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PubMed1991

Patient satisfaction with hospital services: development and testing of a measuring instrument.

The present study was undertaken with the aim of developing and testing an instrument that could be used to measure patient satisfaction with hospital services in Kuwait. The instrument, which comprised 57 items, and measured satisfaction with 7 specific dimensions of hospital services, was administered to 493 patients using the interview technique. Statistical analysis showed that the instrument yields good response variability. Reliability of the instrument, measured in terms of the internal consistency coefficient alpha, exceeded the acceptable criterion level, the coefficients ranging between 0.73 and 0.86. Evidence of the construct validity of the instrument was found in significant positive correlation between the dimension specific satisfaction scale scores and scores for allegiance scale and for overall rating of quality of hospital services. Construct validity was further supported by convergent discriminant analysis, which showed that correlations between items of all 7 scales and their total scale scores were greater than correlations between scale items and the total scores of scales they do not represent. Analysis of an open-ended question about dissatisfying aspects of hospital services not included on the interview was undertaken to examine the instrument's content validity. Results indicated that patients identified 11 items, 8 of which were identified more than once, and 2 of which were not classifiable to the 7 dimensions assessed by the instrument. It was suggested to add the 8 items that were identified more than once, and to reassess the reliability and validity of the revised instrument. Assessment of the test-retest reliability, by comparing scale scores over time, was also suggested.

Evaluation Studies as Topic↗
PubMed1991

Click evoked otoacoustic emissions in adult subjects: standard indices and test-retest reliability.

The present study was designed to evaluate transiently evoked otoacoustic emissions in an otologically normal adult population. Using the ILO 88 Otodynamic Analyzer, the recorded otoacoustic emission responses were analyzed for five parameters. Considering the variability of instrumentation and technique in otoacoustic emission testing, we have defined a normative data pool using standard commercially available testing equipment. These data should facilitate comparison with data acquired in various pathologic states. The test-retest validity of this procedure also was evaluated and was found to be high. Use of click evoked otoacoustic emissions, with some caveats, appears to be a promising technique for further research into the assessment of normal/abnormal cochlear function.

Acoustic Stimulation↗
PubMedDate not supplied

Loneliness in early adolescents: an empirical test of alternate explanations.

Two alternate explanations of loneliness by Weiss (1973), the situational theory and the characterological theory, were tested in a sample of 112 boys and girls between the ages of 12 to 14. In addition to responding to the Revised UCLA Loneliness Scale, participants completed instruments measuring variables linked to either the situational or the characterological explanations of loneliness. Using hierarchical analysis of sets, the results indicated that the set of variables used to test the situational theory explained more variance in loneliness when entered first (62%) or second (34%) in the analysis than did the characterological set when entered first (33%) or second (5%) in the analysis. The findings suggested that the situational explanation played a more significant role than the characterological explanation in understanding loneliness in early adolescents.

Adolescent↗
PubMed1980

The College of American Pathologists Phantom Series--an assessment of current nuclear imaging capabilities.

Twelve sets of emission phantoms were distributed semiannually to laboratories of nuclear medicine from 1973 through 1978. This survey aimed to create a national peer group within which it might become possible to compare and standardize nuclear imaging technics, and to evaluate and define the current state of the art in a clinical setting. Results were analyzed in terms of sensitivity (percentage of true-positives), nonspecificity (percentage of false-positives), and performance indices (true-positive/false-negative ratios) for conventional gamma cameras and for rectilinear scanners. The chief determinants of target detectability proved to be target-to-surface depth, target diameter, and intrinsic target contrast. Operational variables and instrument type produced relatively minor effect upon subscriber performance. Gamma cameras tended to show slightly more sensitivity than rectilinear scanners, but were somewhat troubled by nonspecificity. Improvements in the intrinsic resolution of second- and third-generation gamma cameras increasingly employed since 1975 showed negligible impact on performance indices. A consideration of the overall survey performance indices. A consideration of the overall survey performance permits the beginning of a quantitative estimate of current detection capability in day-to-day nuclear imaging.

Evaluation Studies as Topic↗
PubMed1993

[Diagnosis of alcohol dependence].

The dependence syndrome has gained central importance in diagnosing alcohol abuse disorders, as shown by its incorporation in ICD-10 and DSM-III-R. After dealing with historical concepts of alcoholism, the concurrent and predictive validity of the dependency syndrome is discussed in relation to aspects of typology and comorbidity, and to neurobiological variables. Diagnostic instruments are assessed and research perspectives indicated.

Alcohol Drinking↗
PubMedDate not supplied

Challenges to behavioral research in oncology.

