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Results for “longitudinal data”

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PubMed1998

A survey of the nature and perceived impact of quality improvement activities in pain management.

We surveyed members of the American Pain Society (APS) to determine if they were engaged in quality assurance or improvement (QA/I) activities. If so, we queried them about the characteristics of these activities and their perceptions of whether their data appear to show improvements, decrements, or no change in pain outcomes. Of the 222 respondents from at least 180 institutions, 201 (91%) reported that their institutions had a continuous improvement program. One hundred forty-three respondents reported having data on at least one of six pain outcomes at two points in time. The majority reported that their data revealed improvements in outcomes. A large number, however, had not collected data on important outcomes, such as pain intensity and patient functioning. Many APS members are collecting longitudinal data, and interpreting the data as revealing improvements in outcomes. There is a need for rigorously controlled assessment of the effects of QA/I programs on pain outcomes.

Data Collection↗

PubMedDate not supplied

TW3 bone age: RUS/CB and gender differences of percentiles for score and score increments.

BACKGROUND: Longitudinal data on bone age progression is scarce. AIM: The study aimed to present reference values for Tanner-Whitehouse 3 (TW3) bone age score and score increments, and to provide means and standard deviations of appearance time for all TW3 stages. Gender differences and differences between radio ulna and short bones (RUS) and carpal bone (CB) scores were studied. SUBJECTS AND METHODS: Bone age data collected for ages 3 months to 20 years in 232 subjects during the First Zurich Longitudinal Study (1954-1976) were used. Smoothed empirical percentiles of TW3 RUS and CB scores for age, of score increments for age and of score increments for attained score are presented. Means and standard deviations of the appearance times are calculated by parametric censored regression. RESULTS: There are clear differences between the RUS and CB scores and between the genders. Boys are delayed with respect to girls, with different delays for RUS and CB. For RUS, differences in maturation reflect the known differences of physical growth, with a later and more intense peak in boys. For CB, there is little difference in timing and intensity. However, girls reach the final score about 2 years earlier than boys. The consistently earlier mean appearance times in girls indicate that skeletal maturation is, already in childhood, more rapid in girls than in boys. There are significant gender differences in the sequence of appearance. CONCLUSION: Reference values for TW3 score and score increments and mean appearance times for stages add to existing knowledge and indicate important RUS/CB and gender differences, whose sources are largely unknown.

Adolescent↗

PubMedDate not supplied

Shape-invariant modelling of human growth.

A new approach to modelling human height growth is presented which is also suitable for other variables. In a mathematical algorithm, some guess about the functional form of this growth process is improved consistently using the data; the resulting shape-invariant model (SIM) allows an approximately bias-free fitting for longitudinal data from 1 to 20 years with six parameters assigned to each individual. The SIM approach and the use of velocities rather than distances proved to be suitable for biomathematical modelling in order to answer questions qualitative in nature. In comparison of an additive two-component SIM and one where the appearance of puberty inhibits further growth of the non-pubertal component ('switch-off model'), the latter proved to be superior in various aspects. Among the qualitative features found are notable: a pronounced midspurt, and a dip before the onset of puberty, as well as the asymmetry of the pubertal peak. A preliminary analysis of individual parameters confirmed some results found previously by other methods regarding sex differences and relations between parameters and with adult height.

Adolescent↗

PubMed1999

Preventive dental behaviors and their association with oral health status in older white men.

While prevention practices are widely encouraged, the link between the performance of preventive behaviors and oral health status has rarely been examined. This study investigates the association between preventive dental behaviors (recent and long-term) and oral health status and compares the strength of such associations. Longitudinal data over six time points on 649 dentate white men were obtained from the VA Dental Longitudinal Study (DLS). Participants' oral health was measured through dental examinations, and preventive dental behaviors--i.e., toothbrushing, flossing, using interdental devices, seeking dental prophylaxis, and undergoing dental treatment-were assessed by self-report. Oral health status was measured in terms of (1) functioning teeth, (2) sound-equivalent teeth, (3) decayed, missing, and filled teeth, and (4) decayed and filled root surfaces. Pearson correlation and linear regression analysis revealed significant positive associations between most preventive behaviors and measures of oral health status. Dental prophylaxis emerged as the strongest predictor of oral health status. Long-term preventive dental behavior measures explained more variance in oral health status than short-term preventive behaviors measured cross-sectionally.

