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PubMed2003

The Health Assessment Longitudinal File imperative: foundation for improving the health of the force.

A smaller active duty force and an increased operational tempo have made the Reserve components (RC) essential elements in the accomplishment of the mission of the U.S. Army. One critical factor in meeting mission is maintaining the optimal health of each soldier. Baseline health data about the RC is currently not being collected, even though increasing numbers of reserve soldiers are being activated. The Annual Health Certification and Survey is being developed as a way to meet the RCs' statutory requirement for annual certification of health while at the same time generating and tracking baseline data on each reservist in a longitudinal health file, the Health Assessment Longitudinal File. This article discusses the Annual Health Certification Questionnaire/Health Assessment Longitudinal File, which will greatly enhance the Army's ability to accurately certify the health status of the RC and track health in relation to training, mission activities, and deployment.

Female↗
PubMed1992

[Prevention and reduction of psychological and motor defects in childhood. II. Advantages and risks of longitudinal studies in pediatrics].

The presented investigation characterized the general types of longitudinal projects focused on the long-term follow-up of children in health and disease. First the authors outline briefly the principles and disadvantages of cross-sectional projects. Then follows an account on the methodology of longitudinal projects, evaluation of their advantages and their multiple risks. Approximately 50 years of experience with longitudinal projects indicate that this pretentious research strategy can provide an overall view of developmental trends as regards changes of the health status in the ontogenetic perspective and contribute to the improvement of health care of the child population.

Child↗
PubMed2004

[Effects of smoking habits on pulmonary function. Cross-sectional and longitudinal studies in male subjects on medical check-up].

Cross-sectional and longitudinal studies were done to evaluate effects of cigarette smoking and smoking cessation on age-related pulmonary function decline. Data on pulmonary function from 11,875 healthy asymptomatic men between the ages of 35 and 74 years were analyzed on the basis of smoking habits in each age group. Longitudinal changes in pulmonary function during a 5-yr period were also assessed in relation to smoking habits in 1888 healthy men. Cross-sectional studies showed that the difference of FEV1 between man current smokers and men who had never smoked is small at younger ages but increases with increases in age. A beneficial effect on FEV1 decline was observed in former smokers, even in less than 1 year after smoking cessation. Longitudinally, current smokers showed a more rapid decline in FEV1 in 5 years than nonsmokers. The men who quitted smoking had lower rates of decline in FEV1 than those who continued to smoke. These results indicate that cigarette smoking is associated with reduced pulmonary function and that smoking cessation may have a beneficial effect on FEV1 decline. Provision of a smoking cessation program for all smokers, especially those with a rapid decline of FEV1, should be considered a very important strategy to prevent progression of COPD.

Adult↗
PubMed2004

A longitudinal study of growth patterns in school children in Taipei area I: growth curve and height velocity curve.

BACKGROUND: It has been pointed out that longitudinal rather than cross-sectional growth standards should be used to assess individual linear growth. The purpose of this study is to investigate the growth characteristics of school boys and girls living in Shih-Pai district in Taipei. METHODS: A defined group of 1,139 healthy school children (570 boys and 569 girls) from the Shih-Pai district of Taipei city were followed longitudinally for 3 to 4 years. Anthropometric measurement of height and weight and physical development in each child were obtained. The annual increments were calculated every 6 months to map the peak height velocity (PHV), height velocity curve (HVC), peak weight velocity (PWV) and weight velocity curve (WVC). RESULTS: The age at peak velocity was taken as 12.5 years for boys and 10.5 years for girls, and the whole year PHV as 8.0 cm/yr in boys and 7.0 cm/yr in girls. The mean PHV was less than 1 cm in boys and girls of about 17 years and 15 years, respectively, with mean heights of 170.8 cm and 158.7 cm, respectively. CONCLUSIONS: Our preliminary results were actually calculated from the combination of longitudinal data and cross-sectional data pools. Since this is only a pilot study design, we expect that a longer follow-up period of the same cohorts would give more exact growth characteristics.

Adolescent↗
PubMed2005

Responsiveness, longitudinal- and cross-sectional construct validity of the Pediatric Asthma Quality of Life Questionnaire (PAQLQ) in Dutch children with asthma.

