Dorothy R. Davis

Muscular strength and physical function.

PURPOSE The purpose of this study was to evaluate the potential association of muscular strength and endurance at baseline with the prevalence of functional limitations at follow-up. METHODS Study participants were 3,069 men and 589 women (30-82 yr) who received a clinical examination including a strength evaluation at the Cooper Clinic between 1980 and 1989 and responded to a 1990 mail-back survey. Participants also had to achieve at least 85% of their age-predicted maximal heart rate on a maximal exercise treadmill test and have no history of heart attack, stroke, diabetes, high blood pressure, cancer, or arthritis at their first visit. A strength index composite score (0-6) was calculated using age- and sex-specific tertiles from bench press, leg press, and sit-up tests. Those scoring 5 or 6 were categorized in the high strength group. Functional health status was assessed by responses to questions about the participants ability to perform light, moderate, and strenuous recreational, household, daily living, and personal care tasks. RESULTS After an average follow-up of 5 yr, 7% of men and 12% of women reported at least one functional limitation. A logistic regression model including age, aerobic fitness, body mass index, and new health problems at follow-up found that, relative to those with lower levels of strength, the odds of reporting functional limitations at follow-up in men and women categorized as having higher levels of strength were 0.56 (95%CI = 0.34, 0.93) and 0.54 (95%CI = 0.21, 1.39), respectively. CONCLUSIONS These findings, if replicated in other populations, suggest that maintenance of strength throughout the lifespan may reduce the prevalence of functional limitations.

Major depression and all-cause mortality among white adults in the United States

PURPOSE Depression is the most common psychiatric illness affecting adults. Despite the importance of a potential link between major depression and mortality, research has been surprisingly sparse. METHODS Information on 57,897 white adults aged 25 years and older who were included in the mental health supplement of the 1989 National Health Interview Survey was linked with the National Death Index to examine the relationship of major depression to mortality. Death status was obtained through December 1991. Sex-specific hazard rate ratios for mortality were calculated by Cox proportional hazards regression and Poisson regression to adjust for potential confounders (age, education, marital status, body mass index, and whether the target subject or a family member completed the survey about the subject). RESULTS Major depression was reported for 223 (0.8%) of 27,345 men and 392 (1.3%) of 30,552 women. During the 2.5-year follow-up, death certificate data were obtained for 848 (3.1%) men and 651 (2.1%) women. The adjusted hazard rate ratios for all-cause mortality associated with major depression were 3.1 (95% confidence interval; 2.0-4.9) for men and 1.7 (95% confidence interval; 0.9-3.1) for women. CONCLUSIONS These results suggest that major depression increases risk of all-cause mortality, particularly among men. Further research is needed to explain the mechanism.

Physical activity patterns associated with cardiorespiratory fitness and reduced mortality : The aerobics center longitudinal study

OBJECTIVES This study examined cross sectionally the physical activity patterns associated with low, moderate, and high levels of cardiorespiratory fitness. METHODS Physical activity was assessed by questionnaire in a clinic population of 13,444 men and 3972 women 20 to 87 years of age. Estimated energy expenditure (kcal.wk-1) and volume (min.wk-1) of reported activities were calculated among individuals at low, moderate, and high fitness levels (assessed by maximal exercise tests). RESULTS Average leisure time energy expenditures of 525 to 1650 kcal.wk-1 for men and 420 to 1260 kcal.wk-1 for women were associated with moderate to high levels of fitness. These levels of energy expenditure can be achieved with a brisk walk of approximately 30 minutes on most days of the week. In fact, men in the moderate and high fitness categories walked between 130 and 138 min.wk-1, and women in these categories walked between 148 and 167 min.wk-1. CONCLUSIONS Most individuals should be able to achieve these physical activity goals and thus attain a cardiorespiratory fitness level sufficient to result in substantial health benefits.

Physical activity and self-reported, physician-diagnosed osteoarthritis: is physical activity a risk factor?

This prospective study evaluated regular physical activity and self-reported physician-diagnosed osteoarthritis of the knee and/or hip joints among 16,961 people, ages 20-87, examined at the Cooper Clinic between 1970 and 1995. Among those aged 50 years and older, osteoarthritis incidence was higher among women (7.0 per 1000 person-years) than among men (4.9 per 1000 person-years, P = 0.001), while among those under 50 years of age, osteoarthritis incidence was similar between men (2.6) and women (2.7). High levels of physical activity (running 20 or more miles per week) were associated with osteoarthritis among men under age 50 after controlling for body mass index, smoking, and use of alcohol or caffeine (hazard ratio = 2.4, 95% CI: 1.5, 3.9), while no relationship was suggested among women or older men. These findings support the conclusion that high levels of physical activity may be a risk factor for symptomatic osteoarthritis among men under age 50.

Patterns of non-response to a mail survey

This paper describes a basic investigation of possible non-response bias in a mail survey. We compare characteristics of responders and non-responders to a mail survey of health outcomes among participants of a longitudinal study of physical activity, physical fitness, and health. Results indicate that, at the first clinic visit, the responders were essentially the same as the non-responders on personal health history and laboratory measurements, while reporting significantly more family history of specific chronic diseases (cardiovascular disease, hypertension, stroke). The male responders were younger and reported more positive health behaviors as well as better weight and treadmill times at the first clinic visit. These results suggest that both response groups were equally healthy at entry, and that individuals who had family members with certain chronic conditions and who had positive health behaviors were more likely to respond (participate) in this health-related survey. Differences of this type could affect interpretation of future analyses. This work illustrates the importance of incorporating methods to examine non-response into any epidemiologic study.

