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PubMed1988

Ambidirectional studies--an extension of longitudinal studies in psychiatry.

Both longitudinal and retrospective studies have inherent weaknesses. With psychiatric mortality studies as an example of longitudinal research, this article presents a study design, the ambidirectional study, that combines some of the advantages and minimizes some of the weaknesses inherent in longitudinal and retrospective studies respectively. The method involves 2 phases: first, definition of a base population some of whom proceed to encounter an event of interest (e.g. death, suicide, illness), secondly, a retrospective comparison of those emerging from the same base population with or without the event of interest. The advantages of this design are feasibility and freedom from confounding coherent effects, since cases and controls enter the study at the same point. The difficulties are those of retrospective data collection. Definition of controls, case matching and statistical methodology are discussed.

Cause of Death↗
PubMed1988

[Decrement of respiratory function indices in a case series of workers exposed to cement dust: a longitudinal study].

Longitudinal changes in some respiratory parameters (FEV1 and VC) have been examined in a sample of cement workers (163 male subjects differently exposed to cement dusts); the subjects have been surveyed over a period of 10 years performing yearly spirometric tests (Vital capacity--VC and Forced Expiratory Volume in 1 second--FEV1 measurements). Three possible risk indicators have been considered: occupational exposure, smoking habit and age. 65.6% and 60.7% of the cases showed significant individual annual decreases of VC and FEV1 throughout the time of follow up. According to our results the occupational risk indicator has not significantly influenced the normal trend of decreases of the respiratory parameters; instead age brings about an increase of longitudinal changes of VC and smoke habit an increase of longitudinal changes of FEV1, (but only in the younger group, people less than forty years old). 16 subjects characterized by abnormal losses (more than 100 ml/year) have been selected as "VC-FEV1, losers".

Adult↗
PubMed1987

Craniomandibular disorders in adolescents. A longitudinal study in an urban Swedish population.

The prevalence of craniomandibular disorders was studied in 285 17-year-old adolescents with the aid of a questionnaire and a functional examination of the masticatory system including evaluation of TMJs, masticatory muscles, mandibular mobility, and occlusion. The adolescents were followed up longitudinally two more subsequent years. Totally 27 subjects dropped out, leaving 258 for the longitudinal intraindividual comparisons. At the age of 17 a fifth of the subjects reported some symptoms involving the masticatory system, of which most were mild, according to the anamnestic index (Ai) used. Oral parafunctions were commonly reported of which nail-biting dominated. Grinding and clenching of teeth were reported by 8% and 11% respectively. Signs of mandibular dysfunction were found in 56% of the adolescents and were mostly mild according to the dysfunction index (Di) used. Girls more often had signs of mandibular dysfunction than boys. Morphologic malocclusion was recorded in 35%, unilateral contact in RP in 77%, lateral shift between RP and IP greater than or equal to 0.5 mm in 19% and mediotrusion interferences in 30% among the 17-year-olds. No significant difference between sexes was found. Of the sample 62% had either some sign or symptom of dysfunction and there was a positive relationship between the dysfunction indices used. Neither morphologic nor functional malocclusions were related to the Ai. TMJ sounds were related to palpation tenderness in the lateral pterygoid muscle and impaired mobility of the mandible. The number of masticatory muscles tender to palpation was related to reports of fatigue in the jaw, TMJ tenderness, and mediotrusion interferences. Recurrent headache was reported by about 18% of the girls and by almost 6% of the boys. Fatigue in the jaws and difficulties in chewing were commoner in those with frequent and more intensive headache. Tenderness to palpation of the masticatory muscles and impaired mandibular mobility were significantly commoner findings among those with recurrent headaches and those with more intense headache. Tooth-grinding and clenching were related to frequency but not to intensity of headache. Reports of TMJ sounds increased with age for girls who also more frequently reported recurrent headaches than boys. The prevalence of symptoms of mandibular dysfunction was about 20% each year, but there was no general increase of frequency and severity of symptoms during the observation period in spite of an incidence of 8%. The prevalence was, according to the Ai, significantly higher for 18- and 19-year-old girls than for boys. Most symptoms were mild and fluctuated longitudinally.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1987

Neocortical metabolic abnormalities precede nonmemory cognitive impairments in early dementia of the Alzheimer type: longitudinal confirmation.