OBJECTIVE: Health-related quality of life is an important measure in evaluations of the management of childhood asthma. In this study, we assessed psychometric properties, responsiveness, and longitudinal and cross-sectional construct validity of the Dutch version of the 23-item Pediatric Asthma Quality of Life Questionnaire (PAQLQ). METHODS: The study group consisted of 238 6-18-year olds with asthma, with complete respiratory symptom diaries in the course of one winter season; each child had one (or more) PAQLQ measurement(s) concerning one (or more) week(s) with relatively many symptoms (n = 238). Each child also had one PAQLQ measurement concerning another week with relatively few symptoms (n = 238). The PAQLQ scores of the 238 children for a week with few symptoms (the symptom diary scores remained below a predefined level everyday) were compared with their PAQLQ scores for another week with many symptoms (on day 1 of that week, symptom diary scores had been above the predefined level). Additionally, in a subgroup of the study group that had experienced two or more 'weeks with many symptoms' (n = 101), we compared the PAQLQ-scores for two different weeks with many symptoms of these children. RESULTS: Only the domain Emotions showed a ceiling effect (>25% had the maximum score). All Cronbach's alpha's of the PAQLQ total score and domains were >0.70, except for Activities (alpha = 0.54). Mean PAQLQ-scores were significantly different (p < 0.01; n = 238) between one week with few symptoms and another week with many symptoms. Contrary, in the subgroup of children with PAQLQ-measurements regarding more than one week with many symptoms (n = 101), mean PAQLQ-scores did not differ significantly (p > or = 0.05) between 1 week with many symptoms and another week with many symptoms. These results indicate responsiveness. (Changes in) lower respiratory tract symptoms, indicative of asthma severity, correlated better with (changes in) PAQLQ scores than (changes in) upper respiratory tract symptoms, which supports the longitudinal and cross-sectional construct validity. CONCLUSION: The assessed properties of the PAQLQ linguistic validation into Dutch were similar to those originally established for the PAQLQ in Canada. This study showed that the Dutch PAQLQ has adequate psychometric properties, excellent responsiveness, and that the longitudinal and cross-sectional construct validity is supported.

Adolescent↗
PubMed2006

Longitudinal changes in dietary patterns during adult life.

Despite the growing interest in dietary patterns, there have been few longitudinal investigations. The objective of the present study was to extend an earlier method of dietary pattern assessment to longitudinal binary data and to assess changes in patterns over time and in relation to socio-demographic covariates. A prospective national cohort of 1265 participants completed a 5 d food diary at three time-points during their adult life (at age 36 years in 1982, 43 years in 1989 and 53 years in 1999). Factor analysis identified three dietary patterns for women (fruit, vegetables and dairy; ethnic foods and alcohol; meat, potatoes and sweet foods) and two patterns in men (ethnic foods and alcohol; mixed). Trends in dietary pattern scores were calculated using random effects models. Marked changes were found in scores for all patterns between 1989 and 1999, with only the meat, potatoes and sweet foods pattern in women recording a decline. In a multiple variable model that included the three time-points, socio-demographic variables and BMI time-dependent covariates, both non-manual social class and higher education level were also strongly associated with the consumption of more items from the ethnic foods and alcohol pattern and the mixed pattern for men (P < 0.0001) and the fruit, vegetables and dairy pattern and the ethnic foods and alcohol pattern for women (P < 0.01). In conclusion, longitudinal changes in dietary patterns and across socio-economic groups can assist with targeting public health initiatives by identifying stages during adult life when interventions to improve diet would be most beneficial to health.

Adult↗
PubMed1992

Longitudinal study of the amniotic fluid index in post-dates pregnancy.

Amniotic fluid (AF) was measured in 511 post-dates pregnancies (at least 41 weeks of gestational age) with the use of the AF index. Ultrasonographic evaluations were conducted on a semiweekly basis. Only patients with reliable gestational ages calculated from certain last menstrual period and confirmed by early sonographic estimates participated in the study. Oligohydramnios (AF index of 5.0 cm or less) was detected in 11.5% of the study population. Longitudinal data were available from 121 patients who demonstrated a mean 25% decrease in AF index per week beyond 41 weeks' gestation. The longitudinal change in AF index was statistically significant (P less than .0005). Amniotic fluid index measurements ranged from 1.7-24.6 cm, with a mean of 12.4 at 41 weeks' gestation. Compared with previous cross-sectional studies, this longitudinal study provides a more accurate estimate of changes in AF levels as a function of gestational age.

