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Results for “instrumental variable”

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PubMed2003

Interhospital variability in satisfaction with withdrawal of life support: room for improvement?

OBJECTIVE: To develop instruments to measure the current level of satisfaction with the withdrawal of life support among nurses and respiratory therapists and to use these instruments to determine whether differences in satisfaction levels with the withdrawal of life support could be found among different institutions. DESIGN: A multicenter, self-administered, questionnaire-based study. SETTING: The intensive care units of three academic and 11 community hospitals. SUBJECTS: A total of 412 critical care nurses and 117 respiratory therapists working in these intensive care units. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: After developing two similar questionnaires for critical care nurses and respiratory therapists, we assessed the reliability of the individual items for each questionnaire and only used those found to be reliable in the analyses. We found variability in the satisfaction level of critical care nurses among different intensive care units and among academic and community hospital intensive care units. Being involved in the plan for withdrawal of life support, comfort with the way discussions with the family had gone, comfort with patient sedation, and increasing experience with withdrawal of life support were items associated with increased nurse satisfaction. For respiratory therapists, there seemed to be similar differences among institutions in satisfaction level, although numbers were limited. Having the physician explain the plan to them and becoming more comfortable with withdrawal of life support as a result of increased experience were found to be associated with increased satisfaction levels for respiratory therapists. CONCLUSIONS: Satisfaction levels of intensive care unit nurses and respiratory therapists with the process of withdrawing life support vary among institutions. This variation may represent an opportunity for improvement in the process of withdrawing life support within this region.

Euthanasia, Passive↗

PubMedDate not supplied

Goniometry of the proximal and distal interphalangeal joints, Part I: a survey of instrumentation and placement preferences.

A telephone survey of 231 occupational and physical therapists was conducted to determine goniometric instrumentation and placement preferences for measuring the proximal and distal interphalangeal joints of the upper extremity. The variables included were academic degree, hand therapy certification, years of therapy experience, years of specialty hand experience, and preferences for goniometric instrumentation and placement. Descriptive statistics revealed a highly experienced population (mean, 11 years) who predominantly preferred the 6" cut-off clear and metal goniometers. Eight additional instruments were also noted. Dorsal placement of the goniometer was preferred by 73% of the practitioners. Lateral placement was occasionally preferred (by 20%) in difficult clinical situations. Seven percent of the practitioners reported always preferring the lateral method. Chi-square analyses revealed no significant relationships between the variables.

Chi-Square Distribution↗

PubMed2004

Third degree perineal tears in a university medical center where midline episiotomies are not performed.

OBJECTIVE: Midline episiotomy is a known major risk factor for severe perineal lacerations. The study was aimed to define obstetric risk factors for third-degree perineal tears in a university medical center where midline episiotomies are not performed. STUDY DESIGN: A comparison between vaginal deliveries complicated with third-degree perineal tears and deliveries without third-degree perineal tears was performed. Deliveries occurred between the years 1988-1999 in a tertiary medical center. Multiple gestations, preterm deliveries (<37 weeks' gestation), cesarean deliveries and cases of shoulder dystocia were excluded from the analysis. A multiple logistic regression model was constructed in order to find independent risk factors for third-degree perineal tears. Odds ratios (OR) and their 95% confidence interval (CI) were calculated from the regression coefficient. RESULTS: During the study period, 79 (0.1%) consecutive cases of third degree perineal tears were identified. Significant risk factors from the univariate analysis were fetal macrosomia (OR 2.7, 95% CI 1.2-5.5), nulliparity (OR 2.9, 95% CI 1.8-4.6), labor induction (OR 1.9, 95% CI 1.0-3.5), failure of labor to progress during the second stage (OR 10.8, 95% CI 5.4-21.1), non-reassuring fetal heart rate patterns (OR 11.7, 95% CI 6.1-21.5), mediolateral episiotomy (OR 2.8, 95% CI 1.8-4.5), vacuum extraction (OR 10.6, 95% CI 6.1-18.3), and forceps delivery (OR 29.2, 95% CI 7.3-97.2). However, using a multivariable analysis, only fetal macrosomia (OR 2.5, 95% CI 1.2-4.9), vacuum extraction (OR 8.2, 95% CI 4.7-14.5), and forceps delivery (OR 26.7, 95% CI 8.0-88.5) remained as independent risk factors. The combined risk for instrumental deliveries of macrosomic newborns was 8.6 (95% CI 1.2-62.5; p=0.010). CONCLUSIONS: After adjustment for possible confounding variables, mediolateral episiotomy per se was not an independent risk factor for third-degree perineal tears. Instrumental vaginal deliveries of macrosomic fetuses should be avoided whenever possible to decrease the occurrence of third-degree perineal tears.

