SEARCH · PubMed Health

Results for “instrumental variable”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 1,369 records · Page 76Linked to original sources

PubMed1994

Influence of mood and adjustment to cancer on compliance with chemotherapy among breast cancer patients.

Approximately 75% of the 181,000 breast cancer patients newly diagnosed in 1992 will survive for at least 5 yr, but survival often depends on receiving adjuvant chemotherapy. We determined that mood variables and attitude toward cancer could predict compliance with IV-administered chemotherapy. The participants were seventy-four women diagnosed with primary breast cancer receiving treatment at a state-supported medical center in one of three southeastern metropolitan areas in the U.S. Most patients were members of minority and lower socioeconomic groups. The design was prospective in the sense that mood and attitude variables were assessed before determination of compliance. Two psychological instruments were used in this study, the Mental Adjustment to Cancer (MAC) Scale and the Affects Balance Scale (ABS). Patients who kept fewer than 85% of their appointments were classified as noncompliant; those keeping 85% or more were classified as compliant. Sixty-three percent of the patients for whom the compliance information was complete were classified as compliant; 37% were noncompliant; and four patients were not included in the analysis because their records were incomplete. The discriminant function was able to correctly classify 86% of the patients according to chemotherapy compliance, a 36% improvement over the chance level. High scores on MAC Fighting Spirit and ABS Anxiety, Depression, and Vigor scales were associated with greater adherence to a chemotherapy regimen. High scores on ABS Guilt and Hostility scales predicted lower levels of compliance.

Adaptation, Psychological↗

PubMed1994

Pain measurement in cancer patients: a comparison of six methods.

A consecutive sample of 53 chronic cancer pain patients were administered 5 different pain intensity scales: a visual analogue scale (VAS), a numerical rating scale from 0 to 10 (NRS), a verbal rating scale (VRS), the Italian Pain Questionnaire (Italian version of the McGill Pain Questionnaire) (PRI), and the Integrated Pain Score (IPS) which is an instrument designed at the Pain Therapy and Palliative Care Division of the National Cancer Institute of Milan to integrate pain intensity and duration in a single measure. These scales were administered before and after a definite therapy change. At the time of the second evaluation the patients were also administered a pain relief scale (IRS). A factor analysis of the scoring properties of these instruments revealed a high degree of association between the variables. A single factor clearly emerged explaining most of the different scales variability. A logistic regression analysis showed that VAS, NRS, VRS were more strongly associated with IRS than PRI and IPS.

Adult↗

PubMed2005

Performance of the English and Spanish S-TOFHLA among publicly insured Medicaid and Medicare patients.

The objective of this study was to analyze the psychometric properties of the English and Spanish S-TOFHLA for three patient populations of interest. Despite being widely used, little is written about psychometric properties of the S-TOFHLA, particularly the Spanish version. Participants were Medicaid and Medicare patients: 936 non-Hispanic and 368 Hispanic patients completed the English S-TOFHLA; 1066 Hispanics completed the Spanish S-TOFHLA. Validity of both versions of the S-TOFHLA was supported by strong positive relationships with education and inverse relationships with age. Significant differences between scores for men and women remained after adjusting for level of education. Score differences occurred across numerous items. More research is needed on the S-TOFHLA and other health literacy instruments to determine why women score differently than men. Variability in literacy skills within subgroups of patients highlights the importance of healthcare providers being sensitive to patients' literacy levels in both spoken and written communications.

Adult↗

PubMed2006

Reference equations for spirometry from a general population sample in central Italy.

Aim of this study was to derive new lung function reference equations and compare the predicted values with those from three sets of existing reference equations: one derived from a Northern Italy population and the two others widely used in European (ECCS) and American (NHANES III) clinical practice. Reference equations for flow-volume curve indexes and VC were derived on 497 normal subjects, aged 8-74, from the epidemiological survey in Pisa, Central Italy (1991-1993). By applying natural cubic splines, one single smooth and continuous equation for the entire age range was provided for each index, separately by gender. Along with age and height, reference values also depended on BMI. Differences among the four reference equations for FEV(1), FVC, VC were quantified for average subjects. The magnitude largely varied over the age range in both genders, reaching up to half litre of air volume at specific ages. Age-gender-specific prevalence rates of airway obstruction, as defined by the ERS criterion, largely varied by applying the considered equations, the differences ranging from -3% to 28%. The observed discrepancies confirm that reference equations should be derived from a population most similar to that for which the equations are to be used and based on measurements obtained by the same instrument and testing procedures, in order to minimize technical variability in lung function both for clinical and epidemiological purposes.

