Kyphosis and incident falls among community-dwelling older adults.

Hyperkyphosis commonly affects older persons and is associated with morbidity and mortality. Many have hypothesized that hyperkyphosis increases fall risk. Within this prospective study of older adults, kyphosis was significantly associated with incident falls over 1 year. Measures of hyperkyphosis could enhance falls risk assessments during primary care office visits. INTRODUCTION: To determine the association between four measures of kyphosis and incident and injurious falls in older persons. METHODS: Community-dwelling adults aged 65 and older (n = 72) residing in southern California were invited to participate in a prospective cohort study. Participants had kyphosis assessed four ways. Two standing measures included a flexicurve ruler placed against the back to derive a kyphotic index and the Debrunner kyphometer, a protractor used to measure the kyphotic angle in degrees. Two lying measures included the blocks method (number of 1.7 cm blocks needed to achieve a neutral head position while lying supine) and traditional Cobb angle calculation derived from DXA based lateral vertebral assessment. Baseline demographic, clinical, and other health information (including a timed up and go (TUG) test) were assessed at a clinic visit. Participants were followed monthly through email or postcard for 1 year, with falls outcomes confirmed through telephone interview. RESULTS: Mean age was 77.8 (± 7.1) among the 52 women and 20 men. Over 12 months, 64% of participants experienced at least one incident fall and 35% experienced an injurious fall. Each standard deviation increase in kyphosis resulted in more than doubling the adjusted odds of an incident fall, even after adjusting for TUG. Odds of injurious falls were less consistent across measures; after adjusting for TUG, only the blocks method was associated with injurious falls. CONCLUSIONS: Each kyphosis measure was independently associated with incident falls. Findings were inconsistent for injurious falls; the blocks measure suggested the strongest association. If these findings are replicated, the blocks measure could be incorporated into office visits as a quick and efficient tool to identify patients at increased fall risk.

Predicting lower-extremity injuries among habitual runners.

This prospective study of 583 habitual runners used baseline information to examine the relationship of several suspected risk factors to the occurrence of running-related injuries of the lower extremities that were severe enough to affect running habits, cause a visit to a health professional, or require use of medication. During the 12-month follow-up period, 252 men (52%) and 48 women (49%) reported at least one such injury. The multiple logistic regression results identified that running 64.0 km (40 miles) or more per week was the most important predictor of injury for men during the follow-up period (odds ratio = 2.9). Risk also was associated with having had a previous injury in the past year (odds ratio = 2.7) and with having been a runner for less than 3 years (odds ratio = 2.2). These results suggest that the incidence of lower-extremity injuries is high for habitual runners, and that for those new to running or those who have been previously injured, reducing weekly distance is a reasonable preventive behavior.

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.

Association between exercise and HIV disease progression in a cohort of homosexual men.

PURPOSE: To study the relationship between exercise and human immunodeficiency virus (HIV) disease progression. METHODS: 415 individuals (156 HIV positive, 259 HIV negative), from a cohort study of 851 homosexual men from New York City, 1985-1991. By 1991, 68 of the 156 persons developed Acquired Immune Deficiency Syndrome (AIDS) and 49 died with AIDS. Exercise was defined as self-report of exercising 3-4 times/week or daily at entry; less was considered nonexercise. CD4 lymphocyte decline was constructed for each subject by modeling log CD4 count against time in days. The association between exercise and progression to AIDS and death with AIDS, adjusting for baseline CD4 count, was determined using Cox model. Linear regression was used to model CD4 decline with exercise for HIV positive and HIV negative groups separately, adjusting for initial CD4 count. RESULTS: Having exercised was associated with slower progression to AIDS at 1 year (HR = 0.68, 90% confidence interval (CI): 0.4-1.17); hazard ratios (HR) at 2, 3, and 4 years were 0.96, 1.18, and 1.36, respectively. Having exercised was also associated with slower progression to death with AIDS at 1 year (HR = 0.37, 90% CI: 0.14-0.94) with hazard ratios at 2, 3, and 4 years of 0.68, 0.98, and 1.27, respectively, suggesting a protective effect close to the time exercise was assessed, but an increased risk after 2 years. Exercising 3-4 times/week had a more protective effect than daily exercise. Exercisers in the HIV positive group showed an increase in CD4 count during a year by a factor of 1.07. CONCLUSION: Moderate physical activity may slow HIV disease progression.