Aged↗

PubMed2002

The effect of stepchildren on childbearing intentions and births.

This article reports on a study of the effect of stepchildren (children from previous unions) on couples' fertility intentions and childbearing behavior using longitudinal data from the National Survey of Families and Households. The results indicated that stepchildren negatively affect childbearing intentions and childbearing risks. Intentions to have a child are weakened by one's own previous biological children and the previous biological children of one's current spouse or partner. This effect varies by the parenting configuration of the couple and gender of the respondent. Among couples with stepchildren, intentions remain high until each partner has had a biological child. Unlike women, men's previous biological children do not affect their intentions of having a child. Stepchildren exert a weak negative effect on couples' childbearing risks, and this effect is mediated by the couples' childbearing intentions. The findings suggest that stepchildren should be incorporated into future models of fertility.

Adult↗

PubMed1996

Meta-analysis with longitudinal studies: controlling for analytical bias.

A recent study published in an international medical journal presented an opportunity to demonstrate the difficulties of interpreting meta-analysis results with longitudinal data. We conducted a new meta-analysis using identical data from the published study and showed contradictory results.

Bias↗

PubMed2001

The duration of major depressive episodes in the Canadian general population.

The National Population Health Survey (NPHS) has provided a wealth of new data concerning major depression in the Canadian general population. The NPHS included a brief predictor of major depression, and also two questions (only one of which was asked of each subject) concerned with the duration of episodes in the preceding year. A striking finding was that many of the episodes identified were very brief. In this paper the NPHS data were examined from a different perspective in order to derive a complementary perspective on the episode duration data. Data from the 1994/95 and 1996/97 cycles of the NPHS were used in the analysis. The longitudinal data were used to generate approximations of age and gender-specific incidence for members of the population over the age of 12 years. An estimate of prevalence was made from the 1996/97 cross-sectional file. A basic expression relating prevalence to incidence and mean duration of illness was then applied within age and gender categories. Taken together, the incidence and prevalence data from the NPHS suggest a longer duration than was indicated by the NPHS interview duration item. A probable explanation is that the NPHS duration question had an upper limit of 52 weeks, whereas some episodes of major depression last longer than this. Particularly long episodes could have a large impact on mean duration in the population. Nevertheless, these data confirm the heterogenous nature of this condition; many people with the syndrome of major depression may have quite brief episodes.

Adolescent↗

PubMed1994

Slope estimation in the presence of informative right censoring: modeling the number of observations as a geometric random variable.

A method is proposed for the estimation of rate of change from incomplete longitudinal data where the number of observations made for each subject is assumed to vary depending on the level of the response variable. The proposed method involves a random slope model, in which the number of observations is modeled as a geometric distribution with its mean dependent on the individual subject's rate of change. The method adjusts for informative right censoring and provides estimates of the slopes of individual subjects as well as of the population. Under noninformative right censoring these estimators of the slopes are equivalent to Bayes estimators (Fearn, 1975, Biometrika 62, 89-100). The simulation study demonstrates that, in cases where the censoring process is informative, the proposed estimator is more efficient than either the unweighted or weighted estimator of slope. The method is illustrated by the analysis of renal transplant data.

Adult↗

PubMed1996

Radiographic assessment of knee osteoarthritis: reproducibility and sensitivity to change.

OBJECTIVE: To determine the cross sectional and longitudinal reproducibility of various measures used for assessing radiographic knee osteoarthritis (OA) and to compare the sensitivity to change over a one year period of these measures. METHODS: We studied 55 patients referred to hospital with knee OA (clinical and radiographic ACR criteria). Anteroposterior radiographs at baseline and after 12 months were read by methods both qualitative (Kellgren and Lawrence grading scale, joint space narrowing scale) and quantitative (joint space width measurement at 3 different points). All qualitative methods used standardized atlases. The intraclass correlation coefficient and the graphical method of Bland and Altman were used to assess cross sectional and longitudinal reproducibility. Reproducibility was tested using 2 readers (interreader) and 2 readings for one of the readers (intrareader). Sensitivity to change was assessed using standardized response mean (SRM). RESULTS: All methods tested were shown to be reproducible both for cross sectional and longitudinal data. Intrareader was higher than interreader reproducibility for most radiographic features. Significant changes were observed after one year for methods measuring joint space narrowing. The sensitivity to change of the methods assessing joint space narrowing (joint space narrowing scale and joint space width measurement) was higher, with SRM varying from 0.37 to 0.57, than for the Kellgren and Lawrence grading system (SRM 0.19 and 0.23). CONCLUSION: These data suggest that methods measuring narrowing should be preferred as outcome measures in clinical trials or longitudinal epidemiologic studies; and show that in a particular subset of patients with very active disease, significant radiographic changes in knee OA can be detected after a one year period.

