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Results for “longitudinal data”

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PubMed2002

Effects of chronic epilepsy on declarative memory systems.

Memory is systematically affected by temporal lobe epilepsy. Since surgery is a promising alternative to pharmacological treatment the questions which memory system is affected and what the long-term prognosis of memory is are more relevant than ever. We address these issues by cross-sectional and longitudinal analysis of memory performance in large series of patients with temporal lobe epilepsy (TLE). The findings indicate that episodic memory rather than semantic memory is impaired in TLE, in particular in TLE with mesial temporal pathology. With the exception that mesial functions appear increasingly affected by chronic non-mesial TLE, memory decline in TLE is not different from that observed in healthy control subjects. However, since patients perform poorer than controls at any age, normal senescence brings patients to mnesic disability at a younger age. Semantic memory seems unaffected by this process but early cortical lesions appear to interfere with knowledge acquisition. Longitudinal data come to a different conclusion regarding the contribution of epilepsy/seizures to memory decline. Conservative treatment is associated with significant decline in figural memory and 37% of the patients experience some memory decline in the long run. Surgery partly anticipates the decline observed with conservative treatment, but losses are most marked after left temporal lobe surgery. After surgery, quite stable memory or even late recovery from surgery is indicated. Leaving aside the surgical intervention, the data provide evidence that the longitudinal memory outcome in TLE is determined by seizure control, seizure severity, mental reserve capacities, and the retest interval. Thus early and efficient seizure control and the prevention of any cerebral damage from the beginning of epilepsy are demanded.

Epilepsy↗

PubMed1986

Stability and change in adult intelligence: 1. Analysis of longitudinal covariance structures.

We address two questions of central interest in adult intellectual development: the equivalence of psychometric tests' measurement properties at different ages, and the stability of individual differences in intelligence over time. We performed a series of longitudinal factor analyses using the LISREL program to model longitudinal data from Schaie's Seattle Longitudinal Study. The results indicate complete invariance in the loadings of five subtests of Thurstone's Primary Mental Abilities battery on a general intelligence factor. Individual differences in general intelligence were highly stable over 14-year epochs, with standardized factor correlations averaging about .9 between adjacent 7-year testing intervals. These results indicate that most individuals in this relatively select longitudinal sample maintained their relative ordering in intelligence.

Adult↗

PubMed2001

PQM--Psychiatry Quality Measurement.

As a consequence of an increased awareness of quality management in psychiatry the Lundbeck Institute has developed a software program called Psychiatry Quality Measurement (PQM). This is an electronic documentation and quality measurement system with a large data-collecting function to record longitudinal data of the full psychiatric visit, covering all aspects of an evaluation and follow-up. Using the full ICD-10 and DSM-IV classifications, the system has been designed to assist with quality measurement in all psychiatric diagnoses. A full statistical package is included in the program to calculate outcomes of treatment (including relapse rates, improvements in psychopathology, severity and frequency of side-effects, and costs of treatment) as tables and graphs ready for presentation in a Powerpoint format. The system is fully translatable and flexible for various implementation settings, including stand-alone PCs or hospital network systems, all ICD-10 or DSM-IV diagnoses, and the possibility of the use of over 20 psychopathology and side-effect scales to measure the quality of care of all psychiatry patients.

Data Collection↗

PubMed1989

Getting on your bike: what difference does a migration history make?

"This research is an investigation of the relationship between individuals' histories of migration and their durations of residential sojourns. The use of longitudinal data makes it possible to directly verify the hypothesis that previous migrants will migrate sooner than individuals with no history of migration. The research also provides a random utility justification for a model of residential sojourns." The model is applied to data from the U.S. National Longitudinal Survey of Youth.

Americas↗

PubMed2005

The reliability, validity and responsiveness of the Restless Legs Syndrome Quality of Life questionnaire (RLSQoL) in a trial population.

