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PubMed1999

The National Population Health Survey--its longitudinal nature.

OBJECTIVES: This article discusses some of the benefits and challenges of data from a longitudinal panel as exemplified by the National Population Health Survey (NPHS). DATA SOURCE: The NPHS collects both cross-sectional and longitudinal data from a sample of randomly selected individuals. The longitudinal sample will be reinterviewed every 2 years for up to 20 years. Two NPHS cycles have been completed: cycle 1 in 1994/95 and cycle 2 in 1996/97. SUMMARY: Selected findings from the NPHS are presented to illustrate the benefits of longitudinal data. An overview of questionnaire content, collection methods follows, and sample design is provided. A summary of response rates is followed by a discussion of the methods used to maintain response and to adjust the survey weights in order to reduce nonresponse bias. Confidentiality, dissemination, inconsistencies in reporting, proxy reporting and changes in coding conventions are also discussed.

Canada↗
PubMed2001

A random-effects mixture model for classifying treatment response in longitudinal clinical trials.

A random-effects regression model that allows the random coefficients to have a multivariate normal mixture distribution is described for classifying treatment response in longitudinal clinical trials. The proposed model is capable of dealing with longitudinal data from unknown heterogeneous populations. As applied to longitudinal clinical trials, for example, the model can distinguish subgroups of treatment response. Use of the proposed model is illustrated by analyzing data from two psychiatric clinical trials. The first includes depressed patients assigned to drug treatment who are repeatedly measured in terms of their level of depression. The second trial examined schizophrenic patients longitudinally who were assigned to either a drug or placebo condition. For both, the random-effects mixture model allows an assessment of whether patients comprise distinct populations in terms of their treatment response. Based on parameter estimates of the mixture model, ample evidence for a mixture of response to treatment is observed for both datasets.

Algorithms↗
PubMed2003

Longitudinal magnetic resonance imaging studies of older adults: a shrinking brain.

Age-related loss of brain tissue has been inferred from cross-sectional neuroimaging studies, but direct measurements of gray and white matter changes from longitudinal studies are lacking. We quantified longitudinal magnetic resonance imaging (MRI) scans of 92 nondemented older adults (age 59-85 years at baseline) in the Baltimore Longitudinal Study of Aging to determine the rates and regional distribution of gray and white matter tissue loss in older adults. Using images from baseline, 2 year, and 4 year follow-up, we found significant age changes in gray (p < 0.001) and white (p < 0.001) volumes even in a subgroup of 24 very healthy elderly. Annual rates of tissue loss were 5.4 +/- 0.3, 2.4 +/- 0.4, and 3.1 +/- 0.4 cm3 per year for total brain, gray, and white volumes, respectively, and ventricles increased by 1.4 +/- 0.1 cm3 per year (3.7, 1.3, 2.4, and 1.2 cm3, respectively, in very healthy). Frontal and parietal, compared with temporal and occipital, lobar regions showed greater decline. Gray matter loss was most pronounced for orbital and inferior frontal, cingulate, insular, inferior parietal, and to a lesser extent mesial temporal regions, whereas white matter changes were widespread. In this first study of gray and white matter volume changes, we demonstrate significant longitudinal tissue loss for both gray and white matter even in very healthy older adults. These data provide essential information on the rate and regional pattern of age-associated changes against which pathology can be evaluated and suggest slower rates of brain atrophy in individuals who remain medically and cognitively healthy.

Age Factors↗
PubMed2004

Evaluating behavioral and emotional problems with the Child Behavior Checklist and Youth Self-Report scales: cross-informant and longitudinal associations.

OBJECTIVE: This study investigated the inter-rater agreement between parents' reports and adolescents' self-reports of behavioral and emotional problems using cross-informant scales both cross-sectionally and longitudinally. MATERIAL AND METHODS: Subjects were participants in a longitudinal study of 695 school-aged children from the general population, aged 7-10 during the first assessment. They were evaluated with the Child Behavior Checklist (completed by parents) and later, from 11 year-old, with the Youth Self-Report. The scoring format and factor structure of the two assessment instruments are similar; cross-informant syndromes constructed from the two instruments are based on parents' and self-report information. Measures included anxiety/depression, withdrawal, somatic complaints, aggression, delinquency and attention problems. RESULTS: Findings indicate that there is longitudinal stability in parents' ratings of children's behavioral problems. Our findings also confirm that adolescents, especially as they grow older, are indispensable informants about their problem behavior, because many of the problems they experience remain unnoticed by their parents. Adolescents reported higher levels of anxiety/depression, withdrawal, somatic complaints, aggression and delinquency, but lower levels of attention problems than their parents. CONCLUSIONS: Our results reflect the typical level of parent-child agreement in reports of problem behaviors as it occurs in other samples. Other investigators could use these data as a background, for testing of longitudinal associations and parent-child agreements in different samples.

