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Results for “Longitudinal analysis”

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PubMed2005

Predicting self-care behaviors among older adults coping with arthritis: a cross-sectional and 1-year longitudinal comparative analysis.

OBJECTIVE: The purpose of this investigation is to examine correlates and predictors of self-care activities for persons diagnosed with arthritis both cross-sectionally and longitudinally. METHOD: Data from telephone surveys conducted with 313 older (M = 68.8, SD = 8.93) individuals, chosen from a larger sample, who reported professionally diagnosed arthritis, were used. RESULTS: A total of 10 of the 11 self-care activities changed significantly during the 1-year interval, with 9 showing increased participation. Results from hierarchical regressions showed that all three blocks of predictors explained significant portions of variance, with gender and perceived importance of general health significantly predicting self-care activities at Time 1, at Time 2, and longitudinally. DISCUSSION: These results highlight the influence of demographic, health status, and health belief variables on self-care both cross-sectionally and longitudinally. Future work should focus on the mediating effects of these and other variables to better understand the processes by which individuals engage in self-care behavior.

Adaptation, Psychological↗
PubMed2003

Multilevel modeling for the analysis of longitudinal blood pressure data in the Framingham Heart Study pedigrees.

BACKGROUND: The data arising from a longitudinal familial study have a complex correlation structure that cannot be modeled using classical methods for the analysis of familial data at a single time point. METHODS: To fit the longitudinal systolic blood pressure (SBP) pedigree data arising from the Framingham Heart Study, we proposed to use multilevel modeling. That approach was used to distinguish multiple levels of information with individual repeated measurements (Level 1) being made within individuals (Level 2), and individuals clustered within pedigrees (Level 3). Residuals from the subject-specific and pedigree-specific regression models were summed both for the mean SBP and slope of SBP change over time, in order to define two new outcomes that were then used in a genome-wide linkage analysis. RESULTS: Evidence for linkage for the two outcomes (mean SBP and slope) was found in several chromosomal regions with a maximum LOD score of 3.6 on chromosome 8 and 3.5 on chromosome 17 for the mean SBP, and 2.5 on chromosome 1 for SBP slope. However, the linkage on chromosome 8 was only detected when the sample was restricted to subjects between age 25 and 75 and with at least four exams (Cohort 1) or 3 exams (Cohort 2). DISCUSSION: Multilevel modeling is a powerful approach to detect genes involved in complex traits when longitudinal data are available. It allows for complex hierarchical data structure to be taken into account and therefore, a better partitioning of random within-individual variation from other sources of variability (genetic or nongenetic).

Adult↗
PubMed1987

The role of biomarkers in reproductive and developmental toxicology.

A massive outbreak of methylmercury poisoning took place in the winter of 1971-1972 due to the consumption of homemade bread contaminated with a methylmercury fungicide. The longitudinal analysis of the mother's head hair, collected after delivery of the baby, provided a means of recapitulating exposure to methylmercury during pregnancy. Methylmercury is incorporated into newly formed hair at a concentration that is proportional to the simultaneous concentration in blood. Since hair grows at a rate of approximately 1 cm/month, longitudinal analysis of the hair strand, centimeter by centimeter, will give a month by month recapitulation of blood levels. Depending on the length of the hair strand, it is possible to recapitulate several years of exposure. Using longitudinal hair analysis, it was possible to compare the methylmercury levels in the mother during pregnancy with the severity and frequency of effects in her offspring. As in the previous incidents, high levels of prenatal exposure led to severe brain damage. However, it was also possible to identify milder effects of methylmercury as manifested by delayed development. It was possible to demonstrate a dose-effect and dose-response relationship between the maximum concentration of methylmercury in maternal hair during pregnancy and evidence of delayed development and mild neurological abnormalities in the offspring. These relationships provided quantitative evidence that the developing nervous system is more susceptible to damage than the mature brain.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Intent-to-treat analysis for longitudinal clinical trials: coping with the challenge of missing values.

Drop-out is a common phenomenon in clinical trials of drug treatments involving longitudinal assessments for a fixed duration of follow-up. For these trials intent-to-treat (IT) analysis is usually preferred because time effects are seen in practice. The IT analysis mandates that all subjects randomized to a treatment arm should be included in the analysis. The purpose of the present paper is to acquaint both clinicians and statisticians with recent statistical methodological advances in handling drop-outs and their usage for IT analysis. We discuss a sensitivity analysis of 12-month outcome data to investigate the efficacy of drug therapy from a longitudinal double-blind placebo-controlled clinical trial in the maintenance therapy of geriatric major depressive illness. Outcome measures consist of monthly Hamilton depression scores. The sensitivity analysis includes endpoint analysis, last observation carried forward analysis, repeated measures models and imputation models. Imputation models are based on multiple imputations of missing responses deriving from an 'as-treated' model. The model used imputed doses from a plausible treatment scenario after drop-out and a 'propensity-adjusted' model where the imputations for the drop-outs were obtained from the adhering subjects with the same probability to remain on study (propensity) given the observed trajectory prior to withdrawal. Issues related to bias and efficiency of the estimates obtained by different analyses are discussed. We recommend a more widespread use of imputation models for the IT analysis.