Adult↗

PubMed2006

Scanning microarrays: current methods and future directions.

The microarray platform is a powerful tool for conducting large-scale, high-throughput gene expression experiments. However, careful attention to detail throughout the five major steps in the microarray process--design, printing, hybridization, scanning, and analysis--must be used to ensure that reliable and accurate conclusions are obtained from data. The act of scanning the array has received the least attention of all parts of the microarray process, despite it being a critical quality-limiting component. This chapter specifically addresses the effects of scan parameters and limitations of the scanning technology divided into two categories: instrumentation effects (those that arise from the scanning instrumentation itself) and user-controller parameters (those that an operator chooses) for the most common microarray platform--the two-color cDNA microarray printed on a glass substrate. Significant research efforts have gone into developing microarray analysis techniques, but the field is ripe for research to characterize the variability and errors introduced by the scanning process itself, the scanner instrumentation, and the user. Implications of these errors for large-scale, multiple slide and multiple laboratory experiments are discussed. Wise choices for scanning parameters and consideration of instrument specifics will ultimately increase data reliability and reduce the need for complex preprocessing mechanisms prior to the extraction of expression information. In addition, emerging technologies such as surface plasmon imaging, resonance light scattering, and hyperspectral imaging are presented briefly as promising, complementary techniques to traditional scanning methods.

Animals↗

PubMed1995

Variability of continuously measured arterial pH and blood gas values in the near term fetal lamb.

In fetal sheep, arterial blood gas values show considerable spontaneous fluctuations. The aim of the present study was to obtain quantitative data on fetal blood gas variability. Accurate assessment of the intraindividual variations can hardly be obtained from intermittent blood samples, but requires continuous measurement. For this purpose we developed a small extracorporeal flow-through cuvette, containing pH and blood gas electrodes and the fiber optic probe of an oximeter. The cuvette is connected through two catheters to the fetal circulation. Blood from the carotid artery flows through the cuvette at a constant rate of 2 mL/min and is drained into the jugular vein. Continuous recordings for 6 h were obtained from five chronically instrumented sheep fetuses at 134-137-d gestational age. Intraindividual variability of fetal arterial blood pH (pHa), partial pressure of arterial blood CO2 (Paco2) and O2 (Pao2), and saturation of arterial blood (Sao2) is quantitatively described. The individual variation coefficients ranged from 0.1 to 0.4% (pHa), from 1.4 to 7.6% (Paco2), from 2.5 to 5.5% (Pao2), and from 3.6 to 7.0% (Sao2). The 5th to 95 percentile intervals (delta) of the individual blood gas values ranged from 0.03 to 0.09 (pHa), from 0.3 to 1.6 kPa (Paco2), from 0.22 to 0.5 kPa (Pao2), and from 10.5 to 26.0% (Sao2). These findings indicate that considerable fluctuations in fetal arterial blood gases occur during a 6-h period. These fluctuations are associated with uterine contractures and changes in maternal and fetal activity.

Analysis of Variance↗

PubMed1992

Bone mass measurement by DXA: influence of analysis procedures and interunit variation.

Interunit variability among bone densitometers is due to different factors, including different calibration procedures and algorithms and variability in photon source energies and/or intensities. Other factors, such as the choice of scan parameters or the analysis procedures, can also introduce variability. The new generation of dual-energy x-ray absorptiometry (DXA) has partially improved this situation. The aim of this study was to investigate the operator-dependent analysis procedures that can affect scan results and to evaluate the phantom and in vivo interunit variation of some DXA instruments. Four DXA instruments (QDR 1000 and 1000/W, Hologic, Inc.) were used. Potential sources of variability in the analysis procedures of anteroposterior lumbar spine and hip scans were considered: in most cases these procedures significantly influenced scan results. On lumbar spine, an enlargement of the scan window of less than 3 cm was responsible for an average increase in bone mineral density (BMD) of about 3%. On the hip, lowering the scan window by about 1 cm accounted for an increase in the whole-segment BMD of about 4%. After standardization of analysis procedures, interunit and intraunit coefficients of variation and percentage differences among instruments were less than 1% for all the parameters considered (area and bone mineral content and density) with both an anatomic and a geometric phantom, and in nine subjects scanned by two different devices the percentage difference in BMD was greater than 2%. This study shows that present interunit variability allows comparisons among laboratories, but only if highly standardized analysis procedures are used.

