Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “instrumental variable”

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

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

At least 397 records · Page 22Linked to original sources

The stereotypy analysis: an instrument for examining environmental variables associated with differential rates of stereotypic behavior.

The Stereotypy Analysis, a means of analyzing environmental variables associated with differential rates of stereotypic behavior, was conducted with five persons having moderate to profound developmental disabilities. The process involves partial-interval recording of the occurrence of targeted behaviors and the presence/absence of specific environmental events. The Stereotypy Analysis was able to detect environmental events associated with stereotypic responding for 3 of the 5 subjects. Based on the results of the Stereotypy Analysis, indicated and not-indicated interventions were implemented for two subjects. The data obtained using the Stereotypy Analysis were useful in determining effective interventions for those subjects. Providing activities and prompts every 15 s, later faded to every 30 s, reduced handmouthing from a mean of 40% of intervals to 13% for one subject. Providing prompts every 30 s to engage in an activity decreased body rocking from 60% to 15% for the other. Effects for both interventions were replicated using A-B-A-B designs. The not-indicated intervention was unsuccessful for one subject; it suggested multiple control of the behavior for the other. Implications for behavioral theory and practice are discussed.

Adult↗

Continuing professional education and interacting variables affecting behavioral change in practice: instrument development and administration.

BACKGROUND: Instruments were developed to measure variables identified by Cervero that evaluate the complex processes and effectiveness of continuing professional education. METHOD: Content validity was established with a panel of experts. Four studies were conducted to determine reliability. Data were merged to conduct factor analysis. RESULTS: Reliability was confirmed across studies using Cronbach's alpha. Stability was confirmed in a test-retest study. Factor analysis confirmed instrument items measure the concepts of Cervero's Model. CONCLUSION: The reliable and valid instruments may be useful for continuing education and staff development nurses to measure the effectiveness of education on behavioral change in practice.

Education, Nursing, Continuing↗

Relative error (variability) associated with an improved instrument for measuring gingival crevicular fluid.

This investigation was undertaken to compare the variability in a new Periotron model 6000 to the variability in the previous Periotron model 600 and to the variability of the ninhydrin area method (NAM) for measuring quantities of fluid collected on filter paper strips. A Hamilton microliter syringe was used to deliver normal human serum to filter paper strips. Strips receiving varying quantities were randomly and blindly assigned to Periotron models 6000 and 600 until 10 strips containing each of 0.15, 0.30, 0.45, 0.60, 0.75, 0.90 and 1.05 microliter had been read using model 6000 and 10 strips containing each of 0.15, 0.30 and 0.45 microliter had been read using model 600. All strips were subsequently read using the NAM. The entire procedure was repeated using distilled water containing 0.1% methyl green. Coefficients of variation (CV) were computed for all sets of data. In all cases the CVs for the Periotron 6000 were significantly smaller than those for the Periotron 600 or the NAM. Pooled estimates of CVs (0.15-0.45 microliter) for the Periotron models 6000 and 600 were 0.054 and 0.116, respectively, (P less than or equal to 0.005) with serum and 0.059 and 0.095, respectively, (P less than or equal to 0.05) with distilled water containing 0.1% methyl green. Pooled estimates of CVs (0.15-1.05 microliter) for the Periotron model 6000 and the same strips subsequently measured with the NAM were 0.046 and 0.069, respectively, (P less than or equal to 0.005) with serum and 0.055 and 0.076, respectively, (P less than or equal to 0.001) with distilled water containing 0.1% methyl green.(ABSTRACT TRUNCATED AT 250 WORDS)

Equipment Design↗

Endodontics: Part 7. Preparing the root canal.

Research into root canal preparation has led to significant changes in instrumentation techniques. Hand files should be manipulated by the balanced-force technique. Recent designs of endodontic instruments have variable tapers giving improved shaping ability. Nickel-titanium rotary instruments will rapidly and safely open the main root canals creating deep space to permit full permeation of irrigant solutions. Practitioners considering changing their endodontic technique are advised to attend hands-on practical courses to gain competence before using these in clinical practice.

