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Results for “longitudinal data”

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PubMed2005

A longitudinal investigation of visual event-related potentials in the first year of life.

The goal of the current study was to assess general maturational changes in the ERP in the same sample of infants from 4 to 12 months of age. All participants were tested in two experimental manipulations at each age: a test of facial recognition and one of object recognition. Two sets of analyses were undertaken. First, growth curve modeling with mixed models was used to examine trajectories of development and possible differences in trajectories based on recognition memory (novel versus familiar) and/or stimulus-specific memory (face versus object recognition). Our results suggest that the Pb, Nc and Slow Wave components change significantly in terms of amplitude and latency over the first year of life. Pb amplitude showed a significant non-linear increase over time, whereas Pb latency showed a significant linear decrease over time with a plateau beginning at 10 months. Nc amplitude showed a significant linear decrease over time (i.e. a stronger negative value), whereas Nc latency showed a significant linear decrease over time, with a plateau beginning at 8 months. Second, to relate our findings to those reported in the literature, we examined the effects of memory and stimulus and their combination. Differences between recognition memory and stimulus specific memory were found in the responses to familiar and novel faces and objects for all three components, although the pattern differed across the five ages. These results have implications for future studies that involve the recording of the visual ERP, and point to the advantages of growth curve modeling in examining longitudinal data to account for non-linear development.

Age Factors↗

PubMedDate not supplied

Health, function and survival of a cohort of very old Canadians: results from the second wave of the Canadian Study of Health and Aging.

Seniors 85 years of age and older (85+) make up the fastest-growing segment of the Canadian population. There is a need for longitudinal data on the health status of this group. We used data collected as part of the Canadian Study of Health and Aging to examine how health status changed over five years in a large (n = 1799) cohort of Canadians 85+. By the time of the follow-up assessment, 60.1% had died and 33.9% of those who had been residing in the community when the cohort was initially formed had been institutionalized. Most (79.2%) of the community survivors felt that their health had stayed the same or improved, even though over two thirds (67.9%) reported a decline in their functional abilities. Potential predictors of both good and adverse outcomes were explored. While disease prevention, health promotion and environmental modifications may decrease the personal and societal impacts of these age-associated findings, health care planning for the very old should take these data into account.

Activities of Daily Living↗

PubMed2006

Measuring change in activities of daily living in nursing home residents with moderate to severe cognitive impairment.

BACKGROUND: The objective of this study was to assess the responsiveness of the Minimum Data Set Activities of Daily Living (MDS-ADL) Scale to change over time by examining the change in physical function in adults with moderate to severe dementia with no comorbid illness who had been resident in a nursing home for over 90 days. METHODS: Longitudinal data were collected on nursing home residents with moderate (n = 7001) or severe (n = 4616) dementia in one US state from the US national Minimum Data Set (MDS). Severity of dementia was determined by the MDS Cognitive Performance Scale (CPS). Physical function was assessed by summing the seven items (bed mobility, transfer, locomotion, dressing, eating, toilet use, personal hygiene) on the MDS activities of daily living (ADL) Long Form scale. Mean change over time of MDS-ADL scores were estimated at three and six months for residents with moderate (CPS score of 3) and severe (CPS score of 4 or 5) dementia. RESULTS: Physical function in residents with moderate cognitive impairment deteriorated over six months by an average of 1.78 points on the MDS-ADL Long Form scale, while those with severe cognitive impairment declined by an average of 1.70 points. Approximately one quarter of residents in both groups showed some improvement in physical function over the six month period. Residents with moderate cognitive impairment experienced the greatest deterioration in early-loss and mid-loss ADL items (personal hygiene, dressing, toilet use) and residents with severe cognitive impairment showed the greatest deterioration in activities related to eating, a late loss ADL. CONCLUSION: The MDS-ADL Long Form scale detected clinically meaningful change in physical function in a large cohort of long-stay nursing home residents with moderate to severe dementia, supporting its use as a research tool in future studies.

Activities of Daily Living↗

PubMed2005

Covariate-adjusted varying coefficient models.

