Biomedical subjects

L J Brant

Publications and source records attributed to L J Brant.

At least 19 recordsLinked to original sources

PubMed1992

Estimation of prostatic growth using serial prostate-specific antigen measurements in men with and without prostate disease.

Prostate growth curves were estimated from serial prostate-specific antigen (PSA) measurements on frozen sera in three groups of men: (a) 16 men with no prostatic disease by urological history and examination; (b) 20 men with a histological diagnosis of benign prostatic hyperplasia (BPH) who had undergone simple prostatectomy; and (c) 18 men with a histological diagnosis of prostate cancer. The median number of repeated PSA measurements over an 8- to 26-yr period prior to histological diagnosis or exclusion of prostate disease was eight and 11 for noncancer and cancer subjects, respectively. Predicted rates of change in PSA (PSA velocity) were linear and curvilinear for control and BPH subjects, respectively. Subjects with cancer demonstrated both a linear and an exponential phase of PSA velocity. Based on time to double PSA, we estimated the epithelial doubling time for men without prostate disease to range from 54 +/- 13 yr at age 40 to 84 +/- 13 yr at age 70. For men with BPH, doubling times ranged from 2 +/- 13 yr at age 40 to 17 +/- 5 yr at age 85. Subjects with local/regional and advanced/metastatic cancer had similar PSA doubling times of 2.4 +/- 0.6 yr and 1.8 +/- 0.2 yr, respectively. These data are consistent with what is known about prostatic growth with age in men without prostate disease and BPH, and the kinetics of prostate cancer growth. Estimates of prostatic growth rate from changes in PSA may be useful clinically in management of men with prostate disease.

Aged↗

PubMed1992

k-ratio t tests for multiple comparisons involving several treatments and a control.

We consider the problem of simultaneously comparing several treatment means with a control mean and also with one another. Following an elementary decision-theoretic Bayesian approach requiring the choice of a type-I to type-II error-seriousness ratio k, a posteriori t tests are derived for testing both treatment versus control (TvC) and treatment versus treatment (TvT) differences. These k-ratio t tests are strictly comparisonwise in nature. That is, the test applied to any TvC or TvT difference d, depends in no way at all on whether the other differences are being tested. The test for d, however, does depend on the sizes of the other differences through tG, the standardized average of the observed TvC differences, and through FT, the observed between-treatments F ratio. From these adaptive dependences on tG and FT, the critical t values can be large or small, thus avoiding the intuitive objections of under- or over-conservatism in classical comparisonwise or experimentwise level testing rules.

Bayes Theorem↗

PubMed1992

Response stability and reliability in longitudinal health evaluations.

Two approaches were used to study the stability over time and intravisit reliability of health questions and clinical medical examination items in the Baltimore Longitudinal Study of Aging (BLSA). The stability of responses was determined by evaluating the medical history and physical examination completed at each visit to identify items that once answered in a positive manner, should continue to be answered positively over time. Stability for each question and subject was calculated by the number of positive responses following the first positive response divided by the total number of visits following the first positive response. For 35 questions answered by the subject, the stability was 58% by a simple average or 64% when weighted for the percentage of subjects who had a positive response to the question; for 10 physician-asked questions, the corresponding figures were 29% or 36%. Eighteen items from the physical examination had a stability of 34% or 37%. Intravisit reliability was estimated by comparing responses from the general health questionnaire to responses on the Cornell Medical Index completed at the same visit. Subject-completed questions had substantial agreement (Kappa = 0.74, for questions worded the same), while physician-asked questions had moderate agreement (Kappa = 0.44).

Adult↗

PubMed1992

How comparable are healthy 60- and 80-year-old men?

A critical issue in cross-sectional aging studies is the comparability of subjects of different ages, particularly regarding health status. For example, it is typically assumed that healthy 60-year-old men are equivalent to healthy 80-year-old men when both age groups are selected using the same criteria. The 60-year-old, however, may not survive or be healthy at age 80. To examine this issue, 212 healthy 60-year-old men in the Baltimore Longitudinal Study of Aging were identified. By life table analysis, 30% were expected to survive and remain healthy to age 80. In this study, 61 healthy 60-year-old men were followed to age 80. When compared with 125 healthy 80-year-old men, they had more heart disease, cancer, stroke, arterial, digestive, and peripheral nervous system diseases. Twenty-seven of the 61 men (44%) actually continued to be healthy at age 80. At age 60, systolic pressure and total serum cholesterol were predictive of who would be healthy at age 80.

