Dimensional analysis of actigraphic derived sleep data.

Nonlinear dimensional analyses can be a useful tool in understanding the underlying behavior of dynamical systems, including biological systems. Many biological functions can be modeled as chaotic processes, including sleep. Sleep data can be obtained from several methods, such as electroencephalograms, polysomnography, and actigraph. Actigraphy, because of its low level of invasiveness, is an increasingly popular method of obtaining sleep data. This study analyzed actigraphy data with nonlinear dimensional analyses to determine if such analytic methods would be useful in sleep studies. Participants wore actigraphs on their wrists, which recorded movement for several days. Several sleep quality variables, such as movement during sleep and total sleep time, were derived from these sleep data. These variables were used to determine whether the quality of sleep was good or poor. Lagged phase space plots were graphed and nonlinear parameters for the fractal dimension and the correlation dimension were computed for each participant. Descriptive and inferential statistics were performed to determine if the nonlinear parameters showed significant differences with respect to sleep quality.

Estimation of the maximum flow-mediated brachial artery response using local regression methods.

We consider methods for estimating the maximum from a sequence of measurements of flow-mediated diameter of the brachial artery. Flow-mediated vasodilation (FMD) is represented using the maximum change from a baseline diameter measurement after the release of a blood pressure cuff that has been inflated to reduce flow in the brachial artery. The influence of the measurement error on the maximum diameter from raw data can lead to overestimation of the average maximum change from the baseline for a sample of individuals. Nonparametric regression models provide a potential means for dealing with this problem. When using this approach, it is necessary to make a judicious choice of regression methods and smoothing parameters to avoid overestimation or underestimation of FMD. This study presents results from simulation studies using kernel-based local linear regression methods that characterize the relationship between the measurement error, smoothing and bias in estimates of FMD. Comparisons between fixed or constant smoothing and automated smoothing parameter selection using the generalized cross validation (GCV) statistic are made, and it is shown that GCV-optimized smoothing may over-smooth or under-smooth depending on the heart rate, measurement error and measurement frequency. We also present an example using measured data from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) pilot study. In this example, smoothing resulted in lower estimates of FMD and there was no clear evidence of an optimal smoothing level. The choice to use smoothing and the appropriate smoothing level to use may depend on the application.

Occupational and other risk factors for hand-grip strength: the Honolulu-Asia Aging Study.

BACKGROUND: In certain occupations, including farm work, workers are exposed to hazardous substances, some of which are known to be toxic to the nervous system and may adversely affect muscle strength. Measurement of hand-grip strength may be useful for detecting neurotoxic exposure. METHODS: The authors studied 3522 participants of the Honolulu Heart Program and the Honolulu-Asia Aging Study to determine whether occupational exposures to pesticides, solvents, and metals assessed at exam I (1965-68) are associated with hand-grip strength at exam IV (1991-93) and change in hand-grip strength over 25 years. Correlation, analysis of variance and covariance, and linear regression were used to evaluate the associations. RESULTS: At exam IV, participants ranged in age from 71-93 years; mean hand-grip strength was 39.6 kg at exam I and 30.3 kg at exam IV. Over 25 years, the decline in hand-grip strength was an average of 8-9 kg for all exposures. Hand-grip strength was inversely associated with age and glucose but directly associated with cognitive function, BMI, and haemoglobin level. No other exposures were associated with hand-grip strength. CONCLUSION: This study did not provide evidence that occupational exposure to pesticides, solvents, and metals adversely affected hand-grip strength in this population, but confirmed other important associations with hand-grip strength.

A statistical test to determine the quality of accelerometer data.

Accelerometer data quality can be inadequate due to data corruption or to non-compliance of the subject with regard to study protocols. We propose a simple statistical test to determine if accelerometer data are of good quality and can be used for analysis or if the data are of poor quality and should be discarded. We tested several data evaluation methods using a group of 105 subjects who wore Motionlogger actigraphs (Ambulatory Monitoring, Inc.) over a 15 day period to assess sleep quality in a study of health outcomes associated with stress among police officers. Using leave-one-out cross-validation and calibration-testing methods of discrimination statistics, error rates for the methods ranged from 0.0167 to 0.4046. We found that the best method was to use the overall average distance between consecutive time points and the overall average mean amplitude of consecutive time points. These values gave us a classification error rate of 0.0167. The average distance between points is a measure of smoothness in the data, and the average mean amplitude between points gave an average reading. Both of these values were then normed to determine a final statistic, K, which was then compared to a cut-off value, K(C), to determine data quality.

