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PubMed1978

[Application of the multiple vocabulary test to determining premorbid intelligence levels].

The authors present three basic approaches to solving the problem of determining the premorbid level of intelligence for diagnostic and prognostic purposes. The indirect way of measuring the premorbid level of intelligence was chosen because of the empirical nature of this approach and the possibility of establishing a firm basis for this. Using a number of samples, it has been possible to show that the multiple vocabulary test satisfies all requirements that must be made of a method of measuring the premorbid level of intelligence. They are above all independence of aging and disease processes as well as a high level of internal validity. Results to date indicate that the multiple vocabulary test is a useful method of rapidly and reliably determining the general level of intelligence. Its special importance lies in the fact that it allows the premorbid level of intelligence to be ascertained, thus contributing to an empirical elucidation of problems associated with decreases in proficiency and general mental deterioration due to organic or psychological factors.

Adolescent↗

PubMed1995

Adult dental surveys: a different approach.

Traditional surveys of adult dental health have used calibrated examiners to collect clinical data. This study examines an alternative approach using data collected by general dental practitioners about their adult patients. Twenty-four dentists in Greater Manchester recorded both personal and intra-oral information on 3,832 of their regularly attending dentate patients over 24 years of age. The mean numbers of filled teeth, sound teeth and the proportion of patients with 21 or more teeth were all similar to those found in the 1988 United Kingdom national survey of adult dental health. For example, the mean number of filled teeth in the 25-34 year age group was 11.7 compared with 11.9 for subjects who claimed to attend regularly in the 1988 national survey, and these figures reduced to 11.2 and 10.0 in the 55-64 year age group. The proportion of adults with 21 or more teeth was found to be 99 per cent compared with 98 per cent in the 1988 survey for the 25-34 year age group, falling to 55 per cent compared with 56 per cent in the 55-64 year age group. The collection of epidemiological data by general dental practitioners is feasible, and has construct and internal validity. It is a possible alternative to conventional surveys of adult dental health.

Adult↗

PubMed1995

Speed of onset.

Speed of onset can be an important attribute of drug product performance. In studies employing appropriate designs and outcome measures, it is theoretically possible to make internally valid comparisons of the distribution of onset times associated with the use of two or more drug products. The external validity of such estimates is still potentially arguable. Steps that may be taken to enhance the likelihood that the results of such comparative studies will be accepted as valid bases for comparative claims are discussed.

Humans↗

PubMed1995

Comparison of health-related quality of life in clinical trial and nonclinical trial human immunodeficiency virus-infected cohorts.

Clinical trials randomly assign treatments and select participants to maximize internal validity, but such selection threatens generalizability by excluding important groups with the diseases under study. Particularly in human immunodeficiency virus (HIV) disease, the results of clinical trials are applied broadly to populations, despite limited representation by minorities and disadvantaged groups. Health-related quality of life (HRQOL), which is increasingly recognized as an important outcome in these studies, may be sensitive to differences that affect generalization of trial results to target populations. This study compared HRQOL in two HIV-infected cohorts: 1) multicenter AIDS Clinical Group Trials in which most subjects are white, privately insured, and high-income (n = 1,907); and 2) a study of ethnically diverse, low-income patients recruited from public clinics (n = 205). Both studies included 30 HRQOL items developed in the Medical Outcomes Study (MOS) and items on symptoms, medications, and demographic characteristics. HRQOL scores were significantly lower in the nontrial sample (P < 0.001) by about one standard deviation, even after direct adjustment for clinical and demographic characteristics, and also after comparison of the nontrial sample with the most symptomatic in the trial sample. The relationships of characteristics with HRQOL differed between nontrial and trial samples, suggesting problems generalizing results from HIV clinical trials to important target populations. HRQOL measures such as those from the MOS can be useful in detecting differences that affect generalization.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Epidemiology studies of synthetic vitreous fibers: methods used and current studies.