BACKGROUND: The aim of this study was to determine the reliability, validity and responsiveness of the Restless Legs Syndrome Quality of Life questionnaire (RLSQoL) in a clinical trial setting. METHODS: Two matching, placebo-controlled, multinational studies assessing the effectiveness and safety of ropinirole for treating moderate-to-severe Restless Legs Syndrome (RLS) formed the basis of this psychometric assessment. Validity and reliability were assessed using baseline data. Responsiveness was determined using longitudinal data collected at baseline and 12 weeks. RESULTS: A total of 547 subjects formed the baseline validation population; 519 were used for assessing responsiveness (n = 284/263 and 271/248 for both studies, respectively). Construct validity assessment confirmed that an overall life impact score could be calculated. All item-scale correlations were = 0.4, except items 1 (r = 0.36) and 5 (r = 0.35) in one study. Floor and ceiling effects were minimal. Cronbach's alpha values were 0.82 and 0.87, respectively, confirming internal consistency reliability. Correlations with the International Restless Legs Syndrome Study Group's severity rating scale (International Restless Legs Scale; IRLS) were moderate (r = -0.68 and -0.67, respectively; p < 0.0001). The RLSQoL was able to discriminate between levels of sleep problems (p < 0.0001) and between levels of global health status determined by a Clinical Global Impression of severity (CGI-S) (p < 0.0001). Responsiveness was demonstrated by significant differences in overall life impact change scores between CGI improvement levels after 12 weeks (p < 0.0001). CONCLUSION: The RLSQoL is a valid, reliable and responsive measure of quality of life for patients with RLS, in a clinical trial setting where group comparisons are anticipated.

Adult↗

PubMedDate not supplied

The effect of neonatal universal hearing screening in a health surveillance perspective--a controlled study of two health authority districts.

The contribution describes the effect of a neonatal hearing screening program in terms of estimated prevalence rate of congenital hearing impairment and age at identification in two five-year cohorts born between 1990 and 1994 as a function of health authority districts (HADs). In addition, identically defined five-year birth cohorts from 1970 to 1974 and 1980 to 1984 living in the same HADs evaluated previously are used in the analysis, offering longitudinal data. In 1990 a non-targetted neonatal hearing screening program based on EOAE was introduced in the County-HAD, whereas the City-HAD continued its child hearing health surveillance program unchanged. Assuming an unchanged prevalence estimate of 1.5 per 1000 of congenital or early acquired (i.e. neonatal period) hearing disability, i.e. > or = 25 dB HL for the better ear at 0.5-4 kHz in both HADs, an underestimate of 68 per cent in the City and of 20 per cent in the County, respectively, was found at the time of data collection (January 1995). Significant longitudinal improvements in the early identification from the 1970-1974 cohort compared to the 1980-1984 cohort has been demonstrated, but the improvement in the proportion of children identified as a function of both 6 and 12 months of age in the 1990-1994 cohort is significantly greater, showing a median age at identification of 11 months in the County-HAD. The cross-sectional and longitudinal comparisons between the HADs imply that a neonatal universal hearing screening program with a 20 per cent coverage may add significantly to the early identification of children with early-onset hearing impairment.

Cohort Studies↗

PubMed2005

Relationship between body composition changes and changes in physical function and metabolic risk factors in aging.

PURPOSE OF REVIEW: Several body composition changes are known to occur with aging. The purpose of this review is to evaluate recent literature examining body composition changes with aging and how these relate to changes in physical function and metabolic risk. RECENT FINDINGS: Cross-sectional and longitudinal studies have observed increases in fat mass and decreases in muscle mass or lean tissue mass in older adults, often in the absence of differences or changes in body weight. Cross-sectional studies have also reported increases in intramyocellular lipid and liver fat in older versus younger adults and related changes in body composition with changes in physical function and metabolic risk, but few longitudinal data are available. Furthermore, most longitudinal studies lack precise methods of assessing body fat distribution and muscle and organ quality, resulting in a lack of detailed and precise information on body composition changes with aging and their relationship to health. SUMMARY: Research to date has outlined a need for more detailed body composition measurements of aging adults. Absence of change in a total body compartment may mask a change in subcompartments that may impact health. Furthermore, intervention studies to determine ways to maintain body composition are consistent with healthy living throughout the aging process.