Amniotic Fluid↗
PubMed1991

Analysis of longitudinal data with unmeasured confounders.

Confounding in longitudinal or clustered data creates special problems and opportunities because the relationship between the confounder and covariate of interest may differ across and within individuals or clusters. A well-known example of such confounding in longitudinal data is the presence of cohort and period effects in models of aging in epidemiologic research. We first formulate a data-generating model with confounding and derive the distribution of the response variable unconditional on the confounder. We then examine the properties of the regression coefficient for some analytic approaches when the confounder is omitted from the fitted model. The expected value of the regression coefficient differs in across- and within-individual regression. In the multivariate case, within- and between-individual information is combined and weighted according to the assumed covariance structure. We assume compound symmetry in the fitted covariance matrix and derive the variance, bias, and mean squared error of the slope estimate as a function of the fitted within-individual correlation. We find that even in this simplest multivariate case, the trade-off between bias and variance depends on a large number of parameters. It is generally preferable to fit correlations somewhat above the true correlation to minimize the effect of between-individual confounders or cohort effects. Period effects can lead to situations where it is advantageous to fit correlations that are below the true correlation. The results highlight the trade-offs inherent in the choice of method for analysis of longitudinal data, and show that an appropriate choice can be made only after determining whether within- or between-individual confounding is the major concern.

Analysis of Variance↗
PubMed1991

Sources of variation in longitudinal assessment of maximal aerobic power in teenage boys and girls: the Amsterdam Growth and Health Study.

Maximal oxygen uptake (VO2 max), generally accepted as a valid method for measuring state and change of aerobic fitness, was repeatedly measured in 93 males and 107 females 5 times over a period of 8 years. A direct measurement was made using a treadmill running test with constant speed (8 km/hr) and increasing slope. Oxygen uptake was analyzed continuously by an open-circuit technique. The reproducibility of VO2 max estimated from interperiod correlations resulted in high test-retest correlations of approximately 0.9 in both males and females. Inspection of the longitudinal data from the multiple-longitudinal design with four measurements in three cohorts did not reveal confounding effects, such as time of measurement effects, cohort effects, and drop-out effects. A comparison of the longitudinal data evaluated over four years with data from a comparable control group that was measured once during the four-year period also failed to show any testing effects. In 40% of the males and 50% of the females no leveling-off in VO2 max could be demonstrated; that is, there was an increase of more than 150 ml in the last stage of running. A comparison of subjects who showed leveling-off with those who showed no leveling-off supports the idea that in the age range 12-23 years leveling-off is not a prerequisite for reaching a true VO2 max. Repeated measurement of VO2 max, using a maximal running test on a treadmill appears to be a reliable method to describe the individual development of aerobic fitness in males and females in the age range 12-23 years.

Adolescent↗
PubMed1991

A comparison of cross-sectional and longitudinal survey methods in measuring patient compliance with tuberculosis treatment.

A group of 179 tuberculosis patients, notified within a specific time period in an area served by a community-based TB clinic in Cape Town, was defined. Cross-sectional and longitudinal measurements of compliance were taken to test the validity of the two research methods in compliance surveillance. The cross-sectional method was found to mask significantly the true extent of non-compliance with tuberculosis treatment (19.5% v. a true 40.3%). The sampling and measurement biases inherent in the cross-sectional design were illustrated. The first bias was introduced because the cross-sectional survey captured only treatment survivors. By the date of the cross-sectional survey 45 patients were no longer on the clinic treatment list, between 4 and 13 (2.2 - 7.3% of the original group) having been lost as a result of poor compliance. The second and most extensive bias was introduced because the cross-sectional survey measured the compliance of all patients on a particular day irrespective of the time since notification. Thus for the cross-sectional group the compliant proportion was 80.5% at the time of the cross-sectional survey but fell to 65.4% by the end of treatment (as measured in the longitudinal survey). The absolute significance of the association between compliance and various demographic and treatment variables did not change with survey method. However, in two instances the association approached significance in only one of the two surveys. The study implies that serious clinical repercussions are possible if management decisions are based on the results of inappropriately designed studies. The place of the longitudinal and cross-sectional research methods in compliance surveillance is discussed.

Adult↗
PubMed1990

Reliability of attachment loss measurements in a longitudinal clinical trial.