Adolescent↗

PubMed2005

Sensing the sea.

The development of the 'ecosystem approach' to the management of marine systems is leading to a requirement for data to be collected with greater frequency and spatial resolution than has been necessary in the past. This is being met both by the analysis of more samples (to better describe variability and temporal change) and by the deployment of instrumented platforms that gather data over long time periods. To meet these requirements in the hostile conditions at sea, a range of sensors based on physical, chemical and biological responses is being developed. These sensors have applications in laboratory analysis of collected samples, during field studies and directly in situ at remote sites for real-time observations of environmental trends. Here, we consider the role that biosensors could have in future marine monitoring programmes.

Animals↗

PubMed1999

Neurological and physical maturation in normal growth singletons from 37 to 41 weeks' gestation.

An evaluator blinded to gestational age (GA) assessed a cohort of 397 singletons born at between 37 and 41 week's gestation, by looking at 11 criteria exploring neurological maturity and 12 criteria exploring physical maturity. The analysis of correlation coefficients shows various degrees of association between GA and each of the criteria examined. A highly significant correlation (p < 0.001) was found for 4 neurological criteria defining passive tone in limbs and sucking reflex. The activity of flexor muscles of the neck and crossed extension reflex were also associated with maturity but weakly (p < 0.01). A highly significant correlation (p < 0.001) was found for 8 of the physical criteria, skin colour and texture, lanugo, ear firmness, genitalia, breast size, nipple formation and plantar skin creases. Oedema, skull firmness and ear form were also associated but weakly. With multivariate analysis combining the neurological and physical criteria, predictive values ranked in the following order: 1) plantar skin, 2) breast size, 3) sucking reflex, 4) scarf sign, 5) skin colour, 6) genitalia, 7) popliteal angle, 8) return to flexion of forearms, 9) dorsiflexion angle. In conclusion, a score based on physical and neurological criteria is associated with duration of pregnancy (r2 = 0.32) between 37 and 41 weeks' gestation. Such an instrument allows us to study fetal maturity as a variable independent of GA, and therefore makes it possible to identify various influences that may modify maturational rate during the last weeks of pregnancy.

Cohort Studies↗

PubMed1997

Psychiatric assessment and confirmation of dual disorders in rural substance abusing women.

Accurate diagnosis of a comorbid or dual disorder in substance abusing women is critical to treatment and recovery. However, accurate diagnosis of comorbid disorders is difficult. Factors such as instrumentation and timing of diagnostic interview make results highly variable. This article describes difficulties encountered in screening and diagnosing dual disorders in a sample of rural, substance abusing women. The efficacy of screening and diagnostic measures in detecting depression and substance abuse is evaluated, and factors affecting diagnosis are described. The implications of those findings for case finding and management in psychiatric nursing practice are discussed.

Adolescent↗

PubMed2003

The current staging system for endometriosis: does it help?

A multicenter collaboration for data collection and statistical analysis may be necessary to establish and validate a classification system based on empirically derived scores for specific pathologic observations. The endometriosis pain instrument may be a tool for some of those variables with regard to pelvic pain. A similar strategy for uniform collection of data for analysis of important factors also is necessary for infertility. The challenge of creating a satisfactory classification of endometriosis remains. The ability of the current classification schemes to predict pregnancy outcome or aid in the management of pelvic pain is recognized to be inadequate. Further revisions of the current classification scheme are anticipated as the understanding of how endometriosis contributes to infertility and pelvic pain evolves. In any revision of the classification system, use of empirically derived weights and breakpoints to define disease stages based on outcome data in larger clinical trials should be attempted. It is also possible that additional factors, such as CA-125 level or lesion characteristics, may be shown to play an important role in prognosis. If so, these must be accounted for in the classification scheme. Careful and consistent use of the recommendations of the American Society for Reproductive Medicine classification of endometriosis subcommittee should allow for collection of data for use in further revisions. It is possible that a classification scheme that is designed to predict outcome with respect to pregnancy may be totally inadequate in assessing patients who have endometriosis and pelvic pain. Factors found to be important in the assessment of pelvic pain may be different from those involved with the pathophysiology of endometriosis and infertility. The AFS form suggested for use in the management of endometriosis in the presence of pelvic pain allows for recording of variables such as depth of invasion, histology, and documenting adjunct investigations and preoperative physical findings. Such prospective data collection and review in large centers may provide a large clinical base from which to derive empirical point scores and breakpoints in a classification scheme.

