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PubMedDate not supplied

[International cooperation for research in public health: the case of the Latin American Network of Perinatal Investigation].

Health research in Latin America faces serious shortcomings, especially considering the region's dire needs. Multicenter collaboration can be a valuable tool to promote scientific development. In 1985, investigators of four Latin American epidemiologic research centers created the Latin American Network for Perinatal Research. The analysis of the difficulties we had to face in order to implement the first joint study illustrates the obstacles people involved in multicenter projects have to overcome. The conclusion is that in spite of the difficulties, multicenter work is feasible and to be recommended. Results of this kind of studies reach a great external validity and are applicable to broad population sectors.

Argentina↗
PubMedDate not supplied

[Positive and negative schizophrenic symptoms: a reanalysis of the dichotomous model of schizophrenia].

The positive and negative symptoms were analyzed in 115 schizophrenic patients (DSM-III-R criteria) through correlative and factorial analyses, in order to test the positive-negative hypothesis of schizophrenia. The intercorrelative analysis showed high intercorrelations between negative, but low or no correlations between positive symptoms (excepting delusions with hallucinations), which implies that the group of positive symptoms may represent more than one type of symptom complex. This results were confirmed by factorial analysis which identified three distinct clusters of symptoms: the negative syndrome (affective flattening, alogia, abolition-apathy, and anhedonia-asociality), the disorganizative syndrome (positive formal thought disorder, and attentional impairment) and the positive syndrome (delusions and hallucinations). No inverse relations were observed between positive and negative syndromes. This results no support the bipolar-independence hypothesis of the positive-negative distinction in schizophrenia and they need to be confirmed through external validators.

Adult↗
PubMed1990

Cognitive dysfunction in spinal cord injury patients: sensitivity of the Functional Independence Measure subscales vs neuropsychologic assessment.

The Functional Independence Measure (FIM) has been developed to provide an objective measure of functional gains during acute and chronic rehabilitation of disabled individuals, including those with spinal cord injury (SCI). A unique characteristic of the FIM, as compared with other functional scales, is that it reflects abilities in the areas of communication and social cognition. In order to examine the external validity of these subscales, 41 acute SCI patients were evaluated with the FIM just before discharge from acute rehabilitation. The subscale scores were compared to the results of a comprehensive, predominantly motor-free, neuropsychologic battery administered 74.8 +/- 5.3 days postinjury. Evaluation of scatter plots indicated that there were no relationships between any neuropsychologic test results and the discharge FIM social cognition or communication subscale scores. This was attributed to a ceiling effect in the FIM ratings. The results of this study suggest that the FIM cannot be a substitute for comprehensive neuropsychologic assessment in SCI patients.

Adult↗
PubMed1988

Syndromes in developmental dysphasia and adult aphasia.

We have attempted to draw some parallels between syndromes of adult acquired aphasia and of childhood developmental dysphasia. There appear to be two syndromes that are almost exact duplicates in the adults and the children: (a) pure word deafness and verbal auditory agnosia, and (b) aphemia and verbal dyspraxia. Two other syndromes seem to have rather close but not exact counterparts: Broca's aphasia and the phonologic-syntactic deficit syndrome, and transcortical sensory aphasia and the semantic-pragmatic deficit syndrome. There are two dysphasic syndromes, the phonologic production deficit syndrome and the lexical-syntactic deficit syndrome, that do not seem to have close adult counterparts. Neither of these dysphasic syndromes has been defined in adequate linguistic detail, and it is possible that their description may have to be modified when more data become available. Whether these comparisons between dysphasias and aphasias have heuristic value for guiding external validation studies of the clinically defined dysphasic syndromes of preschool children remains to be determined. Our purpose was to formulate hypotheses as to which cerebral systems are likely to be dysfunctional in children with clinically defined dysphasic syndromes. We recognize that the disorders of language acquisition and those of overlearned adult language have fundamental differences, and that plasticity of the child's developing brain introduces further complexities. Nevertheless, it seems reasonable to think that there are constants in brain organization that span all ages. Looking for language deficits common to aphasic adults (whose lesions can usually be delineated with contemporary neuroimaging techniques) and to dysphasic children (in whom there are rarely any neurologic clues) may be a fruitful way to begin to define the cerebral correlates of the children's deficits.

Adult↗
PubMed1989

[Incidence of childhood diabetes in Hungary].