Epidemiologic designs (case control, cohort, and surveillance) and measures of association are discussed in the context of studies in the Synthetic Vitreous Fibers industry. Current investigations including a case control study for Owens-Corning's Newark, Ohio plant and a Corporate-wide Mortality Surveillance System are described. The importance of internal validity and the need to account for confounding are demonstrated. Estimates of the prevalence of smoking developed for the Newark plant and the U.S. population have been used to adjust a previously reported statistically significant lung cancer Standardized Mortality Ratio (SMR) for Owens-Corning's Newark plant. After adjusting for the confounding effect of cigarette smoking, the Newark SMR based on national mortality rates is reduced to a statistically insignificant 107.7, a level quite similar to that obtained using local mortality rates. While smoking does not account for all of the excess lung cancer mortality in this population compared to U.S. mortality, these investigations make it clear that plant exposures including respirable glass fibers are not responsible for the remaining excess; rather, this excess reflects the effect of some unknown set of social, demographic, or chance factors.

Air Pollutants, Occupational↗

PubMed1995

Multi-frequency bioelectrical impedance for assessing total body water and extracellular water in elderly subjects.

OBJECTIVE: The objective of this study was to investigate the utility of multifrequency bioelectrical impedance for the estimation of total body water (TBW) and extracellular water (ECW) in an elderly population. DESIGN: Body impedance at 8 frequencies (1-1350 kHz) was measured in duplicate within 1 week. TBW and ECW were determined using deuterium oxide and potassium bromide dilution respectively. SETTING: At the Department of Human Nutrition. SUBJECTS: 81 women and 36 men, aged 63-87 years, volunteered as subjects. RESULTS: Application of prediction equations from the literature, which are mostly based on impedance measurements in young and middle-aged subjects, resulted in large prediction errors of TBW and ECW which were related to the water distribution of the body. New sex-specific prediction equations for the estimation of TBW and ECW were developed for the elderly population and internally validated in random sub-groups. TBW and ECW were best predicted using impedance at frequencies of 5 and 50 kHz respectively, and by using body weight. Prediction errors for TBW were 3.1 kg (7.3%) and 2.7 kg (8.5%) and for ECW 2.2 kg (12.3%) and 1.0 kg (7.4%) for men and women respectively. CONCLUSIONS: Multi-frequency impedance measurements are useful to assess TBW and ECW in groups of elderly subjects. However, the prediction errors are larger compared to young and middle-aged subjects, and are related to body water distribution. Individual errors are sometimes unacceptably large.

Aged↗

PubMedDate not supplied

[Therapeutic information: how to transmit current scientific data. Group VALIDATA].

The information on therapeutics is moving at a high path for various causes. Now, tools for informing correctly the prescriber do exist. However, they require the operation of suitable structures. The mainstem of the system consists of an intermediary which should comply with appropriate rules. It will work from an exhaustive collection of pertinent information. This will allowed by the extensive use of literature data banks and clinical trial registries kept with the help of international collaboration. It will rank the strength of evidence of the collected data according to their internal validity. It will elaborate overviews from validated data obtained from meta-analysis, and messages readily readable by the users, and accessible whenever needed. Overviews will be used to set up guidelines, references, editorials... Data banks will be accessible to researchers, teachers, officers concerned by health care.

Clinical Trials as Topic↗

PubMed1994

[Comorbidity and the physician's decision: the case of undertreatment in care of breast tumors].

When a physician has to come to a decision while caring for a given patient, he is supposed to take into account several kind of information related to the disease, illness or patients' personal characteristics. Although it is wellknown that the framework in which such decision has to be taken is complex, most of the scientific knowledge is based on pieces of evidence that derive from studies where complexity is avoided by applying restriction rules. The goal of this approach is to enhance the internal validity while preserving the generalizability of the findings. But in some cases this approach raises more doubts than certainty. It is the case of the process to assemble practice guidelines to reduce the gap between the best care and what is observed into practice using the available knowledge (i.e., available literature or experts' recommendations). As a variety of relevant clinical and patients' personal characteristics are not available at all or little is known on their impact on patients global health status, variables that actually do drive the practice are not included in guidelines that are intended to change it. This paper introduces the conceptual model of such debate and assesses the impact of co-morbidity--a variable seldom taken into account in effectiveness, quality and appropriateness studies- on the kind of medical care given to a sample of 1019 patients with early stage breast cancer. Empirical results and future implications are eventually discussed.