PURPOSE: The difficulties encountered by investigators in conducting behavioral research with oncology patients have received little attention in the literature. This article provides a practical guide to problems that might be anticipated in the planning and conduct of behavioral research. OVERVIEW: Problems include subject accrual and retention, development of a multidisciplinary research team, control of confounding variables, psychosocial instrumentation issues, and acceptance of the need for behavioral research. Methodological and feasibility issues are examined. Strategies for addressing the issues are presented. CLINICAL IMPLICATIONS: Successful behavioral research in oncology requires firm grounding in clinical practice. Clinicians can improve the quality of research and thus, the scientific base for practice by joining or facilitating multidisciplinary research efforts.

Behavioral Sciences↗
PubMed1994

Intramachine and intermachine variability in transesophageal color Doppler images of pulsatile jets. In vitro studies.

BACKGROUND: Color Doppler flow mapping is widely used as a marker of severity of valvular regurgitation, and the transesophageal approach has provided high-quality images in patients with poor acoustic windows. However, different instruments produce significantly variable images. Techniques that use jet spatial information to determine the severity of the lesion may need to be derived specifically for the instrument used. Given a lack of standardization of the many commonly used instruments, the goal of this study was to quantify variability between instruments by imaging well-defined jet flow fields created in vitro. METHODS AND RESULTS: Pulsatile jets were created in vitro using a blood analogue fluid through physiological orifice diameters and imaged from a distal window using six commonly used color Doppler instruments. Transesophageal transducers (5.0 MHz) were used with all instruments studied. Peak jet areas were planimetered and averaged with systematic variations in Nyquist limit, color filter, and sector angle (which produced variations in frame rate). Changes in instrument settings produced significant variation in jet size for all instruments studied. Comparisons within instruments and among instruments were difficult because of preset and ambiguous setting levels. When comparisons were possible between similar settings, variability was dramatic (eg, 57% variability between instruments with very similar Nyquist limits). CONCLUSIONS: A lack of standardized color Doppler instrument settings prohibits translation of jet area techniques from one instrument to another. This should be taken into consideration when using different machines for clinical study.

Algorithms↗
PubMed2003

Measuring outcomes in randomized clinical trials of insomnia treatments.

Significant efforts have been made in the last decade to develop evidence-based guidelines for the treatment of insomnia and other sleep disorders. Despite such progress, there are still no standard assessment methods to document outcome and no accepted criteria to define what should be a successful outcome in the treatment of insomnia. This paper reviews methodological and conceptual issues related to the measurement of outcomes in clinical trials of insomnia. Selected studies of behavioral and pharmacological therapies of insomnia are summarized to illustrate the types of dependent variables and assessment instruments used to document treatment efficacy. Additional outcome variables and assessment methods of potential interest are discussed, and criteria for interpreting and reporting outcomes are summarized. As most studies have relied on fairly narrow criteria to define an effective treatment, the need to broaden the scope of outcome assessment is highlighted. For instance, it is essential to document treatment efficacy beyond the simple reduction of insomnia symptoms and to incorporate additional indicators of success. Given that insomnia is associated with significant morbidity, an effective treatment should not only improve sleep parameters, but it should also produce clinically meaningful changes in daytime functioning, fatigue, mood, and quality of life. The need to evaluate outcome from multiple perspectives and to develop a core-assessment battery that would consider efficacy, clinical significance, and cost-effectiveness are discussed.

Cognitive Behavioral Therapy↗
PubMed1995

An instrument for real-time spectral estimation of heart rate variability signals.

A Digital Signal Processor (DSP)-based instrument is proposed for estimating and displaying the Heart Rate Variability (HRV) spectrum in real-time. It consists of an intelligent module which is properly interfaced to an IBM PC and whose operations are independent from the computer's other tasks. In this way, the simultaneous recording of the ECG sequence, needed for the more complete off-line analysis, can be performed by the same host. The employed hybrid spectral estimator (in which a classical FFT analysis follows the autoregressive extrapolation of data) appears to be the most apt for the present fixed point arithmetics implementation. The reliability of the instrument and its accuracy are checked both with suitable test signals and by comparison with the results obtained through off-line analysis of the same ECG tracks. The instrument is presently used for cardiovascular investigations, in particular for quickly picking patients with cardiac autonomic neuropathy (CAN) out of a population of diabetic subjects.

Adult↗
PubMed2001

Predictive potential of noninvasive methods, inclusive of exercise SPECT Tc99m MIBI imaging, in recognition of high-risk patients with left main coronary artery stenosis.