A retrospective epidemiological study using primary data sources and external validation was made to assess the incidence of childhood diabetes (0-14 yr) over a ten-year period. The degree of ascertainment was 96.2 per cent. Age-specific incidence rates increased until puberty with peak incidence in girls at 10 year and in boys at 13 year. There was a seasonal variation of onset with peaks in autumn and winter. The yearly incidence rates showed an increasing trend, the incidence in 1987 (8.7/100,000) was 2.3 times higher than in 1978. The rise in incidence was not continuous, incidence rates were similar in the years 1978-79, 1980-84 and 1985-87, but relatively sharp increases could be observed in 1980 and in 1985 which were mainly due to increases in incidence of the age group 5 to 9 years. Dynamic changes have taken place in the incidence of childhood diabetes in Hungary between 1978 and 1987, but it is not known whether the increases can be regarded as epidemics or parts of a discontinuous trend.

Adolescent↗
PubMedDate not supplied

[Principles of multivariate memory diagnosis].

In this study results from experimental research on aging memory serve as a basis for standardized memory assessment techniques. By analyzing the covariations of nine memory tasks a structural memory model is proposed, which is shown to be invariant across ages 60 to 90. Findings concerning the external validity of the outlined memory model are discussed. Factorial invariance of memory performance is a prerequisite for detecting therapy-induced changes: It is only on the basis of psychometric test procedures, which have been shown to transcend the factors of age and performance level, that comparative evaluations of individual therapy effects are possible.

Aged↗
PubMedDate not supplied

[Evaluation of epidemiological articles published in 2 journals in the area of public health].

The main aim of this study was to assess the quality and quantity of the Mexican epidemiologic production published in two journals: Salud Pública de México (SPM) and Boletín de la Oficina Sanitaria Panamericana (BOSP). A previously accepted criterion was used to qualify a paper as an epidemiologic work. The period of study was eleven years (1975-1985) with 89 classified paper as "epidemiologic reports" (36 of BOSP and 53 of SPM). The variables included: original or revision's report; epidemiologic design; measures employed (frequency, association or potential impact); condition (contagious diseases, chronic-degenerative diseases or physiologic status); use of prevalent cases, incident cases or deaths; internal and external validity; bias' recognition; and number of references. Among the results that stand out are the proportion of cross-sectional designs (51.75), the weight for communicable diseases (36%), the detection of potential bias (65.7%) and the reports without references (30%). The discussion is centered in the main implications of these results when they are used to make decisions in the planning, operation and assessment of health services and in the generation of new epidemiologic knowledge.

Epidemiologic Methods↗
PubMed1988

Single case studies in psychology and psychiatry.

Single-case experimental designs are presented and discussed from several points of view: Historical antecedents, assessment of the dependent variable, internal and external validity and pre-experimental vs experimental single-case designs. In addition, general characteristics of experimental single-case designs are presented along with examples of the most common design types. Visual inspection as well as statistical methods for the evaluation of data are presented. It is argued that single-case experimental designs are well suited for medical research as well as clinical practice. They provide tools for testing causal hypotheses concerning the effects of interventions in the single case.

Clinical Trials as Topic↗
PubMed1986

A method for constructing case-mix indexes, with application to hospital length of stay.

This article presents the methodological development of an index for case-mix adjustment of hospital data exemplified by our construction of an index for studying length of stay. We describe the development and evaluation of this index, including internal and external validation procedures, and show an example of its use in a policy-relevant context by applying it to the analysis of length-of-stay differences between investor-owned and voluntary hospitals. Some advantages of this approach to adjusting for case mix are applicability to many hospital or patient output measurements/diagnostic scheme situations; usefulness in reducing heterogeneity in other case-mix adjustments, e.g., the Diagnosis-Related Group (DRG) approach; interpretation possibilities; production of a single score for each patient/hospital; statistical approach allowing more accurate and reliable interpretation of hospital and patient output measurements, ability to deal with hospital deaths; and consideration of the complete set of secondary diagnoses. We also suggest other possible uses of this approach.

Diagnosis-Related Groups↗
PubMed1986

Television and violent criminal behavior: beyond the Bobo doll.