Adipose Tissue↗

PubMed2006

Sex differences in outcome and recovery for schizophrenia and other psychotic and nonpsychotic disorders.

OBJECTIVE: It is generally believed by the field of psychiatry that women with schizophrenia have better outcomes and higher rates of recovery than their male counterparts, because many studies on the topic support this finding. Fewer data are available to assess potential sex differences among individuals with other psychotic disorders. This study used longitudinal data on sex differences previously unavailable to the field to examine long-term global outcome, potential recovery, course of illness, and rehospitalization for schizophrenia, other psychotic disorders, and nonpsychotic disorders. METHODS: A total of 239 young psychiatric patients (mean age of 23.4 years) were assessed prospectively at the index hospitalization and then followed over 15 years at five follow-up points (at a mean of two, 4.5, 7.5, ten, and 15 years). The sample consisted of 69 patients with schizophrenia, 56 with other psychotic diagnoses, and 114 with nonpsychotic psychiatric disorders. RESULTS: Sex differences in outcome were found for both patients with schizophrenia and those with other psychotic disorders, with women consistently showing better functioning over time, more frequent periods of good functioning and periods of recovery, less likelihood of uniformly poor outcome, and fewer and shorter rehospitalizations. Unlike both groups of patients who were psychotic, the patients with nonpsychotic disorders showed no significant sex differences in outcome. CONCLUSIONS: Both longitudinally and at each individual follow-up point, the data suggest that women with schizophrenia and with other types of psychotic disorders generally show better outcome than men with similar diagnoses. The sex differences in outcome for patients with schizophrenia were consistent over time. However, these sex differences were only moderate in size compared with the much larger difference in outcome between the diagnostic groups. The longitudinal data add a new dimension to previous research and suggest that sex differences in outcome are not specific to patients with schizophrenia but rather occur among patients with psychotic disorders in general.

Adult↗

PubMedDate not supplied

Some considerations in the analysis of rates of change in longitudinal studies.

This paper discusses and compares several estimators of mean rate of change in unbalanced longitudinal data based on a model with randomly distributed regression coefficients across individuals. The estimators are unweighted and weighted means of these coefficients. The paper also evaluates commonly used variance estimates corresponding to the estimators. Results show that in situations of very slight imbalance, the choice of method is not critical. When imbalance is substantial, however, one should weight the regression coefficients by their estimated precision. An example using data from a nutritional study on premature neonates illustrates some issues encountered in the analysis of longitudinal clinical data sets.

Humans↗

PubMed1989

Application of a two-stage random effects model to longitudinal pulmonary function data from sarcoidosis patients.

We applied a two-stage random effects model to pulmonary function data from 31 sarcoidosis patients to illustrate its usefulness in analysing unbalanced longitudinal data. For the first stage, repeated measurements of percentage of predicted forced vital capacity (FVC%) from an individual were modelled as a function of time since initial clinical assessment. At the second stage, parameters of this function were modelled as a function of certain patient characteristics. We used three methods for estimating the model parameters: maximum likelihood; empirical Bayes; and a two-step least-squares procedure. Similar results were obtained from each, but we recommend the empirical Bayes, since it provides unbiased estimates of variance components. Results indicated that deterioration in FVC% is associated with a higher initial FVC% value and large numbers of both total cells and eosinophils in bronchoalveolar lavage at the initial assessment. Improvement is associated with higher values of pulmonary Gallium uptake at initial assessment and race. Blacks are more likely to improve than whites.

Adolescent↗

PubMed2005

An exploratory baseline study of boy chorister vocal behaviour and development in an intensive professional context.