Patterns or regional cerebral metabolism and neuropsychological function were studied longitudinally in 10 mildly demented patients with dementia of the Alzheimer type (DAT) and compared to those of moderately demented patients and controls. As reported previously (Haxby et al., 1986), the mildly demented patients initially had significant neocortical metabolic abnormalities, namely parietal reductions and right-left asymmetries, but did not differ from controls on any test of neocortically-mediated visuospatial and language functions. Right-left metabolic asymmetries correlated with neuropsychological discrepancies between visuospatial and language function in moderately demented but not mildly demented patients. We now report that longitudinal studies of these mildly demented patients showed significant decline of nonmemory cognitive function. Moreover, correlations of metabolic asymmetries with neuropsychological discrepancies between visuospatial and language functions became significant. These longitudinal results confirm our previous conclusion that neocortical metabolic abnormalities precede neocortically-mediated neuropsychological impairments in early DAT.

Alzheimer Disease↗
PubMed1985

On longitudinal versus cross-sectional studies of obesity: possible artefacts.

Within the framework of a large-scale research project on overweight, relationships between body mass index (BMI; weight/height) and two types of eating behaviour (restrained eating and emotional eating) were determined. All results obtained on one assessment date in a longitudinal study within this project were found to differ significantly from those of a cross-sectional study. The present study aimed to replicate these results on another assessment date of the same longitudinal study, and in another cross-sectional sample. The two types of studies were found to differ systematically. This difference may well be attributable to greater prevalence in the longitudinal study of the response set, acquiescence in the women of normal weight, and social desirability in the overweight women. These response biases may have resulted from sensitization of the subject to the questionnaires, and also from the intensive contact between subject and investigator due to repeated measurements. Thus in further studies use of independent response-set marker scales is recommended to improve identification and control of response sets.

Adult↗
PubMed1979

Longitudinal analysis of the dynamics and risk of coronary heart disease in the Framingham Study.

Statistical methods designed specifically for the analysis of chronic disease incidence and progression in longitudinal studies are presented. These method model the risk of acute phases of chronic disease separately from the temporal change in risk variables. This could be accomplished because, under a specific biological model of the disease mechanism, the problems of estimating the risk of an acute event and of predicting the change in risk variables are independent. Specifically, a quadratic equation relating risk variable values to chronic disease risk and a system of linear equations predicting future risk variable values from present values may beestimated separately. Taken together, they utilize the full information available in a longitudinal study on the temporal dimension of chronic disease progression. In addition, the model is found to possess a number of attractive statistical and theoretical properties. These methods are applied to longitudinal data from the Framingham Study on coronary heart disease (CHD) in males. A quadratic function relating the risk of a CHD event to selected risk variables (age, and the natural logarithms of serum cholesterol, uric acid, diastolic blood pressure and pulse pressure) was estimated from measurements made at four points equally spaced in time (two years) with a further morbidity follow-up at a fifth point. The risk function was found to predict CHD risk accurately. It showed that, apart from the linear effects of the risk variables, cohort effects, quadratic effects and interaction effects were important predictors of CHD risk. The linear regression equations used to predict future risk variable values showed that there was an intricate network of cross-temporal associations. Study of the two types of equations jointly show that putative risk variables could affect the risk of CHD incidence both directly, by being associated with higher levels of risk, and indirectly, by causing other risk variable values to change with time. The results led us to identify several different roles that risk variables might play in CHD incidence.

Coronary Disease↗
PubMed1983

[Significance of longitudinal analysis for the evaluation of early detection studies in childhood].

In 1971, the first preventive examination programme for children up to 4 years of age was started in the Federal Republic of Germany; in 1977 followed a completely revised programme. However, even with this altered documentation a longitudinal analysis is not feasible. An effective evaluation should yield the following results: 1. Assessment of the success through differentiated recording of sufficiently early recognized health disorders and treatment effects. 2. Availability of reliable, regional and nation-wide statistics on incidence and prevalence. 3. An estimate of the number of health professionals required. - These aims can be achieved only by a longitudinal record linkage of the data on individuals of a sufficiently large random sample. For this purpose a revised data-sheet is presented. In addition, specific suggestions are made for longitudinal evaluations.

Child, Preschool↗
PubMed1983

Parental contributions to longitudinal stability of cognitive measures in the Colorado Family Reading Study.

