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 739 records · Page 41Linked to original sources
PubMed1997

Clinical outcome measures and rating scales in multiple sclerosis trials.

In this review, we analyzed clinical outcome measures used in multiple sclerosis (MS) clinical trials in which the primary goal is to slow or arrest progression of disease. In addition, we examined rating scales that quantify symptomatic complications of MS (for example, spasticity) and the current role of magnetic resonance imaging in MS treatment trials. Each proposed scale has advantages and deficiencies, and none meets all the criteria for an ideal outcome measure. The validity of trial design may be improved by using combinations of selected components of current scales as well as new instruments targeted to specific variables (such as motor strength). Symptom-specific rating scales are most appropriately used in trials of symptomatic therapeutic strategies for MS. Until serial magnetic resonance imaging changes are definitely known to predict long-term impairment and disability in patients with MS, clinical outcome measures will remain the primary means of assessing therapeutic efficacy in phase III clinical trials.

Clinical Trials, Phase III as Topic↗
PubMedDate not supplied

[Family dynamics: sleep quality of women caregivers of family members with Alzheimer disease].

This replication study/Riccio 1996) sets out to explore the Quality of sleep of 34 women primary caregivers of Alzheimer's Disease patients at home. A descriptive, correlational and longitudinal design has been used. Key aspects considered were the quality of nocturnal sleep, the daytime sleepiness, the hours of caring, the educational level, the employment, the time for personal needs and the levels of depression and anxiety. After an initial interview, the caregivers were asked to fill in several instruments to measure the variables taken into consideration. The caregivers presented poor quality in their sleep. Quality of nocturnal sleep was negatively affected by more hours of caring (p < 0.02), high depression and anxiety levels (p < 0.05 and 0.007 respectively). The education level, the employment outside home and the amount of time spent for themselves, positively affected the quality of sleep (p < 0.01, 0.04, 0.05 respectively). This research pointed out that hours of caring, directly and indirectly, cause sleep problem to Alzheimer's Disease caregivers enhancing nursing care implications.

Adult↗
PubMed2001

Variability components of standard automated perimetry and frequency-doubling technology perimetry.

PURPOSE: To evaluate and compare intra- and intertest variability components for both standard automated perimetry (SAP) and frequency-doubling technology (FDT) perimetry in a small group of normal individuals and patients with glaucoma. METHODS: The method of constant stimuli (MOCS) was used to examine matched test locations with both SAP and FDT perimetry stimuli in a group of eight normal individuals and seven patients with glaucoma. Subjects were tested weekly at three predetermined visual field loci for 5 consecutive weeks. Frequency-of-seeing (FOS) curves were generated and used to quantify threshold sensitivity (50% seen on FOS, in decibels), intratest variability (FOS interquartile range, in decibels), and intertest variability (interquartile range of weekly repeated threshold determinations, in decibels). RESULTS: In patients with glaucoma, SAP intra- and intertest variabilities were found to increase with sensitivity reductions, as previously reported. FDT perimetry revealed that both intra- and intertest variability components did not appreciably change with reductions in sensitivity. With the measurement scales used in this investigation, both intra- and intertest variability components were significantly greater for SAP than for FDT perimetry (P < 0.001 and P = 0.003, respectively). Intratest variability exceeded intertest variability for both SAP (P = 0.001) and FDT perimetry (P < 0.001). CONCLUSIONS: For both SAP and FDT perimetry, variability occurring within a single test session contributed more to total variability than between-session variability. When the measurement scales available on commercial instrumentation were used, FDT perimetry exhibited significantly less variability than SAP, especially within regions of visual field sensitivity loss. FDT perimetry therefore shows promise as an effective test for detecting progressive glaucomatous visual field loss, although prospective longitudinal validation is still required to determine sensitivity to change.

Adult↗
PubMed1992

Signal delivery/real ear measurement system for hearing aid selection and fitting.

