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PubMed2005

Weight, fat mass, and central distribution of fat increase when women use depot-medroxyprogesterone acetate for contraception.

OBJECTIVE: To compare longitudinal changes in weight, body fat, and ratio of central to peripheral fat mass among first-time depot-medroxyprogesterone acetate (DMPA) users to women using no hormonal contraception, and to evaluate user characteristics associated with that change. DESIGN: Prospective longitudinal study. SUBJECTS: Healthy women, aged 18-35 y, using DMPA for contraception (n=178) and women using no hormonal contraception (n=145). MEASUREMENTS: Weight, body fat, and the central distribution of fat, measured at 3-month intervals for 30 months, by electronic scale and dual-energy X-ray absorptiometry (DEXA). The ratio of central to peripheral distribution of body fat was computed by dividing the body fat in the conventional DEXA trunk region of interest (ROI) by the ROI's that encompass the arms, hips and legs. RESULTS: Women using DMPA had a significantly greater increase in all measures of fatness than women using no hormonal method of contraception (P<0.03). The observed weight of DMPA users increased from a mean of 69.4 kg (s.d.=16.9) at baseline to 75.5 kg (s.d.=25.0) at 30 months; an increase of 6.1 kg (8.8.%). Fat mass increased from a mean of 25.3 kg (s.d.=12.6 kg) at baseline to 31.4 kg (s.d.=17.8); an increase of 6.1 kg (23.6%) in DMPA users. The ratio of central to peripheral fat mass in DMPA users changed from 0.95 (s.d.=0.155) at baseline to 1.01(s.d.=0.198) at 30 months. In contrast, weight, fat mass and the ratio of central to peripheral fat mass of control participants remained virtually unchanged over the same time period. Women with higher baseline physical activity levels had a smaller increase in body fat (P=0.003) and the fat ratio (P=0.03), but not weight (P=0.48). No other user characteristics including, smoking, past oral contraceptive use or previous pregnancies predicted change in level of fatness. CONCLUSIONS: This study has demonstrated a change in body composition toward greater fatness and toward a central redistribution of fat among DMPA users as compared to controls and provides important information to be used when counseling women regarding contraceptive methods. Given the potential long-term implication of these changes, further study is recommended to determine whether the gains in fatness are reversed following DMPA discontinuation and to examine the role of progestins in the development and maintenance of obesity.

Absorptiometry, Photon↗
PubMed2004

Comparison of sequential cytomegalovirus isolates in a patient with lymphoma and failing antiviral therapy.

BACKGROUND: Long-term anti-cytomegalovirus (CMV) treatments in immunocompromised patients are hampered by resistance to antiviral drugs. Longitudinal changes in the resistance genotype may depend on changes in selective pressure and the complexity of CMV isolates. OBJECTIVE: To evaluate longitudinal changes in the CMV resistance genotype and phenotype along with strain-specific variability in a patient with non-Hodgkin's lymphoma in whom successive anti-CMV treatments failed. STUDY DESIGN: The resistance phenotype and genotype of seven CMV isolates collected from one patient during a 2-year follow-up period were retrospectively analysed. In parallel, we used glycoprotein B (gB) genotyping, and a- and UL10-13-sequence analysis to study CMV interstrain variability. RESULTS: The patient was infected by at least three CMV strains plus variants of the parental strains. Resistance to ganciclovir, cidofovir and foscarnet was successively detected during the follow-up period. UL97 protein kinase changes responsible for resistance to ganciclovir were initially detected at residues 591 and 592, and then at position 594. Decreased sensitivity to foscarnet coincided with the appearance of amino acid substitution N495K in DNA polymerase, whereas cross-resistance to ganciclovir and cidofovir was due to the L501I substitution. CONCLUSIONS: The CMV isolates obtained from our patient were complex mixtures of strains. Changes in resistance genotypes depended on resistance selective pressure and were not linked to interstrain variation.

Aged↗
PubMed1987

Longitudinal neuropsychological changes in a "normal" elderly group.