Anti-Infective Agents, Local↗

Quality of life in older people: a structured review of generic self-assessed health instruments.

OBJECTIVE: To review evidence relating to the measurement properties of multi-item generic patient or self-assessed measures of health in older people. METHODS: Systematic literature searches to identify instruments. Pre-defined criteria relating to reliability, validity and responsiveness. RESULTS: 122 articles relating to 15 instruments met the inclusion criteria. The most extensive evidence was found for the SF-36, COOP Charts, EQ-5D, Nottingham Health Profile (NHP) and SIP. Four instruments have evidence of both internal consistency and test-retest reliability--NHP, SF-12, SF-20, SF-36. Four instruments lack evidence of reliability--HSQ-12, IHQL, QWB, SQL. Most instruments were assessed for validity through comparisons with other instruments, global judgements of health, or clinical and socio-demographic variables. Five instruments lack evidence of responsiveness--GQL, HSQ-12, IHQL, QLI and QWB. CONCLUSION: There is good evidence for reliability, validity and responsiveness for the SF-36, EQ-5D and NHP. There is more limited evidence for the COOP, SF-12 and SIP. The SF-36 is recommended where a detailed and broad ranging assessment of health is required, particularly in community dwelling older people with limited morbidity. The EQ-5D is recommended where a more succinct assessment is required, particularly where a substantial change in health is expected. Instrument content should be assessed for relevance before application. The concurrent evaluation of generic instruments in older people is recommended.

Age Factors↗

The reliability of laryngoscope lights.

The aim of this study is to compare the brightness of laryngoscope light between instruments, and the variability within the same instrument. A secondary aim is to compare the light from a reusable laryngoscope with a single use design. Testing equipment was constructed which provided a qualitative measure of light output from laryngoscopes. Anaesthetists assessed the minimum acceptable brightness for intubation using the intubating mannikin and a variable brightness laryngoscope. Laryngoscopes in anaesthetic rooms around the hospital were then tested repeatedly, and the results were compared to the anaesthetists' opinions. There was considerable intersubject and intrasubject variation in the reusable design, often failing to satisfy the minimum brightness. The single use blades were found to be brighter and more reliable than reusable blades.

Disposable Equipment↗

Available instruments for research on prenatal attachment and adaptation to pregnancy.

Research, clinical practice, and cost-effective nursing care are all interrelated and are dependent on the use of reliable and valid instruments. Critical to the success of any research study is the choice of instruments to measure key variables. Locating existing instruments for use in nursing research is an important but often labor-intensive activity. This article provides a review of some available instruments that measure two key clinical phenomena particular to the prenatal period: maternal-fetal and paternal-fetal attachment and adaptation to pregnancy. Examples of specific nursing studies that utilize these instruments are presented along with an assessment of the instruments' reliability and validity. Both nurse researchers and clinicians can benefit from this review of selected instruments used during the prenatal period.

Adaptation, Psychological↗

Mapping variables.

This paper describes Mapping Variables, the principal technique for planning and constructing a test or rating instrument. A variable map is also useful for interpreting results. Modest reference is made to the history of mapping leading to its importance in psychometrics. Several maps are given to show the importance and value of mapping a variable by person and item data. The need for a critical appraisal of maps is also stressed.

Maps as Topic↗

[Caregiver burden in relatives of persons with schizophrenia: an overview of measure instruments].