This study builds on the research concerning television viewing and aggression by extending the external validity, or generalizability, of the dependent variable. We assess the relationship between self-reported television viewing at 8, 10, and 12 years of age and the subsequent commission of a violent criminal act. This study is based on interview data from 48 males incarcerated for violent crimes and 45 nonincarcerated, nonviolent males matched on age, race, and neighborhood of residence during adolescence. Results show that the extent of a respondent's reported television viewing was not, in and of itself, predictive of violent criminal acts. Instead, it was the interaction of heavy doses of television viewing and exposure to either maternal or paternal abuse that related to violent crime. These findings support the efforts of some recent scholars in their attempts to understand why television has a negative effect on only some viewers. The results are discussed in light of the cognitive formulations of neoassociationism, encoding specificity, and the double-dose effect.

Adolescent↗
PubMed1987

The cortisol suppression index and the dexamethasone suppression test in major depression.

The pre- and postdexamethasone cortisol levels are determined at 8 a.m. in 106 depressive patients. The patients are classified according to DSM-III in two categories: minor depression (300.40, 296.82, 309.00) and major depression (296.X2, 296.X3, 296.X4). The cortisol suppression index (CSI) e.g. the ratio of pre- and postdexamethasone cortisol levels is calculated. The clinical relevance of the CSI for major depression is compared to the dexamethasone suppression test (DST). The CSI is significantly (p = 0.018) lowered in patients with major depression as compared to those with minor depression. The CSI depends (r = -0.929) on changes of the postdexamethasone cortisol levels. The DST is more useful as an external validating criterion for major depression than is the CSI. The determination of the CSI is not an asset in the diagnosis of major depression.

Adult↗
PubMed1987

Infant temperament and subject loss due to crying during operant conditioning.

Infants who failed to complete a 2-day operant-conditioning task were compared with a stratified random sample of those who did on measures of infant temperament and several demographic characteristics. A discriminant-function analysis revealed that female infants who cried differed from female infants who did not cry on measures of duration of orienting and latency to approach sudden or novel stimuli. Reliable prediction of crying and noncrying could not, however, be made for males. No sex differences emerged in the incidence of crying or in the number of sessions completed. Partially successful females (i.e., those completing 1 of the 2 sessions) could reliably be discriminated from those who cried during the first session on measures of age at testing and maternal ratings of smiling behavior. The results of this study suggest that, as with habituation studies, subject loss in operant-conditioning studies is influenced by individual differences among the infants which may or may not adversely affect external validity.

Conditioning, Operant↗
PubMed1985

Wechsler Intelligence Tests: do we really have a criterion of mental retardation?

The definition of mental retardation offered by the American Association on Mental Deficiency refers to an IQ of approximately 70 or below. This is identical to the Wechsler criterion of a test performance two standard deviations (SDs) below the population mean. In fact, Wechsler tests have not supplied such a criterion, rather they have deviated from it by anything from .27 to a full SD. Having done without such a criterion for 40 years, we should consider exchanging it for one that is fixed in time and whose external validity is attested to by an accumulated body of evidence.

Child↗
PubMed1979

[The connection between videoanalytic regular measurements of non-verbal behavior and self-assessed mood].

13 manic-depressive patients were examined during a symptom-free interval while under treatment with lithium, and again after a 6-week placebo period. The results are based on a behavioral analysis of video-taped interviews as well as a self-rating of mood with a multidimensional questionnaire (Hecheltjen & Mertesdorf, MSF). This questionnaire was presented on the day of the interviews. The following parameters were examined: 1. Duration of speech activity, 2. Frequency of hand movements accompanying speech, 3. Frequency of discrete body touchings. In order to clarify the interdependency of these behavioral parameters and to obtain an external validation against mood measures we investigated how far these values change when comparing the two examinations. Significant relationships were found between: a) the relative duration of speech activity and the relative frequency of hand movements accompanying speech, b) these two parameters and the mood dimensions "social affection" and "relaxation", whereas the 5% level and barely missed for "activity" and "good mood". A tendency was noted towards a negative relationship with the dimension "anxiety". No connection could be established for the dimensions "fatigue", "depression", "boredom", "anger", "lightheartedness" and "nervousness". The category of discrete body touchings did not show a relation with either of the other behavioral parameters or with the mood dimensions. Finally, we might point out the low sensitivity of the conventional scales for the course evaluation of depression, and the advantage of the behavioral procedure which is sensitive even in the subclinical range. Moreover, the latter approach has a theoretical impact on the fundamental question of the physiological basis of manic-depressive illness.