Age Factors↗

PubMed1992

The role of mental morbidity in the nursing home experience.

The history of a newly admitted cohort to eight nursing homes (N = 454) was studied prospectively over the first year of residence. Data were gathered at admission, 2 months, and 1 year, and included full psychiatric examination and staff reports of behavior. Chart reviews collected additional data on preadmission and postdischarge information. At admission, 80% of the population had mental illnesses, 60% of which were dementia, and about half of demented patients had other complicating mental illnesses. Use of mixed-effects linear model analysis revealed significant associations of mental morbidity, restraints, and psychotropic medication with behaviors indicative of noncoping and nonadaptation to the nursing home settings.

Adaptation, Psychological↗

PubMed1992

A longitudinal approach to modeling outcomes in a nursing home study.

Recent developments in longitudinal statistical methodology have improved our ability to model dynamic processes such as adaptation to nursing homes. Longitudinal observations provide information on individual patterns of change and factors affecting them. However, longitudinal analyses are often complicated by unequal periods of observation and individual variability in patterns of change. This paper demonstrates the use of a linear mixed-effects model to study adaptation in a longitudinal nursing home study with different numbers of repeated measurements for each individual because of discharges, transfers, and mortality.

Adaptation, Psychological↗

PubMed1992

Mental illness and the use of restraints in nursing homes.

Using data from 441 newly admitted nursing home residents, we examined whether the diagnoses of mental illnesses, as well as other resident characteristics, were associated with use of physical restraints in both high restraint and low restraint use homes. Predictors of restraint use during both the first month and the first year of admission were inability to transfer and having a combination of severe ADL and cognitive impairment. Other predictors were wandering, inability to dress, symptoms of depression, and severity of cognitive impairment.

Activities of Daily Living↗

PubMed1992

Physical restraint use and cognitive decline among nursing home residents.

OBJECTIVE: This study investigated the association between physical restraint use and decline in cognition. DESIGN: Cohort analytic study describing changes in resident characteristics. SETTING: Eight nursing homes, both urban and suburban, operated by a proprietary corporation in a large metropolitan area. PARTICIPANTS: 437 nursing home admissions, with 201 remaining at 1 year. MAIN OUTCOME MEASURES: Cognitive status was measured by geropsychiatrists, using the Folstein Mini-Mental State Exam, during a psychiatric evaluation of the resident. Daily restraint use was documented from nursing orders. Observations were made at 2 weeks, 10 weeks, and 1 year. RESULTS: Restraint use alone and in combination with neuroleptic use was associated with poor cognition. Other variables associated with poor cognitive scores were: ADL impairment, poor adaptive behavior, and longer time in the nursing home. The use of neuroleptics alone was not significant. Variables which were associated with good cognitive status were: being non-ambulatory but without dementia and having strong social support. CONCLUSIONS: These findings raise the possibility that restraint use may contribute to cognitive impairment, specifically among residents who have moderate to no cognitive impairment at admission; however, the findings do not exclude an alternative explanation that residents undergoing cognitive decline are more likely to be put in restraints. Further research is needed to understand whether factors which can be manipulated contribute to cognitive decline.

Activities of Daily Living↗

PubMed1991

Depression and mortality in nursing homes.

To determine the prevalence rates of major depressive disorder and of depressive symptoms and their relationship to mortality in nursing homes, research psychiatrists examined 454 consecutive new admissions and followed them up longitudinally for 1 year. Major depressive disorder occurred in 12.6% and 18.1% had depressive symptoms; the majority of cases were unrecognized by nursing home physicians and were untreated. Major depressive disorder, but not depressive symptoms, was a risk factor for mortality over 1 year independent of selected physical health measures and increased the likelihood of death by 59%. Because depression is a prevalent and treatable condition associated with increased mortality, recognition and treatment in nursing homes is imperative.

Activities of Daily Living↗

PubMed1991

Modelling hearing thresholds in the elderly.

This paper concerns a linear mixed-effects repeated measures model in the analysis of a large data set with over 17,000 observations in a longitudinal study of pure-tone hearing perception in the elderly. The repeated measurements are described by fixed and random components in the model. The fixed effects include the age at entry, time of follow-up, a quadratic component in natural logarithm of frequency, a component to allow for participants with hearing impairments, as well as interaction terms between age and frequency and between impairment and frequency. The random factors include a term for subject, a time component and a frequency component. The analysis shows that hearing impaired individuals have similar patterns of hearing loss over time but, on average, have higher hearing thresholds than normal individuals. Estimation of the random effects in the model by restricted maximum likelihood (REML) using the Newton-Raphson method made possible the analysis of this large data set with speed and efficiency.

