However, AOAC methods for measuring total dietary fiber (TDF) in foods include an ethanol precipitation step in which polydextrose and similar carbohydrates are discarded and therefore not quantitated. This study describes a method developed to quantitate polydextrose in foods. The new method includes water extraction, centrifugal ultrafiltration, multienzyme hydrolysis, and anion exchange chromatography with electrochemical detection. Six foods were prepared with 4 levels of polydextrose to test the ruggedness of the method. Internal validation demonstrated the ruggedness of the method with recoveries ranging from 83 to 104% with an average of 95% (n = 24) and relative standard deviation of recoveries ranging from 0.7 to 13% with an average of 3.3% (n = 24). The value is added to that obtained for dietary fiber content of foods using the AOAC methods, to determine the TDF content of the food.

Animals↗

PubMed2000

Measuring continuity of elders' posthospital care.

Continuity of care is a critical component of quality patient care, yet the paucity of reliable and valid measures of continuity of care make it difficult to ascertain the extent to which continuity has been achieved. The purpose of this article is to describe the development of an instrument to measure continuity of care that incorporates the perspectives of elders hospitalized for a chronic illness and their family caregivers. The instrument was used, and its reliability and validity examined, in a series of studies related to elders' posthospital transition. Elders in the studies ranged in age from 55 to 94 years. The findings supported content and construct validity, internal consistency reliability, and ability to detect changes in the same subjects at different points in time for the care management and services subscales. With further refinement, the continuity of provider and conflicting information subscales might also facilitate assessment of care continuity.

Aftercare↗

PubMed2000

[Clinical cardiology and physiology].

Recent concepts of cardiovascular pharmacotherapy are now mainly based on results of multicentre prospective studies performed in several countries worldwide. The main disadvantage of such studies is the heterogeneity of patient-groups compared, caused by ethnic differences, variability of criteria and diverse concomitant medication. To assert internal validity of data compared, substantial section of patients (80-99%) is often excluded before evaluation. Thus, there is always a lack of external validity--the data cannot be generalised and have only a limited predictive value for management of other groups or individual patients. Consequently, we still need reliable preclinical data from animal and human studies under well defined and uniform conditions. The importance of experimental and clinical physiology is demonstrated by well-established hemodynamic rules and pharmacodynamic correlations. Clinical physiology remains an indispensable foundation of clinical medicine which cannot be replaced by formal statistics.

Animals↗

PubMed2000

Will patients use a computer to give a medical history?

BACKGROUND: A patient-entered computerized history, can be used as a means of medical data collection in a large inner city population. We evaluated whether a patient presenting to the Charity Hospital campus of the Medical Center of Louisiana in New Orleans would use a computer to provide medical information. OBJECTIVE: To determine whether patients would self-administer a computerized medical history and find this an acceptable experience DESIGN: A survey questionnaire was given to 100 patients selected from the emergency department walk-in clinic waiting area. SETTING: Charity Hospital emergency room walk-in clinic METHODS: One hundred patients older than 18 years were selected to give a random sample of the population using the Charity Hospital emergency room walk-in clinic for care. The patients received a questionnaire for rating their experience with the computer. Demographics were collected for all patients, including the 13 who declined participation. The main outcome was the patient's perception of the acceptability of using the computerized medical history. A second important outcome measure was patient refusal to participate in the study. RESULTS: Our analysis of the acceptability ratings revealed adequate internal validity (Cronbach alpha=0.75). A single total score was created for these ratings. The participants' scores ranged from 2.0 to 4.0, with a mean of 3.3 (standard error of the mean=0.04). We observed an 83% positive experience in the participating population. CONCLUSIONS: The patients were able to use the computer to enter their medical information. They responded favorably to the experience and appeared to be capable and willing to provide medical information through use of this technology.

Adolescent↗

PubMed2000

Meta-analyses of clinical drug trials--gold standard reviews or statistical alchemy?

Renewed emphasis on the critical appraisal of published evidence has in turn led to critical appraisal of the way clinical studies have been reviewed. Reviews perform the vital function of summarising a wealth of research information in an efficient and trustworthy manner, but traditional narrative reviews have fallen short in this area, not because they are narrative, but because they have allowed reviewer and publication bias to creep in under the guise of expert authority. Meta-analysis or systematic review emphasises the use of a review protocol based on logical principles to minimise bias, together with qualitative and appropriate quantitative summaries of the data. Like any review, the perceived impact of a meta-analysis is dependent on the quality of the reviewed studies, therefore randomised clinical trials are the favoured substrate for the meta-analysis of drug efficacy because of their potentially high internal validity. The importance of meta-analysis as a tool for clinical drug evaluation has prompted this selective account of its nature, theory, practice and interpretation, with particular emphasis on meta-analysis as a review methodology rather than a statistical methodology, the critical distinction between design and result homogeneity and the need to explore issues of heterogeneity rather than gloss over them by using some statistical shortcut.

Clinical Trials as Topic↗

PubMed2000

The European Socio-Demographic Schedule (ESDS): rationale, principles and development.