Endometriosis↗

PubMed2003

Validation of the arthritis self-efficacy short-form scale in German fibromyalgia patients.

Self-efficacy is assumed to account for significant variance in the treatment outcome of chronic pain patients. The aim of this study was to provide a German version of an approved measure of disease-related self-efficacy in fibromyalgia (FM) patients which assesses treatment outcomes and specific differences compared to other pain patients. The 8-item short-form of the arthritis self-efficacy scale was translated into German (ASES-D) and administered to 148 FM patients and 53 patients with rheumatoid arthritis (RA). In addition, similar cognitive constructs (locus of control, optimism/pessimism, and general self-efficacy) and disease-related variables (pain, functioning, depression, and coping) were assessed. The instrument was further applied to 43 FM patients who underwent interdisciplinary group therapy. Validation methods consisted of correlation, principal component analysis and difference testing between the disease groups. The instrument met good psychometric properties. Evidence for construct validity was provided. Self-efficacy was sensitive to changes and could be used in predicting the treatment outcome in FM patients. The German short-form ASES-D is a further step toward an internationally comparable assessment of disease-related self-efficacy in FM.

Adaptation, Psychological↗

PubMed2003

The effect of additives on the crystallization of cefazolin sodium during freeze-drying.

PURPOSE: To monitor the phase transitions during freeze-drying of cefazolin sodium (I) as a function of process and formulation variables. METHODS: Aqueous solutions of I were frozen under controlled conditions in the sample chamber of a variable temperature X-ray powder diffractometer (XRD). The instrument was modified so that the chamber could be evacuated and the samples dried under reduced pressures. Thus, the entire freeze-drying process was carried out in the XRD holder with real time monitoring of the phase transitions during the different stages of freeze-drying. RESULTS: When aqueous solutions of cefazolin sodium (10% w/w) were cooled to -40 degrees C, the XRD pattern revealed only the crystallization of ice. Annealing the frozen sample led to the crystallization of I as the pentahydrate. Differential scanning calorimetry revealed that the presence of isopropyl alcohol (IPA) (5% w/w) led to a decrease in the Tg', the glass transition temperature of the system, and lowered the temperature of crystallization. The crystallization was studied at -8 and at -15 degrees C in the XRD, and, as expected, more rapid crystallization was observed at the higher temperature. Primary drying at -8 degrees C led to the dehydration of the pentahydrate, resulting in a poorly crystalline product. Again, XRD permitted real time monitoring of the decrease in intensities of some characteristic peaks of the pentahydrate. The in situ XRD technique also enabled us to study the effects of processing conditions (different primary and secondary drying temperatures) and crystalline bulking agents on the solid-state of I in the lyophile. When I was lyophilized using mannitol or glycine as an additive, without an annealing step, the drug was X-ray amorphous although the additive crystallized. When annealed and freeze-dried, I remained crystalline in the presence of glycine but not in the presence of mannitol. CONCLUSIONS: The in situ XRD technique has enabled us to characterize the phase transitions during freeze-drying of cefazolin sodium in multicomponent systems.

Cefazolin↗

PubMed2000

Rainfall and drought in equatorial east Africa during the past 1,100 years.

Knowledge of natural long-term rainfall variability is essential for water-resource and land-use management in sub-humid regions of the world. In tropical Africa, data relevant to determining this variability are scarce because of the lack of long instrumental climate records and the limited potential of standard high-resolution proxy records such as tree rings and ice cores. Here we present a decade-scale reconstruction of rainfall and drought in equatorial east Africa over the past 1,100 years, based on lake-level and salinity fluctuations of Lake Naivasha (Kenya) inferred from three different palaeolimnological proxies: sediment stratigraphy and the species compositions of fossil diatom and midge assemblages. Our data indicate that, over the past millennium, equatorial east Africa has alternated between contrasting climate conditions, with significantly drier climate than today during the 'Medieval Warm Period' (approximately AD 1000-1270) and a relatively wet climate during the 'Little Ice Age' (approximately AD 1270-1850) which was interrupted by three prolonged dry episodes. We also find strong chronological links between the reconstructed history of natural long-term rainfall variation and the pre-colonial cultural history of east Africa, highlighting the importance of a detailed knowledge of natural long-term rainfall fluctuations for sustainable socio-economic development.