Covariate-adjusted regression was recently proposed for situations where both predictors and response in a regression model are not directly observed, but are observed after being contaminated by unknown functions of a common observable covariate. The method has been appealing because of its flexibility in targeting the regression coefficients under different forms of distortion. We extend this methodology proposed for regression into the framework of varying coefficient models, where the goal is to target the covariate-adjusted relationship between longitudinal variables. The proposed method of covariate-adjusted varying coefficient model (CAVCM) is illustrated with an analysis of a longitudinal data set containing calcium absorbtion and intake measurements on 188 subjects. We estimate the age-dependent relationship between these two variables adjusted for the covariate body surface area. Simulation studies demonstrate the flexibility of CAVCM in handling different forms of distortion in the longitudinal setting.

Adult↗

PubMed1996

Nuchal translucency measurements: frequency distribution and changes with gestation in a general population.

OBJECTIVE: To investigate nuchal translucency variation with crown-rump length (CRL) in the first trimester in normal fetuses. DESIGN: A prospective observational study. SETTING: Department of obstetrics in a London teaching hospital. PARTICIPANTS: One thousand seven hundred and seven pregnant women (1685 singleton and 22 twin pregnancies) with chromosomally normal fetuses between 9+zero and 14+6 weeks of gestation were recruited sequentially from a dating scan clinic. Nuchal translucency was measured in 94.9% by transabdominal sonography (TAS) and by transvaginal sonography (TVS) if difficulty was encountered with TAS (5.1%). Nuchal translucency measurement was repeated in 136 fetuses: the first scan between between 9+zero-11+6 weeks and the second over 12 weeks of gestation. RESULTS: Of this general population, 4.2% had a nuchal translucency (NT) measurement > or = 2.5 mm, but this proportion varied significantly between gestational age groups (P = 0.011). The repeatability coefficients for NT measurements were 0.44 mm and 0.23 mm for TAS and TVS, respectively. The cross-sectional data demonstrate an increase in nuchal translucency measurement between 9 and 12 weeks of gestation and then a decrease at 13-14 weeks. This relation is best modelled using the quadratic equation: log10 (NT) = -1.03 + (0.0314 x CRL) - (2.20 x 10(-4) x CRL2). Longitudinal data confirmed an increase of nuchal translucency measurements with increasing gestation. CONCLUSION: Nuchal translucency measurements increase significantly with increasing gestation. The use of a single threshold nuchal translucency measurement throughout the first trimester is inappropriate. We propose reference ranges of nuchal translucency measurements with gestation, aiming to improve the performance of nuchal translucency screening for chromosomal abnormalities.

Cross-Sectional Studies↗

PubMedDate not supplied

The secular trend in the height of primary school children in England and Scotland from 1972-1980.

Data from 29 230 children in 22 areas in England and 6 in Scotland were used to estimate the secular trend in height of primary school children over the period 1972-1980. The children were from 15 birth cohorts, born 1961-1975. The method of analysis was selected in order to give estimates from mixed longitudinal data, in which the number of measurements differed from cohort to cohort and children with incomplete data could not be assumed to be comparable to those measured at every age. When the overall goodness-of-fit to height data of polynomials in age was examined, for children measured on 7 or 8 occasions, it was found that cubic polynomials were necessary to describe the growth of boys and girls over the age range 5.0 to 11.0 years, but that cubic and quadratic coefficients could not be interpreted for individual children. No evidence of a mid-growth spurt in height was found. Models fitted to mean heights showed that there was a secular trend of increasing height over the period studied, which was greater when estimated at age eight years than at age five. At age 8 the trend was greatest in Scottish boys, 1.5 cm per decade, and least in English girls, 0.5 cm per decade. The data do not distinguish between a trend due to earlier maturation and a trend resulting in increased adult height; further data will show whether the lack of positive trend at age five estimated from the later cohorts was due to a recent cessation of secular trend.

Body Height↗

PubMed2005

Predictors of successful long-term blood pressure control in type 2 diabetic patients: data from the Swedish National Diabetes Register (NDR).