Quantification of regional glial fibrillary acidic protein levels in Alzheimer's disease.

OBJECTIVES: Our objectives were to quantify glial fibrillary acidic protein (GFAP) in brains of Alzheimer's disease (AD) cases, and non-AD controls to determine the regions with the most severe gliosis in AD. MATERIAL AND METHODS: In a case control design, we used an enzyme-linked immunosorbent assay (ELISA) to quantify GFAP in frozen brain from four areas of neocortex in 10 AD cases, 10 age-matched controls, and 10 younger controls from the Honolulu-Asia Aging Study autopsy archive. RESULTS: Median age at death was 83.5 years for cases and age-matched controls, and 77 years for younger controls. For the AD cases compared with the age-matched controls, levels of GFAP in occipital (P=0.01), parietal (P=0.028), and temporal lobes (P=0.004) (but not frontal) were significantly higher in the cases. The median GFAP excess in AD cases compared with age matched controls was highest in the temporal lobe. CONCLUSIONS: Regional quantification of GFAP reveals that the glial response is most prominent in the temporal lobe in AD.

Metabolic cardiovascular syndrome and risk of dementia in Japanese-American elderly men. The Honolulu-Asia aging study.

Cardiovascular risk factors often cluster into a metabolic syndrome that may increase the risk of dementia. The objective of the present study was to assess the long-term association between clustered metabolic cardiovascular risk factors measured at middle age and the risk of dementia in old age. This prospective cohort study of cardiovascular disease was started in 1965 and was extended to a study of dementia in 1991. The subjects were Japanese-American men with an average age of 52.7+/-4.7 (mean+/-SD) years at baseline. Dementia was diagnosed in 215 men, according to international criteria, and was based on a clinical examination, neuropsychological testing, and an informant interview. The z scores were calculated for 7 risk factors (random postload glucose, diastolic and systolic blood pressures, body mass index, subscapular skinfold thickness, random triglycerides, and total cholesterol). The relative risk (RR [95% CI]) of dementia (subtypes) per 1 SD increase in the sum of the z scores was assessed after adjustment for age, education, occupation, alcohol consumption, cigarette smoking, and years of childhood lived in Japan. The z-score sum was higher in demented subjects than in nondemented subjects, indicating a higher risk factor burden (0.74 versus -0.06, respectively; P=0. 008). Per SD increase in the z-score sum, the risk of dementia was increased by 5% (RR 1.05, 95% CI 1.02 to 1.09). The z-score sum was specifically associated with vascular dementia (RR 1.11, 95% CI 1.05 to 1.18) but not with Alzheimer's disease (RR 1.00, 95% CI 0.94 to 1.05). Clustering of metabolic cardiovascular risk factors increases the risk of dementia (mainly, dementia of vascular origin).

Apolipoprotein A-1 predicts coronary heart disease only at low concentrations of high-density lipoprotein cholesterol: an epidemiological study of Japanese-Americans.

Conventional epidemiological and clinical studies of apolipoprotein A-1 and high-density lipoprotein-cholesterol have demonstrated, when examined jointly, that high-density lipoprotein is a better predictor of coronary heart disease. This strategy does not take into account known lipid metabolic relationships. A statistical approach that takes into account apolipoprotein A-1 being a constituent of the high-density lipoprotein particle is more appropriate. Among 1,177 Japanese-American men of the Honolulu Heart Program cohort free of disease at baseline (1980-1982), 182 new coronary heart disease cases developed over a 12-year follow-up period. After removing the linear relationship with high-density lipoprotein-cholesterol, a relative measure of apoliprotein A-1 concentration was derived. Based on joint conditions of "low" and "high" relative apoliprotein A-1 concentration and < or =40 and >40 mg/dl for the high-density lipoprotein-cholesterol distribution, four groupings were created. Among relative joint groupings of high/< or =40, low/< or =40, high/>40, and low/>40, respectively, the 12-year coronary heart disease incidence varied from 28.6, 18.2, 8.3, to 11.7 cases per 1,000 person-years. A test of statistical interaction was significant (P=0.028). Additional analyses revealed coronary heart disease cases were more likely among men with triglycerides > 190 mg/dl. Observed patterns of relationships among relative apoliprotein A-1 level, high-density lipoprotein cholesterol, and triglycerides with incident coronary heart disease are consistent with patterns noted in clinical, laboratory, and transgenic animal research more capable of elucidating mechanisms of disease causation. This epidemiological study suggests similar mechanisms may be operating at a population level, and may contribute to the public health burden of coronary heart disease.

