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PubMed2000

[Roaming through methodology. XXII. Application of techniques for longitudinal data analysis].

Longitudinal studies are characterised by repeated measurements of the outcome variable on the same individuals. This implicates that observations are correlated and that statistical techniques, such as linear regression analysis cannot be used. Special longitudinal techniques correct for the dependency in repeated observations by analysing the development of a certain individual in time. Depending on the research question, the distribution of the outcome variable, and the number of repeated measurements, a certain technique should be chosen. Sophisticated longitudinal techniques like generalized estimating equations and random-coefficient models are most recommendable.

Data Interpretation, Statistical↗
PubMed2005

Prognostic factors for the surgery for mesial temporal lobe epilepsy: longitudinal analysis.

PURPOSE: Determining long-term prognostic factors of surgery for mesial temporal lobe epilepsy (MTLE) is important for identifying ideal candidates and predicting the prognosis for individual patients. We tried to identify the prognostic factors of anterior temporal lobectomy (ATL) for MTLE with longitudinal multivariate analysis. METHODS: Two hundred twenty-seven patients with MTLE were included in this study. The primary outcome variable was patient status 1-5 years after surgery: seizure free, or not. Clinical characteristics and recent diagnostic modalities were considered as prognostic factors. Univariate and standard multiple logistic-regression analysis for outcome at 1 and 5 years after surgery and the generalized estimation equation (GEE) model for longitudinal multiple logistic regression of the 5-year follow-up period were used. RESULTS: The seizure-free rate at 1 year was 81.1% and decreased to 75.2% at 5 years after surgery. By the univariate or standard multiple logistic-regression analysis, age at surgery or hippocampal sclerosis on magnetic resonance imaging (MRI) ipsilateral to surgery was significant for the postsurgical outcome. However, the longitudinal analysis by the GEE model revealed that younger age at surgery [odds ratio (OR), 0.59; 95% confidence interval (CI), 0.43-0.81], absence of secondarily generalized tonic-clonic seizure (2 degrees GTCS; OR, 0.45; 95% CI, 0.26-0.79), and hippocampal sclerosis on MRI (OR, 2.44; 95% CI, 1.11-5.26) were significant predictors of a good surgical outcome. CONCLUSIONS: Age at surgery, presence of 2 degrees GTCS, and hippocampal sclerosis on MRI are independent prognostic factors for ATL in MTLE. These findings suggest that MTLE is a progressive disorder, and surgical outcome is better when early ATL is performed.

Adolescent↗
PubMed2006

Cognitive functioning in delusions: a longitudinal analysis.

BACKGROUND: This study explored the longitudinal course of the relationship between delusions and different aspects of cognitive functioning. METHODS: Deluded patients were compared to psychiatric and non-clinical controls on three tasks: negative priming, a probabilistic judgement task (the 'beads' task), and the pragmatic inference task (PIT). All groups were tested at two time points, once when actively symptomatic, and once when in remission. RESULTS: Deluded individuals exhibited a 'jump-to-conclusions' (JTC) reasoning bias: i.e., they made decisions on the basis of limited evidence and were more likely to revise their estimates when faced with disconfirmatory evidence. This JTC bias remained stable over time, although probability judgments seemed to normalise in remission. No deficits in cognitive inhibition were found on negative priming. The deluded group displayed an excessive self-focus on the PIT at both time points, but did not show a depressive attributional style. Only a small sub-sample, characterised by the "bad-me" type of paranoia [Trower & Chadwick, 1995 Clinical Psychology: Science and Practice, 2, 263-278.], demonstrated depressive schemas when symptomatic, but no longer did so when remitted. Few relationships were found between tasks, suggesting that different areas of functioning are relatively independent. The only measures associated with delusion symptom scores were from the 'beads' task. CONCLUSIONS: Overall these findings suggest that the JTC bias is a stable factor associated with delusional thinking, while the depressive attributional style characteristic of a small sub-sample of paranoid patients fluctuates with delusional course.

