Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Statistical Regression”

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 1,405 records · Page 78Linked to original sources
PubMed2005

Infratentorial abnormalities in vascular dementia.

BACKGROUND AND PURPOSE: Infratentorial abnormalities may cause cognitive deficits, but current research criteria for vascular dementia (VaD) do not consider them. Our purposes were to determine the prevalence of infratentorial abnormalities in VaD, their relation with supratentorial abnormalities, and whether they are relevant to cognition. METHODS: We examined 182 patients (120 men, mean age=73 years, SD=8) with probable VaD at inclusion into a multicenter clinical trial. MRI scans were evaluated for infratentorial vascular abnormalities, midbrain atrophy, cerebellar atrophy, basilar artery diameter and tortuosity, and supratentorial abnormalities. Cognitive testing included the mini-mental state examination (MMSE) and the vascular dementia assessment scale (VaDAS-cog). RESULTS: One hundred forty-one (77.5%) patients had infratentorial abnormalities: 119 (65.4%) had focal infratentorial vascular lesions, 65 (35.7%) had diffuse pontine vascular abnormalities hyperintense on T2-weighted images, 20 (11.0%) had midbrain atrophy, and 16 (8.8%) had cerebellar atrophy. Significant correlations were found between number of infratentorial vascular lesions and basilar artery diameter (rs=0.26; P<0.0001), infratentorial and basal ganglia (including thalamus) vascular abnormalities (rs=0.30; P<0.0001), as well as between midbrain atrophy and global supratentorial atrophy (rs=0.27; P<0.0001). Infratentorial vascular abnormalities and cerebellar atrophy were not significantly associated with cognitive impairment. Patients with midbrain atrophy performed worse on cognitive tests than those without midbrain atrophy. After correction for sex, age, education, supratentorial abnormalities, and center, midbrain atrophy remained significantly associated with lower MMSE scores (P<0.05). CONCLUSIONS: Infratentorial abnormalities often occur in patients with VaD, but only midbrain atrophy was found to be relevant to cognition.

Aged↗
PubMed1993

Predicting length of stay, functional outcome, and aftercare in the rehabilitation of stroke patients. The dominant role of higher-order cognition.

BACKGROUND AND PURPOSE: Research in recent years has revealed factors that are important predictors of physical and functional rehabilitation: demographic variables, visual and perceptual impairments, and psychological and cognitive factors. However, there is a remaining uncertainty about prediction of outcome and a need to clinically apply research findings. This study was designed to identify the relative importance of medical, functional, demographic, and cognitive factors in predicting length of stay in rehabilitation, functional outcome, and recommendations for postdischarge continuation of services. METHODS: The influence of these factors was determined by comparing diagnostic, medical, demographic, functional, and neuropsychological information that was retrospectively obtained by reviewing the records of 86 patients admitted for comprehensive rehabilitation due to stroke (n = 36) or orthopedic injury (n = 50). Multiple linear regression with statistical adjustment to control for overprediction of variance was used to predict outcomes. RESULTS: The study revealed the primary importance of higher-order cognitive impairments (comprehension, judgment, short-term verbal memory, and abstract thinking) in extending length of stay and increasing referrals for outpatient therapies and home services after discharge for the cerebrovascular accident patients in comparison with orthopedic cohorts. CONCLUSIONS: The need is discussed for early, comprehensive assessment of deficits in cognition that affect a stroke survivor's ability to participate in a rehabilitation program and remediation that facilitates functional improvement by building on residuals of impaired abilities or teaching compensatory behaviors.

Aged↗
PubMed1995

The clinical meaning of Rankin 'handicap' grades after stroke.

