Biomedical subjects

D O Clark

Publications and source records attributed to D O Clark.

15 recordsLinked to original sources

PubMed1995

Socioeconomic status and exercise self-efficacy in late life.

Self-efficacy, or assessments about one's ability to carry out particular tasks, has been shown to play a central role in the adoption and maintenance of exercise. The relationship between exercise self-efficacy and socioeconomic status (SES), however, has not been formally developed or tested, and the implications of SES for exercise interventions are not known. We hypothesize pathways through which income, education, and occupation affect self-efficacy and capitalize on the availability of responses from 1944 older HMO enrollees to investigate the direct and indirect associations of SES indicators with exercise self-efficacy. Direct associations of age and education are found. Indirect associations of age, income, education, and occupation operate primarily through previous exercise experience, satisfaction with amount of walking, depression, and outcome expectations. The potentially modifiable nature of exercise outcome expectations (i.e., belief in the benefits of exercise) in combination with its strong association with exercise self-efficacy argue in support of greater consideration of its role in attempts to improve exercise self-efficacy.

Aged↗

PubMed1995

Antecedents and consequences of physical activity and exercise among older adults.

The antecedents and consequences of four markers of physical activity and exercise are examined for the 6,780 baseline self-respondents to the Longitudinal Study on Aging. These dichotomous markers reflect having a level of physical activity greater than one's peers (45.8%), getting as much exercise as needed (58.9%), having a regular exercise routine (28.4%), and walking a mile or more at least once a week (29.9%). The major factors associated with engaging in these behaviors are having fewer lower body limitations, better perceived health, more non-kin social supports, not worrying about one's health, and having a sense of control over one's health. When added to traditional models predicting subsequent (over the next 6 to 8 years) mortality, nursing home placement, hospital resource consumption, and changes in functional status, the four markers of physical activity and exercise have numerous statistically and substantively significant associations, all of which involve better health outcomes.

Aged↗

PubMed1995

Racial and educational differences in physical activity among older adults.

This study utilized a nationally representative sample of older adults to investigate the association of race and education with five different measures of self-reported physical activity. Rates of physical activity were low among white Americans and even lower among African Americans. However, a majority of the racial variation in activity was accounted for by racial differences in educational attainment. Those with 8 or fewer years of education were found to be less active than those with 9 or more, despite having controlled for educational differences in income, health compared to one year ago, functional status, body mass, and chronic disease. Discussion focuses on self-efficacy and social and cultural contexts.

Black or African American↗

PubMed1995

A chronic disease score with empirically derived weights.

Different types of medication prescribed during a 6-month period for the treatment and management of chronic conditions were utilized in the refinement and validation of a chronic disease score. Prescription data, in addition to age and sex, were utilized to develop a chronic disease score based on empirically derived weights for each of three outcomes: total cost, outpatient cost, and primary care visits. The ability of the revised chronic disease score to predict health care utilization, costs, hospitalization, and mortality was compared to an earlier version of the chronic disease score (original) that was derived through clinical judgments of disease severity. The predictive validity of the chronic disease score is also compared to ambulatory care groups, which utilize outpatient diagnoses to form mutually exclusive diagnostic categories. Models based on a concurrent 6-month period and a 6-month prospective period (ie, the 6-month period after the chronic disease score or ambulatory care group derivation period) were estimated using a random one half sample of 250,000 managed-care enrollees aged 18 and older. The remaining one half of the enrollee population was used as a validation sample. The revised chronic disease score showed improved estimation and prediction over the original chronic disease score. The difference in variance explained prospectively by the revised chronic disease score versus the ambulatory care groups, conversely, was small. The revised chronic disease score was a better predictor of mortality than the ambulatory care groups. The combination of revised chronic disease score and ambulatory care groups showed only marginally greater predictive power than either one alone. These results suggest that the revised chronic disease score and ambulatory care groups with empirically derived weights provide improved prediction of health care utilization and costs, as well as hospitalization and mortality, over age and sex alone. We recommend the revised chronic disease score with total cost weights for general use as a severity measure because of its relative advantage in predicting mortality compared to the outpatient cost and primary care visit weights.