Aged↗

PubMed1998

Quality of life assessment in Hodgkin's disease: a new comprehensive approach. First experiences from the EORTC/GELA and GHSG trials. EORTC Lymphoma Cooperative Group. Groupe D'Etude des Lymphomes de L'Adulte and German Hodgkin Study Group.

Previous reports from available trials have dealt with negative long-term sequelae in Hodgkin's disease (HD) survivors. There is, however, a lack of longitudinal data showing the correlation between outcome and various treatment-related variables and the process of re-adaptation into normal life after the end of treatment. In order to investigate the quality of life (QoL) of patients with HD in different dimensions during active treatment and follow-up and to identify longitudinal patterns of QoL dimensions during re-adaptation to normal life within the EORTC Lymphoma Cooperative Group and Groupe D'Etude des Lymphomes de L'Adulte (EORTC/GELA) and the German Hodgkin Study Group (GHSG), QoL assessment strategies were put into use over the last three to five years. Furthermore, the efforts aimed at obtaining cross-cultural comparisons between the participating countries and study groups (EORTC/GELA and GHSG). Within the randomised EORTC/GELA Trial 'H8' for clinical stage I-II HD which started in September 1993, patients receive a QoL questionnaire for completion at each follow-up visit during the first 10 years after the end of active therapy. The corresponding 'HD8' study of the GHSG employs the assessment of QoL during and after active treatment periods. Within both studies, the EORTC QLQ C30 is used for QoL assessment incorporated in the QLQ-S (quality of life questionnaire for survivors), which additionally addresses the aspects of fatigue/malaise, sexuality, specific side effects, and retrospective evaluation of treatment. In total the QLQ-S includes 45 questions on 14 functional, symptom, and fatigue scales, 15 additional single items, and 3 open questions. In addition to the longitudinal QoL assessment, the GHSG carried out cross-sectional QoL trials with all cured surviving patients from the past HD1-6 studies and a matched normal control sample employing the QLQ-S and the life situation questionnaire (LSQ), an instrument covering objective data from 45 domains of life. To date, within the trials H8 and HD8 over 3000 QoL questionnaires from more than 800 patients from ten countries are available for analysis. Replication of the psychometric properties of the scales revealed satisfactory results using factor analyses and reliability testing across languages for the QLQ-S. A feasibility analysis showed generally a good acceptance of the questionnaire by the patients and physicians. QoL assessment within international multicentre trials in HD proved feasible within the two differently organised study groups of EORTC/GELA and GHSG. The use of subjective QoL data (QLQ-S) together with objective data (LSQ) in a combined cross-sectional and longitudinal trial system will give the most comprehensive insight into the problems of the re-integration process into normal life after cure. This information will provide the basis for the development of remedies/help measures and possible modifications of treatment strategies. The current approach will be further developed in close collaboration between both trial groups, and next steps will include translation of the LSQ into other languages and adaptation to various cultural circumstances.

Adult↗

PubMed2000

Integrating person-centered and variable-centered analyses: growth mixture modeling with latent trajectory classes.

BACKGROUND: Many alcohol research questions require methods that take a person-centered approach because the interest is in finding heterogeneous groups of individuals, such as those who are susceptible to alcohol dependence and those who are not. A person-centered focus also is useful with longitudinal data to represent heterogeneity in developmental trajectories. In alcohol, drug, and mental health research the recognition of heterogeneity has led to theories of multiple developmental pathways. METHODS: This paper gives a brief overview of new methods that integrate variable- and person-centered analyses. Methods discussed include latent class analysis, latent transition analysis, latent class growth analysis, growth mixture modeling, and general growth mixture modeling. These methods are presented in a general latent variable modeling framework that expands traditional latent variable modeling by including not only continuous latent variables but also categorical latent variables. RESULTS: Four examples that use the National Longitudinal Survey of Youth (NLSY) data are presented to illustrate latent class analysis, latent class growth analysis, growth mixture modeling, and general growth mixture modeling. Latent class analysis of antisocial behavior found four classes. Four heavy drinking trajectory classes were found. The relationship between the latent classes and background variables and consequences was studied. CONCLUSIONS: Person-centered and variable-centered analyses typically have been seen as different activities that use different types of models and software. This paper gives a brief overview of new methods that integrate variable- and person-centered analyses. The general framework makes it possible to combine these models and to study new models serving as a stimulus for asking research questions that have both person- and variable-centered aspects.