BACKGROUND: Hypertension in patients with diabetes is a well recognized cardiovascular risk factor for which the benefits of treatment are strongly evidence based. Less is known about predictors for successful long-term blood pressure control in these patients, including the potential role of body mass index (BMI), glycaemic control, microalbuminuria and smoking. MATERIAL AND METHODS: We used longitudinal data on risk factor levels from repeated clinical surveys of 1759 type 2 diabetic patients in the Swedish National Diabetes Register (NDR), a nationwide annual registration of quality indicators in diabetes care. Subjects with successful blood pressure (BP) control (systolic BP < 135 mmHg and diastolic BP < 85 mmHg) at baseline in 1997, in 2001, and at follow-up in 2003, were compared to subjects with BP control >or= 135/85 mmHg. RESULTS: Logistic regression analysis disclosed that successful BP control during the study period was predicted by lower BMI (P < 0.001), a lower frequency of microalbuminuria (P = 0.002), and lower age (P < 0.001) at baseline in 1997, and was still associated with lower BMI (P < 0.001), a lower frequency of microalbuminuria (P = 0.01) and lower age (P < 0.001) at follow-up. Successful BP control was also associated at follow-up with a lower frequency of the metabolic syndrome (30 versus 75%) and lower predicted 10-year risks [United Kingdom Prospective Diabetes Study (UKPDS) Risk Engine] of coronary heart disease (14 versus 29%) and stroke (10 versus 22%) (all P < 0.001). CONCLUSION: A lower BMI and absence of microalbuminuria were strong independent predictors of long-term successful BP control in type 2 diabetic patients, also characterized by a lower frequency of the metabolic syndrome and lower 10-year risk of cardiovascular disease. This implies the long-term benefits on BP control of lifestyle measures as well as control of microalbuminuria.

Adult↗

PubMed2000

Recent developments in child and adolescent social phobia.

The following article discusses research trends in childhood and adolescent social phobia during the past year. Of particular importance are findings regarding prevalence rates, cognitive variables and social skills deficits, temperamental influences, and the use of selective serotonin reuptake inhibitors (SSRIs). Recent prevalence rates of social anxiety disorder in children and adolescents range from 0.5% to 4.0%. Findings regarding the role of cognitive processes and social skills deficits in childhood social phobia are supported. Recent longitudinal data investigating the stability of extremes of behavioral inhibition have found that it persists from childhood into adolescence. Initial data regarding the use of SSRIs suggest that they may be a promising treatment option.

Adolescent↗

PubMed1990

Reconsidering the attribution-adjustment relation following a major negative event: coping with the loss of a child.

Field studies have not yet conclusively established how attributions affect adjustment to unanticipated traumatic events. This may be due, in part, to the adoption of several untested assumptions in most prior research. It has usually been assumed that attributional issues are important to people who experience a traumatic event, that such concern is adaptive, and that specific attributions (e.g., self-blame) influence subsequent adjustment. These assumptions were tested with longitudinal data collected over 18 months from 124 parents whose child died of Sudden Infant Death Syndrome. By 3 weeks postloss, 45% of parents were not concerned with attributional issues. These parents were less distressed and less likely to blame themselves or others for the death. Longitudinal analyses did not support the assumption that attributions influence subsequent adjustment. Rather, attributions to onself or others appear to be symptomatic of distress.

Adaptation, Psychological↗

PubMed2002

Feature development in Cantonese.

The phonetic inventories of 122 typically developing Cantonese-speaking children, aged from 0;10 to 4;7, were examined in terms of feature distinctions. The applicability of Dinnsen. Chin, Elbert and Powell's implicational feature hierarchy to these data was investigated. Results show that modifications to the hierarchy are necessary for the Cantonese phonetic system. A revised hierarchy for Cantonese is proposed. Differences between this proposal and the original work are discussed. The implicational nature of the proposed hierarchy was also tested on longitudinal data from ten children (aged from 0;10 to 3;5 at the beginning of the study) over a 1 year period. The proposed hierarchy successfully predicted the route of sound change of these inventories. Implications for further research on feature development are discussed.

Child Language↗

PubMed2006

Trends in the epidemiology of the first attack of acute pancreatitis: a systematic review.

OBJECTIVE: To systematically review trends in the epidemiology of the first attack of acute pancreatitis (AP) based on reported population-based studies. METHODS: From Medline, we retrieved 18 full-length English language peer-reviewed original articles published from 1966 to June 2005 with population-based information on the epidemiology of first-attack AP. Trends over time were analyzed based on study- and country-specific data and the study site (UK vs non-UK). RESULTS: Eight studies were from the UK and 10 from other European centers. An increase in the annual incidence per 100,000 for first-attack AP was reported in 10 of 12 studies with longitudinal data from 4 countries (UK, Sweden, Denmark, and Netherlands). The overall AP incidence seems to be higher in non-UK studies compared with that of UK, partly explained by a higher incidence of alcoholic pancreatitis in non-UK studies. A linear trend for increase in gallstone pancreatitis incidence over time was observed irrespective of the study site (UK or non-UK). The AP incidence and mortality increased with age. Gallstone pancreatitis was more common in female subjects, and alcoholic pancreatitis was more common in middle-aged male subjects. The AP case fatality (%) has decreased over time, but the overall population mortality rate per 100,000 has remained unchanged. Recurrence after the first attack is milder with a substantially lower mortality. CONCLUSIONS: The incidence of AP seems to be increasing. Differences in the incidence and etiology between and within countries reflect differences in the risk factor prevalence. Case-fatality rate, but not the population-based mortality rate, decreased over time.