Co-morbidity associated with dementia.

Purpose: The purpose of this study was to identify common co-morbid conditions associated with dementia subtypes and to evaluate the association of hypertension, diabetes mellitus, atrial fibrillation, congestive heart failure, and anemia with dementia subtypes relative to controls. Methods: Hospital discharge data were used to identify 15,013 subjects from South Carolina with a diagnosis of dementia between 1998 and 1999. A control group of 15,013 persons without dementia was randomly sampled from hospital discharge records and matched to persons with dementia on the basis of age, race, and gender. Multiple hospitalizations for each patient were merged, and repeated diagnoses during separate hospitalizations were counted once. Results: After adjusting for age, race, and gender, persons with Alzheimers disease and dementia associated with medical conditions were less likely to be diagnosed with hypertension, diabetes, congestive heart failure, and atrial fibrillation than were controls. Patients with multiinfarct dementia were also less likely to have congestive heart failure, but were more likely to have diabetes. Anemia was not associated with any dementia subtype. Conclusions: There are distinct differences in comorbid conditions among dementia subtypes. Our research does not support previous studies that suggest a circulatory component to the development of Alzheimers disease.

A Measure of Perceived Burden among Caregivers

This, report describes an easily administered scale for measuring perceived burden among caregivers offamily members with dementia. During home interviews conducted in 1991, 82 caregivers rated theirfamily member with dementia on several items related to functional ability, the type of care provided, and associated stress. The resulting measure ofperceived burden, based on 15 internally consistent items (alpha = 0.87), is significantly correlated with depressive symptomatology (r = 0.38, p = 0.0004). This measure is useful in assessing perceived stress associated with specific caregiving responsibilities. It can be used, along with other measures of patientfunctional status, to assess overall caregiver burden and to target intervention strategies.

Aging in Place? Evidence That a State Medicaid Waiver Program Helps Frail Older Persons Avoid Institutionalization

ABSTRACT Long-term care will increasingly shift from institutions to home and community based services. Using data from a Medicaid home care waiver program in South Carolina, the Community Long-Term Care (CLTC) program, we evaluated differences in frailty and service use among CLTC clients between 1995 (n = 3,748) and 2005 (n = 9,157). The expectation was that CLTC clients had become more frail in that period, and had greater access to services in the community, results that might suggest the CLTC program had helped individuals to avoid institutionalization. Frailty measures included acute and chronic conditions, other health conditions, and activities of daily living (ADL). We evaluated the percentage of clients using services, and service use intensity. A large majority of clients in both years were impaired in at least four ADL. In 2005, CLTC clients were significantly more likely to have chronic conditions, including hypertension, chronic obstructive pulmonary disease, Alzheimers disease, arthritis, diabetes, and renal failure (all p < 0.05). Clients were significantly more likely to receive specific services in 2005, including physical therapy, dialysis, and oxygen (all p < 0.05). Results suggest CLTC participants were more frail in 2005 than in 1995. This may reflect a successful effort to help individuals age in place in the community, delaying institutionalization. States may be able to control increases in Medicaid long-term care costs through home care programs that delay institutionalization.

The value of strength training for older adults.

Health in older adults can best be measured in terms of functional status. Skeletal muscle strength has been reported to be a determinant of functional status in older individuals. Two major contributors to the decline in muscle function as a person ages are disuse and physical inactivity. Declining muscle function through a loss of muscular strength may decrease functional independence and mobility and increase the risk for falls and injuries, physical frailty, and disability. Older individuals lacking an appropriate amount of muscular strength may not be able to perform various activities of daily living, which are important indicators of independence.

Does physical activity reduce the risk of developing peptic ulcers

Background—Although Helicobacter pylori has been identified as a major cause of chronic gastritis, not all infected patients develop ulcers, suggesting that other factors such as lifestyle may be critical to the development of ulcer disease. Aim—To investigate the role physical activity may play in the incidence of peptic ulcer disease. Methods—The subjects were men (8529) and women (2884) who attended the Cooper Clinic in Dallas between 1970 and 1990. The presence of gastric or duodenal ulcer disease diagnosed by a doctor was determined from a mail survey in 1990. Subjects were classified into three physical activity groups according to information provided at the baseline clinic visit (before 1990): active, those who walked or ran 10 miles or more a week; moderately active, those who walked or ran less than 10 miles a week or did another regular activity; the referent group consisting of those who reported no regular physical activity. Results—With the use of gender specific proportional hazards regression models that could be adjusted for age, smoking, alcohol use, body mass index, and self reported tension, active men were found to have a significant reduction in risk for duodenal ulcers (relative hazard (95% confidence interval) for the active group was 0.38 (0.15 to 0.94) and 0.54 (0.30 to 0.96) for the moderately active group). No association was found between physical activity and gastric ulcers for men or for either type of ulcer for women. Conclusions—Physical activity may provide a non-pharmacological method of reducing the incidence of duodenal ulcers among men.