Screening for coronary heart disease in elderly men based on current and past cholesterol levels.

Efficient use of cholesterol measurements to screen for coronary heart disease in the elderly is not well defined. The purpose of this report is to examine such screening based on national guidelines in a sample of older men. Since relations between cholesterol and coronary heart disease are better established in those who are younger, screening in the elderly will also consider levels of cholesterol that existed earlier in life. Data are from a prospective study of 1,170 men enrolled in the Honolulu Heart Program who were followed over a 12-year period for coronary heart disease. Follow-up began from 1980 to 1982, when cholesterol levels were determined in men who were aged 61 to 81 years. Past cholesterol levels were measured 10 years earlier (1970-1972). During the course of follow-up, coronary heart disease developed in 117 of the men. Risk of disease rose significantly (P = 0.003) with increases in past cholesterol levels (1970-1972) but not with more recent levels (1980-1982). For men with current cholesterol levels that were desirable (<5.2 mmol/L [200 mg/dl], as defined by guidelines from the National Cholesterol Education Program), disease incidence continued to rise with increasing past cholesterol levels (P<0.001). Accounting for high-density lipoprotein cholesterol and other screening factors did little to alter these findings. We conclude that desirable cholesterol levels in the elderly may not be a marker of a healthy risk profile if past cholesterol levels were high. Screening for coronary heart disease in the elderly could be improved by considering past cholesterol levels, rather than just a single measurement in later life.

Glucose intolerance and 23-year risk of coronary heart disease and total mortality: the Honolulu Heart Program.

OBJECTIVE: The associations between glucose intolerance measured at the study entry date and the 23-year incidence of coronary heart disease (CHD), CHD mortality, and total mortality were examined at the Honolulu Heart Program. RESEARCH DESIGN AND METHODS: This prospective study followed a cohort of 8,006 Japanese-American men who were 45-68 years old and living on the island of Oahu, HI, in 1965. Baseline glucose was measured in a nonfasting state 1 h after a 50-g glucose load. History and use of medication for diabetes was obtained during an interview. The cohort was divided into four categories of glucose tolerance: low-normal, high-normal, asymptomatic hyperglycemia, and known diabetes. RESULTS: During the 23 years of follow-up, 864 incident cases of CHD, 384 deaths from CHD, and 2,166 total deaths occurred. The relative risks (RRs) were obtained using Cox proportional hazards modeling, with the low-normal category as a reference. The RRs were adjusted for age only, as well as for age, BMI, hypertension, cholesterol, triglycerides, smoking, alcohol, and a Japanese diet index. The age-adjusted and risk factor-adjusted RRs for all outcomes were significant for the asymptomatic hyperglycemic and known diabetes groups (P<0.05). The age-adjusted RRs for CHD incidence and total mortality were marginally significant in the high-normal group, but the RRs were not significant when adjusted for risk factors. CONCLUSIONS: These results suggest a dose-response relation of glucose intolerance at baseline with CHD incidence, CHD mortality, and total mortality, independent of other risk factors, in this cohort of middle-aged and older Japanese-American men.

Orthostatic hypotension predicts mortality in elderly men: the Honolulu Heart Program.