Acute Disease↗

PubMed2001

Sensitivity analysis for nonrandom dropout: a local influence approach.

Diggle and Kenward (1994, Applied Statistics 43, 49-93) proposed a selection model for continuous longitudinal data subject to nonrandom dropout. It has provoked a large debate about the role for such models. The original enthusiasm was followed by skepticism about the strong but untestable assumptions on which this type of model invariably rests. Since then, the view has emerged that these models should ideally be made part of a sensitivity analysis. This paper presents a formal and flexible approach to such a sensitivity assessment based on local influence (Cook, 1986, Journal of the Royal Statistical Society, Series B 48, 133-169). The influence of perturbing a missing-at-random dropout model in the direction of nonrandom dropout is explored. The method is applied to data from a randomized experiment on the inhibition of testosterone production in rats.

Animals↗

PubMed1989

A three-dimensional representation of linear growth and skeletal maturation.

Traditional two-dimensional (2-D) growth charts do not distinguish between the effects of a particular pathology or therapy on skeletal maturation and the effects on linear growth. In this study, longitudinal data from two growth studies on children were analysed using a computer technique to produce a growth chart in three dimensions. The three-dimensional (3-D) surface of the graph represents both the linear growth and the skeletal maturation of the patients. If the height and the chronological and bone ages of an individual patient are plotted to give a line in 3-D space, the line can be compared with the 3-D surface of the graph. This permits qualitative assessment of the relative effect of a pathology or treatment on skeletal maturation as compared with linear growth. Quantitative assessment is also possible by expressing the data in polar coordinates. The technique can be applied to clinical trials as well as to individual patients.

Adolescent↗

PubMed2004

Major depression and mental health care utilization in Canada: 1994 to 2000.

BACKGROUND: Major depression makes an important contribution to disease burden in Canada. In principle, the burden of major depression can be reduced by the provision of treatment within the health care system. In a previous data analysis, the National Population Health Survey (NPHS) reported an increase in antidepressant (AD) use between 1994 and 1998. In this paper, the analysis is extended to 2000, and additional aspects of health care utilization are described. METHODS: The NPHS provides a unique source of longitudinal data concerning major depression and its treatment in Canada. In this survey, probable cases of major depression were identified using a brief predictive instrument; health care utilization was evaluated using additional survey items; and the latest data release from Statistics Canada (that is, 2000) was used to make weighted estimates of the frequency of health care utilization in relation to major depression status. RESULTS: The use of ADs has continued to escalate. These increases have been largest in men and in persons aged under 35 years. There has been an increase in polypharmacy: in 2000, almost 9% of persons taking an AD reported taking more than 1 AD medication-a tripling since 1994. The frequency of consultations with alternative practitioners has also grown. Although the overall proportion of persons with major depression who report consulting with health professionals about their mental health has not increased, the number of persons with major depressive disorder reporting 6 or more visits to nurses, social workers, and psychologists may have. CONCLUSION: The provision of AD treatment continues to expand in Canada. This probably represents a changing pattern of practice, because the frequency of professional consultation has not increased. More detailed data are required to evaluate the extent to which treatment needs are being met.

Adult↗

PubMed1996

Home documented monitoring of cardiorespiratory pattern and oxygen saturation in healthy infants.