OBJECTIVE: To design an internationally valid and practical instrument on which data can be recorded for small areas that describes the sociodemographic characteristics known to be associated with psychiatric morbidity and service use. METHOD: (1) Identification of a set of sociodemographic characteristics which, on the basis of currently available evidence, would be expected to influence needs for and provision of mental health care in different countries. (2) Selection of a subset of these for inclusion in the schedule based on likely degree of cross-cultural validity and on the types and formats of the data routinely available in each country. (3) Revision of the schedule following a pilot by EPCAT members. RESULTS: The European Socio-Demographic Schedule (ESDS) was successfully employed to collect sociodemographic data in seven catchment areas. Differences were found between the areas in terms of availability of data as well as in the resulting profiles. CONCLUSION: The ESDS has been shown to be applicable in a number of European countries.

Adolescent↗

PubMed2001

Development of a brief, self-administered instrument for assessing sleep knowledge in medical education: "the ASKME Survey".

STUDY OBJECTIVES: This report describes the construction and validation of a brief self-administered scale to assess sleep knowledge in medical education ("ASKME Survey"). Few measures of this type have been developed previously; none have been validated or widely adopted. The current instrument was designed as a standardized assessment measure for use in medical education in sleep. DESIGN: Instrument was developed in four phases: initial item selection, expert panel review, reliability and construct validity assessment, and final item selection. Content validity was assessed in six general domains: basic sleep principles; circadian sleep/wake regulation; normal sleep architecture; sleep disorders; effects of drugs and alcohol on sleep; and sleep in medical disorders. SETTING: N/A. PARTICIPANTS: Medical students at Robert Wood Johnson Medical School (RWJMS) and University of Kentucky College of Medicine; students in clinical psychology, nursing and other health-related professions at Rutgers University; school nurses at Texas Christian University; practicing physicians; accredited sleep specialists. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Individual item analysis of 30-item survey demonstrated a high degree of discriminant validity. Internal consistency for test items was relatively high (KR-20=0.89). Overall mean percentage correct was highest for accredited sleep specialists (85.3%+/-10.8%) and lowest for school nurses (53.1%+/-13.7%). Significant group differences were observed across all question categories (p < 0.0001). Medical students scored significantly higher than the nurses on questions related to sleep architecture (59.5% vs. 42.5%) and narcolepsy (36.4% vs. 21.3%). CONCLUSIONS: "ASKME" demonstrates a high degree of internal consistency and reliability among survey items. It discriminates between samples with varied levels of education, experience, and specialty training. The survey is currently available via the American Academy of Sleep Medicine website (http://www.aasmnet.org).

Attitude to Health↗

PubMed2001

Quality of deployment surveillance data in southwest Asia.

The Global Expeditionary Medical System (GEMS), formerly known as Desert Care II, provides clinical data on every medical encounter that occurs at U.S. Air Force medical treatment facilities in theater. After 22 months of surveillance from March 1997 to January 1999, 59,026 records were generated from 27,305 active duty members. A random sample of 273 individuals were reviewed for four key fields: chief complaint, diagnosis, International Classification of Diseases, 9th Revision, code, and disease and nonbattle injury category. The vast majority (> 99%) of records were consistently classified and reported. An unrelated subset of all cases categorized as "Medical/Other" seen at Prince Sultan Air Base (5,640 records) also were analyzed. Reassignment was made in 19% of cases into other categories, suggesting that further refinement of disease and nonbattle injury reporting is needed for effective deployment medical surveillance. Overall, this electronic data-gathering system has high internal validity, consistency, and reliability for service members in the deployed U.S. Air Force setting.

Asia↗

PubMed2001

[Physical activity and health in young persons].

Epidemiological studies highlighted an inverse relationship between the level of usual physical activity and the risk of cardiovascular accident. Physical inactivity during childhood and adolescence is believed to be a significant risk factor for various health disorders in later life. One makes a clear distinction between on the one hand, exercise and physical fitness and, on the other hand, activity and health. An investigation into the life style (practice of out-of-school physical and sports activities, their frequency, their duration, practice in club and competitive practice) of young Europeans was carried out in nine countries or areas. In the French Community of Belgium, 730 boys and 726 girls of 12 and 15 years were administered an internationally validated questionnaire. The results obtained in all the countries were in agreement with the data of the literature. More than 50% of the girls participated in physical activities only with a very limited frequency and at a low intensity. This is an obvious deficit when compared with the recommendations concerning exercise for health. One can predict without much risk of error that in the adulthood, they will be also classified among the sedentary people.

Adolescent↗

PubMed2001

Design issues and sample size when exposure measurement is inaccurate.

Measurement error often leads to biased estimates and incorrect tests in epidemiological studies. These problems can be corrected by design modifications which allow for refined statistical models, or in some situations by adjusted sample sizes to compensate a power reduction. The design options are mainly an additional replication or internal validation study. Sample size calculations for these designs are more complex, since usually there is no unique design solution to obtain a prespecified power. Thus, additionally to a power requirement, an optimal design should also fulfill the criteria of minimizing overall costs. In this review corresponding strategies and formulae are described and appraised.