BACKGROUND: Population-based data are unavailable concerning the predictive value of orthostatic hypotension on mortality in ambulatory elderly patients, particularly minority groups. METHODS AND RESULTS: With the use of data from the Honolulu Heart Program's fourth examination (1991 to 1993), orthostatic hypotension was assessed in relation to subsequent 4-year all-cause mortality among a cohort of 3522 Japanese American men 71 to 93 years old. Blood pressure was measured in the supine position and after 3 minutes of standing, with the use of standardized methods. Orthostatic hypotension was defined as a drop in systolic blood pressure (SBP) of >/=20 mm Hg or in diastolic blood pressure of >/=10 mm Hg. Overall prevalence of orthostatic hypotension was 6.9% and increased with age. There was a total of 473 deaths in the cohort over 4 years; of those who died, 52 had orthostatic hypotension. Four-year age-adjusted mortality rates in those with and without orthostatic hypotension were 56.6 and 38.6 per 1000 person-years, respectively. With the use of Cox proportional hazards models, after adjustment for age, smoking, diabetes mellitus, body mass index, physical activity, seated systolic blood pressure, antihypertensive medications, hematocrit, alcohol intake, and prevalent stroke, coronary heart disease and cancer, orthostatic hypotension was a significant independent predictor of 4-year all-cause mortality (relative risk 1.64, 95% CI 1.19 to 2.26). There was a significant linear association between change in systolic blood pressure from supine position to standing and 4-year mortality rates (test for linear trend, P<0.001), suggesting a dose-response relation. CONCLUSIONS: Orthostatic hypotension is relatively uncommon, may be a marker for physical frailty, and is a significant independent predictor of 4-year all-cause mortality in this cohort of elderly ambulatory men.

Predictors of healthy aging in men with high life expectancies.

OBJECTIVE: The purpose of this study was to identify risk factors that consistently predict staying healthy in contrast to developing clinical illness and/or physical and mental impairments. METHODS: More than 8000 men of Japanese ancestry were followed for 28 years with repeat examinations and surveillance for deaths and incident clinical illness. Physical and cognitive functions were measured in 1993. Measures of healthy aging included surviving and remaining free of major chronic illnesses and physical and cognitive impairments. RESULTS: Of 6505 healthy men at baseline, 2524 (39%) died prior to the final exam. Of the 3263 available survivors, 41% remained free of major clinical illnesses, 40% remained free of both physical and cognitive impairment, and 19% remained free of both illness and impairment. The most consistent predictors of healthy aging were low blood pressure, low serum glucose, not smoking cigarettes, and not being obese. CONCLUSIONS: Beyond the biological effects of aging, much of the illness and disability in the elderly is related to risk factors present at midlife.

Changes in total and high-density lipoprotein cholesterol over 10- and 20-year periods (the Honolulu Heart Program).

Limited data are available on patterns of change in lipids and lipoproteins as persons age. The purpose of this report is to describe the 10-year change in total and high-density lipoprotein (HDL) cholesterol according to suspected determinants in 898 Japanese-American men enrolled in the Honolulu Heart Program. Data are based on examinations that occurred from 1970 to 1972 and at repeat examinations received 10 and 20 years later. At the last examination, men were aged 71 to 93 years. Mean reductions in total cholesterol in the second 10 years of follow-up (24 mg/dl) were more than double the reductions observed in the first 10 years (9 mg/dl). Levels of total cholesterol declined and levels of HDL cholesterol increased regardless of beginning levels of systolic blood pressure, body mass index, physical activity, cigarette smoking status, or the use of treatment for hypertension or elevated total cholesterol. Men with prevalent coronary heart disease experienced greater reductions (p <0.05) in total cholesterol during the second 10 years of follow-up (32 mg/dl) versus men without coronary heart disease (22 mg/dl). Adjustment for baseline covariates failed to alter these findings appreciably. We conclude that alterations in total and HDL cholesterol with advancing age may be expected to occur regardless of risk factor status, disease prevalence, or pharmacologic intervention. In the presence of such effects, evaluation of treatment programs to alter levels of total and HDL cholesterol in older persons should consider the possibility that even in the absence of intervention, changes could also occur due to aging alone.

Coffee consumption in hypertensive men in older middle-age and the risk of stroke: the Honolulu Heart Program.