Aged↗
PubMed2006

The analysis of longitudinal data using mixed model L-splines.

L-splines are a large family of smoothing splines defined in terms of a linear differential operator. This article develops L-splines within the context of linear mixed models and uses the resulting mixed model L-spline to analyze longitudinal data from a grassland experiment. In the spirit of time-series analysis, a periodic mixed model L-spline is developed, which partitions data into a smooth periodic component plus smooth long-term trend.

Biomass↗
PubMed1987

Sex roles and social support as moderators of life stress adjustment.

In this study we used a longitudinal design to test the stress-buffering effects of sex role orientation in combination with perceived social support on measures of trait anxiety and depression. College undergraduates served as subjects. The cross-sectional analyses provided strong support for the hypothesis that masculinity would function as a life stress buffer. The hypothesis that social support would serve as a stress buffer when coupled with high masculinity was supported by one of the cross-sectional analyses as well as the longitudinal analysis. This pattern was found primarily for perceptions of tangible social support. The longitudinal analysis also revealed a significant interaction involving negative life events and masculinity and femininity. This interaction effect provided unexpected support for a balance model of androgyny, in that non-sex-typed subjects showed greater resilience to recent life stress than did sex-typed subjects. The findings are discussed in terms of their implications for the study of life stress adjustment.

Adolescent↗
PubMed2002

A copula-based model for multivariate non-normal longitudinal data: analysis of a dose titration safety study on a new antidepressant.

A new model for multivariate non-normal longitudinal data is proposed. In a first step, each longitudinal series of data corresponding to a given response is modelled separately using a copula to relate the marginal distributions of the response at each time of observation. In a second step, at each observation time, the conditional (on the past) distributions of each response are related using another copula describing the relationship between the corresponding variables. Note that there is no need to consider the same family of distributions for these response variables. The technique is illustrated in a dose titration safety study on a new antidepressant. The haemodynamic effect on diastolic blood pressure, systolic blood pressure and heart rate is studied. These three responses are measured repeatedly over time on ten healthy volunteers during the dose escalation. The available covariates are sex and the concentration of drug in the plasma at time of measurement.

Antidepressive Agents↗
PubMed1989

Noncomparability of cross-sectional and longitudinal estimates of lung growth in children.

Results from longitudinal and cross-sectional studies of pulmonary function are often compared. However, previous studies in adults suggest that results from longitudinal and cross-sectional studies are different and may not be comparable. In order to evaluate these differences further, prospectively collected data in a group of children were analyzed by both longitudinal and cross-sectional methods. Spirometry was performed longitudinally over a period of 8 years on 58 healthy children. Straight-line regressions of expiratory flow-volume parameters on height were computed by averaging the individual regression lines for each child. A cross-sectional sample from these same children was analyzed and compared to the longitudinal analysis. For all expiratory flow-volume parameters, the cross-sectional analysis resulted in a significantly greater increase in growth with increasing height than the longitudinal analysis (P less than 0.005 for slope for all parameters except PEFR, P less than 0.05 and Vmax75, P less than 0.01). These differences cannot be explained by learning or horse-racing effects, loss to follow-up, or regression to the mean; however, they could be explained by cohort changes, time trends of pulmonary function, differences in the weighted averages used in the two analyses, or incorrect modeling. These observations indicate that comparisons between cross-sectional and longitudinal investigations must be made cautiously. These data do not support many of the reasons suggested for the differences in previous reports. It is recommended that studies of pulmonary function use a control group and investigate the groups at the same time and in the same manner.

Body Height↗
PubMed2025

Elevated Cerebrospinal Fluid Total Tau in Niemann-Pick Disease Type C1: Correlation With Clinical Severity and Response to Therapeutic Interventions.