The aim of the present study was to determine which clinical, exercise and perfusion variables can be instrumental in the identification of left main coronary artery. A multivariate model for prediction of left main disease was developed, based on a number of clinical, exercise and MIBI perfusion variables in two groups of patients. Group I consisted of 38 patients (30 men and eight women) with angiographically proven left main stenosis, while group II consisted of 41 patients (27 men and 14 women) with multivessel coronary artery diseases. A multivariate logistic regression analysis demonstrated that clinical variables including diabetes, hypertension, together with history of typical angina were the only independent predictors of left main stenosis. It was found that p value was 0.05 for hypertension, 0.01 for diabetes as well as 0.01 for the history of typical angina in clinical examination. No exercise or perfusion variables may be instrumental in prediction of left main stenosis, when considered in isolation. Myocardial perfusion by itself is therefore not deemed sufficiently specific to attempt its positive identification. High-risk patients with left main disease can be identified noninvasively by exercise perfusion imaging using a model based on the proposed logistic regression analysis with clinical variables.

Adult↗
PubMed1991

An evaluation of two signal-processing hearing aids.

Various forms of signal processing are used in modern ASP hearing aids. The present study investigated the relationship between sentence recognition ability and two types of signal processing used in commercially available hearing aids. Results indicated a significant improvement in sentence recognition ability employing an instrument with adaptive compression (variable release time) versus an instrument with an adaptive high-pass filter with short attack and release times. Data were obtained for a single-talker competing message at several message-to-competition ratios. The adaptive compression system may prove to be beneficial to hearing-impaired listeners in certain background noise environments.

Aged↗
PubMed1995

Study of the stratum corneum barrier function by transepidermal water loss measurements: comparison between two commercial instruments: Evaporimeter and Tewameter.

The measurement of transepidermal water loss (TEWL) is an important noninvasive method in order to assess the barrier function of the stratum corneum. As a consequence, TEWL has been found to be a very useful technique for studying skin irritation induced by various physical and chemical effects. Exposure of the skin to chemicals (detergents) and physical conditions (occlusion and stripping) generally results in an increase of TEWL. Until recently the only commercially available TEWL instrument was the Evaporimeter developed by ServoMed (Sweden). The instrument is based on the open chamber system with two humidity and temperature sensors which measure the water evaporation gradient at the surface of the skin. Recently a new commercially available instrument based on the same physical principle of measurement was developed by Courage and Khazaka (Tewameter, FRG). Our aim in this study has been to compare the measuring capacities of both instruments. The accuracy, sensitivity, variability and reproducibility of both instruments were compared in vivo under identical conditions on normal skin and skin damaged by external conditions. The influence of external and environmental factors such as air and probe temperature, relative humidity, air turbulence and pressure of application was evaluated for both instruments. Finally, the two instruments were compared in practice when following the increase in TEWL of the skin after stripping, occlusion and exposure to irritant household detergents. A very good correlation (r = +0.97) was found between the results of the two instruments over a wide range of TEWL values.

Adolescent↗
PubMed1989

A covariance structure model test of antecedents of adolescent alcohol misuse and a prevention effort.

As part of an alcohol misuse prevention evaluation, questionnaires were administered to 4,157 junior high school students to determine levels of alcohol misuse, exposure to peer use and misuse of alcohol, susceptibility to peer pressure, internal health locus of control, and self-esteem. A conceptual model of the antecedents of adolescent alcohol misuse and the effectiveness of a prevention effort was tested using covariance structure modeling techniques. The factor loadings for the model were all moderate to high, indicating that the observed variables served well as measurement instruments for the latent variables. The hypothesized structural relationships among the latent variables of alcohol misuse, exposure to peer use and misuse of alcohol, susceptibility to peer pressure, internal health locus of control, and self-esteem were supported by the data. The full model explained 45 percent of the variance in alcohol misuse in the analysis based on the total sample. The direct effect of the intervention on alcohol misuse was small but significant in the hypothesized direction. The direct effects of the intervention on susceptibility to peer pressure and internal health locus of control were not significant. The model was tested separately for groups of students who had high versus low scores on susceptibility to peer pressure in order to test the interaction between susceptibility to peer pressure and exposure to peer use and misuse of alcohol. The percentage of variance accounted for in alcohol misuse did not increase upon testing the model separately for students who had high versus low scores on susceptibility to peer pressure. Observed differences in the significance of the parameter estimates between the high and low susceptibility to peer pressure groups suggest that different approaches to the design and evaluation of substance abuse prevention programs may be necessary for different subgroups of students.

Alcoholism↗
PubMed1997

Reduction of interlaboratory variability in flow cytometric immunophenotyping by standardization of instrument set-up and calibration, and standard list mode data analysis.

