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Biomedical subjects

D B Brock

Publications and source records attributed to D B Brock.

At least 19 recordsLinked to original sources
PubMed2004

Population-based studies of AD: message and methods: an epidemiologic view.

Dementia is a growing public health problem because the numbers suffering the disease is increasing rapidly as the population ages. Over the past decade several longitudinal population-based studies were initiated and are still on-going. These studies will provide valuable insight into the risk factors for, and progression of dementia. However, there are several design and statistical challenges that are unique to studying dementia in the population and that need to be addressed. These challenges include aspects of both ascertainment of disease and definition of exposure. To reduce bias from prospective epidemiologic studies, not only are new approaches to definition of disease and exposure needed, but new epidemiologic or statistical methods may be required as well.

Alzheimer Disease↗
PubMed2000

American Diabetes Association diabetes diagnostic criteria, advancing age, and cardiovascular disease risk profiles: results from the Third National Health and Nutrition Examination Survey.

OBJECTIVE: To evaluate age-specific effects on diabetes prevalence estimates resulting from the American Diabetes Association (ADA) recommendation against use of the oral glucose tolerance test (OGTT), we contrasted the prevalence of two mutually exclusive groups: undiagnosed diabetes according to ADA criteria (no report of diabetes and fasting glucose [FG] > or =126 mg/dl) and isolated postchallenge hyperglycemia (IPH) (FG <126 mg/dl and OGTT > or =200 mg/dl), a group designated to have diabetes by World Health Organization (WHO) criteria but not ADA criteria. RESEARCH DESIGN AND METHODS: The weighted age-specific ratios of undiagnosed diabetes:IPH were calculated for 2,844 subjects aged 40-74 years without reported diabetes who had both FG and OGTT. A ratio > 1.0 indicated that the proportion of undiagnosed diabetes was greater than that of IPH. Mean levels of HbA1c and cardiovascular disease (CVD) risk factors were contrasted among people with undiagnosed diabetes and IPH and those without either abnormality ("nondiabetic"). RESULTS: Both undiagnosed diabetes and IPH increased with age, but age-specific undiagnosed diabetes:IPH ratios decreased from 5.49 in the 40-44 age-group to 0.77 in the 70-74 age-group. Regression analysis showed a significant (P = 0.006) negative association between age and these ratios. Mean HbA1c was 7.1% in the undiagnosed diabetes group and differed significantly from that of the IPH and nondiabetic groups (5.6 and 5.3%, respectively). Individuals with undiagnosed diabetes had less favorable triglycerides, BMI, and HDL cholesterol compared with people with IPH. CONCLUSIONS: Compared with WHO criteria, the ADA criteria underestimate glucose abnormalities more with increasing age. However, compared to those with undiagnosed diabetes, individuals with IPH had a mean HbA1c level that is considered in the nondiabetic range, and this group had significantly more favorable levels of several key CVD risk factors. These findings suggest that the ADA criteria, although underestimating the abnormalities of postchallenge hyperglycemia that occur frequently with increasing age, appear to be effective at identifying a group of individuals with both unfavorable CVD risk factor profiles and evidence of long-term exposure to hyperglycemia.

Adult↗
PubMed1999

Smoking, physical activity, and active life expectancy.

The effect of smoking and physical activity on active and disabled life expectancy was estimated using data from the Established Populations for Epidemiologic Studies of the Elderly (EPESE). Population-based samples of persons aged > or = 65 years from the East Boston, Massachusetts, New Haven, Connecticut, and Iowa sites of the EPESE were assessed at baseline between 1981 and 1983 and followed for mortality and disability over six annual follow-ups. A total of 8,604 persons without disability at baseline were classified as "ever" or "never" smokers and doing "low," "moderate," or "high" level physical activity. Active and disabled life expectancies were estimated using a Markov chain model. Compared with smokers, men and women nonsmokers survived 1.6-3.9 and 1.6-3.6 years longer, respectively, depending on level of physical activity. When smokers were disabled and close to death, most nonsmokers were still nondisabled. Physical activity, from low to moderate to high, was significantly associated with more years of life expectancy in both smokers (9.5, 10.5, 12.9 years in men and 11.1, 12.6, 15.3 years in women at age 65) and nonsmokers (11.0, 14.4, 16.2 years in men and 12.7, 16.2, 18.4 years in women at age 65). Higher physical activity was associated with fewer years of disability prior to death. These findings provide strong and explicit evidence that refraining from smoking and doing regular physical activity predict a long and healthy life.