In order to appropriately carry out a longitudinal assessment of periodontal attachment loss in individuals with untreated periodontitis, reliable criteria for determining "real" changes in attachment level (AL) are required. In the present study, 25 subjects were to be examined every 2 months for up to 2 years to determine changes in AL and to relate clinical and laboratory criteria to such changes. Trained examiners for the study underwent calibration trials to determine inter-examiner and intra-examiner reliability both before the study and at intervals during the study. It was found that AL measurements were in agreement within 2 mm more than 95% of the time. The calibration trials provided an estimate of the error in attachment loss measurements, since no "real" attachment loss had occurred. From estimates of measurement error, the probability of false positive changes were determined. It was found that acceptable false positive rates (less than 5%) could be achieved if 2 examiners each detected 3 mm change at a given site or if 2 examiners each detected 2 mm change at a site and verified that this change persisted at a subsequent examination. The results of the longitudinal trial were then compared to the probability estimates calculated from the calibration trials. It was found that probabilities of AL changes detected during the longitudinal trial for less stringent conditions than described above (e.g., single examiner, 2 examiners unconfirmed) were similar to to previously estimated false positive rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Protecting against nonrandomly missing data in longitudinal studies.

Nonrandomly missing data can pose serious problems in longitudinal studies. We generally have little knowledge about how missingness is related to the data values, and longitudinal studies are often far from complete. Two approaches that have been used to handle missing data--use of maximum likelihood with an ignorable mechanism and direct modeling of the missing data mechanism--have the disadvantage of not giving consistent estimates under important classes of nonrandom mechanisms. We introduce two protective estimators, that is, estimators that retain their consistency over a wide range of nonrandom mechanisms. We compare these protective estimators using longitudinal data from a mental health panel study. We also investigate their robustness to certain departures from normality.

Data Interpretation, Statistical↗
PubMed1989

Longitudinal studies: social and psychological factors.

In spite of the great variety of longitudinal studies, one may consider two main orientations: on one hand the "comprehensive" studies, based on the combined or parallel observation of numerous psychosocial characteristics collected at successive stages of the child's development; on the other hand, studies focussed on limited topics based on the observation and longitudinal analysis of a restricted number of specific characteristics. Some examples of these different approaches are presented. The chapter considers, finally, several methodological issues, including new developments as well as constraints and problems. Recent methodological developments concern, i.a., videoscopic recording techniques which may be applied to the behaviour of mother and child (etc...) whether in the laboratory or in normal life-situations. Moreover, in view of the statistical analysis of the datas appropriate instruments are developed which at the same time keep the nuances and details of the clinical observation. Finally, some examples of problems linked to the attrition-rate of the observed sample are presented, as well as specific ethical issues raised by longitudinal studies.

Child↗
PubMed1989

[Longitudinal study of dental arch forms, with special reference to normal and malocclusions].

The purpose of the present study was to investigate the developmental changes of dental arch forms by using longitudinal materials. The data was derived from dental casts and roentgenographic cephalograms collected from a longitudinal growth study of Japanese children from the age of 5 to 15 years. The materials were divided into three groups of occlusion at the time that the children had full permanent dentitions as follows; normal occlusion group (N-group; N = 19), Angle's class I crowding group (CR-group; N = 11), Angle's class II malocclusion group (CL2-group; N = 7). In addition, members of these groups were classified into three developmental stages as follows; deciduous, mixed and permanent dentition. The developmental changes in dental arch forms were analyzed from metrical measurements of dental casts and roentgenographic cephalograms. The measurements, such as dental arch lengths, widths, amount of interdental space or crowding, mesiodistal crown diameters, overjet and overbite, were obtained from dental casts, and those of incisor inclination angles and ANB angles were from roentgenographic cephalograms. Finally, principal component analysis was performed to clarify the developmental changes of dental arch forms in the series of longitudinal data. The results were as follows; 1. A method was devised for drawing dental arch forms directly from dental casts using compasses, sliding calipers and rulers. 2. Dental arch lengths and widths of the CR-group were uniformly smaller from the deciduous to permanent stages than those of the N-group. 3. The CL2-group showed nearly the same sizes of arch lengths and widths as the N-group at the deciduous stage. Nevertheless, these dimensions of the CL2-group increased considerably and showed larger sizes of arch lengths and widths than the N-group in mixed and permanent stages except in the case of maxillary arch widths. 4. The sum of mesiodistal crown diameters of the CR-group were quite similar to those of the N-group in all three stages. On the other hand, the CL2-group tended to be larger in both arches than the N-group in all stages. 5. So far as the deciduous stage is concerned, the amount of interdental space was significantly larger in the N-group than in the other two groups. 6. Throughout all stages, there were no significant differences in the maxillary central incisor inclination angles among the three groups, while the CR-group tended to show lingual inclination of the mandibular central incisor compared with the other two groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1989

Studies in the distribution of body fat. II. Longitudinal effects of change in weight.