Absorptiometry, Photon↗

PubMed2005

The safety and efficacy of laparoscopic adrenalectomy in children.

HYPOTHESIS: Laparoscopic adrenalectomy (LA) has become standard therapy for benign adrenal masses in adults. The utility of LA in children with adrenal masses is less well defined because of the infrequency and pathologic variability of pediatric adrenal masses, and body size and instrumentation considerations that exist in small children. Evaluation of a case series of children undergoing lateral, transperitoneal LA will reflect the safety and efficacy of this procedure in pediatric patients and identify preferred patient selection criteria. DESIGN: A combined case series including patients treated between March 1999 and November 2004. SETTING: Urban tertiary referral pediatric teaching hospitals. PATIENTS AND INTERVENTIONS: All children with pathologic adrenal masses undergoing LA were included. MAIN OUTCOME MEASURES: The primary study outcome measures included operative duration, conversions to open adrenalectomy, complications, length of hospital stay, and freedom from recurrence of the original pathologic adrenal mass. RESULTS: A total of 21 LAs (including a staged, bilateral LA) were performed in 20 patients (13 girls, 7 boys) with a mean age of 6.4 years (range, 14 months to 18 years). Nine patients (43%) had neuroblastic tumors. Operative duration averaged mean +/- SD 101 +/- 48 minutes, and there was a single conversion to open adrenalectomy in a patient with a left adrenal carcinoma and tumor thrombus extending into the renal vein. There were no perioperative complications, and no patients required blood transfusions. The postoperative hospital stay averaged 1.5 days (range, 1-4.5 days). At a mean +/- SD follow-up of 31 +/- 17 months, all patients remained clinically (radiologically and/or biochemically) free of their original adrenal disease. CONCLUSION: Laparoscopic adrenalectomy can be used to safely treat suspected benign and selected malignant adrenal masses in children.

Adolescent↗

PubMedDate not supplied

Quality time: how parents' schooling affects child health through its interaction with childcare time in Bangladesh.

A child health production function is presented with the key feature being an interaction term between a caregiver's schooling and their exposure time to the child. The production function is estimated using a 2SLS fixed effects model with lagged childcare time, resource allocation and child health as instruments for the first differences of these same endogenous variables. The 1978 Intrafamily Food Distribution and Feeding Practices Survey dataset from Bangladesh is used together with census data. The production function estimates indicate that part of the salutary effects of parental education on child health require that the child actually be exposed to the educated parent. Given the demographic makeup of the study sample and the assumption that age education and gender completely account for productivity, teenage brothers and fathers would have the highest marginal productivity for child health and mothers and grandmothers the least. If economic opportunity draws mothers away from childcare, the presence of other household members with higher schooling levels offers the potential for an improvement in the overall quality of childcare time. In the present study the households failed to set the marginal labour product of child health for each of the caregivers equal. Thus, the quality of childcare may not be the household's sole concern in determining time allocation.

Adolescent↗

PubMed1984

Flow karyology of serially cultured Chinese hamster cell lineages.

Flow karyology of serially cultured Chinese hamster cell lineages has been observed to be influenced by the degree of cellular heterogeneity in culture. The minimum coefficient of variation (CV) and debris fraction obtainable vary as a cell lineage evolves from a primary cell culture to an established cell line. The cell lineages pass through a stage of decreased cellular heterogeneity from which flow karyotypes can be obtained with lower CV and debris fraction. The influence of cellular heterogeneity on flow karyology is observed with constant preparative protocol and constant instrument performance, and can be an additional source of variability.

Animals↗

PubMed2001

Flow cytometric enumeration of micronucleated reticulocytes: high transferability among 14 laboratories.