The use of proportional hazards regression in investigating dropout rates in a longitudinal study.

One difficulty with the interpretation of data from longitudinal studies is the bias associated with those who do not complete the study. In a 12-month study on the occurrence of musculoskeletal problems in 966 runners (583 of whom completed the study), a proportional hazards model with time-dependent covariates was used to assess factors associated with dropout at the various stages of the study. This approach allowed examination of baseline factors as well as the effect of change in mileage, the occurrence of a musculoskeletal problem, or the occurrence of another health problem on the rate of dropout. Those most likely to drop out of the study were younger and heavier at baseline and, prior to drop out, were less likely to experience general health problems and more likely to show a 40% decline in weekly running mileage in the month before dropout. Examination of factors associated with dropout is important since factors influencing dropout may also affect the study outcome for the risk factor analysis (a musculoskeletal problem severe enough to be seen by a physician). The results of the dropout analysis can be used to guide in the choice of analytic methods and to aid in the interpretation of the risk factor analyses.

Changes in lipids associated with change in regular exercise in free-living men.

OBJECTIVE: To investigate the relationship between regular exercise and plasma lipid profiles in free-living men. METHODS: Seven hundred eighty men between the ages of 25 and 65 years were included in this study. The medical history, physical examination, and blood tests were obtained at baseline and 1 year later. At the end of the study, 430 (55.1%) men reported the same amount of regular exercise as a year earlier; 199 (25.5%) men reported an increased level, and 151 (19.4%) men reported a decreased level. RESULTS: Compared to the group with same exercise, men who increased their level of regular exercise had a significant increase in high-density lipoprotein cholesterol (HDLC) (mean 4.76 versus 2.83 mg/dL, p < 0.005) and significant decreases in the ratio of total cholesterol/HDLC (mean -0.72 versus -0.42, p < 0.001) and triglycerides (mean -18.2 versus -6.27 mg/dL, p < 0.001). The changes in lipid profiles appeared to have a dose-response relationship from the increased exercise, same exercise, to decreased exercise groups. Overweight and normal-weight men had a similar tendency to improve their lipid profiles by exercise. The improvement in plasma lipid profile associated with increased regular exercise persisted after controlling for potential confounders. CONCLUSIONS: The results indicate that the relationship between physical activity and favorable lipid profiles exists in men with mild-to-moderate physical activity.

The impact of changes in coffee consumption on serum cholesterol.

To investigate the possible association between changes in coffee consumption and serum cholesterol levels, information was obtained from 2109 healthy nonsmokers aged 25-65 years at two clinic visits to a preventive medical center between 1987 and 1991 (mean interval between visits: 16.7 months). After adjusting for age and changes in other potential confounders, about 2 mg/dl total cholesterol increase was associated with an increase of one cup of regular coffee per day (p < 0.001). A dose-response was found among those who decreased regular coffee consumption, those who continued the same dose, and those who increased consumption. The same trend was observed among those who quit drinking regular coffee, those who never drank coffee, and those who started to drink coffee. No change in cholesterol level was found among those continuing to consume the same quantity of regular coffee compared to those who never drank coffee. The change in cholesterol level was not related to consumption of decaffeinated coffee, regular tea, decaffeinated tea, or cola with caffeine. To our knowledge, this is the first follow-up study correlating change in coffee consumption with change in serum cholesterol in a large group of men and women.

Functional health status as a predictor of mortality in men and women over 65.