Africa, Eastern↗

PubMed1999

The safety and efficacy of treatment with air abrasion technology.

AIMS: To evaluate patient and operator exposure to respirable particulates following the use of air abrasion in tooth preparation, and to compare the microleakage of pit and fissure sealants after conventional, bur and air abrasion preparation of the pits and fissures. METHODS: To examine air abrasion safety, sampling data were collected using a physical model of the upper torso of a patient. Previously extracted bovine incisors were prepared using an air abrasion instrument. Patient and operator exposure samples were collected. The variables examined included the size of the alumina oxide particles, the speed of particle delivery and the method of dust collection. To assess the efficacy of air abrasion, 36 extracted human molars were divided into three groups. The groups were prepared by conventional acid etching, opening the pits and fissures with a round bur, or by air abrasion. To simulate oral conditions, sealed teeth were immersed in artificial saliva and thermocycled. Teeth were immersed in a 1% solution of methylene blue and sectioned to assess the microleakage associated with each sealant. CONCLUSIONS: (1) Dust from the KCP 1000 is insufficient to be a health hazard to patients or operators, (2) chair-side suction can be used as an alternative to the KCP 1000 suction, (3) superior sealants were obtained when tooth surfaces were prepared by a bur, compared to air abrasion and conventionally prepared surfaces, and (4) air abrasion tooth surfaces demonstrated less microleakage than conventionally prepared tooth surfaces.

Aerosols↗

PubMedDate not supplied

Relationship between self-disclosure and serious suicidal behavior.

The ability to predict which suicidal patient is at high risk for a serious attempt is an important clinical problem. On the basis of our clinical research, we hypothesized that self-disclosure may be an important personality variable differentiating suicide attempters and completers. We assessed 80 patients with depressive disorder, divided into four groups of 20 each: suicidal ideation only, nonserious suicide attempts, severe suicide attempts, and no suicidal behavior. Comparisons were also made with 20 healthy controls. All subjects completed Jourad's Self-Disclosure Questionnaire (JSDQ), as well as scales measuring depression/anxiety and hopelessness. The lack of willingness for self-disclosure significantly differentiated the serious attempters from the suicide ideators and mild attempters. The relationship of self-disclosure and more lethal suicide attempts did not appear to be mediated by depression, anxiety, or hopelessness. This preliminary study indicates that self-disclosure may be a promising field for assessment, therapy, and prevention in suicidal patients. Further studies are needed to investigate related variables, wider patients groups, and the use of different instruments.

Adult↗

PubMedDate not supplied

Overview of stress echocardiography: uses, advantages, and limitations.

Responses of the heart to changes in our environment are probably even more important than how the heart functions at rest. Accordingly, stress testing with noninvasive imaging has become important for diagnosis, prognosis, and monitoring the effects of therapy. Echocardiography at rest and with stress permits characterization of global and segmental left ventricular function as well as valvular structure and function. Moreover, echocardiography can be performed during or after a number of different physical or even mental stressors. Advantages of stress echocardiography include its ready availability, relatively low capital cost, and incremental value in that it allows characterization of cardiac anatomy as well as the myocardial response to a potentially ischemic stimulus. Moreover, echocardiography has the potential to image myocardial perfusion along with wall motion and wall thickening. Substantial literature has now been accumulated on the value of stress echocardiography for the diagnosis of ischemic disease, preoperative risk assessment, and assessment of myocardial viability. Echocardiography has compared generally well with nuclear imaging techniques for the detection of angiographic coronary artery disease. Overall sensitivity, however, has been slightly less, particularly for the detection of single-vessel coronary disease, although specificity has been on average somewhat higher than nuclear cardiology techniques. Because of the potential for variability in study acquisition as well as interpretation, careful safeguards need to be employed. Specifically, meticulous technique needs to be applied to obtain high-quality images and to assure that those images are obtained promptly after treadmill exercise stress. Only readers with specific interest and expertise should interpret stress echocardiography studies. Continuing efforts need to be made to assess and minimize variability and to assure continuing quality improvement. Advances in instrumentation, including evolving technology for real-time 3-dimensional imaging, and echocardiography contrast assessment of myocardial perfusion will likely improve the sensitivity of echocardiography and further extend its usefulness.