Adult↗

PubMed1993

Methodological issues in conducting a community-based clinical drug trial.

OBJECTIVE: This paper explores the advantages and disadvantages of implementing a clinical drug trial in a closed community. METHODS: In the study we conducted a randomized, double-blind, placebo-controlled clinical trial to evaluate the effects of an antacid containing aluminum hydroxide on serum lipoproteins in hypercholesterolemic adults. RESULTS: The results of the trial, which was conducted on two Israeli kibbutzim (rural cooperative communities), have been published previously. CONCLUSIONS: The kibbutz presents a unique setting for the conduct of a clinical trial. There were opportunities to uphold inclusion and exclusion criteria carefully, to obtain informed consent, to enhance dietary and drug adherence, to ensure the quality of data collection, to maintain the interest of the participants in the study, and to monitor closely adverse effects and patient safety. This report describes the unique circumstances under which the trial was conducted and the role of the clinician as a clinical investigator and discusses their implications for the internal validity and generalizability of the trial.

Adult↗

PubMed1993

[Clinical criteria in evaluating recovery from depression. Methodologic aspects].

According to recent European epidemiological studies, the lifetime prevalence of major depression ranges between 16 and 20%. Information concerning the natural course of depressive illness remain limited. Longitudinal studies of depressed patients are impeded by the inconsistencies of the labelling of change points in the course of illness (remission, recovery, relapse, recurrence...) and of criteria used to define each of them. Recently, definitions of these terms have been proposed but still need to be clinically validated. Internationally accepted definitions are particularly necessary in order to assess the efficacy of antidepressants at 3 levels: during the acute treatment of an episode, for maintenance treatment (recovery from the complete length of an episode) and for prophylactic treatment (reduction of the risk of future episodes).

Antidepressive Agents↗

PubMed1993

Defining and classifying skin tears: need for a common language.

Very little has been written about skin tears. A common taxonomy and definition for each type of skin tear can organize teaching, practice, and research in the field. In 1990, Payne and Martin published the results of a descriptive clinical nursing research study on the epidemiology and management of skin tears in older adults. The Payne-Martin Classification System for Skin Tears, definitions, and characteristics of skin tears were presented. The purpose of this article is to critique their classification system and definitions. Criteria for evaluating taxonomies, internal validity, external validity, and utility, are used for the critique. A revision based upon continuing research and work with the classification system is presented. Further testing and modification will refine the classification and advance the science of wound care.

Humans↗

PubMed1993

Cultural issues in the psychiatric assessment of Xhosa children and adolescents.

Traditional healers living in Guguletu, Cape Town, were interviewed about their practices in order to ascertain whether or not there are cultural/indigenous expressions of psychological distress or dysfunction in black children and adolescents. Besides bedwetting, fits and school anxiety, five other 'syndromes' were described: ukuphambana, ukuphaphazela, amafufunyane, umoya and ukuthwasa. Although detailed case studies are required to establish the internal validity and exact nature of these 'syndromes', it is clear that any systematic study of psychiatric disorders in Xhosa children and adolescents needs to take them into account.

Adolescent↗

PubMedDate not supplied

Evaluation of the impact of a bedside terminal system in a rapidly changing community hospital.

The impact of a bedside terminal system implemented in a community hospital was evaluated using a one-group before-and-after design. Contrary to predictions, the amount of time registered nurses spent in direct care and the positiveness of registered nurses' attitudes toward bedside terminal technology decreased after the implementation. Registered nurse overtime decreased in accordance with the prediction and unit medication errors remained unchanged. The internal validity of these results was threatened by organizational changes that directly and indirectly affected the study unit. Recommendations are made for conducting evaluation research in a rapidly changing hospital environment.

Adult↗

PubMed1995

Serendipitous results of a pilot study: precaution indicated.