BACKGROUND AND PURPOSE: The Rankin Scale is a frequently used handicap index in stroke outcome research. However, relatively little is known about its validity. The purpose of this study was to investigate the clinical meaning of Rankin grades by identifying the functional health aspects that contribute to Rankin scores. METHODS: We studied 438 patients 6 months after stroke. Data were collected on the following functional health indicators: alertness, communication, independence, disability in activities of daily living, mobility, instrumental disability, social interaction, and recreation. Disability in activities of daily living was assessed with the Barthel Index, whereas the other indicators were measured with subscales of the Sickness Impact Profile. The association between functional health and Rankin Scale was expressed in terms of relative frequencies and Somers' D statistic. Linear regression analysis (after ordinal transformation) was used to identify the significant health factors that explain Rankin scores. RESULTS: Mobility, disability in daily and instrumental activities, and living arrangements showed a stronger association with Rankin scores (Somers' D range, 0.60 to 0.74) than cognitive and social functioning (Somers' D range, 0.34 to 0.47). Disability in activities of daily living turned out to be the most important explanatory factor of Rankin scores (R2 = 67%). CONCLUSIONS: The Rankin Scale is not a pure handicap measure but should be viewed as a global functional health index with a strong accent on physical disability. The index is useful as a simple and time-efficient outcome measure in largescale multicenter trials. It is argued that at present there is no clear need to assess handicap as the primary outcome in medically oriented stroke intervention studies.

Aged↗
PubMed2001

Changes in stroke mortality rates for 1950 to 1997: a great slowdown of decline trend in Japan.

BACKGROUND AND PURPOSE: Stroke is the second leading cause of death in Japan. We sought to examine changes in stroke mortality rates by age, sex, and birth cohorts from 1950 to 1997. METHODS: The numbers of deaths from stroke and the population by age and sex in subjects aged 55 to 79 years between 1950 and 1997 were obtained from national vital statistics. Poisson regression analyses for annual percentage changes were used to explore these trends. RESULTS: Stroke mortality rates decreased since the mid-1960s for both men and women. Four periods of the decline are identified. In the first period (1950 to 1964), the age-adjusted annual percent changes averaged 0.9% for men (P<0.05) and -0.6% for women (P>0.05). In the second period (1965 to 1974), the annual change averaged -5.0% for men and -5.2% for women (both P<0.01). In the third period (1975 to 1989), the annual change averaged -8.6% for men and -8.7% for women (both P<0.01). In the fourth period (1990 to 1997), the annual change averaged -1.2% for men (P>0.05) and -3.0% for women (P<0.01). In the fourth period, the slowdown of the decline in stroke mortality was most evident in the older age groups of men. CONCLUSIONS: The findings suggested that along with an increasing aging population, the slowdown in the decline of stroke mortality rates, especially for men, is of considerable concern. Efforts to control stroke should be vigorously continued in the 2000s.

Age Distribution↗
PubMed1994

Longitudinal estimates of pulmonary function decline in grain workers.

We conducted a cohort analysis of longitudinal changes in pulmonary function test values in male grain elevator workers in five regions of Canada over a 6-yr period involving three observations. Pulmonary function tests were obtained approximately each 3 yr during an observation interval called a "cycle". The periods of the cycles were 1978-81 (Cycle I), 1981-84 (Cycle II), and 1984-87 (Cycle III), respectively. Data on respiratory symptoms and pulmonary function tests were collected on the same 881 workers in Cycles I and II (mean ages +/- SE: 37.0 +/- 0.48 yr at Cycle I), on the same 1,294 workers in Cycles I, II, and III (34.6 +/- 0.34 yr at Cycle I), and on the same 1,021 workers in Cycles II and III (33.9 +/- 0.38 yr at Cycle II) for a total of 3,196 workers with two or more observations over the 6-yr period. The proportion of current smokers decreased from Cycle I to Cycle III. Autoregression analysis of longitudinal changes in lung function data showed that predictors of FEV1 were height, years in the industry, smoking status, and geographic region. The mean annual losses in FEV1 (FVC) were 28.7 ml (26.4 ml), 38.4 ml (41.9 ml), and 41.7 ml (32.3 ml) for nonsmokers, ex-smokers, and current smokers, respectively. The annual loss of FEV1 (FVC) was 9.2 ml (21.1 ml) for those who were in the grain industry for less than 5 yr and 52.6 ml (60.8 ml) for those who were exposed for 20 yr or more.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2005

Construction of a novel peptide nucleic acid piezoelectric gene sensor microarray detection system.