The high prevalence and chronic evolution of schizophrenia are responsible for a major social cost. The adverse consequences of such psychiatric disorders for relatives have been studied since the early 1950s, when psychiatric institutions began discharging patients into the community. According to Treudley (1946) "burden on the family" refers to the consequences for those in close contact with a severely disturbed psychiatric patient. Grad and Sainsbury (1963) and Hoenig and Hamilton (1966) developed the first burden scales for caregivers of severely mentally ill patients, and a number of authors further developed instruments trying to distinguish between "objective" and "subjective" burden. Objective burden concerns the patient's symptoms, behaviour and socio-demographic characteristics, but also the changes in household routine, family or social relations, work, leisure time, physical health.... Subjective burden is the mental health and subjective distress among family members. While the first authors referred to those problems which are deemed to be related to, or caused by the patient, Platt et al. (1983) tried to distinguish between the occurrence of a problem, its alleged aetiology, and the perceived distress, when developing the SBAS questionnaire. These authors also proposed separate evaluations of behavioral disturbance and social performance by relatives, and a report of extra-disease stressors in family life. The SBAS is actually the most complete, but also complex instrument for evaluating burden in caregivers. Since 1967 Pasamanick and others proposed questionnaires for burden evaluation in relatives of schizophrenic patients. Relatives may be included in specific psychoeducational programs, but few of these programs have been evaluated in terms of caregiver burden. The theoretical approach in schizophrenia was not different from that one adopted in mentally ill population. Some instruments were validated first in a mentally ill group and then adapated for schizophrenic population. This paper describes the available data about intruments measuring caregiver burden in relatives of schizophrenic patients. Measures are summarized according to purpose, content and psychometric properties. Sixteen instruments have been collected from the litterature (1955-2001), and 2 instruments developed for relatives of mentally ill have also been taken into account. A group of 5 instruments focuses on the measurement of behavioural disturbance in persons with schizophrenia as perceived by their family members. Eleven scales include behavioural disturbance in a more complete decription of objective burden. Thirteen questionnaires also report the subjective distress in caregivers. One instrument has been developed in french language. Few of these instruments have been developed from a verbatim and really describe the caregiver's point of view. Most of them rely on experts point of view or on previously published studies. The content and domains explored by these instruments are variable. The psychometric properties are poorly documented for a number of them and no information is published about responsiveness. Some validated instruments are the Perceived Family Burden Scale (PFBS) the Involvement Evaluation Questionnaire (IEQ) and the Experience of Caregiving Inventory (ECI). In past studies, researchers more or less agreed about the dimensions that comprise the family burden. There was less agreement with regard to the definition of objective and subjective burden, and quite no agreement about the theoretical approach to the concept of burden. The evaluation of behavioural disturbance should now be excluded from the objective burden dimension. It is a specific domain, both objective and subjective, which can be described as a stressor in the stress-appraisal-coping model. A good approach of this domain can be found in the PFBS. It comprises 24 items and the principal components analysis produces 2 factors ("active" and "passive"), explaining 35% of the variance, with good consitency and acceptable test-retest reliability. The evaluation is both objective (presence or absence) and subjective (induced distress). The Behavior Disturbance Scale (BDS) may also be taken into account, although it is less validated. This scale derives from the SBAS, modified as a self-questionnaire, with both objective and subjective evaluations of all items. The concept of burden was recently modified in a new theoretical approach by Schene, when developing the IEQ. According to this author, the burden scale is supposed to exclude stressors (patient's behaviors), as well as outcome variables (distress or psychological impairment in caregiver). The "caregiving consequences" section comprises 36 items, which focus on the subjective aspects of the caregiver's experience. Principal component factor analysis generates 4 factors which explain 45% of the variance: tension, supervision, worrying, urging. The overall caregiving score substantially explains the connection between patient, caregiver, relationship variables and the caregiver's distress. This scale is a valid and simple instrument for caregiving eveluation The ECI also introduces a new approach of caregiving and rejects the notion of burden. The 66 item version is composed of 10 factors (8 "negative" and 2 "positive") with good internal consistency. The introduction of two positive factors (rewarding personal experiences, good aspects of the relationship with the patient) might be the basis of a useful outcome measure for intervention aimed at promoting caregiver well-being. Nevertheless, the authors fail to develop an overall score that includes these factors, and focus on the negative dimensions as predictors of morbidity and well-being. None of the variables included in the regression model explain a significant percent of the variance of the ECI positive score. None of these instruments was employed for evaluating programs or treatments, even psychoeducational programs for caregivers. This may be partly due to the lack of data about sensitivity to change. No instrument is now available for evaluating therapeutics from the caregiver's point of view. Developing such an instrument is necessary, in view of the increasing role of families in care for schizophrenic patients. These data and the review of the literature leeds us to propose the development of a self-administered questionnaire for evaluating subjective health-related quality of life in caregivers of schizophrenic patients. The instrument should be developed from the caregiver's point of view and be derived from qualitative interviews with relatives of patients suffering from schizophrenia. It's responsiveness should be documented before inclusion in clinical trials or evaluation of psychoeducational programs. We are now working with the National Union of Friends and Families of Patients to validate an instrument in french language.