A pilot study was conducted to estimate sample size for a clinical trial in a F area. In 1992, 98 children 14 years of age living in Fall River, MA were examined for dental caries: Fall River was fluoridated in 1973. Residence histories showed that 74% lived there from birth (B), 12% were residents from kindergarten or 1st grade (K1) and 14% moved into the community at a later time (LT). Findings on caries prevalence showed an inverse relation between DMFS and initial age of residence; mean DMFS was 3.00 for Group B, 5.33 for Group K1 and 6.93 for Group LT. A one-way ANOVA indicated significant differences among the groups (p=0.05). Because residence from birth or from early life can be considered a proxy for systemic fluoride exposure, and because controversy currently surrounds the issue of topical versus systemic benefits in explaining the mechanism of action of fluoride, the results appeared to have importance. However, internal analyses of the data comparing surface-specific (pit and fissure) results among the groups for early erupting teeth with varying systemic exposure to fluoridated water and for late erupting teeth, all with appreciable systemic exposure, showed comparable relative differences in DMFS scores. Lack of internal validity, therefore, discounted a conclusion from overall results of the role of systemic fluorides in providing decay preventive benefits. If there is any conclusion that can be drawn it is that serendipitous escapades with data from a pilot study, if not rigorously analyzed and cautiously interpreted, tend to further muddy the waters (fluoridated in this case) on controversial issues and should best be avoided.

Adolescent↗

PubMedDate not supplied

Upper cervical instability: fact or fiction?

OBJECTIVES: The purpose of this review is to examine the internal validity of the standardized clinical stability tests for the upper cervical spine in relation to symptomatology. Whether radiology can confirm the clinical diagnosis is also examined. The importance of radiology in this situation, the pathogenesis and the prevalence of atlanto-axial hypermobility and the clinical symptomatology are discussed. DATA SOURCES: A literature search from January 1984 to March 1995. We consulted the CD-ROM Medline with the keywords "atlanto-axial instability," "atlanto-axial dislocation," "hypermobility," "cervical spine" and "atlanto-axial joint." Ninety-six Dutch, French, German, and English publications were selected. The Documentation Centre of the Institute for Research and Postgraduate Education Physiotherapy (SWSF) was consulted with the keywords: atlanto-axial joint, upper cervical spine, segmental examination, interobserver-reliability, intraobserver-reliability, interobserver variation, intraobserver variation, manual therapy, examination, diagnostics. Finally, recent developments and views published during this study were added. RESULTS: There seems to be no correlation between the amount of hypermobility or subluxation and the presence of clinical signs or neurological signs. The clinical signs can vary from relatively diffuse complaints, no symptoms and signs to serious ones. Radiology does not seem to be a reliable diagnostic mechanism in relation to upper-cervical instability. Conventional X-rays fail to give adequate information about atlanto-axial stability. CT-scan and MRI can visualize much more because of the direct sagittal projection but neither is an absolute standard. Furthermore, in relation to upper-cervical hypermobility, the validity of radiology is under debate. CONCLUSION: There is no correlation between the measure of hypermobility and the presence of clinical symptoms. Also, the validity of the upper-cervical stability tests is questionable. In diagnostics, every radiological examination measures anatomical and morphological variables, not functional variables. Despite this, CT and MRI should be preferred in diagnostics over conventional functional radiology.

Atlanto-Axial Joint↗

PubMed1996

Reuse of disposable laparoscopic instruments: cost analysis.