The need for age-related normative data on neuropsychological measures is clearly important. This longitudinal study examines a "normal" elderly group's performance on the Luria-Nebraska Neuropsychological Battery (LNNB) across four years. This report is based on the 59 "normal" elderly volunteers seen in an earlier cross-sectional aging study (MacInnes et al., 1983). The LNNB Clinical Scales exhibited few significant changes across the four year time period. The test-retest correlations of the LNNB Clinical Scales ranged from.32 to.81. Few differences between males and females were seen. Similarly, being in an older subgroup did not affect the rate of change on the LNNB scores. Although, health status changed very little over the four years, health status at Time 2 did significantly predict 16 of the 17 LNNB Clinical Scales at Time 2. In summary, we found the LNNB accurately identified the "normal" elderly as normal. Similarly, their performance on the LNNB exhibited little meaningful change across four years.

Journal Article↗
PubMed2001

1H magnetic resonance spectroscopic imaging of permanent focal cerebral ischemia in rat: longitudinal metabolic changes in ischemic core and rim.

The purpose of this study was to determine whether regional differences in metabolites can be seen chronologically in permanent focal cerebral ischemia using 1H magnetic resonance spectroscopic imaging (MRSI), and whether these changes reflect pathological outcome. Regional variation in metabolites after permanent focal ischemia were investigated longitudinally in rats using 1H MRSI for a total of 7 days and then compared to histopathological findings. Four hours after the induction of ischemia, N-acetyl-L-aspartate (NAA) levels in the lateral caudo-putamen and the somatosensory cortex, core ischemic regions, decreased 22 and 40%, respectively. This reduction in NAA was coupled with a marked rise in lactate. In the medial caudo-putamen, the ischemic rim, however, NAA was preserved in spite of a marked increase in lactate. By 24 h post ischemia, the levels of NAA in medial caudo-putamen (ischemic rim in caudate) also decreased significantly. However NAA in cingulated cortex (ischemic rim in cortex) decreased more gradually between 24 and 48 h. This regional difference can reflect the severity of metabolic derangement in the acute stage. After 96 h following ischemia, the levels of all metabolites detected by 1H MRSI had decreased and the levels of NAA decline reflected the severity of histopathological damage. In conclusion, the regional metabolic differences could be assessed by 1H MRSI chronologically, and the depth of NAA decline reflected histopathological changes in the chronic stage.

Animals↗
PubMed1998

Postorthodontic dental changes: a longitudinal study.

The conventional adolescent orthodontic patient is treated during a phase of active growth, but growth of the skeletodental complex continues after treatment and into adulthood at a much slower pace. Selection of orthodontic diagnostic and treatment regimens that produce stable and esthetic dental relationships is a continual endeavor for the orthodontic specialist. Patients should be recalled for long periods of time and the results evaluated. The present longitudinal study was completed on 36 individuals, all of whom had received comprehensive orthodontic treatment. Dental changes were assessed from cephalograms for the in-treatment period (ca. 12 to 15 years of age), posttreatment to first recall (0 = 22 years of age), and first to second recall period (0 = 30 years of age). There was considerable change in the absolute locations of the teeth, but, in reality, these changes are almost wholly attributable to growth of the bony reference structures, not dental changes per se. Growth proceeded at a very slow pace after the first recall (ca. 22 to 30 years of age ). Dental relationships, eg., FMIA, IMPA, 6L angulation, exhibited no systematic change after treatment.

Adolescent↗
PubMed2005

Effect of temperature on the longitudinal variability of quantitative ultrasound variables.

It is unclear whether longitudinal change in phantom measurements bears any relation to the long-term in vivo instrument performance of quantitative ultrasound devices. Longitudinal quantitative ultrasound phantom data were obtained by measuring the manufacturer-provided phantom at ambient temperature and two different sets of Leeds phantoms at either ambient temperature or following a phantom temperature-control protocol. Measurements were performed using the Achilles Plus bone densitometer. Changes in longitudinal phantom data were compared to in vivo quantitative ultrasound data obtained from seven healthy, young volunteers. A cosinor model with linear trend and Hotelling's T2-test were used to quantify seasonal rhythms and long-term drift in quantitative ultrasound variables. Temperature effects and marked seasonal rhythms on quantitative ultrasound phantom measurements were evident but were far less apparent in vivo. Longitudinal precision of quantitative ultrasound variables was poorer for the manufacturer-provided phantom than for phantoms that were subjected to a temperature-control protocol or for healthy volunteers. This study has shown that longitudinal precision and longitudinal change differs between in vivo and phantom data. Longitudinal quantitative ultrasound measurements for monitoring change in skeletal status cannot, as yet, be properly controlled.