OBJECTIVE: To examine the association between coffee consumption and the development of stroke in men at high risk for cardiovascular disease. METHODS: Coffee intake was observed from 1965 to 1968 in a cohort of men enrolled in the Honolulu Heart Program with follow-up for incident stroke over a 25-year period. Subjects were 499 hypertensive men (having systolic or diastolic blood pressures at or above 140 and 90 mm Hg, respectively) in older middle-age (55 to 68 years) when follow-up began. Past and current cigarette smokers were excluded from follow-up. RESULTS: In the course of follow-up, 76 men developed a stroke. After age-adjustment, risk of thromboembolic stroke increased significantly with increases in coffee consumption (P = 0.002). No relationships were observed with hemorrhagic stroke. When adjusted for other factors, the risk of thromboembolic stroke was more than doubled for men who consumed three cups of coffee per day as compared to nondrinkers of coffee (RR = 2.1; 95% CI = 1.2-3.7). CONCLUSIONS: Although in need of further confirmation, consumption of coffee appears to be positively associated with an increased risk of thromboembolic stroke in hypertensive men in older middle-age. Findings suggest that it may be prudent to advise older middle-aged men with hypertension who consume large amounts of coffee to consider reducing their coffee intake.

Influence of myocardial infarction, coronary artery bypass surgery, and stroke on cognitive impairment in late life.

Relations between cognitive test scores in later life and prior myocardial infarction (MI), coronary artery bypass graft surgery (CABG), and stroke were examined for this study. Subjects were 3,734 Japanese-American men (80% of surviving Honolulu Heart Program cohort) aged 71 to 93 years at the time of cognitive testing. Impairment was defined as scoring below the 16th percentile on a validated cognitive assessment scale. Prior MI, stroke, and CABG were established using hospital surveillance, history, and record review. After adjustment for age, years of education, and years of childhood spent in Japan, men with prior stroke were significantly more likely than others to have poor cognitive performance (odds ratio 4.4, 95% confidence limits 3.0 to 6.7). History of > 1 stroke was associated with an odds ratio of 50 (95% confidence limits 10.5 to 238.3). There was no significant association between cognitive performance and > or = 1 prior MI or history of CABG. Time between events and cognitive function testing did not affect results. Analyses support a significant association between clinical stroke and persistent cognitive impairment, but fail to implicate CABG or MI.

Factors of the insulin resistance syndrome in nondiabetic and diabetic elderly Japanese-American men.

Factor analysis has previously identified four independent factors that characterize the insulin resistance syndrome in women, interpreted as 1) weight/waist, 2) lipids, 3) insulin/glucose, and 4) systolic and diastolic blood pressure. Because it is not known whether similar factors emerge for men, or for diabetics, factor analysis was used to investigate the clustering of features characterizing the insulin resistance syndrome using data from 3,159 elderly (71-93 years) Japanese-American men participating in the fourth examination of the Honolulu Heart Program during 1991-1993. Consistent with previous results, factor analysis reduced eight risk factors (insulin, glucose, systolic blood pressure, diastolic blood pressure, triglycerides, high-density lipoprotein cholesterol, weight, and waist circumference) to four uncorrelated factors that explained 78.2% and 74.7% of the variance in nondiabetics (n = 2,760) and diabetics (n = 399), respectively. These factors were interpreted as 1) weight/waist, 2) blood pressure, 3) lipids, and 4) insulin/glucose. Modest differences in the associations between fasting insulin and factors 1, 3, and 4 were noted for diabetics. These consistently identified composite factors may represent markers for underlying pathophysiologic mechanisms of the insulin resistance syndrome and risk of non-insulin-dependent diabetes mellitus.

Association of insulin levels with lipids and lipoproteins in elderly Japanese-American men.