Niemann-Pick disease, type C1 (NPC1) is an inborn error of intracellular cholesterol transport. Impaired function of NPC1 leads to endolysosomal accumulation of unesterified cholesterol, which results in progressive neurodegeneration. Although the age of onset is variable, classical NPC1 is a pediatric disease. Identification of biomarkers that correlate with clinical phenotype and respond to therapeutic interventions will be essential for developing effective therapeutic interventions. A&#x3b2; peptides and Tau protein are primary components of amyloid plaques and neurofibrillary tangles, respectively, which are major pathological features in neurodegenerative disorders. Cerebrospinal fluid (CSF) levels of total Tau, a biomarker of axonal damage, were elevated ~3-fold (p&#x2009;<&#x2009;0.0001) in 106 individuals with Niemann-Pick disease, type C1, relative to age-appropriate comparison samples. Baseline CSF total Tau levels correlated with clinical measures of disease severity. Specifically, CSF total Tau levels decreased with increased age of neurological onset (rs&#x2009;=&#x2009;-0.42, FDR adj. p&#x2009;<&#x2009;0.0001) and increased with increased Annual Severity Increment Score (rs&#x2009;=&#x2009;0.52, FDR adj. p&#x2009;<&#x2009;0.0001). Baseline CSF total Tau levels were decreased 40% (p&#x2009;=&#x2009;0.0066) in individuals being treated with miglustat, and longitudinal analysis substantiated this observation with a 40% decrease (p&#x2009;<&#x2009;0.0001, 95% CI 32%-47.4%). Longitudinal analysis also showed a significant (p&#x2009;=&#x2009;0.004) decrease of 19% (95% CI 7%-30%) in total Tau levels associated with intrathecal 2-hydroxypropyl-&#x3b2;-cyclodextrin therapy. These data show that CSF total Tau levels are significantly increased in individuals with NPC1, positively correlated with increased disease severity, and respond to therapeutic interventions.

Humans↗
PubMed2026

The Incidence of Suicide Following Metabolic and Bariatric Surgery: A Prognosis Systematic Review and Meta-Analysis of Longitudinal Studies.

BACKGROUND: Metabolic and bariatric surgery (MBS) effectively manages severe obesity but may lead to psychological complications such as completed suicides and suicide attempts. This review aimed to analyze suicide and self-harm incidence post-MBS. METHODS: We searched MEDLINE, EMBASE, PsycINFO, and the Cochrane Library databases on August 16, 2022, for longitudinal studies with incidence data on suicide following MBS. We performed a single proportion meta-analysis on the incidence of outcomes and assessed the certainty of evidence using the GRADE approach. The review was registered with PROSPERO (CRD42022352137). RESULTS: Eighty-four studies were included. The meta-analysis showed an incidence of 230.64 suicides per 100,000 participants (95% CI: 167.51 to 317.49) in pooled individual-level data and an incidence of 43.02 suicides per 100,000 person-years (95% CI: 32.49 to 56.97) in pooled person-year data. Evidence was low certainty or very low certainty. CONCLUSIONS: The average suicide incidence (231 per 100,000 people) in people with obesity who underwent MBS significantly exceeded the 2019 WHO global estimate for the general population (nine per 100,000 people). These findings underscore the need to incorporate structured psychological screening and follow-up into the perioperative management process of MBS, as patient mental health may play a pivotal role in postoperative adherence and long-term outcomes.

Humans↗
PubMed1987

Analysis of longitudinal "time series" data in toxicology.

Studies focusing on chronic toxicity or on the time course of toxicant effect often involve repeated measurements or longitudinal observations of endpoints of interest. Experimental design considerations frequently necessitate between-group comparisons of the resulting trends. Typically, procedures such as the repeated-measures analysis of variance have been used for statistical analysis, even though the required assumptions may not be satisfied in some circumstances. This paper describes an alternative analytical approach which summarizes curvilinear trends by fitting cubic orthogonal polynomials to individual profiles of effect. The resulting regression coefficients serve as quantitative descriptors which can be subjected to group significance testing. Randomization tests based on medians are proposed to provide a comparison of treatment and control groups. Examples from the behavioral toxicology literature are considered, and the results are compared to more traditional approaches, such as repeated-measures analysis of variance.

Analysis of Variance↗
PubMed1996

Latent transition analysis for longitudinal data.

Assessing outcome is a critical problem for the study of addictive behaviors. Traditional approaches often lack power and sensitivity. Latent Transition Analysis is an alternative procedure that is applicable to categorical latent variable models such as stage models. The method involves four different types of parameters, each of which may be relevant to different research questions. Two examples that employ the Stages of Change construct are used to illustrate the method. In the first example, three different models of longitudinal change are compared. In the second example, the effects of an expert system intervention for smoking is compared to a control condition. The method permits the investigation of a series of specific comparisons: (1) the effectiveness of the intervention for individuals in different stages can be assessed; (2) the effectiveness of the intervention can be evaluated for different time intervals; and (3) the effects of intervention on both progression through the stages and regression through the stages or relapse can be assessed. Other potential applications of the method are also discussed.

Alcoholism↗