Adolescent↗
PubMedDate not supplied

Analysis of longitudinal marginal deterioration of ceramic inlays.

This study quantitatively and morphologically analyzed and clarified the longitudinal marginal changes of ceramic inlays and determined the mechanism for those changes. Epoxy replicas of 15 Class II ceramic inlays in permanent premolars prepared at baseline, 6, 12, 24, 48, 72 and 96 months after placement were selected. A CCD optical laser scanner was employed to measure quantitative changes in the occlusal surfaces of restored teeth. Longitudinal cross-sections of marginal areas of a ceramic inlay were computed, and two profiles of the same location obtained at different periods were superimposed using software. The area enclosed by the two profiles obtained at different periods was defined as the quantitative marginal change, and both the area and maximum depth in the area enclosed were calculated with picture analysis software. The marginal deterioration pattern was analyzed by drawing a longitudinal curve of quantitative change for each restoration. Morphological observation was carried out by scanning electron microscopy at magnifications from 20x to 75x. Quantitative measurement and morphological observation identified a sequential three-stage pattern of marginal deterioration; initial rapid progress of wear of resin composite cement in the first stage, followed by a second stage without any remarkable visible change, then rapid progression of microfractures of ceramics and/or enamel in the third stage. Boundaries between the first and second stage were found in the six and 21-month period, and those between the second and third stage at 72 months. It was concluded that longitudinal marginal deterioration of fired ceramic inlays progressed in a sequential three-stage pattern.

Dental Porcelain↗
PubMed2006

[Diagnosis and treatment for the injury of cervical disc and longitudinal ligament].

OBJECTIVES: To study the diagnosis and treatment for the injury of cervical disc and longitudinal ligament. METHODS: From 2001 to 2005, the clinical data of sixty-three patients with cervical disc and longitudinal ligament injury were studied. Early treatment was done based on spinal cord injuries and spinal stabilities by X rays and MRI. Early operation was done in fifty-four cases and early non-operation in nine cases. RESULTS: The follow-up time was six to forty-one months in all patients. The neurological recovery was found in two of eight complete SCI post-operation, thirty-one in thirty-nine incomplete SCI. Cervical collar or plaster orthotic were used in nine cases with four to six weeks. Evidence of instability was noted in four patients, who were operated with anterior decompression fusion. Neck chronic pain was found in two patients, anterior decompression and fusion was done in one with cervical spinal cord compression. CONCLUSIONS: MRI examination is the most value measure for the diagnosis of cervical disc and longitudinal ligament injury. Early anterior decompression and fusion was an important approach for cervical disc and longitudinal ligament injury.

Adolescent↗
PubMed1989

[Hungarian growth standard from birth up to the age of 2 years. Data based on results of longitudinal growth studies of a 2 percent representative sample].

The longitudinal project under the title "The health and demographic study of pregnant females and infants" started on a 2 per cent national sample in November 1979.--In a first stage of the project the pregnant women have been examined, in the second stage a longitudinal study of children born alive to these mothers was carried out (still under way).--This is the first longitudinal survey on growth performed on a national representative sample in Hungary. The first results of the project are presented: growth standards for the period from birth to the age of two years (weight and length percentiles referred to age, and body weight related to length).--The growth standards were developed from the data of the longitudinal study of 5,689 children born with a normal weight (between 2500 to 4500 g) and further which developed healthy. The data presented here are thought to be used as standards for growth monitoring and health surveillance of children in Hungary.

Body Height↗
PubMed1984

Longitudinal methods for evaluating therapy.