Information on the effects of age, sex, obesity and weight change on the fat distribution pattern has not been systematically reported. As an index of body fat distribution, the waist hip circumference ratio (WHR) was computed in 370 men and 177 women aged 22-86 years, participants of the Baltimore Longitudinal Study of Aging. For cross-sectional analysis, initial data on the participants were analyzed; for longitudinal study, the changes in the measurements related to weight change during a 5-year follow-up were analyzed. From cross-sectional analysis: (1) waist circumference is larger in men than in women and increases progressively with age; (2) hip circumference shows no consistent age or sex differences; (3) thus, the well known sex differences in WHR are totally attributable to differences in waist circumference; (4) increases in WHR with age occur in both men and women. From longitudinal analysis of weight change: (1) changes in waist and hip circumferences are correlated directly with changes in weight in both sexes, but there are large differential sex effects; (2) in men, waist changes dominate; (3) in women, waist and hip changes are nearly the same; (4) thus, weight changes in men have large effects on the WHR, while in women changes in WHR are very small. Men, as a group, have a more dangerous fat distribution pattern than women, but men as a group will show a more beneficial pattern of change in WHR with weight control than women.

Adipose Tissue↗
PubMed1989

Intra-uterine growth: a comparison of longitudinal and cross-sectional approaches.

The great majority of the fetal growth curves are constructed through a cross-sectional approach. Before the use of ultra-sonography, fetal growth was first evaluated from birthweights of infants born at different gestational ages. More recently, curves were established for different ultrasonographic parameters which combination can provide an immediate but imperfect evaluation of fetal weight. All the curves used as standards of normal growth derive from cross-sectional studies. Several longitudinal studies of fetal growth exist, with two aspects. The first method is to make serial measurements at special intervals, among a group of fetuses with known dates of conception, in order to determine average longitudinal curves. The aim of the standards of fetal growth is obstetric management and the threshold of a percentile, for instance the tenth, of an ultra-sonographic parameter can define the intra-uterine growth retardation. The result of the fetal growth is evaluated with the standards of birthweight which define the small for gestational age infant. Another longitudinal approach is the use of a mathematical growth model to establish an individual growth curve, each fetus is then its own control. This last approach still belongs to the research field.

Birth Weight↗
PubMed1989

[The physical development of infants and young children. 5. Body height--a longitudinal study].

As a result of a longitudinal study (1979-1982) distance values increments and growth velocity of the body length of 84 male and 91 female children are presented for the first three years of life. As compared to earlier longitudinal for the first three years of life. As compared to earlier longitudinal studies performed by other authors and to the G.D.R.-study of 1970/71, the investigated children are taller, in spite of a smaller body length at birth.

Body Height↗
PubMed1987

Quantitative blood flow in the fetal descending aorta and in the umbilical vein in normal pregnancies. Longitudinal and cross-sectional studies.

Quantitative blood flow in the fetal descending thoracic aorta and in the umbilical vein was measured both in a longitudinal study where each of 13 fetuses was examined three times and in a cross-sectional study where 45 fetuses were examined once only in the last trimester of normal pregnancy. The waveform of the velocity curves from fetal descending aorta was examined and the Pulsatility Index, the A/B ratio and the least diastolic velocity were calculated. The longitudinal study showed that all these parameters and the fraction of the flow in the fetal descending aorta, which was distributed to the placental circulation, were constant during the last trimester. The problems of longitudinal inference from cross-sectional studies are discussed. For all 58 fetuses the flow in the descending thoracic aorta was 234 ml/min/kg and in the umbilical vein 127 ml/min/kg. The Pulsatility Index was 1.83, the A/B ratio 4.75, the least diastolic velocity 9.9 cm/s. The fraction of blood flow in the descending aorta distributed to the placental circulation was 55%.

Aorta, Thoracic↗