Adult↗
PubMed1996

Double jeopardy, aging as leveler, or persistent health inequality? A longitudinal analysis of white and black Americans.

Longitudinal data from a 15-year national survey of adults are used to test the double jeopardy to health hypothesis as well as the alternative hypotheses that aging levels ethnic differences and that health inequalities persist across the life course. Findings show that African Americans began the study in poorer health and manifested higher mortality. Among survivors, young and middle-aged Black adults developed more serious illness and their subjective health declined more rapidly than their Whites counterparts during the first 10 years of the study. Among subjects with heart failure, Black people were also more likely than Whites to become more disabled over time. Depending upon the health measure considered and the analytic strategy applied, there was evidence for all three processes, but the weight of the evidence shows persistent health inequality over the life course. Indeed, evidence for the age-as-leveler thesis was eliminated by accounting for mortality during the study.

Adult↗
PubMed2002

Patterns of inhaled asthma medication use: a 3-year longitudinal analysis of prescription claims data from British Columbia, Canada.

STUDY OBJECTIVES: To assess trends in asthma management and to identify factors associated with increasing short-acting (SA) beta-agonist utilization in British Columbia using administrative prescription data. DESIGN: A retrospective cohort analysis. SETTING: All patients between 13 and 50 years of age who had received at least one prescription for a SA beta-agonist covered by BC Pharmacare between January 1, 1996, and December 31, 1998. METHODS: Cross-sectional analysis of all patients, and longitudinal analyses only of patients who had received at least one SA beta-agonist prescription in each of the 3 years. Trends in asthma medication use over time were evaluated using repeated-measures Mantel-Haenszel tests. Multiple logistic regression was used to identify factors associated with increasing SA beta-agonist use. RESULTS: A total of 78,758 patients were included in the cohort. No decrease in the annual prevalence of receiving more than four canisters per year of a SA beta-agonist was identified between 1996 and 1998. A total of 12,844 patients filled at least one SA beta-agonist prescription each year. Time-trend analysis showed an overall increasing probability of not receiving an inhaled corticosteroid (ICS) agent in this population (p = 0.002). In patients exhibiting low SA beta-agonist use, > 18 years of age (adjusted odds ratio [OR], 1.5), male gender (adjusted OR, 1.7), and in receipt of social assistance (adjusted OR, 2.3) were associated with receiving increasing amounts of SA beta-agonist agents over the 3 years. In patients with a high degree of use of SA beta-agonists, only the receipt of social assistance (adjusted OR, 1.3) was significantly associated with increasing use. CONCLUSIONS: Despite the development and dissemination of asthma management guidelines, there was no trend toward decreasing SA beta-agonist use. An unexpected trend toward decreasing ICS utilization was identified. Receiving social assistance was a risk factor for increasing SA beta-agonist use, independent of baseline utilization.

Administration, Inhalation↗
PubMed1997

Age-related changes in T cell surface markers: a longitudinal analysis in genetically heterogeneous mice.

In a longitudinal design in which each animal was examined repeatedly throughout its life, we used flow cytometry to determine the numbers or proportions of a variety of T lymphocyte subsets in the peripheral blood of mice aged 8-20 months. Half of the 128 mice were given a low calorie diet which is known to extend lifespan and to reduce the rate of age-associated change in T cell immune function. In these genetically heterogeneous mice, bred as the progeny of CB6F1 females and C3D2F1 males, aging led to statistically significant increases in the number of CD3 cells and the proportions of CD4 memory and CD8 memory cells, and declines in the proportions of CD4 cells and CD4 virgin cells. Older mice also had increased proportions of CD4 and CD8 cells that were able to extrude the fluorochrome R123 through the action of P-glycoprotein. Caloric restriction delayed or prevented most of these age-dependent changes, but had little effect on expression of P-glycoprotein. Correlation analysis showed that those individual mice with high levels of CD4 memory or CD8 memory T cells tended also to have relatively low levels of CD4 virgin cells and low proportions of CD4 T cells, particularly at older ages. In addition, those mice which had the greatest rate of increase in CD4 memory and CD8 memory T cells also tended to show the greatest decline in CD4 virgin and in the proportion of CD4 cells. High numbers of CD4R (and high rates of change in the CD4R subset) were associated with high numbers (and change scores) for the CD8R subset, but there were no strong correlations between the R123-extruding subsets and other age-sensitive markers. Thus some, but not all, age-sensitive T cell subsets show correlated levels and correlated rates of change throughout the middle of the lifespan.