Adult↗
PubMedDate not supplied

The association between changes in skin echogenicity and the fibroblast production of biglycan and versican in systemic sclerosis.

OBJECTIVE: To investigate a possible association between the longitudinal changes in skin involvement and the fibroblast production of proteoglycans in vitro, among patients with early and untreated systemic sclerosis (SSc). METHODS: In 11 patients, 6 with diffuse cutaneous systemic sclerosis (dSSc) and 5 with limited cutaneous systemic sclerosis (ISSc), and in 6 controls skin thickness and skin echogenicity of the forearm was measured by high frequency (20 MHz) ultrasound. A skin biopsy was taken from the area of the ultrasound measurements, and from cultivated fibroblasts the production of the proteoglycans versican, perlecan, biglycan and decorin were measured. To investigate longitudinal changes in skin involvement, the ultrasound examination was repeated after 1-3 years. RESULTS: Compared to controls, SSc patients had increased skin thickness at the first evaluation. Patients with dSSc had lower skin echogenicity than both patients with lSSc and the controls. Patients with greater changes in skin thickness and skin echogenicity produced more versican, whereas the production of biglycan and decorin was higher only in patients with greater changes in skin echogenicity. There was a negative correlation between fibroblast production of biglycan and disease duration. CONCLUSION: High fibroblast synthesis of the proteoglycans versican and biglycan is associated with changes in skin echogenicity and may predict more progressive skin sclerosis in SSc.

Adult↗
PubMed2004

Comparison of patella cartilage volume and radiography in the assessment of longitudinal joint change at the patellofemoral joint.

OBJECTIVE: To compare radiological assessment of the patellofemoral (PF) joint and cartilage volume as measured by magnetic resonance imaging (MRI) in a longitudinal study. METHODS: One hundred and two subjects with osteoarthritis (OA) had baseline and followup skyline and lateral radiographs and MRI of the same knee. Duration of followup was 1.94 +/- 0.23 years. Mid-patella joint space and narrowest joint space were measured on lateral PF radiographs. Minimum joint space in the lateral and medial facets was measured on skyline radiographs. Rate of progression of PF joint OA was measured quantitatively at each site. Patella cartilage volume was measured from the MRI. The rate of change in each radiographic measure was compared to the rate of change in patella cartilage volume. RESULTS: The average loss of patella cartilage was 133 +/- 143 microm(3)/yr (4.4%). The loss of joint space over the same period on lateral radiographs was 0.7 +/- 2.6 mm at the narrowest joint space and 0.2 +/- 3.8 mm at the mid-patella joint space. On the skyline radiographs, the loss of joint space at the medial facet was 0.4 +/- 3.9 mm and 0.2 +/- 3.4 mm at the lateral facet. Only change in narrowest joint space on the lateral PF radiographs correlated with change in patella cartilage volume (R = 0.22, p = 0.03). CONCLUSION: Our data suggest that narrowest joint space measured on lateral PF radiographs correlates best with loss of patella cartilage. Further work will be needed to determine how different radiological measures of the PF joint relate to the disease process in OA.

Aged↗
PubMed2005

Longitudinal study of pure-tone thresholds in older persons.