Coronary Disease↗

PubMed1986

The "Melancholia Rating Scale": a useful instrument for the assessment of affective disorders. Validity and reliability of the Spanish adaptation.

This instrument has been constructed with the purpose of quantifying the severity of depressive states, i.e. to identify the depressive patient and to measure the response to treatment with an antidepressant. Type of instrument: Ordinal rating scale, 11 items, 5 grades. Eleven variables are assessed: Activity (motor); Activity (verbal); Retardation (intellectual); Anxiety (psychic); Suicidal impulses; Lowered mood; Self-depreciation and guilt feelings; Emotional retardation; Sleep disturbances; Tiredness and pain; Work and interests. Tests were done to verify concurrent validity with the Hamilton Depression Scale (HDS); some data on inter-observer reliability are given.

Affective Disorders, Psychotic↗

PubMed1999

Latent structure of the Wisconsin Card Sorting Test after pediatric traumatic head injury.

The performance of 80 pediatric patients with traumatic head injury (THI) on the Wisconsin Card Sorting Test (WCST; Heaton, Chelune, Talley, Kay, & Curtiss, 1993) was examined to determine the underlying latent structure. Exploratory factor analysis with oblique rotation identified three factors: response accuracy, failure to self-monitor, and learning. The response accuracy factor was directly affected by both age and length of coma. Level of performance on this factor also covaried with post-injury psychometric intelligence. It is concluded that interpretation of the WCST results of children with THI should consider the multifactorial nature of the instrument in combination with injury severity characteristics and demographic variables.

Adolescent↗

PubMed1997

Risk factors and prognosis for brachial plexus injury and clavicular fracture in neonates: a prospective analysis from the United Arab Emirates.

The purpose was to identify risk factors and document the incidence and prognosis for brachial plexus palsy (BPP) and clavicular fracture (CF) among consecutive hospital liveborn (LB) infants in the United Arab Emirates. During a 2-year period, all hospital-born infants were examined twice by paediatricians before discharge and those found to have BPP or CF were evaluated and followed up by an orthopaedic surgeon. Each clavicular fracture was confirmed radiologically. For the assessment of risk factors, three controls were selected for each case of BPP or CF. Of the 9231 LB, 27 (2.9/1000) had BPP while 24 (2.6/1000) sustained CF. After controlling for potential confounding variables, shoulder dystocia (SD), fetal macrosomia (birthweight > 4000 g), instrumental vaginal delivery and diabetes remained risk factors for BPP while only fetal macrosomia and instrumental delivery increased the risk of CF. The frequency of these risk factors was higher than that reported from the West. Infants with BPP had a higher incidence of SD (p = 0.0001) and tended to be heavier (p = 0.052) than those with CF. All infants with CF recovered while 20% of those with BPP had moderate to severe residual disabilities. This study highlights geographic differences in risk factors for BPP and CF and the possible contribution of BPP to morbidity in infancy. Early recognition of fetal macrosomia and improved management of SD and maternal diabetes are necessary to reduce the incidence of BPP and CF as well as morbidity from BPP in this community.

Adult↗

PubMed2005

The disablement process: factors associated with progression of disability and recovery in French elderly people.

PURPOSE: To study the factors associated with progression, recovery and death from different grades of disability in elderly people. METHOD: The sample included 3198 participants of the PAQUID ('Personnes Agées QUID') cohort, aged 65 and over and community-dwellers at baseline. Subjects were re-interviewed 1, 3, 5, 8 and 10 years after baseline. A five-state Markov model was used to estimate transition intensities between four grades of disability and toward death. We used a hierarchic scale of disability, which combines basic and instrumental activities of daily living and mobility. Several explanatory variables were investigated: medical, personal and environmental factors. RESULTS: The factors associated with progression and/or no recovery of disability were cardiovascular diseases, stroke and diabetes, low cognition, visual impairment and dyspnoea (for pathologies and impairments), older age, female gender, low educational level (for risk factors), depression (for intra-individual factor) and being married, recent hospitalization and number of drugs (for extra-individual factors). Older age, male gender, tobacco consumption and living in an urban area were associated with mortality. CONCLUSIONS: These findings confirm the independent contribution of each group of variables in the disablement process and stress their different impact on progression of disability or on recovery from different grades of disability.

Age Factors↗