Caregivers↗

Treatment of thoracolumbar burst fractures with variable screw placement or Isola instrumentation and arthrodesis: case series and literature review.

BACKGROUND: The controversy of burst fracture surgical management is addressed in this retrospective case study and literature review. METHODS: The series consisted of 40 consecutive patients, index included, with 41 fractures treated with stiff, limited segment transpedicular bone-anchored instrumentation and arthrodesis from 1987 through 1994. RESULTS: No major acute complications such as death, paralysis, or infection occurred. For the 30 fractures with pre- and postoperative computed tomography studies, spinal canal compromise was 61% and 32%, respectively. Neurologic function improved in 7 of 14 patients (50%) and did not worsen in any. The principal problem encountered was screw breakage, which occurred in 16 of the 41 (39%) instrumented fractures. As we have previously reported, transpedicular anterior bone graft augmentation significantly decreased variable screw placement (VSP) implant breakage. However, it did not prevent Isola implant breakage in two-motion segment constructs. Compared with VSP, Isola provided better sagittal plane realignment and constructs that have been found to be significantly stiffer. Unplanned reoperation was necessary in 9 of the 40 patients (23%). At 1- and 2-year follow-up, 95% and 79% of patients were available for study, and a satisfactory outcome was achieved in 84% and 79%, respectively. These satisfaction and reoperation rates are consistent with the literature of the time. CONCLUSIONS: Based on these observations and the loads to which implant constructs are exposed following posterior realignment and stabilization of burst fractures, we recommend that three- or four-motion segment constructs, rather than two motion, be used. To save valuable motion segments, planned construct shortening can be used. An alternative is sequential or staged anterior corpectomy and structural grafting.

Adolescent↗

Managers' leadership and critical care nurses' intent to stay.

BACKGROUND: Cyclical fluctuations in turnover of critical care nurses are a large and complex problem. Managers' leadership characteristics may be a determinant of critical care nurses' intent to stay in the job. OBJECTIVE: To examine the direct and indirect effects of nurse-managers' characteristics of power, influence, and leadership style on critical care nurses' intent to stay in the nurses' employment positions. METHODS: The sample was 255 staff nurses in intensive care units at 4 urban hospitals. Established instruments with sound reliability and validity were used to assess the predictor, intervening, and outcome variables. Path analysis was used to examine the relationships in a conceptual model of intent to stay. RESULTS: The model explained 52% of the variance in intent to stay, and managers' characteristics were significant at each stage. Managers' position power and influence over work coordination had a direct link to intent to stay; structuring expectations and consideration contributed indirectly through the variables of instrumental communication, autonomy, and group cohesion. Instrumental communication, autonomy, and group cohesion decreased job stress and thus increased job satisfaction. Job satisfaction was directly linked with intent to stay. CONCLUSIONS: Inclusion of nurse-managers' characteristics explained more variance in intent to stay than did previous models. Managers with leadership styles that seek and value contributions from staff, promote a climate in which information is shared effectively, promote decision making at the staff nurse level, exert position power, and influence coordination of work to provide a milieu that maintains a stable cadre of nurses.

Adult↗

[Comparative study of two latest generation flexible ureterorenoscopes].