Data on reading-disabled and control probands and their families tested in the Colorado Family Reading Study were subjected to a comprehensive longitudinal-familial path analysis. Covariance matrices were constructed from composite scores for reading performance and for coding and symbol processing speed, and maximum likelihood estimates of familial parameters were obtained. With regard to the reading data, these estimates suggest that parental influences contribute importantly to longitudinal stability for reading-disabled children but not for controls. Such a difference in covariance structure between the 2 types of families could be due to a gene (or genes) with major effect. In the case of coding and symbol processing speed, covariance structure is similar for the 2 types of families, and combined parameter estimates indicate that parental contributions to longitudinal stability for this measure are relatively unimportant.

Adolescent↗
PubMedDate not supplied

[Longitudinal changes in rigidity in old age].

This investigation attempted to deal with the question of longitudinal changes in the rigidity of attitudes and behaviour in a sample of elderly persons (68--90 years old). This was done by collecting data twice (1969/70 and 1976) from 86 subjects on a serie of measures of rigidity. At the same time additional data were collected on external variables such as intelligence, anxiety, state of health, extraversion, neuroticism, etc. Analyses of variance with the factors "time of measurement" and "sex" indicated a change in the predicted direction for the majority of the measures used. After an internal of six years, the capacity for adaptive and spontaneous flexibility had decreased, whereas intolerance and dispositional rigidity had increased. On the Riegel-scales R1 and R2, a rise in age was accompanied by a rise in rigidity, as measured in terms of statement in the form of personal judgments. Agreement with other judgments in the form of more generally formulated statements, on the other hand, decreased. Sex differences were found for Brengelmann's NR-scale and the Gottschaldt Hidden Figure test. Women were found to be less rigid than men, but also revealed less adaptive flexibility. A comparison of the test scores of longitudinal subjects and a comparable group of control group subjects yielded no signs of differences which would be traced back to a biased selection of the longitudinal sample.

Adaptation, Psychological↗
PubMed1995

Longitudinal evidence of crystalline lens thinning in children.

PURPOSE: Most earlier studies indicated that the eye's crystalline lens grows continually throughout life, but cross-sectional results of crystalline lens thinning during childhood have been reported. The authors investigated crystalline lens thickness in childhood using cross-sectional and longitudinal data. METHODS: The Orinda Longitudinal Study of Myopia is a community-based study of normal eye growth and myopia development in school-age children. During a 1-to 3-year period, A-scan ultrasonographic lens thickness measurements of 869 children 6 through 14 years of age were analyzed. RESULTS: On average, between the ages of 6 and 10 years, the crystalline lens thins in its axial dimension by almost 0.2 mm. This thinning can be depicted by a cubic model. In this sample, the children with myopia had thinner crystalline lenses than the children with emmetropia of the same age. CONCLUSIONS: This article provides the first longitudinal evidence that the crystalline lens thins during the period of coordinated ocular growth between the ages of 6 and 10 years. Further, it shows that lens thickness is associated with refractive error. Thinner crystalline lenses in children with myopia may result from one of two underlying mechanisms: Either the crystalline lens exhausts its ability to compensate for axial elongation after undergoing accelerated lens thinning before the onset of myopia, or the crystalline lens in the myopic eye may be thinner throughout childhood, during which it thins at a rate consistent with other refractive errors. If mechanical forces link eye growth to crystalline lens compensation, more complex, visually guided feedback loops may not be needed to explain the normal eye growth that results in emmetropization.

Adolescent↗
PubMed1995

Longitudinal assessment of bone mineral density in children with chronic asthma.

BACKGROUND: With the emphasis on asthma as a chronic inflammatory process, the management of moderate to severe asthma, even in the pediatric population, has shifted to the regular use of inhaled anti-inflammatory agents, including inhaled corticosteroids. Accompanying the use of these agents has been the precaution that long-term use may have subtle or potential side effects, including growth suppression or decreased bone mineral deposition. OBJECTIVE: We sought to study the effects of inhaled anti-inflammatory agents on bone mineral density accumulation in growing asthmatic children. Included in this report is the longitudinal acquisition of bone mineral density in children with moderate to severe asthma. METHODS: Bone mineral density in normal and asthmatic children was measured longitudinally by dual-energy absorptiometry. Bone densitometry was determined twice over a 7- to 16-month period in 21 asthmatic children and a 13- to 60-month period in 14 normals. These children with two longitudinal visits were compared with a group of 107 normal children who had a single bone mineral density measurement. RESULTS: Nineteen of 21 asthmatic children used regular inhaled corticosteroids during the interval visits. The majority of the asthmatic boys had bone mineral density measurements, at both visits, that were at a higher percentile than normal boys with two visits. Asthmatic girls had bone density measurements at percentiles not significantly different than normal girls with two visits. CONCLUSIONS: The advancement of bone mineral density in asthmatic children provides support for the safety of inhaled anti-inflammatory medications on bone mineral density in children with significant asthma.

