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1.  Cardiorespiratory Fitness as a Predictor of Dementia Mortality in Men and Women 
There is evidence that physical activity may reduce the risk of developing Alzheimer’s disease and dementia. However, few reports have examined the physical activity-dementia association with objective measures of physical activity. Cardiorespiratory fitness (hereafter called fitness) is an objective reproducible measure of recent physical activity habits.
We sought to determine whether fitness is associated with lower risk for dementia mortality in women and men.
We followed 14,811 women and 45,078 men, ages 20-88 at baseline, for an average of 17 years. All participants completed a preventive health examination at the Cooper Clinic in Dallas, Texas during 1970-2001. Fitness was measured with a maximal treadmill exercise test, with results expressed in maximal metabolic equivalents (METs). The National Death Index identified deaths through 2003. Cox proportional hazards models were used to examine the association between baseline fitness and dementia mortality, adjusting for age, sex, examination year, body mass index, smoking, alcohol use, abnormal ECGs, and health status.
There were 164 deaths with dementia listed as the cause during 1,012,125 person-years of exposure. Each 1-MET increase in fitness was associated with a 14% lower adjusted risk of dementia mortality (95% confidence interval, CI 6%-22%). With fitness expressed in tertiles, adjusted hazard ratios (HRs) for those in the middle and high fitness groups suggest their risk of dementia mortality was less than half that of those in the lowest fitness group (respectively: HR 0.44, CI 0.26-0.74; HR 0.49, CI 0.26-0.90).
Greater fitness was associated with lower risk of mortality from dementia in a large cohort of men and women.
PMCID: PMC3908779  PMID: 21796048
physical fitness; cognitive function; Alzheimer’s disease; vascular dementia; metabolic equivalents (METs)
2.  School Readiness Among Children Insured by Medicaid, South Carolina 
The American Academy of Pediatrics recommends a schedule of age-specific well-child visits through age 21 years. For children insured by Medicaid, these visits are called Early and Periodic Screening, Diagnosis, and Treatment (EPSDT). These visits are designed to promote physical, emotional, and cognitive health. Six visits are recommended for the first year of life, 3 for the second year. We hypothesized that children with the recommended visits in the first 2 years of life would be more likely than others to be ready for school when they finish kindergarten.
We studied children insured by Medicaid in South Carolina, born during 2000 through 2002 (n = 21,998). Measures included the number of EPSDT visits in the first 2 years of life and an assessment of school readiness conducted at the end of kindergarten. We used logistic regression to examine the adjusted association between having the recommended visits and school readiness, controlling for characteristics of mothers, infants, prenatal care and delivery, and residence area.
Children with the recommended visits had 23% higher adjusted odds of being ready for school than those with fewer visits.
EPSDT may contribute to school readiness for children insured by Medicaid. Children having fewer than the recommended EPSDT visits may benefit from school readiness programs.
PMCID: PMC3457755  PMID: 22677161
3.  More May Be Better: Evidence of a Negative Relationship between Physician Supply and Hospitalization for Ambulatory Care Sensitive Conditions 
Health Services Research  2005;40(4):1148-1166.
To conduct an empirical test of the relationship between physician supply and hospitalization for ambulatory care sensitive conditions (ACSH).
Data Sources/Study Setting
A data set of county ACSH rates compiled by the Safety Net Monitoring Initiative of the Agency for Healthcare Research and Quality (AHRQ). The analytical data set consists of 642 urban counties and 306 rural counties. We supplemented the AHRQ data with data from the Area Resource File and the Environmental Protection Agency.
Study Design
Ordinary least squares regression estimated ACSH predictors. Physician supply, the independent variable of interest in this analysis, was measured as a continuous variable (MDs/100,000). Urban and rural areas were modeled separately. Separate models were estimated for ages 0–17, 18–39, and 40–64.
Data Extraction Methods
Data were limited to 20 states having more than 50 percent of counties with nonmissing data.
Principal Findings
In the urban models for ages 0–17, standardized estimates indicate that, among the measured covariates in our model, physician supply has the largest negative adjusted relationship with ACSH (p<.0001). For ages 18–39 and 40–64, physician supply has the second largest negative adjusted relationship with ACSH (p<.0001, both age groups). Physician supply was not associated with ACSH in rural areas.
Physician supply is positively associated with the overall performance of the primary health care system in a large sample of urban counties of the United States.
PMCID: PMC1361189  PMID: 16033497
Physician supply; ambulatory care sensitive conditions; primary care access
4.  Estimated Functional Capacity Predicts Mortality in Older Adults 
To examine associations between functional capacity estimated from cardiorespiratory fitness (CRF) and mortality risks in adults aged 60 and older.