This study evaluated the effect of functional health status on mortality in a sample of community-dwelling older people. White and African-American self-respondents to the 1986 National Health Interview Survey Functional Health Supplement (n = 5, 320) were included in the study. Functional health status was measured by a ten-item unidimensional activities of daily living-instrumental activities of daily living (ADL-IADL) scale and a three-item cognitive ADL scale. Proportional hazards regression was used to evaluate the effect of increasing score on the ten-item ADL-IADL scale on risk of mortality over a 5-year period while controlling for demographic, social, and health status covariates. In both men and women, increasing score on the ADL-IADL scale was predictive of mortality, adjusting for increasing age, poor self-rated health, low body mass index in women, and being an unmarried man. These findings indicate that a unidimensional scale consisting of both ADL and IADL items is useful in predicting mortality, controlling for the effect of covariates in sex-specific models.

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.

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.

Exaggerated blood pressure response to dynamic exercise and risk of future hypertension.

This study examined the association between an exaggerated blood pressure response to treadmill exercise and the risk of developing hypertension. Subjects were healthy normotensive men (n = 5386) who had a baseline graded maximal exercise test between 1971 and 1982, and completed a mailed follow-up questionnaire. At follow-up in 1986, cases (n = 151) reported physician diagnosed hypertension and controls (n = 201) reported normotension. Those who had developed hypertension at follow-up were more likely to have had an exaggerated blood pressure response to exercise (OR = 2.4, 1.4-4.3). In multiple logistic regression analysis an exaggerated response was significantly associated (OR = 3.0, 1.5-6.1) with future hypertension after controlling for sitting systolic and diastolic blood pressure, weight change from age 21 to follow-up, entry age, family history of hypertension, body mass index, treadmill time, alcohol consumption, and years of follow-up. These results suggest that an exaggerated blood pressure response to exercise is independently associated with increased risk of future hypertension, and therefore, may be an important factor in determining hypertension risk.

Sensitivity and specificity of death certificate diagnoses for dementing illnesses, 1988-1990.

OBJECTIVE: To evaluate the extent to which mortality data, which is often used to track secular trends for specific diseases, underestimates the prevalence of dementia. DESIGN: Retrospective analysis of existing data. SETTING: Department of Mental Health inpatient facilities in South Carolina. SUBJECTS: Inpatients at Department of Mental Health facilities who were listed in the South Carolina Statewide Alzheimer's Disease and Related Disorders Registry and who died between 1988 and 1990 (n = 450). MAIN OUTCOME MEASURES: Sensitivity and specificity of dementia diagnoses on death certificates compared to medical record diagnoses for inpatients with a pre-mortem dementia diagnosis. RESULTS: Twenty-three percent of death certificates contained any dementia diagnosis (104/450). The sensitivity of death certificates varied by type of dementia (28 percent for Alzheimer's disease; 8 percent for multi-infarct dementia) as well as by race, sex, and age. CONCLUSIONS: Mortality statistics substantially underestimate the prevalence of dementing illnesses and do not fully represent the public health burden of dementia.

Television watching, energy intake, and obesity in US children: results from the third National Health and Nutrition Examination Survey, 1988-1994.

OBJECTIVES: To examine the relationship between television watching, energy intake, physical activity, and obesity status in US boys and girls, aged 8 to 16 years. METHODS: We used a nationally representative cross-sectional survey with an in-person interview and a medical examination, which included measurements of height and weight, daily hours of television watching, weekly participation in physical activity, and a dietary interview. Between 1988 and 1994, the Third National Health and Nutrition Examination Survey collected data on 4069 children. Mexican Americans and non-Hispanic blacks were oversampled to produce reliable estimates for these groups. RESULTS: The prevalence of obesity is lowest among children watching 1 or fewer hours of television a day, and highest among those watching 4 or more hours of television a day. Girls engaged in less physical activity and consumed fewer joules per day than boys. A higher percentage of non-Hispanic white boys reported participating in physical activity 5 or more times per week than any other race/ethnic and sex group. Television watching was positively associated with obesity among girls, even after controlling for age, race/ethnicity, family income, weekly physical activity, and energy intake. CONCLUSIONS: As the prevalence of overweight increases, the need to reduce sedentary behaviors and to promote a more active lifestyle becomes essential. Clinicians and public health interventionists should encourage active lifestyles to balance the energy intake of children.

Postrace morbidity among runners.