This report describes a signal delivery/real ear measurement system for application in the hearing aid selection and fitting process. This signal delivery/real ear measurement system provides a means for quantifying a listener's auditory characteristics (e.g., thresholds, loudness discomfort levels) in a manner that is compatible with electroacoustic measures of hearing aid performance. The signal delivery/real ear measurement system consists of a button-type hearing aid receiver coupled to the listener's personal earmold, and a probe tube microphone system to measure the signal level within the occluded ear canal. This signal delivery/real ear measurement system was used to measure detection thresholds and loudness discomfort levels in severe/profoundly hearing-impaired school-age children, with results indicating good test-retest reliability in behavioral responses. The findings presented in this report relate to the intersession electroacoustic variability associated with this instrumentation. In addition, the potential application of this or a similar system for measuring real ear to 2-cc coupler difference values is illustrated and discussed.

Acoustic Impedance Tests↗
PubMed1992

Effects of ketanserin on blood pressure variability in conscious spontaneously hypertensive rats.

Computerized analysis of blood pressure (BP) was used to study for the effects of ketanserin (Ket) on BP and blood pressure variability (BPV). Rats were instrumented chronically and BP was sampled every 4 ms by a computer from 2:00 to 14:00. Then a single dose of Ket (3 mg.kg-1) was given iv. BP and heart period (HP) were recorded for the next 30 min. The results showed that Ket lowered systolic BP (26.7 kPa to 21.1 kPa), diastolic BP (20.5 kPa to 15.8 kPa), and systolic BPV (1.3 kPa to 0.94 kPa). Otherwise, a positive relationship was found between antihypertensive effects of Ket and BPV. These findings may be of importance in antihypertensive treatment.

Animals↗
PubMedDate not supplied

[Psychiatric disorders in elderly patients with physical problems. Critical review of the recent literature].

The authors review some studies of the recent psychiatric literature on the elderly medically ill. The large variability in setting, screening instruments, and diagnostic criteria makes comparison of results somehow difficult and probably accounts for the differences in prevalence rates. We also outline methodological issues relating to the standardization of screening instruments and to special features ("pseudodementia", "masked" depression) of psychiatric disorders in old age.

Aged↗
PubMed2004

Fibromyalgia in men: comparison of psychological features with women.

OBJECTIVE: To describe possible differences in psychological factors in men compared to women with fibromyalgia syndrome (FM). METHODS: Forty men and 160 women with FM were evaluated for anxiety, stress, and depression measured by ordinal scales and validated psychological instruments. Clinical and psychological variables were evaluated by a protocol. RESULTS: Both men and women scored high in the psychological variables measured but the results were not significantly different between them. CONCLUSION: There was no significant difference between men and women with FM in their psychological status.

Adaptation, Psychological↗
PubMed1988

Effect of progressive relaxation on dyspnea and state anxiety in patients with chronic obstructive pulmonary disease.

The symptom of dyspnea and the associated anxiety is a primary concern of millions of patients with chronic obstructive pulmonary disease (COPD). An experimental study was conducted of 20 outpatients with COPD to measure the effect of progressive muscle relaxation (PMR) on dyspnea and anxiety. Patients were divided into a treatment group (n = 12) and a control group (n = 8). Patients in the treatment group underwent four weekly sessions of live PMR plus daily home practice with taped instructions. The effect of the independent variable, PMR, was measured during each session and at the end of 4 weeks. Measurements were made before and after treatment of the dependent variables, dyspnea and anxiety. Instruments used were Spielberger's State Anxiety Inventory for anxiety and a 20 cm visual analogue scale for dyspnea. Heart rate (HR), respiratory rate (RR), forced vital capacity (FVC), and forced expiratory volume in 1 second (FEV1) were also measured. Data analysis was done by using two-tailed t tests and Pearson's correlation coefficient. Reductions in anxiety and dyspnea were positively correlated during each session (r = 0.37) and at the end of 4 weeks (r = 0.60). PMR was shown by t tests to be more effective than the control in reducing dyspnea (p = 0.04), anxiety (p = 0.001), RR (p = 0.000), and HR (p = 0.05) during each session but only RR (p = 0.04) at the end of the 4-week period. Dyspnea and RR were correlated positively during each session (r = 0.21). Dyspnea and state anxiety were correlated positively at the end of 4 weeks with RR (r = 0.62) and HR (r = 0.50).