Longitudinal studies of therapy are unparalleled in their ability to ensure scientifically cogent results by clearly separating cause (therapy) from effect (therapeutic outcome), by allowing incorporation of duration of follow-up into the assessment of comparative outcomes, and by permitting the use of safeguards against non-concurrent therapies, unequal prognostic susceptibilities, unequal therapeutic performance, and unequal detection of outcomes. The price of these advantages includes the reduced ability of longitudinal studies to evaluate therapies whose outcomes occur rarely or with long latencies, as well as the specific logistic, ethical, and design problems that limit the ability of clinical trials to answer many of the therapeutic questions which are important to clinical practice. The implications of these limitations are that longitudinal evaluations may not be suitable for addressing many therapeutic issues--particularly those involving preventive therapies--and that even when longitudinal studies are suitable, randomized trials may not be logistically feasible or ethically permissible to answer every clinically important question. One of the important challenges for research in this area is to develop alternative methods for assessing therapeutic effectiveness.

Clinical Trials as Topic↗
PubMed1995

[The longitudinal development of smoking behavior in men and women between 13 and 27 years and the relationship with biological risk factors for cardiovascular diseases].

OBJECTIVE: To describe the longitudinal development of smoking behaviour from adolescence (age 13 years) into young adulthood (age 27 years) and to analyse the longitudinal relationship between smoking behaviour and biological risk factors for cardiovascular disease. DESIGN: Longitudinal. SETTING: Amsterdam school children. METHODS: This study was carried out as part of the Amsterdam Growth and Health Study, an observational longitudinal study. Six measurements were carried out over a period of 15 years in 84 males and 98 females, and included a questionnaire regarding smoking behaviour and blood analysis for cholesterol parameters. Tracking analysis and generalized estimating equations analysis were used. RESULTS: Both the percentage of smokers and the amount of tobacco smoked by smokers increased until the age of 21 years. After that smoking behaviour remained more or less stable in males and decreased slightly in females (period effect). Between 16 and 21 years half the number of persons tried to stop smoking but failed to succeed. The development of smoking behaviour appeared to be related to low systolic blood pressure and to development of a negative risk profile regarding hypercholesterolaemia (i.e. low high-density lipoprotein (HDL) cholesterol and high ratio of total cholesterol and HDL cholesterol). There was no relationship between smoking and the amount of subcutaneous fat.

Adolescent↗
PubMedDate not supplied

[Age differences versus aging--a cross-sectional and longitudinal analysis on the development of memory in advanced age].

This study examines the development of episodic memory in later adulthood and old age in a combined cross-sectional and longitudinal design. 124 normal aging subjects, aged 50-87 years, representing four age groups (M1 = 53.65 years, M2 = 60.60 years, M3 = 68.44 years, M4 = 75.83 years) participated in a cross-sectional study. Seven years later a retest was done in which 70% of the original sample again participated. Significant differences between the cross-sectional and the longitudinal results were found, with the latter showing the more severe decline in memory performances. Moreover, the age decline occurred earlier in the longitudinal study. Cohort differences account for these differences between the cross-sectional and longitudinal findings, favoring subjects of earlier-born cohorts.

Aged↗
PubMed1995

[Dynamics of tolerance of +G loads by non-flying subjects: a longitudinal study].

Selected cosmonauts-investigators may be held on wait for many years. The longitudinal health study is of great significance in the context of prediction of tolerance to various flight stresses. The purpose of this work was to investigate the tolerance to +Gz-loads during extended (up to 18 years) dynamic longitudinal study of 50 male cosmonauts and candidates of non-flying occupations by the data of 363 medical observation runs on a centrifuge with the radius of 7.25 m. Analysis of these data showed that 82 % of the subjects sustained good tolerance of G-loads and only 18 % of the subjects displayed its decrement or instability. A new proof received the data concerning better +Gz-tolerance by subjects aged 31-35 and less tolerance by the subjects younger than 30 and older than 46-50 years. The longitudinal study allowed to identify 4 types of G-tolerance variation, i.e., stable, relatively stable with individual drops down to decreased, non-stable with periodic drops, and a distinct trend towards a decrease. These investigations provided new scientific data about the dynamics of separate physiological functions during exposure to +Gz-loads resultant from longitudinal study of the same group of subjects, and allowed to make an expert prediction of shifts in the G-tolerance.

Adult↗
PubMed1996

Findings from longitudinal cohort studies: Gothenburg and Jerusalem.