Prospective study, averaging 13.6 years follow-up.
Preventive medical clinic.
Four thousand sixty adults who completed preventive medical examinations between 1971 and 2001; 24.7% women, mean age ± standard deviation 64.6 ± 4.9, body mass index (BMI) 25.9 ± 3.8 kg/m2.
CRF was quantified as metabolic equivalents (METs) achieved during maximal treadmill exercise. The lowest 20% of the age- and sex-specific MET distribution was defined as having low CRF, the middle 40% moderate CRF, and the upper 40% high CRF. Cox regression was used to estimate death rates (per 1,000 person-years), hazard ratios (HRs), and their 95% confidence intervals (CIs).
Nine hundred eighty-nine deaths occurred during follow-up. Death rates adjusted for age, sex, and examination year were 30.9, 18.3, and 13.4 for all causes (P<.001); 15.9, 8.6, and 5.4 for cardiovascular disease (CVD) (P<.001); and 6.1, 4.9, and 4.2 for cancer (P=.04) for subjects with low, moderate, and high CRF, respectively. After adjusting for smoking, abnormal electrocardiograms at rest or while exercising, percentage of age-predicted maximal heart rate achieved during exercise testing, baseline medical conditions, BMI, hypercholesterolemia, and family CVD and cancer history, subjects with high CRF had notably lower mortality risk than those with low CRF from all causes (HR = 0.59, 95% CI = 0.47–0.74) and from CVD (HR = 0.57, 95% CI = 0.41–0.80).
CRF is an important independent predictor of death in older adults. The results add to the existing evidence that promoting physical activity in older adults provides substantial health benefits, even in the oldest old.
PMCID: PMC3410432  PMID: 17979958
functional capacity; exercise testing; mortality; cardiovascular diease; metabolic equivalents (METs)
5.  Cognitive Health Messages in Popular Women’s and Men’s Magazines, 2006-2007 
Preventing Chronic Disease  2010;7(2):A32.
Growing evidence suggests that physical activity, healthy diets, and social engagement may promote cognitive health. Popular media helps establish the public health agenda. In this study, we describe articles about cognitive health in top-circulating women's and men's magazines.
To identify articles on cognitive health, we manually searched all pages of 4 top-circulating women's magazines and 4 top-circulating men's magazines published in 2006 and 2007 to identify articles on cognitive health. We examined article volume, narrative and illustrative content, information sources, and contact resources.
Women's magazines had 27 cognitive health articles (5.32/1,000 pages), and men's magazines had 26 (5.26/1,000 pages). Diet was the primary focus (>75% of content) in 30% of articles in women's magazines and 27% of men's magazines. Vitamins/supplements were the focus of 15% of articles in men's magazines and 11% in women's magazines. Articles mentioned physical activity, cognitive activity, and social interaction, although these subjects were rarely the focus. Articles focused more on prevention than treatment. Topics were primarily "staying sharp," memory, and Alzheimer's disease. Colleges/universities were most often cited as sources; contacts for further information were rare. Most articles were illustrated.
Although the volume of cognitive health articles was similar in the magazines, content differed. More articles in men's magazines discussed multiple chronic conditions (eg, Alzheimer's disease), whereas more in women's magazines discussed memory. Including more articles that focus on physical activity and direct readers to credible resources could enhance the quality of cognitive health communication in the popular media.
PMCID: PMC2831786  PMID: 20158960
6.  Prospective Study of Cardiorespiratory Fitness and Depressive Symptoms in Women and Men 
Journal of psychiatric research  2008;43(5):546-552.
Most studies of the relationship between cardiorespiratory fitness (CRF) and depression have been limited to cross-sectional designs. The objective of this study was to follow individuals over time to examine whether those with higher levels of CRF have lower risk of developing depressive symptoms. Participants were 11,258 men and 3,085 women enrolled in the Aerobics Center Longitudinal Study in Dallas, TX. All participants completed a maximal treadmill exercise test at baseline (1970–1995) and a follow-up health survey in 1990 and/or 1995. Individuals with a history of a mental disorder, cardiovascular disease, or cancer were excluded. CRF was quantified by exercise test duration, and categorized into age-stratified groups as low (lowest 20%), moderate (middle 40%), or high (upper 40%). Depressive symptoms were assessed using the 20-item Center for Epidemiologic Studies Depression Scale (CES-D). Those who scored 16 or more on the CES-D were considered to have depressive symptoms. After an average of 12 years of follow-up, 282 women and 740 men reported depressive symptoms. After adjusting for age, baseline examination year, and survey response year, the odds of reporting depressive symptoms were 31% lower for men with moderate CRF (odds ratio, OR 0.69; 95% confidence interval, CI 0.56–0.85) and 51% lower for men with high CRF (OR 0.49, CI 0.39–0.60), compared to men with low CRF. Corresponding ORs for women were 0.56 (CI 0.40–0.80) and 0.46 (CI 0.32–0.65). Higher CRF is associated with lower risk of incident depressive symptoms independent of other clinical risk predictors.