Two workshops addressed the question to which degree standardization of instrument set-up and calibration, and standard list mode data analysis would reduce interlaboratory variability of flow cytometric results on prestained peripheral blood mononuclear cells (PBMC). Standard instrument set-up included uniform positioning of the "windows of analysis" for the forward and sideward light scatter and fluorescence (FL) 1 (i.e., fluorescein isothiocyanate [FITC]) and 2 (i.e., phycoerythrin [PE]) parameters. Reference standards and PBMC, double-stained with FITC- and PE-conjugated monoclonal antibodies covering a wide range of FL intensities and coexpression patterns, were sent out to 25 laboratories in Workshop 1 and to 35 laboratories in Workshop 2 with the following requests: a) to set up instruments according to local and standard protocols, b) to acquire list mode data on the PBMC with both instrument settings, and c) to analyze both datasets according to local protocols. Standard analysis of the list mode data acquired with uniform instrument settings was performed centrally using so-called "latent class model" software (Van Putten et al., Cytometry 14:86-96, 1993). This software provides an automated, "no-gating" analytical method of lymphocyte immunophenotypes and employs fixed FL marker settings as defined prior to each analytical run. In Workshop 1, these markers were set in identical histogram channels for all instruments based on results obtained with a reference instrument. Standard analysis of list mode data acquired after uniform instrument set-up led only to a 13% reduction of interlaboratory variability of results as compared to data analysis using local protocols. The standard protocol for instrument set-up led to uniform positioning of relatively strong FL signals but variable positioning of unstained cells on the FL histogram scales. Hence, standard FL marker settings were inappropriate for some instruments. Therefore, instrument responses to FITC and PE signals in Workshop 2 were calibrated using microbeads labeled with FITC or PE in a range of predefined FL intensities expressed in MESF units (molecules of equivalent soluble fluorochrome). That approach allowed the positioning of the FL markers for the standard analysis on the basis of identical FL1 and FL2 intensities, expressed in MESF units, for all instruments. Standard analysis of list mode data acquired after uniform instrument set-up and calibrated FL marker settings led to a 43% reduction of interlaboratory variability as compared to data analysis to local protocols. We conclude that standard list mode data analysis using fixed FL marker settings reduces the interlaboratory variability of flow cytometric results on prestained PBMC, provided that the instruments have been set up in a uniform way and that FL markers have been standardized on the basis of calibration of each instrument's response to the corresponding FL signals.

Antigens, CD↗
PubMed2005

Precision profiling and components of variability analysis for Affymetrix microarray assays run in a clinical context.

Although gene expression profiling using microarray technology is widely used in research environments, adoption of microarray testing in clinical laboratories is currently limited. In an attempt to determine how such assays would perform in a clinical laboratory, we evaluated the analytical variability of Affymetrix microarray probesets using two generations of human Affymetrix chips (U95Av2 and U133A). The study was designed to mimic potential clinical applications by using multiple operators, machines, and reagent lots, and by performing analyses throughout a period of several months. A mixed model analysis was used to evaluate the relative contributions of multiple factors to overall variability, including operator, instrument, run, cRNA/cDNA synthesis, and changes in reagent lots. Under these conditions, the average probeset coefficient of variation (CV) was relatively low for present probesets on both generations of chips (mean coefficient of variation, 21.9% and 27.2% for U95Av2 and U133A chips, respectively). The largest contribution to overall variation was chip-to-chip (residual) variability, which was responsible for between 40 to 60% of the total variability observed. Changes in individual reagent lots and instrumentation contributed very little to the overall variability. We conclude that the approach demonstrated here could be applied to clinical validation of Affymetrix-based assays and that the analytical precision of this technique is sufficient to answer many biological questions.

DNA, Complementary↗
PubMed2006

High-efficiency liquid chromatography on conventional columns and instrumentation by using temperature as a variable I. Experiments with 25 cm x 4.6 mm I.D., 5 microm ODS columns.

High plate numbers were obtained in conventional LC by coupling columns and by using temperature to reduce the viscosity of the mobile phase. At 80 degrees C up to eight columns of 25 cm x 4.6 mm I.D. packed with 5 microm ODS particles could be coupled generating 180,000 effective plates while the pressure drop was only 350bar. For routine work, a set of four columns is preferred. The analysis times on one column operated at 30 degrees C and 1 mL/min flow rate and on four columns at 80 degrees C and 2 mL/min flow rate are the same in isoeluotropic conditions while the resolution is doubled. Multicolumn systems were successfully applied in isocratic and gradient mode for the analysis of pharmaceutical and environmental samples.

Chromatography, Liquid↗
PubMed2006

High efficiency liquid chromatography on conventional columns and instrumentation by using temperature as a variable. Kinetic plots and experimental verification.

Theoretical aspects of temperature in liquid chromatography (LC) have mostly been studied to elucidate changes in retention behavior of small and large molecules in various solvents. That temperature also plays a significant role in chromatographic performance is less known. Kinetic plots are an established tool to predict chromatographic performance in terms of speed and efficiency that can be obtained with a certain particle size at the maximum attainable column pressure. In this paper, temperature effects on mobile phase viscosity and analyte diffusion are incorporated in these plots to prove that superior performances are within experimental reach for conventional LC columns and equipment. Verification of the modified kinetic plots with experimental data points is presented.

Chromatography, Liquid↗