Currently, there is no existing published empirical longitudinal data on the singing behaviours and development of choristers who perform in UK cathedrals and major chapels. Longitudinal group data is needed to provide a baseline against which individual chorister development can be mapped. The choristers perform to a professional standard on a daily basis, usually with linked rehearsals, whilst also following a full school curriculum. The impact of this intensive schedule in relation to current vocal behaviour, health and future development requires investigation. Furthermore, it is also necessary to understand the relationship between the requirements of chorister singing behaviour and adolescent voice change. The paper will report the initial findings of a new longitudinal chorister study, based in one of London's cathedrals. Singing and vocal behaviours are being profiled on a six-monthly basis using data from a specially designed acoustic and behavioural instrument. The information obtained will enable us to understand better the effects of such training and performance on underlying vocal behaviour and vocal health. The findings will also have implications for singing teachers and choral directors in relation to particular methods of vocal education and rehearsal.

Adolescent↗

PubMed2002

Rural-urban home health care differences before the Balanced Budget Act of 1997.

This study arose from concerns that home health care may be more difficult to provide to rural than urban elderly patients (because of geographic barriers, personnel shortages, and other factors) and may therefore be less effective in terms of patient outcomes. Case mix, home health care service use, and outcomes (primarily discharge status) were analyzed for a national random sample of 3,869 rural and urban elderly home health patients. Longitudinal data covered the period from home health admission to discharge or 120 days (whichever occurred first). Primary data collection instruments were designed to obtain longitudinal patient-level health status data; agency records and Medicare data provided service use information. (The study did not address access but focused on services and outcomes after admission to home health care.) Two-group statistical tests and multivariate analyses were employed to assess rural-urban differences. The major findings were that, after adjustment for rural-urban case mix and agency differences, rural compared to urban patients received fewer home health services and attained less favorable discharge outcomes. For example, the rural patients had a higher case mix adjusted hospitalization rate. Because the study data pertain to 1995 through 1996, the results provide a baseline for future analyses of possibly different rural compared to urban effects of the Balanced Budget Act of 1997, which resulted in major changes in Medicare payment for home health care.

Aged↗

PubMed2004

Functional data analysis in longitudinal settings using smoothing splines.

Data in many experiments arise as curves and therefore it is natural to use a curve as a basic unit in the analysis, which is termed functional data analysis (FDA). In longitudinal studies, recent developments in FDA have extended classical linear models and linear mixed effects models to functional linear models (also termed varying-coefficient models) and functional mixed effects models. In this paper we focus our review on the functional mixed effects models using smoothing splines, because functional linear models are special cases of this more general framework. Due to the connection between smoothing splines and linear mixed effects models, functional mixed effects models can be fitted using existing software such as SAS Proc Mixed. A case study is presented as an illustration.

Biomedical Research↗

PubMed2000

Total body protein in chronic diseases and in aging.

Substantial losses of total body protein (TBP) can occur in chronic diseases and in aging. Such losses impact negatively on immunity and quality of life, and on growth rates in children. Direct measurements of total body nitrogen (TBN) monitor the integrated changes in TBP over time and allow comparison with normal subjects. TBN assessment via neutron capture analysis is therefore the gold-standard method of TBP estimation, so that risk factors for protein deficit can be identified and patient management optimized. The nitrogen index (NI) can be used to predict prognostic outcome: an NI < 0.9 is associated with substantial wasting in HIV disease, an NI < 0.8 predicts significant pathophysiology in chronic renal failure, and a low NI is predictive of neutropenia in breast-cancer patients. These findings emphasize the central importance of adequate protein stores in recovery from disease or in maintaining quality of life. Aging appears to involve a gradual loss of TBP throughout adulthood. Cross-sectional data suggest that TBP declines curvilinearly with age, such that there is an accelerated decline after 65 years of age. However, longitudinal data are scarce, and little is known about the relative loss of visceral protein, as opposed to skeletal muscle protein. More clearly-defined data are essential if the effects of aging per se are to be separated from the effects of chronic disease. A further complication is the knowledge that physical activity also declines with age. Thus sarcopenia, the loss of skeletal muscle mass, could primarily result from disuse rather than aging. The economic impact of unsuccessful aging places a pressing need for multicompartment data in longitudinal study designs.