The objective of this study was to establish longitudinal normative limits for home memory monitors during early infancy. Eighty-eight healthy infants were monitored overnight at 0.25-19 wk of age using the Healthdyne Smart Monitor. Apnea settings were 14 s for recording and 40 s for alarm; the bradycardia setting was 50 beats/min (5-s delay) for both recording and alarm. Arterial oxygen saturation (SaO2) was documented whenever an event was recorded. The monitor was used 77% of all possible days; median daily use was 8.0 h. Eighty-three percent of all monitor alarms were caused by loose leads, the other 17% by false apnea or false bradycardia. Of all recorded events, 68.9% were caused by false apnea or false bradycardia; the other 31.1% were central apneas that reached the recording threshold of 14 s. The longest apnea was 36 s (wk 1); the 95th percentile for longest apnea was 19.9 s in wk 1 and 18.0 s in wk 17-19 (p < 0.001). Periodic low SaO2 values occurred with periodic breathing; the lowest value was 72%. The 5th percentiles for lowest SaO2 were 82 and 86% in wk 1 and 13-19, respectively (p < 0.001), but the minimum value observed in any week was never > 81%. The median duration of SaO2 < 90% was only 5 s but the range was wide (1-183 s), and 39/527 episodes (7.4%) were > 10 s. In summary, these longitudinal data provide the first available normal limits for cardiorespiratory pattern and SaO2 during documented home monitoring in early infancy. Utilization of these normative data will improve the diagnostic validity and clinical usefulness of event recordings.

Apnea↗

PubMed1992

Epidemiology of dental diseases in the elderly.

The aging of the American population will have enormous social ramifications, among which will be a greater focus on the elderly patient. Traditionally, the dental status of this group has been extracted teeth and full dentures, but that is now steadily changing. There were 41.1% of Americans aged 65 or older who were edentulous in 1985 to 1986, but a good proportion of them have been edentulous for many years. The prevalence of total tooth loss will continue to decline with time. The growth of a dentate elderly population, however, leaves more of that group at risk of caries. Caries, once seen as a disease of childhood, is now clearly a lifelong disease. Elderly persons are particularly at risk of root caries, which follows as a consequence of periodontitis. Total tooth loss and severe caries are both associated with lower socioeconomic status. Although cross-sectional survey data invariably show, on average, a greater extent of periodontitis among older than among younger persons, periodontitis is not considered a disease of aging. The age difference in surveys is not because of greater susceptibility among the elderly but represents disease accumulated over time. Limited longitudinal data suggest that rapid loss of periodontal attachment, serious enough to threaten the dentition, is found in 7% to 15% of any population. But this group exhibits the disease when young. Those who have retained a more-or-less intact dentition into old age rarely exhibit a sudden onset of periodontitis. If such a change is seen it could be indicative of broader changes in the immune system.

Aged↗

PubMed1994

A cross-sectional and longitudinal comparison of the Rome criteria for active rheumatoid arthritis (equivalent to the American College of Rheumatology 1958 criteria) and the American College of Rheumatology 1987 criteria for rheumatoid arthritis.

OBJECTIVE: To compare the diagnostic properties of the Rome 1961 criteria for active rheumatoid arthritis (RA) and the American College of Rheumatology (ACR; formerly, the American Rheumatism Association) 1987 criteria for RA with regard to their ability to classify, diagnose, and predict outcome in RA. METHODS: Analysis of cross-sectional and longitudinal data from repeated health examinations and review of clinical records of 3,509 Pima Indians followed up from January 1966 to December 1990. RESULTS: The ACR 1987 criteria identified approximately 50% of the cases identified by the Rome 1961 criteria, in both cross-sectional and longitudinal analyses. The ACR 1987 criteria were better predictors of subsequent development of a clinically supported diagnosis and treatment with slow-acting antirheumatic drugs (both P < 0.001), but were less sensitive than the Rome 1961 criteria for detecting cases for which there already was a clinically supported diagnosis (P < 0.001). CONCLUSION: In a population-based analysis, the ACR 1987 criteria are less sensitive for detecting clinical disease, but predict a clinically more severe prognosis, compared with the Rome 1961 criteria. The sensitivity of both sets of criteria to identify clinical disease is improved if multiple examinations or inactive disease are taken into account.

Arizona↗

PubMed1993

Analysis of crossover designs with multivariate response.

Crossover designs involve observing the same response variate under different experimental conditions for each subject. Univariate methods are commonly used for analysis of data arising in these designs, but multivariate procedures offer a more general approach. The general multivariate linear model provides a natural framework for the simplest data structure as well as more complex settings with two or more response variates and measurements repeated over time. Multivariate models for crossover designs provide a unified approach that clarifies specification of hypotheses, assumptions required, and testing procedures in a wide class of applications that include longitudinal data as a special case. We focus on the 2 x 2 crossover design, but also describe models for analysing more complex crossover designs.

Adolescent↗