Adult↗
PubMed1978

Physician participation in state Medicaid programs.

Medicaid requires that physicians who accept Medicaid reimbursement for treating a patient agree to accept its payment as payment in full. Policy instruments under Medicaid's control are both levels of reimbursement and various administrative burdens imposed on physicians by the program. A model depicting the physician's participation decision is developed, and predictions from the comparative statics analysis are discussed. Data came from a 1975--76 survey of fee-for-service physicians. The results indicate that high fee schedules and low administrative burdens are ways to stimulate physician involvement with Medicaid patients. Results on the Medicaid policy instruments and other explanatory variables on the whole lend support to the model of physician behavior proposed earlier in the paper.

Economics, Medical↗
PubMedDate not supplied

Network structure, social support, and psychological outcomes of pregnancy.

Fifty primigravid fathers and mothers responded to an investigator-developed tool that measured social network characteristics and perceived social support during the third trimester of pregnancy. At six weeks postpartum, these same parents completed the Postpartum Self-evaluation Questionnaire (PSQ) (Lederman, Weingarten, & Lederman, 1981). Relationships among network factors, perceived support, and postpartum outcomes were documented for four of the seven PSQ scales. A greater percentage of relatives in the network and more overlap with the spouse's network were important factors associated with positive postpartum outcomes for men, but not for women. Emotional and instrumental support were important variables in explaining six-week postpartum outcomes, whereas information and appraisal support were not significant variables at this time. Men scored lower than women on the PSQ scale measuring confidence in ability to cope with the tasks of parenting.

Adaptation, Psychological↗
PubMed1979

Cognitive aspects of suicidal behavior.

Recent efforts to quantify various aspects of suicide ideation are described. The Suicide Intent Scale, Hopelessness Scale, and the Scale for Suicide Ideation all assess components of the individual's suicidal ruminations. Hopelessness seems to account for the bulk of the relationship between depression and suicidal intent. The Scale for Suicide Ideation seems to show promise as a predictive instrument, as a dependent variable in research on treatment efficacy, and as a tool for clinical assessment of suicide potential. Implications for further research and clinical practice are discussed.

Cognition↗
PubMedDate not supplied

The development of an instrument to measure social support.

This article describes the development of a new instrument, the Norbeck Social Support Questionnaire, designed to measure multiple dimensions of social support. Based on Kahn's (1979) conceptual definitions of social support and definitions from network theory (Barnes, 1972), the instrument has three main variables--Total Functional, Total Network, and Total Loss--each with three subscales. Graduate and undergraduate nursing students were used as subjects in this phase of testing, which established high levels of test-retest reliability and internal consistency. The social desirability response bias was ruled out, and moderate levels of concurrent validity were found. Additional work to establish construct validity is needed. Two groups of students were compared to study the normative trend for this population, and differences were minimal except for recent losses and aid, reflecting the actual situations of the two groups.

Adult↗
PubMed1982

Role of self-esteem and autonomy in determining medication compliance among adolescents with juvenile rheumatoid arthritis.

This study was designed to improve understanding of adolescents' compliance with medical regimens. Compliance with salicylate therapy among adolescents with juvenile rheumatoid arthritis was examined in relationship to two of the most important issues of adolescent psychosocial development--self-image and autonomy. Standardized instruments that assessed these variables were administered to 38 adolescents with juvenile rheumatoid arthritis during the year in which compliance was determined, utilizing serum salicylate measurements. Patients and disease-related characteristics were also recorded, and interactions with personality variables were examined. The data show that adolescents with juvenile rheumatoid arthritis who comply with their medical regimen are those who have high self-esteem and are allowed more autonomy than the noncompliers. The longer the duration of the illness and the more symptoms present at onset, the poorer was self-concept, and hence compliance, at adolescence.

Adolescent↗
PubMed1981

[Characteristics of evaluating nursing home residents in the Netherlands; a rating instrument].