A novel 2 x 5 clamped style piezoelectric gene sensor microarray has been successfully constructed. Every crystal unit of the fabricated gene sensor can oscillate independently without interfering with each other. The bis-peptide nucleic acid (bis-PNA) probe, which can combine with target DNA or RNA sequences more effectively and specifically than a DNA probe, was designed and immobilized on the surface of the gene sensor microarray to substitute the conventional DNA probe for direct detection of the hepatitis B virus (HBV) genomic DNA. Detection conditions were then explored and optimized. Results showed that PBS buffer of pH 6.8, an ion concentration of 20 mmol/liter, and a probe concentration of 1.5 micromol/liter were optimal for the detection system. Under such optimized experimental conditions, the specificity of bis-PNA was proved much higher than that of DNA probe. The relationship between quantity of target and decrease of frequency showed a typical saturation curve when concentrations of target HBV DNA varied from 10 pg/liter to 100 microg/liter, and 10 microg/liter was the watershed, with a statistic linear regression equation of I gC = -2.7455 + 0.0691 deltaF and the correlating coefficient of 0.9923. Fortunately, this is exactly the most ordinary variant range of the HBV virus concentration in clinical hepatitis samples. So, a good technical platform is successfully constructed and it will be applied to detect HBV quantitatively in clinical samples.

Base Sequence↗
PubMed1995

Attempted suicide among Vietnam veterans: a model of etiology in a community sample.

OBJECTIVE: Data from the National Vietnam Veterans Readjustment Study, conducted from 1986 to 1988, were used to develop an etiological model of attempted suicide among a community sample of 1,198 male Vietnam veterans. METHODS: In a three-step process, the authors used structural equation modeling to develop a model that they refined, cross-validated, and then specified in terms of its replicable paths. RESULTS: The final model possesses highly satisfactory fit and parsimony. General psychiatric disorders were the sole factors contributing directly to attempted suicide. General psychiatric disorders were in part products of both nonmilitary and military traumas, most specifically participation in abusive violence. Posttraumatic stress disorder (PTSD) and substance abuse were related to attempted suicide bivariately but not when considered in conjunction with general psychiatric disorders. Among premilitary risk factors, family instability contributed to attempted suicide indirectly through its influence on general psychiatric disorders. CONCLUSIONS: The etiology of attempted suicide among Vietnam veterans remains largely unexplained. A partial explanation is that the predominant and direct causes spring from general psychiatric disorders rather than from traumatic exposure, PTSD, or substance abuse. Traumatic exposure contributes directly to the development of PTSD and general psychiatric disorders but only indirectly to making a suicide attempt.

Adult↗
PubMed1991

The effect of the initial family interview on a pediatric practice.

To examine the effect of initial family interviews by health care providers on patients' use of health services, 177 patients and their families were randomly assigned to an interviewed (I) or a non-interviewed (NI) subgroup. Initial interviews would encourage families to bring their children in for health supervision visits, but discourage families from making after-hour telephone calls, using the emergency room and bringing the children to the clinic frequently for problem visits. The I families had an initial interview, attended by all family members. Both a physician and a nurse elicited patient histories and explained use of the emergency room, when to make after-hour calls, how to schedule appointments and other information about the clinic. If I families failed to have an initial interview, they were deleted from the study. In the NI subgroup, patient histories were elicited during a routine health supervision visit without the entire family in attendance, and information about emergency room visits, after-hour calls and appointment scheduling was provided during the same visit. After one year (1987) into the study and two years (1988) into the study, all patient charts were examined. Data analysis was performed using analysis of variance for repeated measures (ANOVA) and step-wise multiple regression of Statistical Analysis System. For 1987, the interview intervention explained a significant (p = 0.01) amount of variance in the number of problem visits (less in I) after controlling for months in the study and age of the child.(ABSTRACT TRUNCATED AT 250 WORDS)

Family↗
PubMedDate not supplied

Firearm homicide and firearm suicide: opposite but equal.