Adult↗

PubMed1994

Dynamics of functional impairment in late adulthood.

The inconclusive debate about Fries' theory of "natural death and the compression of morbidity" has diverted attention from two key issues--the modifiability and related dynamics of functional impairment in late adulthood. Evidence is presented from a large (N = 11,000) panel of adults aged initially 58-63 over the period of a decade which documents substantial modification of functional status. Further, patterned changes in functional status are related to the dynamics of income, historically a major determinant of functional status, and independently to educational attainment. The dynamics of functional status, of income, and of their relationship are explored using discrete time hazard models in an event history analysis incorporating time-varying income and functional status indicators. The importance of income and of education as positive, independent predictors of functional status and patterned changes of functional status is confirmed. The implications of this finding for differentiating distal (e.g. education) and proximate (e.g. income) measures of socioeconomic status and for assessing competing theories of social causation and social selection are discussed.

Aged↗

PubMed1992

Racial and social correlates of age-related changes in functioning.

Six waves of observations spanning a decade on a panel of 566 Black and 5,196 non-Black survivors were utilized to examine social and racial differences in age-related changes in functioning. An index consisting of three dimensions was used to assess functioning: physical functioning, self-care capacity, and self-rated well-being. Growth curve analysis was used to assess variations in trajectories of functional impairment across Black/non-Black, poor/nonpoor, male/female, and high-school/non-high-school graduate subpanels. Trajectories vary across social groups in the expected manner. However, we note that the trajectories are not linear and that substantial variability exists within both the Black and non-Black subpanels. Moreover, we note that Blacks report poorer functional status than non-Blacks even with income and education controlled. However, age changes do not differ across Black and non-Black subpanels, as predicted by the multiple-jeopardy hypothesis.

Activities of Daily Living↗

PubMed1992

Residence differences in formal and informal long-term care.

This study, using a large, nationally representative sample of noninstitutionalized disabled older persons, found that urban residents were much more likely than rural residents to receive formal assistance in every ADL and IADL considered. Rural residents were more likely to receive informal assistance and to receive two-thirds more person days of informal assistance per week. No residence differences in unmet need for care were identified.

Activities of Daily Living↗

PubMed1992

Trajectories of functional impairment in later life.

Functional impairment trajectories in late adulthood over a decade are characterized using the Longitudinal Retirement History Study (LRHS) data set. Non-linear patterns of age-related increase in impairment are documented with longitudinal data. Subsets of panelists from the initial large, nationally representative probability sample of employed males and unmarried employed females (N = 11,000) also exhibit differential non-linear trajectories of impairment by sex, income, and educational attainment. Concurrent analysis of the relationship over a decade among sex, SES, and functional impairment suggests that in health research, both sex and SES are broad proxy variables whose usefulness for understanding health outcomes and for policy analysis would be enhanced by the specification of components.

Activities of Daily Living↗

PubMed1987

A comparison of a new graduated estrogen formulation with three constant-dosed oral contraceptives.

Four-hundred-twenty-six women, aged 18 to 36, completed a four-cycle comparative, randomized, single-blind (observer blind), multicenter study of a new graduated estrogen formulation with three constant-dosed combination oral contraceptives containing the same synthetic steroid compounds. The products studied were Loestrin 1/20, Loestrin 1.5/30, Norlestrin 1/50, and a new graduated estrogen product, Estrostep. A total of 1,850 cycles were completed and analyzed for efficacy, side effects, metabolic changes, and cycle control. Four pregnancies occurred during the course of the study. None of the pregnancies occurred in the group receiving Estrostep. The new formulation produced the lowest rate of breakthrough bleeding (BTB) compared with the other three products. All four combination oral contraceptives resulted in an increase in high-density lipoprotein cholesterol (HDL-C). The levels of HDL-C were greatest with Estrostep.

Adolescent↗

PubMed1973