We examined two general measures of morbidity, musculoskeletal problems and respiratory symptoms, among participants of a 42 km race. We compared the morbidity experience of these participants to runners racing shorter distance events (5 km and 10 km) on the same day. Male marathon runners were almost twice as likely (and female marathon runners four times as likely) to report a lower extremity musculoskeletal problem in the month after the race as nonmarathon runners. Although adjusting for other factors did not change the crude odds ratio for either men or women, logistic regression results indicated that the strongest factor associated with lower extremity musculoskeletal problems in the month after the marathon was the report of a musculoskeletal problem in the year before the marathon. Neither male nor female marathon runners reported an excess of respiratory symptoms compared to those who ran shorter distances. However, a report of respiratory symptoms in the month before the race was statistically associated with respiratory symptoms in the month after the race. These results suggest that runners who have had lower extremity musculoskeletal problems in the year before, or those who have recently experienced respiratory symptoms, should use caution when preparing for and recovering from racing events.

Health promotion practices among physicians.

Personal belief concerning both the validity of health promotion and the physician's ability to influence patient behavior may affect how much effort a physician spends on health promotion strategies. We assessed these beliefs through a mail survey to physicians practicing in a predominantly rural southern state in 1987 (n = 83) and 1991 (n = 96). Response rates in both studies exceeded 75%. The instrument was obtained from similar studies conducted in Massachusetts in 1981 and Maryland in 1983. Between 1987 and 1991 we found slight improvements in the perceived importance of many health behaviors, but significant improvement was observed in the importance of reducing intake of dietary saturated fat (66% in 1987 to 80% in 1991; P < .05). Less than 10% of the physicians thought they could be "very successful" in modifying patients' behaviors. However, in 1991 physicians perceived that their ability to be "very successful" in helping patients to modify their behavior would increase threefold (8%-24% for exercise; 4%-18% for smoking) if given appropriate support. Although the type of appropriate support was not identified, the credibility of physician's advice in promoting health changes is important. These results suggest that efforts should be made to provide support to physicians who are inclined to discuss health behavior changes with their patients. Medical Subject Headings (MeSH): dietary fats, exercise, patient education, physician's practice patterns, smoking.

Lower extremity injuries in runners. Advances in prediction.

Recreational and competitive running is practised by many individuals to improve cardiorespiratory function and general well-being. The major negative aspect of running is the high rate of injuries to the lower extremities. Several well-designed population-based studies have found no major differences in injury rates between men and women; no increasing effect of age on injuries; a declining injury rate with more years of running experience; no substantial effect of weight or height; an uncertain effect of psychological factors; and a strong effect of previous injury on future injuries. Among the modifiable risk factors studied, weekly distance is the strongest predictor of future injuries. Other training characteristics (speed, frequency, surface, timing) have little or no effect on future injuries after accounting for distance run. More studies are needed to address the effects of appropriate stretching practices and abrupt change in training patterns. For recreational runners who have sustained injuries, especially within the past year, a reduction in running to below 32 km per week is recommended. For those about to begin a running programme, moderation is the best advice. For competitive runners, great care should be taken to ensure that prior injuries are sufficiently healed before attempting any racing event, particularly a marathon.

Community intervention and trends in dietary fat consumption among black and white adults.

OBJECTIVE: This study assessed whether a state public health department could effectively implement an affordable nutrition intervention program at the community level. DESIGN: Cross-sectional data were collected via telephone surveys of 9,839 adults, aged 18 years or older, in 1987, 1989, and 1991 in two South Carolina communities. Nutrition education programs began in 1988 in one community. The other community served as a comparison site. We assessed and compared changes in community levels of dietary fat and weekly meat consumption, salt use, and nutrition promotion awareness with analysis of covariance regression techniques that included race, sex, and age as covariates. RESULTS: We observed favorable changes in most eating behaviors and levels of awareness in both communities. The intervention community experienced greater absolute changes that the comparison community in use of animal fats (-8.9% vs -4.0%; P = .02) and liquid or soft vegetable fats (+8.4% vs +3.6%; P = .04), and in awareness of restaurant nutrition information (+33.0% vs +19.4%; P = .0001). Although the primary type of dietary fat used differed between black and white respondents, we observed significant change among both groups. CONCLUSIONS: These results suggest that community-wide nutrition education programs may have augmented regional or national changes in dietary behavior among white and black adults in the intervention community.