Adolescent↗
PubMed1993

A longitudinal study of craniomandibular disorders in Finnish adolescents.

Longitudinal variations of subjective symptoms and clinical signs of craniomandibular disorders, orofacial parafunctions, and occlusal conditions were examined in 131 Finnish adolescents. Patients were interviewed and clinically examined at the ages of 14, 15, and 18 years. Signs and symptoms of craniomandibular disorders were common, although usually mild. Reported and recorded temporomandibular clicking sounds were the most frequent findings and increased with age. They showed, however, no predictable pattern, and only a few patients consistently reported clicking sounds or had them recorded. Although the frequency of craniomandibular disorders according to Helkimo's clinical dysfunction index was high at each examination, there also was great intraindividual fluctuation longitudinally; impairment and improvement occurred almost equally often, showing no predictable pattern. Only 3% of those tested consistently had an index value of more than I. Thus, even longer follow-up studies are needed to understand natural longitudinal variations and evaluate the need and demand for treatment of craniomandibular disorder.

Adolescent↗
PubMed1993

[Involvement of the anterior longitudinal ligament of the spine in the morphogenesis of osteophytes in spondylosis deformans].

Morphology and relief of the mineralizing front of osteophytes associated with lumbar spondylosis have been studied by means of scanning electron microscopy. During osteophyte formation deep-laid fibers of anterior longitudinal ligament of the spine undergo mineralization followed by their resorption and subsequent replacement by bone structures. Osteophyte surface at its apex consists of mineralized fibers of longitudinal ligament of the spine, formed by mineralized cartilage structures in the area adjacent to the intervertebral disk and by resting bone surface with zone of bone formation and resorption in the area adjacent to longitudinal ligament of the spine.

Aged↗
PubMed1993

A randomized and longitudinal study of human menopausal gonadotropin with intrauterine insemination in the treatment of infertility.

OBJECTIVE: To study in a randomized and longitudinal manner the efficacy of human menopausal gonadotropin (hMG) superovulation combined with intrauterine insemination (IUI) versus IUI alone in the treatment of various causes of infertility in the presence of normal ovulation. METHODS: An initially randomized and subsequently longitudinal study of infertile couples was performed at a university-based clinical research center. One hundred nineteen couples with longstanding infertility (average duration 3.7 years) associated with male factor infertility, unexplained infertility, and/or endometriosis were enrolled. All patients were randomized in the initial cycle to treatment with either hMG/IUI or urine LH-timed IUI alone. They were then followed longitudinally as they alternated subsequent cycles between the two modalities. Outcome indices measured were cycle fecundity, pregnancy outcome, and cumulative pregnancy rates evaluated by life-table analysis. RESULTS: Human menopausal gonadotropin/IUI therapy was consistently more effective than IUI alone in the treatment of endometriosis, male factor infertility, and unexplained infertility, with cycle fecundities ranging from 7.1-19.0% versus 0-6.7%, respectively, during the first seven cycles. CONCLUSION: Human menopausal gonadotropin/IUI is a more effective therapy for enhancing fertility than is IUI alone for the treatment of endometriosis, male factor infertility, and unexplained infertility.

Adult↗
PubMed1993

[Detection and reduction of mental and motor disorders in childhood. 2. Fundamentals and risks in longitudinal research in pediatrics].

The study characterizes basic types of longitudinal research designs for the long-term follow-up of children in health and disease. First the authors mention briefly the principles and disadvantages of cross-sectional research designs. Then they present a detailed account of methods of longitudinal research projects, evaluation of their advantages and their risks. Roughly fifty-year experience with longitudinal designs indicates that this pretentious research strategy can provide an overall view of developmental trends as regards changes of the health status of children in the ontogenetic perspective and contribute to improvement of health care of the child population.

Child↗
PubMedDate not supplied

Reconciling cross-sectional with longitudinal observations on annual decline.