PMCID: PMC2683669  PMID: 18845305
Cardiorespiratory fitness; CES-D; depressive symptoms; physical activity
7.  Attitudes on Aging Well Among Older African Americans and Whites in South Carolina 
Preventing Chronic Disease  2009;6(4):A113.
Cognitive impairment in older adults is a major cause of functional disability. Interest in protecting brain health is likely to grow as the US population ages and more people have experiences with cognitive decline. Recent scientific evidence suggests that physical activity, heart-healthy diets, and social involvement may help to maintain brain health. We investigated attitudes about aging well among older African Americans and whites to inform the development of interventions to promote cognitive health.
We used a purposive sample to conduct 5 focus groups with African Americans (n = 42) and 4 with whites (n = 41). Participants also completed a brief survey. In discussions centered on brain health, participants were asked to describe someone they know who is aging well. We used a grounded theory approach to guide the analysis and interpretation of the data.
Both African Americans and whites said that components of aging well include social activity, a strong spiritual life, not taking medications, and traveling. African Americans said aging well means being cognitively intact, free of serious mobility impairment or other health problems, and independent. Whites described aging well as living a long time, staying physically active, maintaining a positive outlook, and having good genes.
African Americans did not commonly associate physical activity with aging well, which suggests that tailored intervention strategies for promoting brain health should emphasize physical activity. African Americans and whites did not commonly associate nutrition with aging well, which also suggests a useful focus for public health interventions.
PMCID: PMC2774627  PMID: 19754989
8.  Using hospitalization for ambulatory care sensitive conditions to measure access to primary health care: an application of spatial structural equation modeling 
In data commonly used for health services research, a number of relevant variables are unobservable. These include population lifestyle and socio-economic status, physician practice behaviors, population tendency to use health care resources, and disease prevalence. These variables may be considered latent constructs of many observed variables. Using health care data from South Carolina, we show an application of spatial structural equation modeling to identify how these latent constructs are associated with access to primary health care, as measured by hospitalizations for ambulatory care sensitive conditions. We applied the confirmatory factor analysis approach, using the Bayesian paradigm, to identify the spatial distribution of these latent factors. We then applied cluster detection tools to identify counties that have a higher probability of hospitalization for each of the twelve adult ambulatory care sensitive conditions, using a multivariate approach that incorporated the correlation structure among the ambulatory care sensitive conditions into the model.
For the South Carolina population ages 18 and over, we found that counties with high rates of emergency department visits also had less access to primary health care. We also observed that in those counties there are no community health centers.
Locating such clusters will be useful to health services researchers and health policy makers; doing so enables targeted policy interventions to efficiently improve access to primary care.
PMCID: PMC2745375  PMID: 19715587
9.  Association between community health center and rural health clinic presence and county-level hospitalization rates for ambulatory care sensitive conditions: an analysis across eight US states 
Federally qualified community health centers (CHCs) and rural health clinics (RHCs) are intended to provide access to care for vulnerable populations. While some research has explored the effects of CHCs on population health, little information exists regarding RHC effects. We sought to clarify the contribution that CHCs and RHCs may make to the accessibility of primary health care, as measured by county-level rates of hospitalization for ambulatory care sensitive (ACS) conditions.
We conducted an ecologic analysis of the relationship between facility presence and county-level hospitalization rates, using 2002 discharge data from eight states within the US (579 counties). Counties were categorized by facility availability: CHC(s) only, RHC(s) only, both (CHC and RHC), and neither. US Agency for Healthcare Research and Quality definitions were used to identify ACS diagnoses. Discharge rates were based on the individual's county of residence and were obtained by dividing ACS hospitalizations by the relevant county population. We calculated ACS rates separately for children, working age adults, and older individuals, and for uninsured children and working age adults. To ensure stable rates, we excluded counties having fewer than 1,000 residents in the child or working age adult categories, or 500 residents among those 65 and older. Multivariate Poisson analysis was used to calculate adjusted rate ratios.