Adolescent↗

PubMed2006

Concentrations of plasminogen activators and their inhibitors in blood preconceptionally, during and after pregnancy.

BACKGROUND: Haemostasis is a complex balance of activating and inhibitory pathways resulting in coagulation and lysis. Normal pregnancy is associated with hypercoagulation that is even more profound in complicated pregnancies. OBJECTIVE: To study the role of the plasminogen-activator system in complicated pregnancy with regard to haemostasis, it is essential to have reference values of components of this system during uneventful pregnancy. In this study we investigated the concentrations of six different components of the plasminogen-activator system preconceptionally, during and after uncomplicated pregnancies. MATERIAL AND METHODS: Tissue-type and urokinase-type plasminogen activator (tPA and uPA), plasminogen inhibitor type-1 and -2 (PAI-1 and-2), and the complexes between tPA and PAI-1, and between uPA and PAI-1 (tPA-PAI-1, uPA-PAI-1) were measured by ELISAs in blood obtained preconceptionally, at 6, 10, 20, 32 weeks of gestation, and 6 weeks after delivery in uncomplicated pregnancies (n=41; all six parameters n=22). RESULTS: tPA and uPA concentrations decreased in the first 10 weeks of pregnancy and subsequently increased in the third trimester. PAI-1 concentrations increased in the third trimester and PAI-2 concentrations increased throughout pregnancy (preconception versus 32 weeks of gestation; 38.73 versus 102.23ng/ml, and 0.024 versus 151.06ng/ml, respectively). tPA-PAI-1 and uPA-PAI-1 complex concentrations decreased in the first trimester, followed by an increase in the third trimester. The concentrations of all components returned to the preconception values 6 weeks after delivery. CONCLUSION: This study provides longitudinal data on activating and inhibitory components of the plasminogen-activator system during pregnancy. Insight in the longitudinal changes in these concentrations may be of help in the understanding of the thrombotic tendency in pregnancy complications such as preeclampsia.

Adult↗

PubMed2025

Clinical and genetic variant re-analysis among pediatric probands undergoing genetic testing for arrhythmia syndromes.

BACKGROUND: Despite increases in genetic testing, longitudinal data regarding changes in diagnostic yield and variant reclassification for inherited arrhythmia syndromes are limited. OBJECTIVE: Determine longitudinal changes in diagnostic yield and variant classification. METHODS: Single-center retrospective study of probands <18 years undergoing genetic testing for suspected inherited cardiac conditions associated with arrhythmias, 2007 to 2018. Variants were classified as diagnostic (pathogenic/likely pathogenic), non-diagnostic (benign/likely benign [B/LB]), or variants of uncertain significance (VUS). Variant reclassification was performed in October 2023 using VarSome and American College of Medical Genetics criteria. We evaluated results by era (early 2007-2013 vs. later 2014-2018, coinciding with Sanger and next-generation sequencing, respectively) and by likelihood of disease based on clinical evaluation. RESULTS: Of 306 probands, initial testing was 23.2% diagnostic, 55.6% non-diagnostic (33.7% no variant, 21.9% B/LB), and 21.2% VUS. When comparing eras, diagnostic yield decreased (34.1%-15.3%), VUS increased (9.3%-29.9%), and non-diagnostic remained similar (55% to 57%). Variants for 22.7% (46/203) of probands with ≥1 variant changed: 9.9% of diagnostic variants (7/71) downgraded to VUS or non-diagnostic, and 60.0% of VUS changed (23.1% upgraded, 36.9% downgraded). B/LB variants did not change. Probands with higher disease likelihood had 6-times the odds of diagnostic results compared to lower disease likelihood, regardless of era (odds ratio 6.3, 95% confidence interval 3.2-12.4, P < .0001). CONCLUSION: Variant reclassification led to changes in 23% of probands, both downgrading and upgrading status, even among probands initially thought to be pathogenic. When comparing later to earlier eras, VUS variants increased while diagnostic yield decreased. Findings support the need for variant re-interpretation and periodic reclassification over time.