Affect↗
PubMed1981

Some examples for the possibilities and limitations of pharmacoelectroencephalography as a method in clinical pharmacology.

Pharmacoelectroencephalography is a new methodology using clinical pharmacological research designs and the method of electroencephalography, and its parametrisation by computer analysis. Pharmacoelectroencephalography is considered to be the most sensitive method for describing drug effects on the human CNS on a functional electrophysiological level. There is an unrevoked hypothesis that all drugs effecting the CNS do reflect those effects in well designed, well conducted and well analysed pharmacoelectroencephalographical studies. On the other hand, if a systematic pharmacoelectroencephalographical study does not verify an effect, then, according to this hypothesis, the drug does not have functional effects on the CNS. The EEG however, is not a direct indicator of toxic effects on the central nervous system. Therefore, from lack of pharmacoelectroencephalographical effects it cannot be concluded that a drug has no toxic effects on the CNS. Pharmacoelectroencephalography has been used to show the efficacy of drugs on a functional CNS level, to establish dose- and time relationships of CNS active drugs, and to suggest dosage levels for therapeutic use and time intervals for their application. Furthermore, with pharmacoelectroencephalography a drug's influence on vigilance and vigilance regulation can be described, and substances can - within certain limits - be screened for their eventual psychotropic properties. It will be demonstrated that pharmacoelectroencephalography provides a sensitive and very useful method for clinical pharmacology, without which the development of new drugs is nowadays almost impossible. However, there are strict limitations for the use of this method and the interpretation of its results: The EEG is not sufficiently validated externally. It is an experimental model based on the electrical activity of the awake brain. The meaning of the changes in this activity is almost completely unknown. Although it has been possible to classify a high number of psychotropic drugs into a predetermined five drug class system on the basic of their EEG effects (19) and although certain drugs have been found whose psychotropic properties were predicted from the EEG (26), it is not possible to describe a drug's psychotropic properties by means of the EEG. The EEG indicates CNS effects, but not necessarily psychotropic properties, even though useful information can be obtained at very early stages in a drug's development, about its influence on vigilance and the organization of the brain's electrical activity.

Adrenergic beta-Antagonists↗
PubMed1995

[Status of the integration of the antileprosy campaign in the general health services in Senegal].

The survey on the integration of leprosy control in Senegal with the general health services has shown that the level of integration varies according to the services offered. Both strong and weak points have been detected and it is therefore advisable to reinforce the findings that are positive and to seek solutions to the problems. 82.1% of the male nurses in charge of health center included in the survey have already had to refer suspected cases of leprosy to the Leprosy Specialist for confirmation. In 85.7% of the cases, it is the Nurses-Persons in Charge who administer the supervised dose of multidrug therapy. The external validity of this study is problematic; nevertheless, these results could still draw the attention of administrators, decision-makers, and other persons of influence to the problems that could curb the integration of leprosy control with the general health services.

Drug Therapy, Combination↗
PubMed1995

Human population changes caused by hazardous waste.

Evidence for health effects at hazardous waste sites is scanty, largely because of problems with the studies and not because effects are not present. A few, well-designed studies with a priori hypotheses have shown excesses of birth defects, low birth weight children, liver damage, skin rashes, mood disorders, narcotic symptoms, and respiratory problems in populations around certain hazardous waste sites. Each of these studies have their own limitations in terms of internal and external validity. Recent advances in biomarker epidemiology hold promise for future studies of this important world wide problem.

Biomarkers↗
PubMed1994

Can observational studies replace or complement experiment?

The therapeutic effects of interventions in patients with rheumatoid arthritis (RA) are frequently modest. In the assessment of treatments effects, variability due to a variety of sources causes problems that are best controlled by randomized clinical trials. Currently most trials give only a short term picture of RA, a chronic disease whose outcome is multidimensional. Inclusion criteria of clinical trials are frequently very strict, raising concern about the external validity of the results. More longterm data is needed to guide clinical practice. Observational studies may contribute to the body of evidence, but have inherent shortcomings. They are liable to bias and supply weaker evidence. There must be creative development of trial designs suitable for evaluating longterm outcomes. Such trials may include many of the positive features of observational studies, but should not omit the principles of randomization and controlled comparison.

Antirheumatic Agents↗