Aged↗

PubMed1991

Effect of age of entry to a longitudinal study on cross-sectional determination of cardiovascular disease.

Cross-sectional analysis from longitudinal studies for a specific age can include subjects who entered the study at different ages (i.e. younger individuals followed to the age of interest, and those who entered at the age of interest). This represents a potential source of bias, since the state of health at a given age may vary based on age at entry. We investigated such bias as it affected the prevalence of cardiovascular diagnoses in men from the Baltimore Longitudinal Study of Aging. Subjects who entered the study in either their 60's, 70's or 80's (New subjects) were compared to individuals who entered the study at an age at least 10 years younger and were followed into these same age decades (Continuing subjects). No differences were found between New and Continuing subjects for coronary heart or cerebrovascular diseases, but were present for hypertension. The greater prevalence of hypertension in Continuing subjects appeared to be of minor clinical importance because other diagnostic differences were absent. The study found evidence for potential selection bias based on age at entry, but the consequence of the bias appeared to be slight.

Age Factors↗

PubMed1991

Basal DNA damage in individual human lymphocytes with age.

A role for DNA damage is central to many theories of aging, but attempts to show an increase in DNA damage with age have yielded contradictory results. However, previous experiments have been of limited sensitivity, only able to examine induced (not basal) damage or pooled (not individual) cells. In this report, we apply a novel technique (Singh et al., 1988) to directly measure basal levels of DNA single-strand breaks and alkali-labile sites in individual human peripheral blood lymphocytes (PBL) obtained from young (less than 60 years) and old (more than 60 years) male donors. This approach shows that while average changes with age are small, changes in certain individuals and in certain cells may be large: the mean increase in damage was only 12%, but the increase in a subpopulation of highly damaged lymphocytes was 5-fold. However, most of this increase was contributed by just 3 of 17 older subjects. Further characterization of these individuals may shed light on the relationship between DNA damage and aging.

Adult↗

PubMed1990

The prevalence and management of dementia and other psychiatric disorders in nursing homes.

The prevalence of psychiatric disorders among new admissions to nursing homes is unknown. Such data are needed to estimate the psychiatric needs of this population. We report the prevalence of specific psychiatric disorders in 454 consecutive new nursing home admissions who were evaluated by psychiatrists and diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, third edition, revised. Eighty percent had a psychiatric disorder. The commonest were dementia syndromes (67.4%) and affective disorders (10%). Also, 40% of demented patients had additional psychiatric syndromes such as delusions or depression, and these patients constituted a distinct subgroup that predicted frequent use of restraints and neuroleptics, and the greatest consumption of nursing time. These data demonstrate that the majority of nursing home residents have psychiatric disorders on admission, and that their management is often quite restrictive. Research is now needed to determine the best methods of treatment for nursing home patients with mental disorders.

Aged↗

PubMed1990

Next steps in describing aging and disease in longitudinal studies.

Longitudinal studies have contributed much to the understanding of aging. Traditionally, age-specific changes in physiological functioning are inferred from studies in which persons with disease processes believed to be relevant to the function in question are excluded from the results. The main theme of this review is that, in the future, studies of aging must better attempt to capture the interplay between disease and aging processes. A variety of research results, mostly from the Baltimore Longitudinal Study of Aging, are used to support this argument. Topics covered include: the role of longitudinal studies in aging research; the complexity of the aging process; the significance of cohort and secular changes for understanding both aging and disease processes; age changes over the adult life span in the significance of risk factors for disease; and age-related increases in morbidity in a longevous group of men.

Aging↗

PubMed1990

Age changes in pure-tone hearing thresholds in a longitudinal study of normal human aging.