OBJECTIVE: To evaluate the cost benefits of reusing disposable laparoscopic instruments. DESIGN: A cost-analysis study based on a review of laparoscopic and thoracoscopic procedures performed between August 1990 and January 1994, including analysis of disposable instrument use, purchase records, and reprocessing costs for each instrument. SETTING: The general surgery department of a 461-bed teaching hospital where disposable laparoscopic instruments are routinely reused according to internally validated reprocessing protocols. METHODS: Laparoscopic and thoracoscopic interventions performed between August 1990 and January 1994 for which the number and types of disposable laparoscopic instruments were standardized. MAIN OUTCOME MEASURES: Reprocessing cost per instrument, the savings realized by reusing disposable laparoscopic instruments and the cost-efficient number of reuses per instrument. RESULTS: The cost of reprocessing instruments varied from $2.64 (Can) to $4.66 for each disposable laparoscopic instrument. Purchases of 10 commonly reused disposable laparoscopic instruments totalled $183,279, and the total reprocessing cost was estimated at $35,665 for the study period. Not reusing disposable instruments would have cost $527,575 in instrument purchases for the same period. Disposable laparoscopic instruments were reused 1.7 to 68 times each. CONCLUSIONS: Under carefully monitored conditions and strict guidelines, reuse of disposable laparoscopic and thoracoscopic instruments can be cost-effective.

Cost-Benefit Analysis↗

PubMed1996

The effectiveness of chiropractic for treatment of low back pain: an update and attempt at statistical pooling.

OBJECTIVE: To determine the effectiveness of chiropractic treatment for patients with low back pain by means of a systematic review of the literature. DATA SOURCES: Randomized clinical trials (RCTs) on chiropractic were identified with a Medline and Embase search (1966-1995), by citation tracking, and by hand searching of the relevant chiropractic reference systems (CRAC and Index to Chiropractic Literature). STUDY SELECTION: All RCTs on low back pain that involved chiropractors as therapists. DATA EXTRACTION: Methodological quality was assessed independently by two reviewers on 14 items covering internal validity, informativeness and study size. Data were extracted on: patients (initial referral, duration of complaints, radiation of pain); outcomes (four different types); and timing of follow-up (short-term, intermediate and long-term). Statistical pooling was intended, according to a preset analysis plan, to include subgroup analysis. DATA SYNTHESIS: Eight RCTs were identified. All RCTs had serious flaws in their design, execution and reporting. Because of the great variety of outcome measures and follow-up timing, there was insufficient data to enable statistical pooling of the RCTs. A narrative review, however, did not provide convincing evidence for the effectiveness of chiropractic for acute or chronic low back pain. CONCLUSIONS: There is certainly a need for correctly executed trials. In future research on the effectiveness of chiropractic, guidelines for uniform execution and reporting of RCTs should first be established to enable subsequent statistical pooling in systematic reviews of chiropractic trials.

Chiropractic↗

PubMed1997

Estimating lung cancer mortality from residential radon using data for low exposures of miners.

Some recent estimates of lung cancer risk from exposure to radon progeny in homes have been based on models developed from a pooled analysis of 11 cohorts of underground miners exposed to radon. While some miners were exposed to over 10,000 working level months (WLM), mean exposure among exposed miners was 162 WLM, about 10 times the exposure from lifetime residence in an average house and about three times the exposure from lifetime residence at the "action level" suggested by the U.S. Environmental Protection Agency. The extrapolation of lung cancer risk from the higher exposures in the miners to the generally lower exposures in the home is a substantial source of uncertainty in the assessment of the risk of indoor radon. Using the pooled data for the miners, analyses of lung cancer risk were carried out on data restricted to lower exposures, either <50 WLM or <100 WLM. In the pooled data, there were 115 lung cancer cases among workers with no occupational WLM exposure and 2,674 among exposed miners, with 353 and 562 lung cancer cases in miners with <50 WLM and <100 WLM, respectively. Relative risks (RRs) for categories of WLM based on deciles exhibited a statistically significant increasing trend with exposure in each of the restricted data sets. In the restricted data, there was little evidence of departures from a linear excess relative risk model in cumulative exposure, although power to assess alternative exposure-response trends was limited. The general patterns of declining excess RR per WLM with attained age, time since exposure and exposure rate seen in the unrestricted data were similar to the patterns found in the restricted data. Risk models based on the unrestricted data for miners provided an excellent fit to the restricted data, suggesting substantial internal validity in the projection of risk from miners with high exposures to those with low exposures. Estimates of attributable risk for lung cancer (10-14%) in the U.S. from residential radon based on models from the unrestricted data were similar to estimates based on the data for miners receiving low exposures.

Air Pollutants, Radioactive↗