OBJECTIVE: Pure-tone thresholds for conventional and extended high frequencies were analyzed for 188 older adult human subjects (91 females, 97 males). The objectives were to study longitudinal changes in thresholds as well as the effects of initial threshold levels, age, gender, and noise history on these longitudinal changes. DESIGN: At the time of entry into the study, subjects' ages ranged from 60 to 81 years, with a mean age of 68 years. Subjects had between 2 and 21 visits (mean = 9.81 visits) over a period of 3 to 11.5 years (mean = 6.40 years). Conventional pure-tone thresholds at 0.25 to 8 kHz were measured during most visits. Extended high-frequency (EHF) thresholds at 9 to 18 kHz were measured every 2 to 3 years. The slope of a linear regression was used to estimate the rate of change in pure-tone thresholds at 0.25 to 18 kHz for each ear. A questionnaire was used to identify those subjects with a positive noise history. RESULTS: The average rate of change in thresholds was 0.7 dB per year at 0.25 kHz, increasing gradually to 1.2 dB per year at 8 kHz and 1.23 dB per year at 12 kHz. The rate of change for thresholds increased significantly with age, at 0.25 to 3, 10, and 11 kHz for females and at 6 kHz for males. After adjusting for age, females had a significantly slower rate of change at 1 kHz but a significantly faster rate of change at 6 to 12 kHz than males. For 0.25 and 1 kHz, subjects with more hearing loss at higher frequencies had a faster rate of change at these frequencies, whereas for 6 and 8 kHz, subjects with more hearing loss at mid and high frequencies had a slower rate of change at these frequencies. The rates of threshold change for subjects with a positive noise history were not statistically different from those with a negative noise history. CONCLUSIONS: On average, hearing threshold increased approximately 1 dB per year for subjects age 60 and over. Age, gender, and initial threshold levels can affect the rate of change in thresholds. Older female subjects (> or =70 years) had faster rate of change at 0.25 to 3, 10, and 11 kHz than younger female subjects (60 to 69 years). Older male subjects had faster rate of change at 6 kHz than younger male subjects. Females had a slower rate of change at 1 kHz and a faster rate of change at 6 to 12 kHz than males. Subjects with higher initial thresholds at low and mid frequencies tended to have faster rate of threshold change at 0.25 to 2 kHz in the following years. Subjects with higher initial thresholds at mid and higher frequencies tended to have slower rate of change at 6 to 8 kHz in the following years. Noise history did not have a significant effect on the rate of threshold changes.

Aged↗
PubMed1990

Behavioral change in longitudinal studies: adoption of condom use by homosexual/bisexual men.

We compared reporting serial cross-sectional prevalence of sexual behavior over time, to reporting individual patterns of behavioral change in a cohort of homosexual men at a six-month interval. Aggregate prevalence rates underestimated the magnitude of change to safer practices, and failed to provide information on relapse to less safe practices. We conclude that it is important to report data based on individual fluctuations in behavior for the evaluation of change over time.

Adult↗
PubMed1996

Insulin levels and the natural history of glucose intolerance in Nauruans.

Longitudinal changes in serum insulin concentrations in relation to the natural history of glucose intolerance and factors associated with the incidence of NIDDM were studied in 838 nondiabetic Micronesian Nauruans over the 5.1-year period from 1982 to 1987. In 13 individuals who had data at three time-points and who developed NIDDM only at the final test, 2-h insulin levels followed an inverted V-shaped pattern as glucose tolerance declined to NIDDM. Subjects who were normal (n = 651) or had impaired glucose tolerance (IGT) (n = 187) at the 1982 baseline survey were divided into six natural history categories depending on glucose tolerance in 1987. Changes in glucose tolerance were accompanied by changes in mean 2-h insulin concentration that paralleled the inverted V pattern seen in the 13 individuals. Longitudinal changes in fasting insulin were less consistent, but mean levels increased as subjects developed NIDDM. The 5.1-year incidence of NIDDM was strongly related to baseline fasting and 2-h glucose concentrations, but associations with insulin levels were weak and inconsistent. Neither fasting nor 2-h insulin concentrations contributed to logistic regression models predicting deterioration in glucose tolerance, whereas fasting and 2-h glucose levels were included in all models and BMI also predicted deterioration from normal. These data showing sequential changes in insulin concentrations support the beta-cell exhaustion theory of NIDDM pathogenesis. However, in contrast to glucose concentrations and obesity, insulin levels are poor predictors of NIDDM risk in Nauruans. This reflects the complexity of interactions with other metabolic markers and the inability of a single examination to characterize the point along the inverted V curve of insulin secretion that an individual has reached.