Aged↗
PubMed1998

Demography and epidemiology of dying in the U.S. with emphasis on deaths of older persons.

As chronic disease continues to be the major cause of death and as the elderly population grows, it is important to evaluate the adequacy and completeness of health care strategies for the elderly. Two studies, the National Mortality Followback Survey and the National Institute on Aging Survey of the Last Days of Life, were designed to examine the circumstances of death for representative samples of decedents. Four areas of focus are location of death, transitions among health care settings, circumstances at the time of death, and changes in physical and cognitive function in the last year of life. Although the data are helpful for family planning, they are limited by a lack of data on costs.

Activities of Daily Living↗
PubMed1997

Black-white differences in risk of becoming disabled and recovering from disability in old age: a longitudinal analysis of two EPESE populations.

This study compared the odds of becoming disabled and recovering from disability among blacks and whites aged 65 years and over in two sites of the Established Populations for Epidemiologic Studies of the Elderly (EPESE) project. The authors examined the influence of mortality differences, socioeconomic status, and health-related factors on racial differences in risk of disability and recovery. A Markov model was employed using nine waves of data from the New Haven, Connecticut, site (529 blacks, 2,219 whites) and seven waves of the North Carolina (Piedmont) site (2,260 blacks, 1,876 whites), collected between 1982 and 1992. Blacks below age 75 years had an increased risk of developing disability relative to whites in New Haven (odds ratio (OR) at age 65 years = 3.33, 95% confidence interval (CI) 2.13-5.22) as well as in North Carolina (OR at age 65 years = 1.58, 95% CI 1.25-1.99). This excess risk diminished with increasing age, and crossed over in New Haven (OR at age 85 years = 0.45, 95% CI 0.22-0.95), but not in North Carolina (OR at age 85 years = 1.22, 95% CI 0.98-1.51). Adjustment for socioeconomic and health-related factors only partially reduced the excess disability risk among blacks below age 75 years in New Haven, but eliminated the difference in disability risk between blacks and whites in North Carolina. Blacks below age 75 years also had higher mortality risks at both sites. There were no consistent racial differences in recovery from disability.

Black or African American↗
PubMed1996

Analysis of change in self-reported physical function among older persons in four population studies.

Change in self-reported physical function was examined using baseline and 5 years of follow-up data between 1982 and 1991 from the four Established Populations for Epidemiologic Studies of the Elderly studies. In East Boston, Massachusetts (n = 3,809), Iowa and Washington Counties, Iowa (n = 3,673), New Haven, Connecticut (n = 2,812), and North Carolina (n = 4,163), noninstitutionalized persons aged 65 years and older were asked a series of questions to assess their physical function: a modified Katz Activities of Daily Living (ADL) scale, three items from the Rosow-Breslau Functional Health Scale, and questions on physical performance, adapted from Nagi, as well as information on demographic, social, and health characteristics. Longitudinal statistical analyses (random effects and Markov transition models) were used to evaluate improvement, stability, and deterioration in functional ability at both an individual and a population level over multiple years of data. The average decline in physical function associated with age was found to be greater than previous cross-sectional studies have suggested, and the rate of decline increased with increasing age. Considerable individual variation was evident. Although many people experienced declines, a smaller but substantial portion experienced recovery. Women reported a greater rate of decline in physical function and were less likely to recover from disability.

Activities of Daily Living↗
PubMed1996

Effect of age and severity of disability on short-term variation in walking speed: the Women's Health and Aging Study.