PURPOSE: Elevated insulin levels have been associated with cardiovascular disease, but the relationship of insulin with other risk factors and its position in the atherosclerotic pathway is uncertain. A cross-sectional study was conducted to determine whether insulin concentrations were associated with lipids and lipoproteins independently of adiposity and other cardiovascular risk factors. METHODS: Subjects included 3417 Japanese-American men from the Honolulu Heart Program who completed a follow-up examination between 1991 and 1993 and were 71-93 years of age. Men were categorized by quintiles of fasting and 2-hour insulin concentration. RESULTS: Age-adjusted mean high-density lipoprotein (HDL) cholesterol and triglyceride levels varied significantly across quintiles of fasting and 2-hour insulin (P < 0.001, tests for trend), but insulin was not related to total cholesterol and low-density lipoprotein (LDL) cholesterol. HDL cholesterol decreased from 59.3 to 43.7 mg/dL and triglycerides increased from 95.6 to 175.8 mg/dL comparing lowest to highest quintiles of fasting insulin, respectively. These associations were slightly stronger in lean than obese subjects and in nondiabetic versus diabetic individuals particularly for 2-hour insulin levels. Multiple linear regression analysis adjusting for several adiposity measures separately (body mass index (BMI), subscapular skinfold thickness, waist circumference, and waist/hip ratio) and other cardiovascular risk factors attenuated associations slightly but they still remained statistically significant. Estimated differences in HDL cholesterol across extreme quintiles of fasting insulin were reduced slightly from 15.6 mg/dL with adjustment for age to 12.5 mg/dL with adjustment for age and BMI, and to 11.3 mg/dL with adjustment for age, BMI, and cardiovascular risk factors. CONCLUSIONS: Insulin concentration was strongly and independently associated with HDL cholesterol and triglycerides in this cohort of elderly Japanese-American men. Since this study was cross-sectional, further investigation is required to determine whether elevated insulin levels are causally related to dyslipidemia.

Prolonged QTc interval, impaired pulmonary function, and a very lean body mass jointly predict all-cause mortality in elderly men.

PURPOSE: Assess the joint impact of prolonged QTc interval (QT interval corrected for heart rate), impaired lung function, and low body weight on all-cause mortality. METHODS: This is a population-based, prospective study of the Honolulu Heart Program cohort, performed in Oahu Island, Hawaii, during the 1991-1993 fourth examination of cohort survivors. The participants were 3056 Japanese-American men, 71 to 93 years of age. The measurement consisted of: 1) instrument calculated, heart rate corrected QT interval; 2) one second forced expiratory volume (FEV1) as a percentage of age- and height-predicted FEV1; and 3) body mass index (BMI, kg/m2). Relations of subsequent 3 1/2 year, on average, mortality rates with high risk states of these variables are determined. High risk states are QTc > 440 msec, percent predicted FEV1 < or = 80%, and BMI < or = 21 kg/m2. RESULTS: Mortality rates synergistically increase among groups with one, two, or three high risk states. Men having all three high risk states are seven times more likely to die in the follow-up period than men with no high risk conditions. Very thin men having one other high risk state, pulmonary impairment or prolonged QTc, are four times more likely to die. Excluding diabetics, active smokers, or men taking drugs affecting QT interval does not alter findings. Excluding prevalent coronary heart disease decreases mortality rates among joint high risk groups. CONCLUSION: Results are consistent with clinical studies identifying an autonomic neuropathy associated with wasting chronic lung disease, prolonged QTc, and mortality. Aging populations in developed nations will increase the prevalence of diseases associated with these conditions in decades to come.

Hyperinsulinemia and cardiovascular disease in elderly men: the Honolulu Heart Program.

Hyperinsulinemia has been associated with cardiovascular disease (CVD), but whether this relation is independent of other CVD risk factors is uncertain. Most studies have focused on coronary heart disease (CHD), but few have included peripheral vascular disease (PVD) and stroke. Moreover, evidence in elderly and minority populations is limited. Between 1991 and 1993, 3562 elderly (71 to 93 years) Japanese-American men from the Honolulu Heart Program were examined and had fasting insulin levels measured. Hyperinsulinemia, defined as a fasting insulin > or =95th percentile among nonobese men with normal glucose tolerance and no diabetic history or medication use, was observed in 22% of the population. Subjects with hyperinsulinemia had a more adverse CVD risk factor profile and had higher age-adjusted prevalences of CHD, angina, PVD, thromboembolic stroke, and hemorrhagic stroke compared with those without hyperinsulinemia. Age-adjusted fasting insulin levels but not 2-hour levels were also significantly elevated (P<.01) in those with prevalent CVD compared with those without. In logistic regression analyses, adjustment for multiple CVD risk factors attenuated the relations of hyperinsulinemia with CHD, angina, and PVD to nonsignificant levels, whereas those involving thromboembolic and hemorrhagic stroke were strengthened and remained significant (odds ratios=2.27 and 7.53, 95% confidence intervals=1.25 to 4.13 and 1.65 to 34.25, respectively). When multivariate analyses were restricted to nondiabetic subjects, associations were slightly weaker and in general nonsignificant. Nondiabetic men with thromboembolic stroke were twice as likely to have hyperinsulinemia as those who were stroke-free, although this association was of borderline significance (odds ratio= 1.99, 95% confidence interval=0.95 to 4.17, P=.069). In subjects with elevated total cholesterol levels, somewhat stronger associations were observed for PVD and stroke but not for CHD. Although further prospective studies are indicated, particularly for PVD and stroke, these cross-sectional results are consistent with an indirect role for insulin in CVD, wherein hyperinsulinemia or an underlying insulin-resistant state may adversely affect other CVD risk factors or serve as a marker for an atherogenic or thrombogenic state.