Humans↗

PubMed1996

Family response to childhood chronic illness: description of management styles.

Based on family members' subjective accounts of the illness experience, this study identifies unique styles of family response to childhood chronic illness. Drawing on principles of triangulation, the investigators collected data longitudinally from multiple family members (ill child, parents, well sibling) in 63 families using structured and unstructured data collection techniques. In all families there was a school-age child with a chronic illness. Five family management styles (FMSs) were identified. Each is made up of a distinct configuration of qualitative themes. Across the five FMSs, the configurations reflect differences in the following major aspects of the chronic illness experience: definition of the illness experience, management goals and approach, and illness consequences. The five FMSs (thriving, accommodating, enduring, struggling, and floundering) represent a continuum of difficulty families experience in managing a child's chronic illness. The FMSs also contribute to understanding the underlying processes associated with differing outcomes for families and their individual members when a child has a chronic illness.

Adaptation, Psychological↗

PubMed2004

The analysis, interpretation, and presentation of quality of life data.

All too often in clinical trials the assessment of quality of life is seen as a bolt-on study. Consequently insufficient consideration is often given to its design, collection, analysis and presentation, and its impact on the trial results and on clinical practice is minimal. In many trials quality of life is a key endpoint, and it is vital that quality of life expertise is involved as soon as possible in the design. Setting a priori quality of life hypotheses will focus the decisions regarding which questionnaire to use, when to administer it, the sample size required, and the primary analyses. Nevertheless quality of life data are complex, and require much skill in determining how to deal with multi-dimensional and longitudinal data, much of which is often missing. There are no agreed standard ways of analysing and presenting quality of life data, but there are guidelines, which if followed, will add transparency to the way results have been calculated. Understanding the impact of treatments on their quality of life is vital to patients, and it is up to us, as statisticians and trialists, to present the data as clearly as we can.

Data Interpretation, Statistical↗

PubMed2001

On measuring inequalities in health.

In a recent series of papers, Murray et al. have put forward a number of important ideas regarding the measurement of inequalities in health. In this paper we agree with some of these ideas but draw attention to one key aspect of their approach--measuring inequalities on the basis of small area data--which is flawed. A numerical example is presented to illustrate the problem. An alternative approach drawing on longitudinal data is outlined, which preserves and enhances the most desirable aspects of their proposal. These include the use of a life course perspective, and the consideration of non-fatal health outcomes as well as the more usual information on mortality patterns.

Analysis of Variance↗

PubMed1984

The chronic disease data bank: first principles to future directions.

Chronic diseases represent the major illness burden of developed nations. A chronic disease databank system consists of parallel longitudinal data sets from diverse locations describing the courses of thousands of patients with chronic illness over many years. Illustrated by ARAMIS (The American Rheumatism Association Medical Information System), such data resources facilitate analysis of long term health outcomes and the factors associated with particular outcomes. A model for clinical investigation of contemporary disease is presented, based on the overwhelming prevalence of chronic illness, the variability, complexity, and uniqueness of the individual patient course, the difficulties of traditional univariate reductionist approaches, and the time span required for study. In this model, data are systematically accrued and continually analyzed, and the data collected are gradually modified based upon evolving anticipation of future needs. The strategies underlying the development of ARAMIS are described, investigational results summarized, and future directions outlined.

Arthritis, Rheumatoid↗

PubMedDate not supplied

Construction of rhythm-specified reference intervals and regions, with emphasis on 'hybrid' data, illustrated for plasma cortisol.

Time-specified reference intervals, so-called chronodesms for the interpretation of single samples, have heretofore been proposed for longitudinal data, consisting of repeated samples from a single individual, and for transverse data: single time-specified samples from many individuals. Herein the problem of dealing with hybrid data, namely time series of data collected on a group of subjects, is considered for a derivation of reference intervals that take into account both inter- and intra-individual variability. The formulae are applied to cortisol data (72 samples from each of 10 healthy young adult North American women) with interpretation from both Bayesian and frequentist viewpoints. The provision of reference limits for both single samples and paired rhythm characteristics offers the opportunity of introducing an overdue time-specification and time-structure evaluation into microscopic chronobiology and through it into medical, veterinarian and other practice.

Adult↗