Age Factors↗
PubMed1999

Estimation and comparison of rates of change in longitudinal studies with informative drop-outs.

Many cohort studies and clinical trials have designs which involve repeated measurements of disease markers. One problem in such longitudinal studies, when the primary interest is to estimate and to compare the evolution of a disease marker, is that planned data are not collected because of missing data due to missing visits and/or withdrawal or attrition (for example, death). Several methods to analyse such data are available, provided that the data are missing at random. However, serious biases can occur when missingness is informative. In such cases, one needs to apply methods that simultaneously model the observed data and the missingness process. In this paper we consider the problem of estimation of the rate of change of a disease marker in longitudinal studies, in which some subjects drop out prematurely (informatively) due to attrition, while others experience a non-informative drop-out process (end of study, withdrawal). We propose a method which combines a linear random effects model for the underlying pattern of the marker with a log-normal survival model for the informative drop-out process. Joint estimates are obtained through the restricted iterative generalized least squares method which are equivalent to restricted maximum likelihood estimates. A nested EM algorithm is applied to deal with censored survival data. The advantages of this method are: it provides a unified approach to estimate all the model parameters; it can effectively deal with irregular data (that is, measured at irregular time points), a complicated covariance structure and a complex underlying profile of the response variable; it does not entail such complex computation as would be required to maximize the joint likelihood. The method is illustrated by modelling CD4 count data in a clinical trial in patients with advanced HIV infection while its performance is tested by simulation studies.

Biomarkers↗
PubMed2002

Changes in refraction over 10 years in an adult population: the Beaver Dam Eye study.

PURPOSE: To quantify the 10-year change in refraction in persons more than 40 years of age. METHODS: All people 43 to 84 years of age and living in Beaver Dam, Wisconsin, in 1988 were invited for a baseline examination (1988-1990), a 5-year follow-up examination (1993-1995), and a 10-year follow-up examination (1998-2000). Refractions were determined according to the same protocol at all examinations. Aphakic and pseudophakic eyes and eyes with best corrected visual acuity of 20/200 or worse were excluded. After exclusions, refraction data were available on 2362 right eyes of the 2937 people examined at baseline and 10-year follow-up. RESULTS: Age was related to the direction and amount of change in refraction. Spherical equivalent became more positive in the youngest subjects and more negative in the oldest. After adjustment for the severity of nuclear sclerosis and other factors, the 10-year change in refraction was +0.48, +0.03, and -0.19 D for persons 43 to 59, 60 to 69 and 70+ years of age at the baseline examination, respectively. Severity of nuclear sclerosis was also strongly related to amount of change. Those with mild nuclear sclerosis at baseline had a change of +0.35 D, whereas those with severe nuclear sclerosis had a change of -0.53 D. The amount of change was also related to diabetes and weakly related to baseline refractive error, but was unrelated to gender and education. In addition to the longitudinal changes observed, there was a birth cohort effect. In comparing people of the same age across examinations, those born in more recent years had more myopia than those born in earlier years. CONCLUSIONS: Significant changes in spherical equivalent in adults occur over a 10-year period. Younger people became more hyperopic, whereas older people became more myopic. These data provide evidence of a longitudinal change in refraction in adults, which may explain the refractive patterns observed in cross-sectional studies.

Adult↗
PubMed2000

Analysis strategies for longitudinal attachment loss data.