Standardized objective measures of human performance have been introduced in clinical and epidemiologic studies of older populations. Reliability of these measures has usually been estimated by comparing two measures obtained in the same person. However, no information is available on variability of multiple measures collected serially over short time intervals. This study uses data from the Weekly Disability Study, a component of the Women's Health and Aging Study, to describe fluctuations in physical performance over multiple, consecutive time intervals. Walking speed was measured weekly over a 6-month period in 99 older women affected by mild to severe disability. Overall, 2120 observations were explored using techniques developed for the analysis of repeated measures. Results showed that the correlations between observations in the same person were inversely related to their separation in time. The decay in the autocorrelation function was steeper in the least disabled. However, even with 20-week separations in assessments, correlations remained above 0.6 in all age and severity of disability subgroups. Changes over time in performance differed somewhat between disability subgroups, but the relative performance across subgroups remained stable over the entire course of the study. A clear learning effect was found only in those in the middle disability subgroup. Results support the utilization of repeated measures of physical performance in research that evaluates older persons over time.

Aged↗
PubMed1996

Hospital and nursing home use in the last three months of life.

We describe decedents' days of care and changes in residence due to episodes of hospital and institutional care in the last 90 days of life. Data are from the National Institute on Aging's Survey of the Last Days of Life (SLDOL) with informants' responses for a sample of 1,227 decedents age 65 years and older from Fairfield County, Connecticut. Overall, three-fourths of the decedents made only one transition to or from a health care facility in the last 3 months of life and another 10% made two or three transitions. Hospital days decreased slightly with age, but nursing home days increased dramatically. Physical disability, lack of social contacts, incontinence, and a diagnosis of dementia were significantly associated with a long, terminal, institutional stay. Future cost savings are likely to be achieved more through the reduction of nursing home care in the last months of life than in a reduction of hospital care.

Aged↗
PubMed1995

Use of antihypertensive drugs and trends in blood pressure in the elderly.

BACKGROUND: During the 1980s data became available from randomized trials concerning the clear benefits of treating hypertension in the elderly. In three large communities, we examined the impact of these findings on rates of treatment, use of specific antihypertensive drugs, and rates of elevated blood pressure as well as distributions of levels. METHODS: In 1981 the National Institute on Aging initiated population-based cohort studies in the residents of three communities who were 65 years and older. East Boston, Mass; Washington and Iowa counties, Iowa; and New Haven, Conn. Participation rates ranged from 80% to 85% across sites with 10,294 community-dwelling participants in the combined cohorts. Baseline evaluation included inhome blood pressure assessment and medication inventory. Repeated in-home evaluations occurred 3 and 6 years after baseline and follow-up rates ranged from 71% to 88%. RESULTS: Use of antihypertensive drugs increased over time in all three communities: the age- and sex-adjusted rates of use were between 14% and 32% higher in 1988 and 1989 relative to 1982 and 1983. Parallel declines in the use of thiazide diuretics occurred in all three populations along with large increases in the use of angiotensin-converting enzyme inhibitors and calcium channel blockers. In East Boston and New Haven mean systolic blood pressure decreased substantially over time and the prevalence of elevated systolic pressure (> or = 160 mmHg) decreased overall as well as by age and sex. In Iowa the mean levels of systolic blood pressure were lowest at baseline and increased slightly. CONCLUSIONS: The reported evidence about the benefits of treatment for hypertension in the elderly was followed by substantial increases in treatment rates. The use of drugs with proven efficacy declined while the use of newer agents with theoretical advantages, not yet tested in clinical trials of mortality, increased. In the United States, the ongoing therapeutic efforts to lower elevated blood pressure in elderly populations may be contributing to the continuing decline in cardiovascular and stroke mortality.

Aged↗
PubMed1995

Recounts of elderly deaths: endorsements for the Patient Self-Determination Act.

Circumstances in the last 3 days of life were examined for a sample of 1,227 elderly decedents in Fairfield County, Connecticut, in 1985. Interviews were with a surviving next-of-kin or a nonrelative about 3 months after the event of death. Most decedents were in a hospital or a nursing home the night before death (45% and 24%, respectively). In the days preceding death, about 34% of the decedents knew that death was impending and about 40% had difficulty recognizing family members. These and other findings support the need for elderly people to complete advance directives.

Advance Directives↗
PubMed1995

Functional disability among elderly blacks and whites in two diverse areas: the New Haven and North Carolina EPESE. Established Populations for the Epidemiologic Studies of the Elderly.