OBJECTIVE: Homicide and suicide are intentional acts of violence that disproportionately involve firearms. Much more effort has been devoted to the ecological study of homicide; methods that have been developed to better understand and subsequently prevent homicide may be applicable to suicide. The purpose of the present study was to compare the occurrence of firearm homicide and firearm suicide using routine activity theory as a framework for analysis. METHODS: Detailed mortality data pertaining to decedents, their neighborhoods, and use of firearms were collected from 1994 to 1998 for the counties containing and surrounding three small to medium-sized U.S. cities. Data from a total of 468 neighborhoods that collectively experienced 1,025 intentional deaths from firearms (396 firearm homicides and 629 firearm suicides) were analyzed. RESULTS: Firearm homicide was consistently associated with out-of-home, nighttime activity in neighborhoods where many people were likely to be coming and going. In an opposite-but-equal fashion, firearm suicide was consistently associated with in-home, daytime activity in out-of-the-way neighborhoods. CONCLUSIONS: Firearm homicide and firearm suicide were found to be consistently associated with markers of routine activity in all three cities, albeit in an opposite-but-equal manner. Because firearm suicides very often occur as lonely events in lonely neighborhoods, they may go under-noticed relative to firearm homicides. More awareness and additional public health studies of firearm suicide, in tandem with firearm homicide, should be pursued to better identify individuals and neighborhoods that are at greatest risk of experiencing each event.

Adult↗
PubMed1996

Box-Jenkins modelling in medical research.

Notifications of diseases, entries in a hospital, injuries due to accidents, etc., are frequently collected in fixed equally spaced intervals. Such observations are likely to be dependent. In environmental medicine, where series such as daily concentrations of pollutants are collected and analysed, it is evident that dependence of consecutive measurements may be important. A high concentration of a pollutant today has a certain 'inertia', i.e. a tendency to be high tomorrow as well. Dependence of consecutive observations may be equally important when data such as blood glucose are recorded within a single patient. ARIMA models (autoregressive integrated moving average models, Box-Jenkins models), which allow the stochastic dependence of consecutive data to be modelled, have become well established in such fields as economics. This article reviews basic concepts of Box-Jenkins modelling. The methods are illustrated by applications. In particular, the following topics are presented: the ARIMA model, transfer function models (assessment of relations between time series) and intervention analysis (assessment of changes of time series).

Data Collection↗
PubMed1998

Components of variance: a miscellany.

Some general issues connected with components of variance are reviewed. These include matters of definition, of formal inference in a normal-theory context, of goodness of fit, and of simple methods for unbalanced data.

Analysis of Variance↗
PubMed2003

A framework for power analysis using a structural equation modelling procedure.

BACKGROUND: This paper demonstrates how structural equation modelling (SEM) can be used as a tool to aid in carrying out power analyses. For many complex multivariate designs that are increasingly being employed, power analyses can be difficult to carry out, because the software available lacks sufficient flexibility. Satorra and Saris developed a method for estimating the power of the likelihood ratio test for structural equation models. Whilst the Satorra and Saris approach is familiar to researchers who use the structural equation modelling approach, it is less well known amongst other researchers. The SEM approach can be equivalent to other multivariate statistical tests, and therefore the Satorra and Saris approach to power analysis can be used. METHODS: The covariance matrix, along with a vector of means, relating to the alternative hypothesis is generated. This represents the hypothesised population effects. A model (representing the null hypothesis) is then tested in a structural equation model, using the population parameters as input. An analysis based on the chi-square of this model can provide estimates of the sample size required for different levels of power to reject the null hypothesis. CONCLUSIONS: The SEM based power analysis approach may prove useful for researchers designing research in the health and medical spheres.

Analysis of Variance↗
PubMed2004

Interaction among general practitioners age and patient load in the prediction of job strain, decision latitude and perception of job demands. A cross-sectional study.

BACKGROUND: It is widely recognized and accepted that job strain adversely impacts the workforce. Individual responses to stressful situations can vary greatly and it has been shown that certain people are more likely to experience high levels of stress in their job than others. Studies highlighted that there can be age differences in job strain perception. METHODS: Cross-sectional postal survey of 300 Lithuanian general practitioners. Psychosocial stress was investigated with a questionnaire based on the Reeder scale. Job demands were investigated with the Karasek scale. The analysis included descriptive statistics; logistic regression beta coefficients to find out predictors and interactions between characteristics and predictors. RESULTS: Response rate was 66% (N = 197). Logistic regression as significant predictors for job strain assigned - duration of work in primary care; for job demands- age and duration of working in primary care; for decision latitude- age and patient load.The interactions with regard to job strain showed that GP's age and job strain are negatively associated to a low patient load. Lower decision latitude for older GP age is strongly related to higher patient load. Job demands and GP age are slightly positively related at low patient load. CONCLUSIONS: Lithuanian GP's have high patient load and are at risk of stress, they have high job demands and low decision latitude. Older GP's perceive less strain, lower job demands and higher decision latitude in case of low patient load. Young GP's decision latitude has week association to patient load. Regarding to the changes in patient load younger GP's perceive it more sensitively as changes in job demands.