Aging↗
PubMedDate not supplied

A longitudinal analysis of predictors of quitting smoking among participants in a self-help intervention trial.

Predictors of 7-day abstinence from smoking were identified among participants in a randomized self-help smoking-cessation intervention trial conducted from 1985 to 1988 in Seattle, WA. Subjects were adult smokers belonging to a health maintenance organization who responded to an offer of free quitting assistance. Self-reported smoking status was assessed at 8, 16, and 24 months following enrollment. Predictors of abstinence were identified by longitudinal data analysis using Generalized Estimating Equations (GEEs), a modeling approach which handles repeated-measures data and accommodates time-dependent as well as time-independent covariates. Seventeen items emerged as significant (p < .05) predictors, with odds ratios ranging from 1.3 to 2.1. While much of the previous work in smoking-cessation research has focused on demographic and smoking history variables, results of this study indicate that emphasis should also be placed on psychosocial/motivational factors and quitting activities as important predictors of abstinence. Longitudinal data analysis represents a powerful technique for handling correlated (repeated measures) data, which may prove very useful for future studies of smoking cessation as well as other dynamic processes.

Adult↗
PubMed2001

The reciprocal effects of leisure time activities and intellectual functioning in older people: a longitudinal analysis.

By using data from a representative longitudinal survey, the authors provide strong evidence that complex leisure time activities increase intellectual functioning for workers and nonworkers. Although the effects were relatively moderate, both the present article and its predecessor on the effects of paid work (C. Schooler. Mulatu, & Oates. 1999) showed that, even in old age, carrying out complex tasks has a positive effect on intellectual processes. In both cases, initially high levels of intellectual functioning led to high levels of environmental complexity, which in turn raised levels of intellectual functioning, thus providing a pathway contributing to the high correlation of intellectual functioning over a 20-year period in middle and late adulthood. The present findings indicate that even in old age carrying out substantively complex tasks builds the capacity to deal with the intellectual challenges such complex environments provide.

Adaptation, Psychological↗
PubMed1999

A multidimensional longitudinal analysis of family coping with brain injury.

Longitudinal research is needed to advance knowledge and practice in the area of family coping with brain injury. The purpose of this investigation was to examine the dimensions that underlie family coping with brain injury across a 2-year time period (1995 to 1997). Two-dimensional configurations of 30 family coping behaviours indicated a like family coping pattern of cognitive versus behavioural coping (Dimension 1) in both 1995 and 1997. The data also showed that families had a differing, or changed, family coping pattern along Dimension 2 from brain injury-focused coping versus family-to-community fit in 1995 to seeking professional help versus intra-family coping in 1997. Results thus indicated both changes and consistent coping patterns within the same group of families across time. Such information can be used to guide clinical family intervention, the development of long-term family support services, and future brain injury family research.

Adaptation, Psychological↗
PubMed1987

The impact of attributions in marriage: a longitudinal analysis.

In this study, we investigate the longitudinal relation between attributions for relationship events and marital satisfaction. Thirty-four couples were assessed at two points separated by approximately 12 months. Causal and responsibility attributions for marital difficulties and negative spouse behaviors were strongly related to concurrent marital satisfaction. For wives, later marital satisfaction was predicted by both causal and responsibility attributions after the effects of earlier satisfaction were removed. For husbands, attributions did not predict later marital satisfaction. Marital satisfaction did not predict later attributions for either husbands or wives. Marital satisfaction and the two types of attributions were related to concurrent unrealistic relationship expectations, but these expectations did not predict later marital satisfaction. The results are discussed in terms of a possible causal relation between attributions and marital satisfaction.