Hearing thresholds were obtained on 813 adult males (20-95 years) measured at 11 frequencies ranging from 0.125-8 kHz from pure-tone audiograms collected over a 20-year period from 1968 to 1987. Audiograms taken at two to six different ages spanning a maximum observation period of 15 years were obtained for each male belonging to one of seven different age groups (20,30,...,80 years) based on the age of initial observation. The males were participants in the Baltimore Longitudinal study of Aging (BLSA), a multidisciplinary community-based study of normal human aging. Changes in hearing thresholds occurred in all age groups during the 15-year follow-up period. For example, at 0.5 and 8 kHz for combined left and right ears there was an average longitudinal loss of 5.7-7.6 and 5.1-21.1 dB, respectively, for 20-year-olds, 10.0-12.7 and 35.2-53.0 dB for 50-year-olds, and 22.9-48.5 and 69.0-84.5 dB for 80-year-olds. As in results from previous cross-sectional studies, hearing loss in the males 70 years and older is greatest at the highest frequencies. The rate of change for these older males is faster in the speech-range frequencies 0.5-2 kHz than in the higher frequencies, since their hearing has already diminished at the high frequencies.

Adult↗

PubMed1990

Can serial exercise testing improve the prediction of coronary events in asymptomatic individuals?

An abnormal ST segment response to treadmill exercise has a low predictive value for future coronary events (angina pectoris, nonfatal myocardial infarction, or cardiac death) in apparently healthy individuals. To determine whether the conversion from a normal to an abnormal ST segment response might identify individuals at high risk for a future coronary event, we analyzed the results of serial exercise tests performed at 2-4-year intervals in 726 male and female volunteers, aged 22-84 years (mean, 55.1 years), from the Baltimore Longitudinal Study of Aging (BLSA). All subjects were free of cardiovascular disease at entry by history, physical examination, and resting 12-lead electrocardiogram. Over a mean overall follow-up of 7.4 years, coronary events occurred in 34 of 178 (19.1%) of those with an abnormal ST response to exercise versus 30 of 548 (5.5%) in those with a normal response (p = 0.001). Angina pectoris was the most common presenting coronary event regardless of ST segment exercise response. Among individuals with an abnormal ST segment response, the incidence of events was virtually identical between those with an initially abnormal response (group 1) and those who converted from a normal to an abnormal response (group 2), 19.8% versus 18.5%. After adjustment for standard coronary risk factors by proportional hazards regression analysis, the risk of a coronary event relative to subjects with persistently normal ST segment responses (group 3) remained nearly identical in the two groups, 2.72 in group 1 (p less than 0.003) and 2.80 in group 2 (p less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

Evaluation of an Alaskan streptococcal control program: importance of the program's intensity and duration.

Prospective follow-up information from the throat culturing results of 1,653 Eskimo children in 12 Alaskan villages was used to evaluate the effect of duration and intensity of a streptococcal control program begun in 1971 while controlling for several other risk factors related to streptococcal colonization. Relative risks of colonization for each of the subsequent study years relative to the first year indicate that the risk of colonization decreased over the duration of the study by 42% in Year 2 to 55% in Year 4 (P less than 0.0001). Cost-cutting measures such as lengthening the time interval between routine throat cultures led to a 37% increase in the risk of colonization (P = 0.0002). A comparison of the number of cases of acute rheumatic fever during the 5-year period before the streptococcal control program with the number of cases during the 5-year program period showed that cases in villages with the program decreased from 11 to 0. In a similar group of comparison villages without the program, the number of cases decreased from 7 to 4. A benefit-cost study of the program indicates that benefit exceeds cost. These findings and the changes in the carriage of streptococcal organisms during the control program underscore the importance of such long-term programs with regularly scheduled culturing in high-risk populations of children.

Acute Disease↗

PubMed1986

Factors affecting attrition in the Baltimore Longitudinal Study of Aging.

In a longitudinal study of aging, the influence on attrition of age, marital status, education, occupation, distance between a subject's residence and study center, self-health and financial assessment, and method of recruitment was examined. Prospective, follow-up information on the subsequent active/dropout and alive/dead status on the 1088 subjects, who joined the Baltimore Longitudinal Study of Aging during the first twenty years (1958-1977), were studied using a proportional hazards model. Three analyses, each controlling for death in a different manner, produced similar results. The analysis indicates that age, education and distance have the strongest association with attrition (p less than 0.001), while self-health assessment has a lesser association (p less than 0.05). The lowest risk in age, for example, occurs in 40-49.9 year olds with subjects less than 30 having an increased risk of 91% and subjects 70 or older having an increased risk of 189%. Examination of attrition probabilities show that subjects living 500 or more miles from study center, ages 70 and older, with less than bachelors degree, and perceiving their health as average or below have the greatest probability of dropping out-approximately 3-fold greater than the average subject's probability.

Adolescent↗