The purpose of this invited review is to describe and discuss methods currently in use to quantify the progression of attachment loss in epidemiological studies of periodontal disease, and to make recommendations for specific analytic methods based upon the particular design of the study and structure of the data. The review concentrates on the definition of incident attachment loss (ALOSS) and its component parts; measurement issues including thresholds and regression to the mean; methods of accounting for longitudinal change, including changes in means, changes in proportions of affected sites, incidence density, the effect of tooth loss and reversals, and repeated events; statistical models of longitudinal change, including the incorporation of the time element, use of linear, logistic or Poisson regression or survival analysis, and statistical tests; site vs person level of analysis, including statistical adjustment for correlated data; the strengths and limitations of ALOSS data. Examples from the Piedmont 65+ Dental Study are used to illustrate specific concepts. We conclude that incidence density is the preferred methodology to use for periodontal studies with more than one period of follow-up and that the use of studies not employing methods for dealing with complex samples, correlated data, and repeated measures does not take advantage of our current understanding of the site- and person-level variables important in periodontal disease and may generate biased results.

Disease Progression↗
PubMed1999

Stability and change in longitudinal water-level task performance.

Three longitudinal samples of children (N = 481), 8 to 16 years old, were assessed 3 times at yearly intervals on 8 water-level items. The within-child change in task performance over age is viewed as a stochastic process of the child changing or remaining in 1 of 3 latent (strategy) states: (a) bottom-parallel responders, (b) random responders, or (c) accurate responders. A random-effects binomial mixture distribution is used to model performance at each age. Change over age is gauged by a stochastic transition model. Although there was improvement in task performance over age, the more general finding is that strategy stability, not change, is most typical.

Adolescent↗
PubMed2003

Quality of life for children with persistent sinonasal symptoms.

OBJECTIVE: The goal was to validate the SN-5 survey as a measure of longitudinal change in health-related quality of life (HRQoL) for children with persistent sinonasal symptoms. DESIGN AND SETTING: We conducted a before and after study of 85 children aged 2 to 12 years in a metropolitan pediatric otolaryngology practice. Caregivers completed the SN-5 survey at entry and at least 4 weeks later. The survey included 5 symptom-cluster items covering the domains of sinus infection, nasal obstruction, allergy symptoms, emotional distress, and activity limitations. RESULTS: Good test-retest reliability (R = 0.70) was obtained for the overall SN-5 score and the individual survey items (R >/= 0.58). The mean baseline SN-5 score was 3.8 (SD, 1.0) of a maximum of 7.0, with higher scores indicating poorer HRQoL. All SN-5 items had adequate correlation (R >/= 0.36) with external constructs. The mean change in SN-5 score after routine clinical care was 0.88 (SD, 1.19) with an effect size of 0.74 indicating good responsiveness to longitudinal change. The change scores correlated appropriately with changes in related external constructs (R >/= 0.42). CONCLUSIONS: The SN-5 is a valid, reliable, and responsive measure of HRQoL for children with persistent sinonasal symptoms, suitable for use in outcomes studies and routine clinical care.

Adaptation, Psychological↗
PubMed1997

Mini-Mental State Examination item scores as predictors of Alzheimer's disease: incidence data from the Kungsholmen Project, Stockholm.

BACKGROUND: The present study examined the power of individual Mini-Mental State Examination (MMSE) items in predicting incidence of Alzheimer's disease (AD). In addition, 3-year longitudinal changes in MMSE items were contrasted between incident AD and nondemented persons. METHODS: A population-based group of very old adults, 75-95 years of age, were followed longitudinally. Of the original 327 participants, 32 were diagnosed with probable or possible AD after a 3-year follow-up interval and 189 remained nondemented. Cognitive performance was indexed by the individual item scores from the MMSE. These sample from multiple domains of cognitive functioning, including visuospatial skill, recent memory, orientation to time and place, language, and the ability to sustain attention. RESULTS: Items dealing with delayed episodic memory and orientation to time were significant predictors of AD incidence, independent of age, gender, and years of education, as determined by logistic regression analyses. Longitudinally, changes in performance were largest among individuals diagnosed as incident AD, although the magnitude of change across items was highly variable. In particular, decline was relatively small for the delayed memory item, whereas most other measures showed dramatic decline in performance among individuals with incident AD. CONCLUSIONS: Individual MMSE items, especially those with some type of episodic memory referent, were the best predictors of incident cases of AD. Moreover, MMSE items displayed differential rates of changes, particularly for the incident AD participants.

Aged↗