INTRODUCTION AND OBJECTIVES: Miniaturization and development of flexible instruments have led to the development of flexible ureterorenoscopy. The objective of this study was to compare the capacities of active deflection of two latest generation flexible ureterorenoscopes and to evaluate alteration of deflection and flow of irrigating fluid in the presence of instruments in the operating channel. MATERIAL AND METHODS: Two ureterorenoscopes were evaluated in this study. The Karl STORZ Flex-X and the ACMI DUR-8 Elite. Comparison of deflection movements was performed ex situ by super-imposing all active movements of the two ureterorenoscopes. Alteration of deflection was performed by alternately placing an extraction or fragmentation instrument of variable dimensions in the operating channel. Alteration of flow was also assessed in the presence of the same instruments. RESULTS: The ex situ deflection capacities of the DUR-8 Elite flexible ureterorenoscope were more extensive than those of the Flex-X, but it was more complicated to manipulate. Alterations of deflection and flow of irrigation fluid were comparable for the two ureterorenoscopes. CONCLUSION: On the basis of these data, we can confirm that the two latest generation ureterorenoscopes present comparable capacities, but different functioning modalities. We therefore recommend that each operator test the two ureterorenoscopes to become familiar with their manipulation. Other studies are necessary to evaluate the optical properties, ease of use in clinical practice and fragility of these new ureterorenoscopes.

Equipment Design↗

Transient forces generated by projectiles on variable quality mouthguards monitored by instrumented impact testing.

OBJECTIVES: (a) To determine the force-time trace that occurs when a spring mounted simulated upper jaw is impacted; (b) to examine if mouthguards of variable quality have significant influence on such force-time traces; (c) to attempt to relate physical events to the profile of the force-time traces recorded. METHODS: A simulated jaw, consisting of ceramic teeth inserted into a hard rubber arch reinforced with a composite jawbone, was fitted with various mouthguards as part of a previous round robin study. A clinical assessment distinguished good, bad, and poor mouthguards, and these were each fitted to the jaw, which was then submitted to instrumental impact tests under conditions expected to produce tooth fractures. The force-time trace was recorded for such impact events. RESULTS: The spring mounting method caused two distinct peaks in the force-time trace. The initial one was related to inertia effects and showed an increase in magnitude with impactor velocity as expected. The second peak showed features that were related to the differences in the mouthguards selected. CONCLUSIONS: The use of a force washer within a conical ended impactor enabled force-time traces to be recorded during the impact of a spring mounted simulated jaw fitted with mouthguards of variable quality. The spring mounting system causes an initial inertial peak followed by a second peak once the spring mount has fully compressed. Good fitting guards, which keep most teeth intact, result in high stiffness targets that in turn generate high reaction forces in the impactor. If the spring mounting is omitted, the two peaks are combined to give even higher reaction forces. The force-time trace offers some potential for assessing both overall mouthguard performance and individual events during the impact sequence. Mouthguards with good retention to the jaw remained attached during the impact event and helped to preserve the structural integrity of the target. This in turn developed high forces in the second part of the force-time trace. Guards that detached during impact and allowed tooth fractures showed lower forces in the second part of the test. The force profile measured offered some quantitative support to, and agreement with, the observed clinical quality of the mouthguards.

Athletic Injuries↗

An empirical test of alternate theories of anger in early adolescents.

BACKGROUND: Anger is an especially important phenomenon to understand in early adolescents. While many explanatory theories of state anger can be applied to early adolescents, few, if any, researchers have attempted to test these theories in this age group. OBJECTIVE: To test three theories explaining state anger vis-a-vis each other using hierarchical analysis of sets. METHOD: This was a theory-testing study with a complex correlational design. A total of 141 adolescents aged 12 to 14 years responded to the State Anger Scale and instruments measuring variables linked to stress theory (perceived stress and primary appraisal), differential emotion theory (depression and state anxiety), and trait theory (trait anger and hostility), that were randomly ordered across instrument packets. RESULTS: Using hierarchical analysis of sets, the results indicated that the sets of variables used to test all three theories explained a statistically significant proportion of variance in state anger when entered first in the analysis. Comparatively, the trait theory variables explained more variance in state anger when entered first (41%) in the analysis than did the emotion theory variables when entered first (31%) in the analysis or the stress theory variables when entered first (21%) in the analysis. CONCLUSIONS: The stress theory, the differential emotion theory, and the trait theory all provided theoretically sound and relevant explanations of state anger for early adolescents. However, the trait theory provided the most powerful explanation.