Bias↗

PubMed2001

[Roaming through methodology. XXXIV. Limitations of predictive models].

Predictive models can be readily used within the populations in which they were developed but they often give a less than satisfactory performance when applied to another population. The main cause of this poorer performance is the fact that predictive models are often developed and evaluated within one single population. In a lot of cases, the model includes too many predictors (or a small population is used), which increases the chance of overfitting. Both external and internal validation techniques have been developed to evaluate predictive models. The most stringent test is an external validation: the application of the model to a new population. The usability of a predictive model can be evaluated using the receiver operating characteristic (ROC) curve.

Data Interpretation, Statistical↗

PubMed2001

Does how you do depend on how you think you'll do? A systematic review of the evidence for a relation between patients' recovery expectations and health outcomes.

BACKGROUND: Most clinicians would probably agree that what patients think will happen can influence what does happen over the clinical course. Yet despite useful narrative reviews on expectancy of therapeutic gain and the mechanisms by which expectancy can affect health outcomes, we were unable to locate a systematic review of the predictive relation between patients' recovery expectations and their health outcomes. METHODS: We searched MEDLINE for English-language articles published from 1966 to June 1998 with a title or abstract containing at least 1 of the medical subject headings (MeSH) "self-assessment," "self-concept" or "attitude to health," or the MeSH subheading "psychology," and at least 1 word from each of 3 sets: "patient" and similar words; a form of "expectation," "belief" or "prediction"; and a form of "recover," "outcome," "survival" or "improve." Relevant articles contained original research data, measured patients' recovery expectations, independently measured a subsequent health outcome and analyzed the relation between expectations and outcomes. We assessed internal validity using quality criteria for prognostic studies based on 6 categories (case definition; patient selection; extent of follow-up; objective outcome criteria; measurement and reporting of recovery expectations; and analysis). RESULTS: A total of 1243 titles or abstracts were identified through the computer search, and 93 full-text articles were retrieved. Forty-one of these articles met the relevance criteria, along with 4 additional articles identified through other means. Agreement beyond chance on quality assessments of 18 randomly selected articles was high (kappa = 0.87, p = 0.001). Sixteen of the 45 articles provided moderate-quality evidence and included a range of clinical conditions and study designs; 15 of the 16 showed that positive expectations were associated with better health outcomes. The strength of the relation depended on the clinical conditions and the measured used. INTERPRETATION: Consistency across the studies reviewed and the evidence they provided support the need for clinicians to clarify patients' expectations and to assist them in having appropriate expectations of recovery. The understanding of the nature, extent and clinical implications of the relation between expectations and outcomes could be enhanced by more conceptually driven and methodologically sound research, including evaluations of intervention effectiveness.

Humans↗

PubMedDate not supplied

Three silent periods in the orbiculari oculi muscles of man: normal findings and some clinical vignettes.

PURPOSE: To investigate how many true silent periods could be found in the orbiculari oculi muscles of man. MATERIAL AND METHODS: 10 subjects, clinically healthy (5 male, 5 female), with a mean age of 34 years-old (range: 23 to 48) were evaluated by mean of the blink reflex at resting and during contraction of the orbiculari oculi reflex according to protocols validated internationally. RESULTS: Three responses called R1, R2 and R3 were obtained in the orbicular oculi muscle at resting state which had latencies and amplitudes within normal limits. What was new was to obtain three silent periods when the subjects were evaluated during muscle contraction. The duration of the first silent period was statistically longer than the second one (p < 0.004) and shorter than the third silent period (p < 0.0001). In addition, this test was found useful in detecting more specific findings in patients with hemifacial spasm and Meigge syndrome. CONCLUSION: This is by the first time that three silent periods in the orbicular oculi muscles are consistently demonstrated. The refractoriness of the alpha motoneurons and the action of gamma-collateral activity seem to be the main conditions leasing to display the first two periods of muscle suppression. The modification of gamma motoneurons firing as well as a pause of muscle spindles in facial muscles due to the action of nociceptive stimuli traveling unmyelinated C fibers of the supraorbital nerve might be the most important mechanisms involved in the production of the third silent period. These results enables further clinical application of this test.

Adult↗

PubMed2001

[Quality assurance of data collection and data processing in epidemiologic study data].

Quality assurance of the data generating processes in epidemiologic studies is a prerequisite for the internal validity of study results. This paper presents practical aspects of such a quality assurance system pertaining to the planning, data gathering, data entry and data processing phase of a study. It is concerned with data obtained in the framework of a project rather than with data accumulating continuously in private practices, research institutes or veterinary faculties. During the planning phase of a project, standard operating protocols should be developed that assure a reliable performance of observation, coding and data entry. The data base structure, consisting of tables, input validation rules and queries, should be predefined and well documented. A data safety concept will provide the necessary integrity, physical safety and availability of the data. The paper presents technical solutions to common data processing problems with emphasis on re-coding and relational data base facilities (Microsoft-ACCESS) using a hypothetical study on risk factors for mastitis.

Animals↗