This laboratory previously described a single-laser flow cytometric method, which effectively resolves micronucleated erythrocyte populations in rodent peripheral blood samples. Even so, the rarity and variable size of micronuclei make it difficult to configure instrument settings consistently and define analysis regions rationally to enumerate the cell populations of interest. Murine erythrocytes from animals infected with the malaria parasite Plasmodium berghei contain a high prevalence of erythrocytes with a uniform DNA content. This biological model for micronucleated erythrocytes offers a means by which the micronucleus analysis regions can be rationally defined, and a means for controlling interexperimental variation. The experiments described herein were performed to extend these studies by testing whether malaria-infected erythrocytes could also be used to enhance the transferability of the method, as well as control intra- and interlaboratory variation. For these studies, blood samples from mice infected with malaria, or treated with vehicle or the clastogen methyl methanesulfonate, were fixed and shipped to collaborating laboratories for analysis. After configuring instrumentation parameters and guiding the position of analysis regions with the malaria-infected blood samples, micronucleated reticulocyte frequencies were measured (20,000 reticulocytes per sample). To evaluate both intra- and interlaboratory variation, five replicates were analyzed per day, and these analyses were repeated on up to five separate days. The data of 14 laboratories presented herein indicate that transferability of this flow cytometric technique is high when instrumentation is guided by the biological standard Plasmodium berghei.

Animals↗

PubMed2002

Methodological concerns for non-Hispanic investigators conducting research with Hispanic Americans.

The fastest-growing ethnic population in the United States, Hispanic Americans are underrepresented in health care research because of an insufficient number of Hispanic American researchers, study teams without Spanish-speaking members, a lack of Spanish-language instruments, and investigator ignorance about cultural differences. Culturally insensitive research produces biased results that can inaccurately represent Hispanic Americans. The purpose of this article is to discuss methodological concerns when conducting research with Hispanic Americans including: instrument response format, translation issues, population-related extraneous variables, and response tendencies that can influence results.

Communication Barriers↗

PubMedDate not supplied

Multivariate profile of smoking in Southeast Asian men: a biochemically verified analysis.

BACKGROUND: Cigarette smoking prevalence rates among Southeast Asian males are among the highest reported in comparison with other ethnic male groups in the United States. The objective of this study is to profile current smokers, former smokers, and never smokers among Southeast Asian males, based on subject characteristics. METHODS: Southeast Asian (Cambodian, Laotian, and Vietnamese) males residing in the Greater Columbus, Ohio, area were surveyed, utilizing culturally sensitive instruments and interviewers, with respect to demographic and acculturation variables. All subjects were biochemically verified by collecting a saliva sample at the time of the interviews. RESULTS: Those Southeast Asian males who quit smoking tended to be older, employed, more assimilated into the U.S. culture, and of Cambodian ethnicity. The current smokers, relative to never smokers, tended to be older, not in the labor force, traditionally oriented to their native culture, less educated, and of Laotian or Vietnamese ethnicity. CONCLUSIONS: Specific strategies for smoking cessation programs would indicate more intense, and possibly different, efforts be directed at Southeast Asian males of Laotian and Vietnamese ethnicity who are younger, unemployed and less assimilated into the U.S. culture. On the other hand, smoking prevention programs would target those individuals who are at highest risk of smoking.

Acculturation↗

PubMed2000

Characteristics of exercise behavior among college students: application of social cognitive theory to predicting stage of change.

BACKGROUND: Young adulthood is characterized by a steep decline in the level of physical activity, but few theory-based studies have examined characteristics associated with regular exercise in this population. This study applied Social Cognitive Theory (SCT) and the Stages of Change Model (SCM) to determine personal, behavioral, and environmental characteristics associated with exercise behavior and intentions among undergraduate university students. METHODS: A random sample of 937 undergraduate students (mean age 22.0 +/- 5.6 years; 84.7% ages 17-24 years) enrolled at a large Midwestern university completed a mailed questionnaire. Valid and reliable instruments were used to measure personal, behavioral, and environmental variables based on the SCT that were hypothesized to influence stage of exercise behavior change. Multivariate discriminant analysis was used to determine associations among these variables with stage of exercise behavior change. RESULTS: Exercise self-efficacy, physical activity history, and nonexercise estimation of aerobic capacity were significant predictors of the stage of exercise behavior change for both males and females. Among females, exercise self-efficacy (P < 0.001) and family social support (P < 0. 001) for physical activity were the best predictors of stage of exercise behavior change. Friend social support (P < 0.001), physical activity history (P < 0.001), and exercise self-efficacy (P < 0.001) were significant predictors of stage of exercise behavior change among males. CONCLUSIONS: The SCT framework predicted stage of exercise behavior change as defined by the SCM. Exercise self-efficacy was associated with exercise stage, but the source of significant social support (family versus friends) was different for males and females.