In summary, numerous factors may contribute to observed differences between longitudinally and cross-sectionally derived measures of annual decline in lung function. The direction and magnitude of these differences appear hard to predict. Furthermore, although these differences can be minimized by careful modeling of the data, they cannot, in general, be completely avoided. It seems plausible, however, that both types of studies should give similar qualitative comparisons of risk factor effects if appropriately modeled. Longitudinal studies are likely to provide the most accurate and reliable estimates of lung function decline for both individuals and populations. Such data may be especially useful in identifying individuals with accelerated declines in lung function but who still have "normal" lung function as measured cross-sectionally. However, such studies require careful attention to quality control and typically require at least 4 years of follow-up before the noise in the data settles down. Multiple measurements, preferably four or more, are also necessary to reliably detect and adjust for survey effects. Cross-sectional studies, on the other hand, are simpler, cheaper, and quicker to conduct than are longitudinal studies. They may be particularly useful as a screening tool for identifying potentially affected or high-risk subjects (e.g., those with low levels of lung function) who may require further medical follow-up and/or ongoing monitoring. Both types of studies have a role in population-based occupational health hazard assessments.

Bias↗
PubMed1996

Longitudinal weight changes over four years and associated health factors in 629 men and women aged over 65.

OBJECTIVES: (1) To assess changes in body weight longitudinally over 4 years in a representative group of men and women aged over 65 years, living in their own homes. (2) To assess whether initial weight (or weight in proportion to skeletal size) was associated with health 4 years later. (3) To assess whether any changes found in body weight were associated with changes in physical or mental health. (4) To compare the cross-sectional age-related changes in weight found in the initial survey with the longitudinal changes found over 4 years. DESIGN: A large randomised age-stratified survey using a structured questionnaire and measurements of body weight and demispan (for skeletal size), with a 4-year follow-up. SETTING: The survey was conducted in the respondents' own homes. SUBJECTS: 958 subjects age over 65 years, who were recruited from the Nottingham general practitioners' lists, took part in the initial survey; 629 of these subjects completed the second survey 4 years later. RESULTS: (1) The mean 4-year change in body weight was a small but significant loss; in women (n = 385) it was 1.56kg (P <0.001, 95% CI 1.02-2.10) and in men (n = 244) 0.85kg (P = 0.010, 95% CI 0.21-1.49). (2) Initial weight did not predict mortality, new morbidity nor health 4 years later. (3) There were no robust associations between weight change ans either absolute measures of physical health or changes in these measures. (4) The longitudinal change in weight was similar to that predicted by the cross-sectional data. CONCLUSIONS: (1) Ageing, in old age, is associated with loss of body weight, but with a large intra-individual variation. (2) Neither initial body weight nor the change, was associated with mortality or morbidity over 4 years in a large representative sample of old people living in their own homes in a food-rich country.

Age Factors↗
PubMed1996

[Myelopathy caused by hypertrophy of the posterior longitudinal ligament of the cervical spine in a patient with long-term hemodialysis].

A 48-year-old female was admitted to our hospital because of progressive gait deterioration over a period of 4 months. She had been treated by hemodialysis for 14 years after bilateral nephrectomy. She originally suffered achondroplasia. Otherwise she was a healthy woman. Neurological examination showed weakness and hypesthesia below C5, accelerated deep tendon reflexes and inability in walking. T1 weighted magnetic resonance imaging revealed severe cord compression from C4 to C6 due to an epidural isointensity mass located in the ventral surface of the dura. This mass was enhanced by a contrast medium. Anterior decompression followed by an autogenous vertebral bone graft at C4/5 and C5/6 was performed. The posterior longitudinal ligament was remarkably thickened resulting in severe cord compression. Histologically this thick ligament contained amyloid deposition both in the superficial and deep layers. Ossification was not noticed in the ligament. Diagnosis of hypertrophy of the posterior longitudinal ligament (HPLL) was made. HPLL is known to be frequently associated with herniated intervertebral discs or segmental ossification of the posterior longitudinal ligament (OPLL). Myelopathy in this patient with long-term hemodialysis was aggravated by HPLL without ossification due to imbalance of systemic metabolism such as amyloidosis. The authors report a unique case of HPLL caused by amyloidosis as one of the complications of chronic hemodialysis with special emphasis on its pathophysiology and management.

Amyloidosis↗