Adult↗
PubMedDate not supplied

Are changes in sensory disability, reaction time, and grip strength associated with changes in memory and crystallized Intelligence? A longitudinal analysis in an elderly community sample.

BACKGROUND: Little is known about predictors of cognitive changes in the elderly. Sensory disability, grip strength, and speed of processing have been established as associates of cognitive performance in cross-sectional studies. However, it is not known whether changes in these predictor variables are associated with changes in cognitive functioning. OBJECTIVES: (1) to examine the relationship between initial level of three predictor variables - speed of processing, sensory disability, and grip strength - and changes in memory and crystallized intelligence (CIQ); (2) to examine the relationships between change in grip strength, cognitive speed, and sensory disability and changes in memory and CIQ, and (3) to investigate these relationships with the effects of age and sex statistically removed. METHODS: Cognitive ability was assessed in two domains: CIQ (3 tests) and memory (3 tests) measured on two occasions approximately three and a half years apart in a large community sample (n = 425; mean age = 75.8, range 70-93 years). Repeated-measures Anova was used to analyze descriptive data. Latent-change models were used to examine structural relationships between constructs. RESULTS: Initial levels of reaction time or grip strength did not predict rate of change on memory tasks. Changes in grip strength, speed, and memory correlated moderately, suggesting that these variables have some tendency to move together over time. Sensory disability correlated with age but not with change in speed, grip, memory, or CIQ. These relationships held across the age range studied after adjustment for age and sex. CONCLUSIONS: The findings are consistent with the action of a common causal mechanism underlying changes in speed, grip, and memory. A number of methodological caveats arise from our analysis. Cross-sectional and longitudinal data sets yield different interpretations about the basic component associates of cognitive performance.

Aged↗
PubMed2004

The relationship between disease activity and radiologic progression in patients with rheumatoid arthritis: a longitudinal analysis.

OBJECTIVE: Radiologic progression in rheumatoid arthritis (RA) is considered the consequence of persistent inflammatory activity. To determine whether a change in disease activity is related to a change in radiologic progression in individual patients, we investigated the longitudinal relationship between inflammatory disease activity and subsequent radiologic progression. METHODS: The databases of the University Medical Center Nijmegen (UMCN) cohort and the Maastricht Combination Therapy in RA (COBRA) followup study cohort were analyzed. The UMCN cohort included 185 patients with early RA who were followed up for up to 9 years. Patients were assessed every 3 months for disease activity and every 3 years for radiologic damage. The COBRA cohort included 152 patients with early RA who were followed up for up to 6 years. Patients were assessed at least every year for disease activity and every 12 months for radiologic damage. Disease activity was assessed with the Disease Activity Score (DAS) (original DAS in the UMCN cohort, DAS28 in the COBRA cohort). Radiologic damage was measured by the Sharp/van der Heijde score in both cohorts. Data were analyzed with longitudinal regression analysis (generalized estimating equations [GEE]), using autoregression for longitudinal associations and radiologic damage as the dependent variable. Time, time(2) baseline predictors for radiologic progression and their interactions with time, as well as DAS/DAS28 (actual values or interval means and interval SDs of the means) were subsequently modeled as explanatory variables. RESULTS: Data analyzed by GEE showed a decrease in radiologic progression over time (regression coefficient for time(2) -1.0 [95% confidence interval -1.4, -0.6] in the UMCN cohort and -0.4 [95% confidence interval -0.8, 0.0] in the COBRA cohort). After adjustment for time effects and baseline predictors of radiologic progression and their interactions with time, a positive longitudinal relationship was indicated by autoregressive GEE between the mean interval DAS and radiologic progression in the UMCN cohort (regression coefficient 5.4 [95% confidence interval 2.1, 8.6]), and between the DAS28 and radiologic progression in the COBRA cohort (regression coefficient 1.4 [95% confidence interval 0.8, 2.0]). In the UMCN cohort, the SD of the mean interval DAS was independently longitudinally related to the radiologic progression over the same periods (regression coefficient 20.2 [95% confidence interval 7.2, 33.3]). In both cohorts, the longitudinal relationships between (fluctuations in) disease activity and radiologic progression were found selectively in rheumatoid factor (RF)-positive patients. CONCLUSION: Radiologic progression is not linear in individual patients. Fluctuations in disease activity are directly related to changes in radiologic progression, which supports the hypothesis that disease activity causes radiologic damage. This relationship might only exist in RF-positive patients.