Adolescent↗

PubMed1993

WHO's work on the epidemiology of mental disorders.

The WHO programme on epidemiology of mental disorders started in the early 1960's with a series of reviews of knowledge. These were followed by activities aiming at four main goals: the standardization of psychiatric diagnosis, classification and statistics; the development of standardized internationally applicable instruments for the assessment of mental patients and of variables relevant to the assessment of mental illness; the conduct of epidemiological studies of mental disorders; and the training relevant to the above goals. The paper provides a description of the activities undertaken to achieve these goals and stresses the importance and usefulness of the collaboration of individuals, experts and institutions all over the world in this effort.

Female↗

PubMed1995

Empirically derived subtypes of pervasive developmental disorders: a cluster analytic study.

A cluster analytic study was conducted to empirically derive behaviorally homogeneous subtypes of pervasive developmental disorders (PDD). Subjects were clustered based on a broad range of behavioral symptoms which characterize autism. Behavioral variables were measured using several of the standardized psychometric instruments most commonly employed in assessing autistic individuals. The cluster solution indicated the presence of four distinct groups. Validity checks generally confirmed significant between-group differences on independent measures of social, language, and stereotyped behaviors. In addition, the four-group cluster solution was compared to previously developed typological systems of PDD (i.e., subcategories based on IQ early onset, styles of social interaction, and DSM-III-R diagnosis). Results generally supported both the behavioral homogeneity of the four subgroups and also several important between-group differences. The potential utility of using cluster analyses to explore subtypes of PDD is discussed.

Adolescent↗

PubMed2002

Is EQ-5D a valid measure of HRQoL in patients with movement disorders? A comparison with SF-36 and FIM questionnaires.

We assessed the descriptive part of the EQ-5D system in rehabilitation patients with validity severe moving disorders and compared it with the FIM and the SF-36 Health Survey in a sample of 60 patients. We analyzed the EQ-5D convergent validity and the correlations between EQ-5D scores and a clinical variables. The internal validity of the EQ-5D instrument proved good. Moreover, the EQ-5D discriminated symptom severity as scored by the FIM and the SF-36 correspondent subscales. We analyzed the sensitivity of the EQ-5D only with respect to the ability of patients to move with or without a wheelchair. Most patients considered "moving a wheelchair" as a good way of "getting about." This investigation can be considered a pilot study on the performance of the EQ-5D in a group of pathologies involving various degrees of movement disorders. The findings show possible problems of misinterpretation in the levels of the mobility dimension.

Journal Article↗

PubMed2006

Effect of marker cluster design on the accuracy of human movement analysis using stereophotogrammetry.

This paper presents a new, simple model to evaluate the instrumental random errors in kinematic analysis of human movements using stereophotogrammetry. By means of equations analogous to that relate linear or angular momentum with linear or angular velocities, a direct measurement of instantaneous motion can be made without previous finite displacement analysis. Single explicit expressions can be obtained to evaluate the influence of instrumental random errors in the accuracy of the kinematic variables. From these expressions, some conclusions about the effect of marker cluster design on the experimental errors are obtained. An experiment has been carried out in order to validate the proposed technique and to assess the experimental errors in linear and angular velocity measurement and its influence in instantaneous helical axis determination.

Biomechanical Phenomena↗

PubMed1996

The relationship of hospital process variables to patient outcome post-myocardial infarction.

This study examined the hospital process variables of nursing care, medical care, information, and hospital environment, as evaluated by patients, in relation to their outcome post-myocardial infarction (MI). The sample included 68 hospitalized men and women, aged 29-92, who were diagnosed with an MI. At the time of discharge, they responded to four subscales of the Patient Judgment of Hospital Quality Questionnaire, which measured the hospital process variables, and the Revised Haussman and Hegyvary Outcome Criteria Instrument for Acute Myocardial Infarction, which measured patient outcome post-MI. Data also were collected from patient charts and nurses. Correlational analyses revealed statistically significant relationships between nursing care and patient outcome, and between hospital environment and patient outcome; neither medical care nor information correlated appreciably with patient outcome post-MI. Regression analysis indicated that nursing care was the only significant predictor of patient outcome post-MI.

Adult↗