Adolescent↗

Assessing the quality of life--a study in newly-diagnosed breast cancer patients.

Quality of life (QL) assessment is an increasingly important component of clinical research, especially with cancer patients. The literature strongly supports the view that QL should be assessed by the patient rather than the clinician. While clinical parameters such as performance status or toxicity ratings may bear some relationship to QL, they are not a substitute for its measurement. In spite of these observations, clinicians have been reluctant to accept the need for patient-rated measures of QL. In this paper, data from a sample of 109 newly-diagnosed breast cancer patients were used to examine the relationship between expert-rated measures and a patient-rated measure of QL; to determine whether the Cancer Rehabilitation Evaluation System (CARES), an instrument for assessing the rehabilitation needs of cancer patients, is a measure of QL; to explore whether there are any medical, social or demographic variables which the clinician can use to predict how patients assess their QL; and to determine which variables (expert-rated scales, medical, social or demographic variables, or rehabilitation needs) have the most effect on how patients evaluate their QL. In this sample, patient ratings of QL were widely distributed and were only moderately correlated with the expert-rated Karnofsky Performance Status (r = 0.53) and Global Adjustment to Illness Scale (r = 0.59). In addition, there were no significant correlations between important clinical variables (axillary node status, type of surgery, receipt of chemotherapy) and patient-rated QL. Among the clinical variables and instruments studied, the Global CARES score demonstrated the best correlation (r = -0.74) with the patient-rated assessment of QL. A stepwise multiple linear regression procedure was performed with QL as the dependent variable in order to identify which factors accounted for the most variance in patient assessment of QL. The potential predictor variables used in this procedure were chosen from among those that would be available to a clinician. The Global CARES score was the best single predictor of QL, accounting for 55% of the variance, followed by Karnofsky Performance Status, the Medical Interaction and Sexual summary scales of the CARES, and the patient's educational status. Data from the CARES provided additional descriptive information about the type and frequency of rehabilitation problems experienced by these patients in relation to their ratings of QL.(ABSTRACT TRUNCATED AT 400 WORDS)

Activities of Daily Living↗

Healthy aging among inner-city men.

OBJECTIVE: Until now, prospective studies of aging have begun with 50- to 60-year olds, not adolescents. Premature deaths, childhood variables, and alcohol abuse have been often ignored. So has positive aging. As people live longer, gerontology needs to understand the determinants of health as well as illness in the later years. METHOD: The present study follows a cohort of adolescent boys (332 inner-city youths) for 60 years or until death. Complete physical exams were obtained every 5 years and psychosocial data every 2 years. Predictor variables assessed prior to age 50 include six variables reflecting uncontrollable factors--parental social class, environmental strengths, number of family problems, major depression, ancestral longevity, and premorbid physical health at age 50--and six variables reflecting (at least some) personal control: alcohol abuse, smoking, marital stability, body mass index, coping mechanisms, and education. The four outcome variables chosen to assess healthy aging at 70 reflected both "mind" and "body." They included objectively assessed variables (death and/or disability prior to 70, and objective mental health) and two subjectively assessed variables (perceived instrumental activities of daily living and life enjoyment). RESULTS: Multivariate analysis suggested that positive aging at 70 could be predicted by variables assessed prior to age 50. More hopeful still, if the six variables under some personal control were controlled, depression was the only uncontrollable variable that affected the quality of subjective and objective aging. CONCLUSIONS: First, we may have greater personal control over our biopsychosocial health after retirement than previously recognized. Second, in this cohort, psychiatric rather than sociological predictors appeared more important.

Adolescent↗