This study examines the prevalence of functional disability (limitation in at least one basic activity of daily living) among elderly Black and White community residents in the New Haven (n = 2812) and North Carolina (n = 4162) sites of the Established Populations for Epidemiologic Studies of the Elderly (EPESE). In New Haven, elderly Blacks, particularly women below age 75, had a higher prevalence of disability compared with Whites, which was partially attributable to a higher prevalence of chronic conditions. In North Carolina, Blacks had only a slightly higher risk of being disabled than Whites, and this was fully accounted for by differences in socioeconomic status. Black-White differences in the prevalence of functional disability reveal geographic variation.

Activities of Daily Living↗
PubMed1994

Mortality and physical functioning in epidemiologic studies of three older populations.

Mortality experienced in the first three years of follow-up for three Established Populations for Epidemiologic Studies of the Elderly (EPESE) is examined in relation to the participants' self-reported functional ability. In East Boston, Massachusetts (N = 3,812), Iowa and Washington Counties, Iowa (N = 3,673), and New Haven, Connecticut (N = 2,812), noninstitutionalized persons aged 65 and older were asked a series of questions to determine their functional status. These measures, used in logistic regression analyses of the mortality data, showed that an increased number of reported disabilities significantly increased the risk of mortality over and above the effects of the age and sex of the participant, or the methodological differences among the sites. Disabilities in gross mobility (e.g., ability to walk a half mile, climb stairs, or perform heavy work around the house) were more strongly related to mortality than were measures of activities of daily living.

Aged↗
PubMed1988

Mortality among diabetics in a national sample.

The authors compare the mortality experience of a national sample of diabetic men and women with their nondiabetic counterparts. The study population consists of respondents from the First National Health and Nutrition Examination Survey (NHANES I), conducted in 1971-1975, who were traced in 1982-1984 through the NHANES I Epidemiologic Follow-up Study. Over the nine-year follow-up period, the age-adjusted death rates for diabetic men and women were twice the rates for nondiabetics. About 75% of the excess mortality among diabetic men and 57% among diabetic women was attributable to cardiovascular disease deaths. After adjustment for age, systolic blood pressure, serum cholesterol, body mass index, and smoking, the relative risk of death was 2.3 for diabetic men and 2.0 for diabetic women. The relative risk for diabetics was highest for ischemic heart disease mortality (2.8 for men and 2.5 for women) and lowest for noncardiovascular disease deaths (1.4 for men and 1.1 for women). When subjects who reported having had a heart attack prior to the baseline examination were excluded, the relative risks for ischemic heart disease mortality among diabetics remained substantial (2.4 for men and 2.6 for women). There was little evidence that the relative risk of death for diabetics compared with nondiabetics differed by age or sex, although 95% confidence intervals around these estimates were wide.

Adult↗
PubMed1986

Epidemiologic characteristics of the United States elderly population in the 20th century.

In 1900 approximately 25 percent of all deaths occurred in people age 65 years of age and over while by 1980 30 percent of deaths occurred in those over age 80. The greatest declines in age-specific mortality for those 65 and over occurred from 1920 to 1945 and since 1970. Some evidence exists that illness and disability may be rising in all age groups. Understanding the reasons for the declines in mortality for the elderly in this century and basic research in chronic disease causation and prevention are urged.

Aged↗
PubMed1985

The relationship of diabetes with race, sex, and obesity.

Noninsulin-dependent diabetes typically has its onset in the adult years, and appears to have both genetic and non-genetic factors in its etiology. Data from the 1976 National Health Interview Survey were used to study the independent and interactive relationship of race, sex, obesity, and age with the reported prevalence of noninsulin-dependent diabetes. The percent of the population reported with this type of diabetes ranged from about 0.5 among Black and Caucasian (white) people of both sexes 20-44 years of age in the least obese group to 20.2 percent among black males 65 years and over in the most obese group. Black people were slightly more likely to report diabetes than white people, especially at the older ages and in the more obese groups. Diabetes generally increased more rapidly with obesity among women than among men, but there was no other consistent sex difference. Diabetes was reported more frequently with increasing levels of obesity, especially at the older age.

Adult↗