Effects of walking on mortality among nonsmoking retired men.

BACKGROUND: The potential benefit of low-intensity activity in terms of longevity among older men has not been clearly documented. We examined the association between walking and mortality in a cohort of retired men who were nonsmokers and physically capable of participating in low-intensity activities on a daily basis. METHODS: We studied 707 nonsmoking retired men, 61 to 81 years of age, who were enrolled in the Honolulu Heart Program. The distance walked (miles per day) was recorded at a base-line examination, which took place between 1980 and 1982. Data on overall mortality (from any cause) were collected over a 12-year period of follow-up. RESULTS: During the follow-up period, there were 208 deaths. After adjustment for age, the mortality rate among the men who walked less than 1 mile (1.6 km) per day was nearly twice that among those who walked more than 2 miles (3.2 km) per day (40.5 percent vs. 23.8 percent, P=0.001). The cumulative incidence of death after 12 years for the most active walkers was reached in less than 7 years among the men who were least active. The distance walked remained inversely related to mortality after adjustment for overall measures of activity and other risk factors (P=0.01). CONCLUSIONS: Our findings in older physically capable men indicate that regular walking is associated with a lower overall mortality rate. Encouraging elderly people to walk may benefit their health.

The synergy of low lung function and low body mass index predicting all-cause mortality among older Japanese-American men.

OBJECTIVE: To assess the joint characteristics of low standardized weight and compromised pulmonary function in predicting all-cause mortality. DESIGN: A population-based, prospective cohort study. SETTING: Oahu Island, Hawaii. PARTICIPANTS: Surviving Japanese-American men of the Honolulu Heart Program cohort, 71 to 93 years of age (N = 3059). MEASUREMENTS: Body mass index (BMI-weight in kilograms/square of height in meters) and 1-second forced expiratory volume (FEV1) as a percentage of age- and height-predicted FEV1 from the 1991 to 1993 examination of the cohort. Mortality data derived from the ongoing tracking of deaths of the cohort. Relations of selected risk factors among joint levels of BMI (< or = 21, > 21 to < 25, > or = 25 kg/m2) and percent predicted FEV1 (< or = 70%, > 70%) were determined. The impact of these covariates on relations between joint BMI/percent predicted FEV1 levels and subsequent all-cause mortality was assessed. RESULTS: The highest age-adjusted mortality rate (91.9 deaths per 1000 person-years) was noted among men characterized by the joint conditions of percent predicted FEV1 < or = 70% and BMI < or = 21 kg/m2. This rate was 4.0 times the mortality rate of a "healthy" reference group characterized by percent predicted FEV1 > 70% and 21 < BMI < 25 kg/m2. This rate ratio is attenuated to 3.2 upon statistical control for measures of current and past smoking behavior. Among the three strata of BMI, statistical interaction is reflected in a heterogeneity of mortality rate differences (49.7, 21.8, -9.6 deaths/person-year, respectively) and rate ratios (2.18, 1.98, .66, respectively) comparing men with percent predicted FEV1 < or = 70% to > 70%. CONCLUSION: Joint loss of pulmonary function and relative weight is predictive of subsequent all-cause mortality in excess of additive or multiplicative effects of each condition separately. Smoking behavior may contribute to this observation.