The longitudinal study of age-homogeneous cohorts is a powerful tool to elucidate age-related changes and to attempt to distinguish normal aging from the effects of disease. Many influences, such as the effect of changing lifestyle, medical practices and environmental factors with time must be considered when designing and interpreting such studies. Cross-cultural differences manifest in comparing different studies must also be accounted for, but alternately provide a tool to distinguish between endogenous and exogenous factors influencing human aging. The first stage of the longitudinal study of 70 year olds in Gothenburg, Sweden, a cross-sectional survey performed in 1971, is compared to a similar cross-sectional survey performed in Jerusalem in 1991 as part of a projected longitudinal study. The similarities between the two cohorts with regard to living conditions, functional independence and disease prevalence are striking. There are also significant contrasts that reflect the 20 years that elapsed between the execution of the two studies, as well as the cultural and social differences. In particular, the ethnic diversity of the Jerusalem population, hailing from 40 separate countries, is emphasized. The comparison of these two studies highlights many of the principles critical to the role of longitudinal cohort studies in gerontology.

Activities of Daily Living↗
PubMed1996

Characteristics and mechanism of the ossification of posterior longitudinal ligament in the tip-toe walking Yoshimura (twy) mouse.

To elucidate the mechanism of ossification of the posterior longitudinal ligament (OPLL), we examined the serial changes in the intervertebral disc of tip-toe walking Yoshimura (twy) mouse. At the age of 6 weeks, the volume of the nucleus pulposus increased in all intervertebral discs causing anterior and posterior herniation. Secondary to this herniation, the cartilagineous tissue of the annulus fibrosus was disrupted and showed regenerative proliferation with PCNA-positive cartilagineous cells. These cells were S-100 positive and the matrix was positive for chondroitin-4-sulfate proteoglycan, indicating the development of calcification. At the age of 15 weeks, the regenerative cartilagineous tissue of the annulus fibrosus reached the posterior longitudinal ligament together with neovascularization and appearance of PCNA-positive proliferating primitive mesenchymal cells. These cells were considered to be osteoblasts since they were positive for alkaline phosphatase and the matrix contained type I collagen. Using electron microscopic X-ray analysis, vesicles present in the matrix of regenerative cartilagineous cells of the annulus fibrosus were confirmed to contain calcium phosphate crystals, also indicating the development of calcification. In conclusion, our serial analysis indicates that ossification of posterior longitudinal ligament in twy mouse was triggered by enlargement of the nucleus pulposus followed by herniation, disruption and regenerative proliferation of annulus fibrosus cartilagineous tissues. Enchondral ossification of the new annulus fibrosus cartilagineous cells and membraneous ossification by primitive osteoblasts proceed to the final ossification of the posterior longitudinal ligaments.

Alkaline Phosphatase↗
PubMed1997

On longitudinal caries index data. A comparison study between cohort and cross-sectional attempts.

The aim of the present study was to compare registered data of caries prevalence and incidence from cross-sectional studies of specified age groups with the corresponding caries data from cohorts of individuals receiving dental health service from the same dental clinic during the years studied. The study covered two 15-19-year groups, who had been offered complete dental care from three years of age in the City of Göteborg for the time periods 1986/7-1990/1. When compared, the longitudinal cohort attempts often gave statistically significant different values to those of the cross-sectional year classes, which should be considered when presenting caries index mean values in dental health reviews. It is not indifferent to choose between longitudinal cohort and cross-sectional year class attempts when searching for dental health treatment effects. Due to the advantages of using longitudinal cohort study methods, and with regard to the differences of the study design used, as pointed out in the study, the use of longitudinal cohort patient material, extracted from cross-sectional epidemiological data bases, could favour analysis of the effects of different preventive dental care programs.

Adolescent↗
PubMed1998

[Ultrasonography of the uterine cervix in pregnancy. Curve of normality in a longitudinal and cross-sectional study].

BACKGROUND: The aim of the study was to establish a normality curve of cervical length variations during pregnancy in our pregnant women population, to be compared with pathological cases (risk of preterm labor and cervical incompetence). DESIGN: A prospective longitudinal and cross-sectional study in women with single pregnancy and without risk factors for preterm labor was carried on. SETTING: Obstetric and Gynecology Department, University of Brescia, Italy. POPULATION OR SAMPLE: One hundred and thirty-four pregnant women with single pregnancy, 112 cross-sectionally and 22 longitudinally followed, with labor at term, were selected. Sixty-eight were nulliparous, 66 pluriparous. Multiple pregnancy, previous placental and vaginal bleeding were excluded. METHODS: A transvaginal probe was used to assess uterine cervix and the patients were studied from the 12th to 41st gestational week. Statistical analysis was carried out by Student's "t"-test and Z-test. MEASURES: Cervical longitudinal diameter, internal uterine os and funneling were assessed. RESULTS: No statistically significant differences emerged in the curves with regard to nulliparous and pluriparous patients. The cut-off between normality and pathology, from the 24th to the 32nd gestational week (2ndSD), seems to correspond to a cervical length lower than 25 mm; a significant progressive decrement of the cervical longitudinal diameter begins from the 28th gestational week. CONCLUSIONS: These results allows the gathering of reference data about normality to compare with pathology (cervical incompetence and preterm delivery), which could be useful both for prevention and follow-up of these cases.