Adult↗

PubMedDate not supplied

Growth patterns of Filipino children indicate potential compensatory growth.

BACKGROUND: The extent to which compensatory growth can occur after 2 years of age among children who were stunted in infancy has been questioned due, in part, to limitations in the data used to explore the issue. AIM: This study uses longitudinal data with multiple measurements over the entirety of the growth period to explore the potential for post-infancy compensatory growth in a developing country context. SUBJECTS AND METHODS: Data comes from >2000 Filipino youths from the Cebu Longitudinal Health and Nutrition Survey. Anthropometric data were collected bimonthly from 0 to 2 years, and at mean ages of 8, 11.5, 15.5 and 18.5 years. Growth indicators and influences on growth are compared among three groups: those that improved, tracked or worsened in change in height-for-age Z-score from 2 to 18.5 years of age. RESULTS: Those that improved in growth from 2 to 18.5 years grew slowest before 2 years of age, while the opposite was true among those that worsened. The reversal took place during the prepubescent growth spurt. Those that improved tended to have less educated but taller mothers. Regression to the mean and the potential for compensatory growth are discussed.

Adolescent↗

PubMed1996

Hope from the perspective of homeless families.

Homeless families represent one-third of the homeless population. These families have few resources and experience multiple stressors. This study explored the meaning of hope and the influence of specific characteristics on hope, and identified strategies that are used to foster hope in homeless families living in four homeless shelters. Using the technique of methodological triangulation (interview, Herth Hope Index, and Background Data Form), the author collected cross-sectional data on 52 homeless families and longitudinal data on 10 families over a 9-month period of time in order to provide a clearer understanding of the hope process. Hope was described as a power within the self that mobilizes one to move beyond the present situation and to envision a better tomorrow for one's self and others. Six hope-engendering strategies and four hope-hindering factors were identified based on the interview responses of adult family members. Overall hope levels in those residing in the homeless shelter were low and remained stable across the background variables with the exception of those receiving nurse-provided health care on the premises. Across time, hope levels were found to be low at interview time one, to rise significantly at time two, and to level off at time three. An understanding of hope from the perspective of the homeless family could provide a basis upon which to develop interventions that engender hope.

Adaptation, Psychological↗

PubMed2005

Long-run consequences of parental paid work hours for child overweight status in Canada.

This paper explores the connection between the labour market and child overweight status in Canada. The labour market is a social institution which plays a critical role in determining how families live their day-to-day lives, for example, how much time and which parts of the day are available for cooking, eating and exercise. Using longitudinal data from the Statistics Canada National Longitudinal Survey of Children and Youth, we find that a history of higher hours of paid work by mothers (but not fathers) is associated with a higher probability of being 'at risk of overweight'/overweight for children aged 6-11. The policy implication we draw from this work is that additional support to better enable parents to engage in paid work without penalty to their own health or that of their children is clearly warranted.

Adult↗

PubMed2001

Immunology and the REACH study: HIV immunology and preliminary findings. Reaching for Excellence in Adolescent Care and Health.

This review paper presents the immunology findings in human immunodeficiency virus (HIV) infected and uninfected youth in the Reaching for Excellence in Adolescent Care and Health (REACH) Project within the context of basic and HIV immunology concepts. Methods employed in the study for specimen collection, management, and laboratory analysis are presented. This paper reviews published analyses of cross-sectional data; longitudinal analyses are underway. These preliminary data extend the work of others in demonstrating the potential for substantial thymic reserve in youth. This finding in HIV infected adolescents has implications for a fuller response to antiretroviral or immune-based therapies compared to that seen in adults. Dysregulation in mucosal immunity may appear before systemic HIV effects are seen and requires attention particularly to screening and treatment of genital co-infections. REACH has demonstrated gender differences in immunologic measures irrespective of HIV infection status.

Adolescent↗