Adult↗
PubMed1999

Changes in household composition among the over sixties: a longitudinal analysis of the Health and Lifestyles Surveys.

Analyses of longitudinal data from the Health and Lifestyles Surveys (HALS) were carried out in order to examine the household changes of older people. Respondents who were interviewed at both the first HALS survey in 1984/85 (HALS1) and the second survey 7 years later (HALS2) and were aged 60 or over in HALS1 were selected (1156). Changes in household composition between the two surveys were examined and the relationship of these changes to socio-demographic factors and to both cross-sectional and longitudinal health factors investigated. Results of the analysis showed there was great diversity of experience and a considerable amount of change in what is often considered a fairly stable and homogeneous section of the population. Almost one-third of respondents changed household type, the majority changing to live alone and only a small proportion changing to live in households with their child/children or with others. Household changes were associated with poor and declining health (both physical and mental) and the rate of change was found to increase with age. In the case of ill health the first source of practical support and care is generally from within the household. Where this is not available it is sought from the wider community or the state. An increase in the proportion of the population aged over 60 and in the numbers of the oldest people, coupled with a rate of household change that increases with age, means that demand on health and community services can only be expected to increase.

Journal Article↗
PubMed2006

Leisure time exercise and personal circumstances in the working age population: longitudinal analysis of the British household panel survey.

OBJECTIVES: Investigate the impact of social, economic, and family circumstances on participation in weekly leisure time exercise. DESIGN: Longitudinal regression analysis of the British household panel survey. PARTICIPANTS: 9473 people (4521 men and 4952 women) giving 27,881 person years of responses across eight years and four survey waves. MAIN RESULTS: There was considerable variation among people in regular exercise participation over time. Having children was associated with a reduced likelihood of exercise for both men and women, although there were sex differences in this association according to the age of the youngest child. For both men and women working long hours was associated with a reduced likelihood of exercise, as was having a lower grade job. Retired men and women were more likely to exercise, as were those who attended a fee paying school. There was no strong independent association between household income and exercise. CONCLUSIONS: For most people, participation in leisure time exercise "comes and goes" rather than being something they always or never do. Those with time pressures from work or domestic life are less likely to participate in leisure time physical activity. There are important sex differences in the impact of having children, with women experiencing longer term detrimental effects. Working long hours reduces leisure time exercise participation. Opportunities for physical activity as part of our daily working routines should be increased.

Adolescent↗
PubMed1998

Longitudinal analysis of deciduous tooth emergence: II. Parametric survival analysis in Bangladeshi, Guatemalan, Japanese, and Javanese children.