This article describes the way in which an instrument has been developed to measure the need for help of patients in the nursing homes of the Netherlands. The instrument is an important variable in the so-called Basic Research into the cost structure of the Dutch nursing homes (in Dutch BKV). The need for help is expressed as an index ('help-index') per patient. The index is based on the strong hierarchical relations between a number of patient-variables: washing, clothing, feeding, toileting, transferring (in and out of bed, walking, standing, wheelchair-activities), continence (urine and/or faeces) and contact function (speech). The 'help-indices' of the individual patients of a specific nursing home can be summarized in the average 'help-index' of that nursing home. The averages of the individual nursing homes differ to a great extent. The average 'help-index' per nursing home is considered to be of great importance as an independent variable with respect to staff per 100 beds and costs (total or per patient day) in the nursing homes. The latter is the subject of further research.

Activities of Daily Living↗
PubMed1996

Outcomes research: a primer for plastic surgeons.

The growing emphasis on cost-effectiveness in the United States health care industry has highlighted the need for comprehensive outcomes research in a variety of medical specialties. Currently, there is a relative paucity of reliable data characterizing the long-term results of many medical and surgical treatments. This shortage of outcomes research is particularly acute within plastic surgery where the benefits of treatment are often intangible and notoriously difficult to measure. In evaluating the effectiveness of medical treatment, conventional clinical research has focused primarily on morbidity and mortality as the outcomes of interest. In contrast, current outcome studies assess the results of interventions from the patient's perspective, measuring the impact of medical care on physical functioning, well-being, and quality of life. The resulting data can assist consumers, providers, and payers in making more appropriate health care decisions. As the outcomes movement has matured, it has evolved into two major areas of study: effectiveness research that evaluates the relationships between specific medical interventions and outcomes of care, and quality assessment that seeks to provide the best outcomes at the most reasonable costs. This review details the origins and trends of current outcomes research, examining the implications of this movement for plastic surgery. The growing impact of outcomes data on treatment guideline formulation in both the public and private sectors is also described. Finally, a brief review of outcomes study design, including definition of variables and selection of instruments, is presented.

Cost-Benefit Analysis↗
PubMed1996

Reproducibility of DNA ploidy and S-phase values from paraffin-embedded tissue.

OBJECTIVE: To determine the degree of variability of DNA flow cytometric results between two types of flow cytometers. STUDY DESIGN: Single-cell suspensions were made from 40 paraffin blocks of ovarian carcinoma using a modified Hedley procedure. These samples were consecutively analyzed in both Coulter's Profile II and Elite Flow cytometers. Gated and ungated data were collected and analyzed using Phoenix flow system's multicycle software. RESULTS: There were 16 (40%) DNA diploid, 23 (58%) DNA aneuploid and 1 DNA tetraploid tumor. The degree of variability in the DNA index coefficient of variation of the G0/G1 diploid peak, percentage of S phase, percentage of G2M, percentage of debris plus percentage of clumps were compared. Excellent correlations of the results were obtained in the DNA index (r = .999) and in percentage of S phase (r = .946). CONCLUSION: It is feasible to standardize variables of flow cytometric instruments to obtain reproducible results.

DNA, Neoplasm↗
PubMed1997

Critical evaluation of anterior drawer measurement methods in the ankle.

Anterior drawer testing has been used to assess the integrity of the lateral collateral ligaments, most notably the anterior talofibular ligament. Various radiographic measurement methods have been designed to assess sagittal plane talar displacement under stress. This investigation examined the anterior drawer test in 8 fresh frozen lower extremity cadaver specimens. Each specimen was mounted on a fabricated test frame and instrumented with a linear variable displacement transducer to directly measure talar displacement during stress application. Lateral radiographs were taken before and during stress application. Two radiographic measurement techniques (concentric circle and plafond to dome), each corrected for magnification effect, were compared with directly measured talar displacement values with the foot placed in 20 degrees plantar flexion. There were no significant differences between talar displacements measured directly and radiographically using the concentric circle method. Significant differences were found between directly and radiographically measured displacements using the uncorrected plafond to dome method. Subtracting the unstressed from the stressed tibiotalar distance for the plafond to dome method resulted in no significant difference from directly measured talar displacement values. It is not necessary to correct talar displacement values obtained when using the concentric circle method.

Aged↗