Cervix Uteri↗
PubMed1996

Longitudinal melanonychia in children. A study of eight cases.

BACKGROUND AND DESIGN: Longitudinal melanonychia is rare in white children and represents a difficult clinical challenge. Because of the fear of malignant melanoma, a surgical excision is usually performed, sometimes with definitive aesthetic and functional consequences. Eight children with longitudinal melanonychia who were between the ages of 2 and 14 years underwent follow-up. Surgical excision was performed in five cases. For three children, a wait-and-see policy was adopted, because their longitudinal melanonychia had been unchanged for years at the time of their examination. RESULTS: Melanoma was never observed in our cases (follow-up, 5.5 years). Histologic examinations performed in five cases showed junctional nevi of the nail matrix, often with dysplasia as commonly seen in juvenile nevi. Two children had postoperative nail dystrophy. CONCLUSION: In white children, longitudinal melanonychia rarely disappears. Since an ungual melanocytic band can appear at the age when other nevi appear, surgical excision should not be undertaken on different grounds than for other congenital or acquired nevi in children.

Adolescent↗
PubMed2003

Estimates of incidence rates with longitudinal claims data.

OBJECTIVE: To estimate incidence rates of the 3 major chronic eye diseases--diabetic retinopathy (DR), glaucoma, and age-related macular degeneration (ARMD)--by using longitudinal claims data from Medicare. METHODS: Longitudinal cases were ascertained by using a national probability sample of Medicare beneficiaries aged 65 years and older in 1991 who initially had none of the eye diseases documented. After adjusting for death and enrollment in a health maintenance organization, claims filed by optometrists or ophthalmologists with an International Classification of Diseases, Ninth Revision, Clinical Modification code for all forms of DR, glaucoma, and ARMD were used to indicate diagnosis. RESULTS: Annual incidence rates for the 3 conditions after the first year of observation ranged from 14.3% to 17.7% (higher earlier) across an 8-year longitudinal follow-up. Incidence rates among those with diabetes mellitus for any form of DR varied between 3.8% and 6.5%, while those for glaucoma varied between 4.6% and 7.8% and those for ARMD varied between 7.5% and 9.3%. CONCLUSIONS: Longitudinal claims data after the first year provide relatively stable estimates of incidence rates on an annual basis. These estimates are comparable with those of the few population-based studies available.

Centers for Medicare and Medicaid Services, U.S.↗
PubMedDate not supplied

Characteristics of beta-adrenergic receptors in longitudinal muscle membranes of rat uterus: changes in kinetic properties of the receptor during gestation.

Binding characteristics of beta-adrenergic receptors of longitudinal muscle membranes isolated from different stages of pregnant rat myometrium were investigated using [3H]dihydroalprenolol. Between Days 15 and 21 of gestation, the ratio of beta 1- and beta 2-adrenergic receptors of longitudinal membranes was constant. The membranes were found to be predominant in beta 2-adrenergic receptors. The concentration of longitudinal muscle beta-adrenergic receptors increased significantly during the last 7 days of gestation. Kinetic binding studies implied that the affinity of the membrane beta-adrenergic receptors decreased through a slight decrease in the association rate and a large increase in the dissociation rate with progression of pregnancy. A Scatchard plot indicated that longitudinal muscle in beta-adrenergic receptors on Days 15 and 18 constitute a single class of independent sites. By contrast, the dissociation kinetics, the convex downward curvature in a Scatchard plot and a Hill coefficient (h) of less than 1.00 of [3H] DHA binding to beta-receptors of muscle on Day 21 suggested the existence of negatively cooperative multiple binding sites for beta-adrenergic ligand. These results suggest that changes in the dynamics of uterus beta-adrenergic receptors play an important role in the onset of labor.

Adrenergic beta-Antagonists↗