We present a form of parametric survival analysis that incorporates exact, interval-censored, and right-censored times to deciduous tooth emergence. The method is an extension of common cross-sectional procedures such as logit and probit analysis, so that data arising from mixed longitudinal and cross-sectional studies can be properly combined. We extended the method to incorporate and estimate a proportion of agenic teeth. While we concentrate on deciduous tooth emergence, the method is relevant to studies of permanent tooth emergence and other developmental events. Deciduous tooth emergence data were analyzed from four longitudinal studies. The samples are 1,271 rural Guatemalan children examined every three months up to age two and every six months thereafter as part of the INCAP study; 397 rural Bangladeshi children examined monthly to age one and quarterly thereafter as part of the Meheran Growth and Development Study; 468 rural Indonesian children examined monthly as part of the Ngaglik study; and 114 urban Japanese children examined monthly in studies from 1910 and 1920. Although all four studies were longitudinal, many observations from the Guatemala and Bangladesh studies were effectively cross-sectionally observed. Three different parametric forms were used to model the eruption process: a normal distribution, a lognormal distribution, and a lognormal distribution with age shifted to shortly after conception. All three distributions produced reliable estimates of central tendencies, but the shifted lognormal distribution produced the best overall estimates of shape (variance) parameters. Estimates of emergence were compared to other studies that used similar methods. Japanese children showed relatively fast emergence times for all teeth. Bangladeshi and Javanese children showed emergence times that were slower than are found in most previous studies. Estimates of agenesis were not significantly different from zero for most teeth. One or two central incisors showed significant agenesis that ranged from 0.1 to 0.8% in three of the samples; even so, failure to model the agenic proportion did not seriously bias the estimates.

Bangladesh↗
PubMed1984

A longitudinal analysis of the antecedents of organizational commitment.

From longitudinal data from 129 nursing department employees, organizational commitment was found to be antecedent to job satisfaction rather than an outcome of it. Furthermore, several other variables were found to be causally related to satisfaction but not commitment. Implications of unsubstantiated assumptions regarding causes of commitment are discussed.

Humans↗
PubMed2004

Quality of life: a longitudinal analysis of correlates of morale in old age.

This paper examines recurrent continuous morale in old age within a statistical modelling paradigm. The Anglicised Philadelphia Geriatric Centre Morale Scale was used as a small component of a major longitudinal study of old age in rural North Wales, U.K. The literature review and cross-sectional analysis of morale in old age is published elsewhere. This paper deals with the aspect of the longitudinal analysis of morale in old age. The proposed statistical modelling relates recurrent morale to a set of explanatory variables that includes subjective as well as objective measures. In order to assess the degree to which explanatory variables influence morale, an adequate statistical model must handle the possibility that substantial variation between respondents will be due to unmeasured and potentially unmeasurable variables (residual heterogeneity), multicollinearity, and past behaviour effect. These applications are illustrated using morale in old age from the North Wales Longitudinal Study Old Age. The results suggested a strong presence of heterogeneity effect, i.e., current levels of morale appear to be individual specific and independent of its previous levels.

Aged↗
PubMed2002

Children's food preferences: a longitudinal analysis.

OBJECTIVE: To compare children's food preferences longitudinally and identify factors related to food preferences. DESIGN: Mothers completed the Food Preference Questionnaire for children at 2 to 3 years of age (T1), 4 years (T2), and 8 years (T3) and for themselves at T1 and T3. Both groups completed a Food Neophobia Scale at T3. SUBJECTS: 70 child/mother pairs who had participated continuously in the longitudinal study. STATISTICAL ANALYSES PERFORMED: Changes in food preferences over time were tested with paired t tests and correlations. Consistency percentages were calculated by summing the consistent matches (like/like) for each food between two time periods. Similarly, concordance percentages were calculated for child/mother pairs by summing the concordant matches for each food. General linear models were developed to identify influences on children's food preferences. RESULTS: Although children liked most foods, the number of liked foods did not change significantly during the 5 to 5.7 years of the study. The strongest predictors of the number of foods liked at age 8 years (R2=0.74) were the number liked at 4 years (P<.0001) and the food neophobia score (P=.0003). Newly tasted foods were more likely to be accepted between T1 and T2 than T2 and T3. Mothers' and children's food preferences were significantly but moderately related. Foods disliked by mothers tended not to be offered to children. APPLICATIONS/CONCLUSIONS: The important role of children's early food preferences is confirmed by this study. Mothers influence children via their own preferences, which may limit foods offered to children.

Aging↗