Adult↗
PubMed2003

Statistics review 7: Correlation and regression.

The present review introduces methods of analyzing the relationship between two quantitative variables. The calculation and interpretation of the sample product moment correlation coefficient and the linear regression equation are discussed and illustrated. Common misuses of the techniques are considered. Tests and confidence intervals for the population parameters are described, and failures of the underlying assumptions are highlighted.

Analysis of Variance↗
PubMed2003

Wavelets and statistical analysis of functional magnetic resonance images of the human brain.

Wavelets provide an orthonormal basis for multiresolution analysis and decorrelation or 'whitening' of nonstationary time series and spatial processes. Wavelets are particularly well suited to analysis of biological signals and images, such as human brain imaging data, which often have fractal or scale-invariant properties. We briefly define some key properties of the discrete wavelet transform (DWT) and review its applications to statistical analysis of functional magnetic resonance imaging (fMRI) data. We focus on time series resampling by 'wavestrapping' of wavelet coefficients, methods for efficient linear model estimation in the wavelet domain, and wavelet-based methods for multiple hypothesis testing, all of which are somewhat simplified by the decorrelating property of the DWT.

Brain↗
PubMed1996

Graphs to estimate an individualized risk of breast cancer.

PURPOSE: Clinicians who counsel women about their risk for developing breast cancer need a rapid method to estimate individualized risk (absolute risk), as well as the confidence limits around that point. The Breast Cancer Detection Demonstration Project (BCDDP) model (sometimes called the Gail model) assumes no genetic model and simultaneously incorporates five risk factors, but involves cumbersome calculations and interpolations. This report provides graphs to estimate the absolute risk of breast cancer from the BCDDP model. PATIENTS AND METHODS: The BCDDP recruited 280,000 women from 1973 to 1980 who were monitored for 5 years. From this cohort, 2,852 white women developed breast cancer and 3,146 controls were selected, all with complete risk-factor information. The BCDDP model, previously developed from these data, was used to prepare graphs that relate a specific summary relative-risk estimate to the absolute risk of developing breast cancer over intervals of 10, 20, and 30 years. RESULTS: Once a summary relative risk is calculated, the appropriate graph is chosen that shows the 10-, 20-, or 30-year absolute risk of developing breast cancer. A separate graph gives the 95% confidence limits around the point estimate of absolute risk. Once a clinician rules out a single gene trait that predisposes to breast cancer and elicits information on age and four risk factors, the tables and figures permit an estimation of a women's absolute risk of developing breast cancer in the next three decades. CONCLUSION: These results are intended to be applied to women who undergo regular screening. They should be used only in a formal counseling program to maximize a woman's understanding of the estimates and the proper use of them.

Adult↗
PubMed2005

Does a history of childhood sexual abuse affect sexual outcomes in breast cancer survivors?

PURPOSE: Little is known about a history of childhood sexual abuse (CSA) in breast cancer survivors and its relationship to sexual functioning after cancer. As part of a larger survey study examining sexuality and intimacy in breast cancer survivors, we conducted in-person interviews with a subsample of participants. METHODS: A total of 147 women in Los Angeles, CA, and Washington, DC, completed a structured interview that addressed sexual socialization and a history of sexual abuse. Trained female interviewers conducted the interviews. Descriptive statistics and regression analyses were used to examine the prevalence of CSA, and its potential impact on sexual health and functioning. RESULTS: One in three women reported at least one CSA incident. Among women who had experienced CSA, 71% reported a single incident, and 22% reported a penetrative form of sexual contact. In multivariate regression analyses examining physical and psychological aspects of sexuality and body image, CSA was not a significant predictor of physical discomfort. However, a history of penetrative CSA was a significant predictor of psychological discomfort (P = .02). CONCLUSION: The prevalence of CSA in this sample was similar to the general population literature on this topic. In this small sample, a past history of CSA did not contribute significantly to the physical discomforts associated with sexual intimacy after breast cancer; however, our findings suggest that a past history of penetrative CSA is associated with increased psychological discomfort, and may warrant additional examination in future research.

Adaptation, Psychological↗