Population attributable risk: implications of physical activity dose.

PURPOSE: The purpose of this study is to describe the application of population attributable risk estimates in relation to the dose-related benefits or risks of physical activity. METHODS: Assumptions and limitations of population attributable risk calculations and interpretations are reviewed and evaluated in the context of physical activity dose. Theoretical estimates are developed for several hypothetical situations. RESULTS: National estimates of population attributable risk may be inaccurate because definitions and measurement techniques applied in physical activity research studies and physical activity prevalence surveys do not correspond. In addition, it is not established whether vigorous or moderate physical activity are independent contributors, sequential categories, or interactive variables in the process of disease reduction. This information is necessary to calculate population attributable risk most appropriately. CONCLUSION: Estimates of the disease burden of physical inactivity will be improved by two advances in empirical studies: first, the pairing of prevalence and relative risk estimates for nationally representative population-based samples; and second, refined relative risk estimates for various doses of physical activity.

Levels of physical activity and inactivity in children and adults in the United States: current evidence and research issues.

PURPOSE: The purpose was to describe current levels of physical activity and inactivity among adults and young people in the United States. METHODS: Estimates of participation in regular physical activity were derived from three national surveys for adults (National Health Interview Survey, National Health and Nutrition Examination Survey, and the Behavioral Risk Factor Surveillance System) and from the Youth Risk Behavior Survey for high school students. RESULTS: Overall, 63.8% of high school students surveyed on the 1997 YRBS reported participating in vigorous physical activity for at least 20 min on 3 or more days per week. Participation in vigorous activity was higher for boys (72.3%) than girls (53.5%), whites (66.8%) compared with blacks (53.9%) and Hispanics (60.4%), and decreased with advancing grade. Among adults, 27.7% meet recommended levels of either moderate or vigorous physical activity, whereas 29.2% report no regular physical activity outside of their work. Gender differences in participation in physical activity are less pronounced than in youth, and age-related patterns were complex. Whites are more active than blacks and Hispanics, and persons with higher family incomes and more education report being more physically active. There have been only minor changes in reported participation in leisure time physical activity over the past 15 yr. CONCLUSION: National estimates of physical activity appear to be reliable and valid for adults but may be less so for adolescents and are poor measures for children. Research is needed to determine the role that objective monitoring with accelerometers may play in surveillance. Reliable and valid measures of occupational, household, and transportation-related physical activity and sedentary behaviors are needed to better characterize the range of activity that is associated with health.

Physiological, anthropometric, and training correlates of running economy.

Potential physiological, anthropometric, and training determinants of running economy (RE) were studied in a heterogeneous group of habitual distance runners (N = 188, 119 males, 69 females). RE was measured as VO2 (ml.kg-1.min-1) during level treadmill running at 161 m.min-1 (6 mph) (VO2-6). Examined as potential determinants of RE were heart rate and ventilation while running at 6 mph (HR6, VE6), VO2max (ml.kg-1 x min-1), % fat, age, gender, height, weight, estimated leg mass, typical training pace, training volume, and sit-and-reach test performance. RE was entered as the dependent variable and the potential determinants as independent variables in zero-order correlation and multiple regression analyses. Zero-order correlation analysis found VO2max, HR6, and VE6 to be significantly, positively correlated with VO2-6 (P < 0.001). Multiple regression analysis, in which the independent effect of each predictor variable was examined, revealed VO2-6 to be positively correlated with VO2max (P < 0.001), HR6 (P < 0.001), VE6 (P < 0.001), and age (P < 0.05) and negatively correlated with weight (P < 0.01). These findings indicate that, in a diverse group of runners, better RE (VO2-6) is associated with lower VO2max, lower submaximal exercise VE and HR, lower age, and greater weight.