Among working age adults, rate ratio (RR) comparing ACS hospitalization rates for CHC-only counties to those of counties with neither facility was 0.86 (95% Confidence Interval, CI, 0.78–0.95). Among older adults, the rate ratio for CHC-only counties compared to counties with neither facility was 0.84 (CI 0.81–0.87); for counties with both CHC and RHC present, the RR was 0.88 (CI 0.84–0.92). No CHC/RHC effects were found for children. No effects were found on estimated hospitalization rates among uninsured populations.
Our results suggest that CHCs and RHCs may play a useful role in providing access to primary health care. Their presence in a county may help to limit the county's rate of hospitalization for ACS diagnoses, particularly among older people.
PMCID: PMC2727502  PMID: 19646234
10.  Cardiorespiratory Fitness and Adiposity as Mortality Predictors in Older Adults 
Associations among cardiorespiratory fitness (thus referred to as “fitness”), adiposity, and mortality in older adults have not been adequately examined.
To examine these associations, we report on a 12-year follow-up of adults ages 60 years and older, in whom fitness was assessed by a maximal exercise test and adiposity was assessed by body mass index (BMI), waist circumference (WC), and percent body fat.
Design, Setting, and Patients
2603 adults (age 64.4±4.8 yr; 19.8% women) completed a baseline health examination at the Cooper Clinic during 1979-2001. Low fitness was defined as the lowest fifth of the gender-specific distribution of maximal treadmill exercise test duration. The distributions of BMI, WC, and percent body fat were grouped for analysis according to clinical guidelines.
Main Outcome Measures
All-cause mortality.
There were 450 deaths during an average follow-up of 12 years and 31 236 person-years of exposure. Death rates per 1000 person-years, adjusted for age, gender, and examination year were: 13.9, 13.3, 18.3, and 31.8 across BMI groups of 18.5-24.9, 25.0-29.9, 30.0-34.9, and ≥35 kg/m2, respectively (trend P=.01); 13.3 and 18.2 for normal and high WC (≥102 cm in men; ≥88 cm in women), respectively (P=.004); 13.7 and 14.6 for normal and high percent body fat (≥25% in men; ≥30% in women), respectively (P=.51); and 32.6, 16.6, 12.8, 12.3 and 8.1 across incremental fifths of fitness, respectively (P<.001). The association between WC and mortality persisted after further adjustment for smoking, baseline health status, and BMI (P=.02), but not after additional adjustment for fitness (P=.86). Fitness predicted mortality risk after further adjustment for smoking, baseline health, and either WC, BMI or percent body fat (P<.001).
Fitness is a significant mortality predictor in older adults independent of overall or abdominal adiposity. Practitioners should consider the importance of preserving functional capacity, by recommending regular physical activity for older individuals, normal weight and overweight alike.
PMCID: PMC2692959  PMID: 18056904
11.  Improving knowledge about disability transitions by adding retrospective information to panel surveys. Population Health Metrics 
Panel data are often used to estimate key measures of public health, such as years lived with and without disability. Panel surveys commonly measure disability at intervals of one or two years, and occasionally more than two. It is likely that these intervals often include unreported changes in functional status. Unreported changes may bias estimates of disability transition probabilities, which are commonly used to estimate years lived with and without disability. Most surveys do not ask participants about periods with and without disability in the time since they last responded to the survey. We examined a way to improve the usefulness of panel surveys and our understanding of disability processes, by eliciting retrospective disability information.
Data were from the United States' National Long Term Care Survey. At each wave, this survey asks disabled respondents how long they have been disabled. We tested whether estimates of probabilities predicting changes in disability status can be improved by making use of this retrospective disability information. Methods included embedded Markov Chain analysis, microsimulation, and the Hausman specification test.
Estimates based on data that include retrospective information are significantly different from those that use only the more limited information that is contemporaneous to the surveys. They are also more efficient. At age 65, all estimated probabilities for becoming disabled were higher when retrospective information was used, and all probabilities for remaining disabled were lower. Microsimulation revealed that using retrospective information increased the number of functional status transitions. For example, for women the mean number of transitions from nondisabled to disabled or dead was 52.7% greater when retrospective information was added to the analysis.
Our results suggest that the value of future panel studies for estimating transitions in disability could be notably enhanced by adding a small number of questions asking respondents for details about their disabilities–and lack of disabilities–in the period since a preceding survey wave. Information provided by such questions could substantially improve both the measurement of disability histories and estimates of disability processes.
PMCID: PMC1716181  PMID: 17166277

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