Biomedical subjects

Duanping Liao

Publications and source records attributed to Duanping Liao.

18 recordsLinked to original sources

PubMed2006

Age-related macular degeneration is associated with incident myocardial infarction among elderly Americans.

OBJECTIVE: To investigate whether age-related macular degeneration (AMD) is associated with the development of myocardial infarction (MI) among elderly Americans. DESIGN: Population-based cross-sectional and cohort study. PARTICIPANTS: Five percent random sample of 2000 to 2003 Medicare enrollees. METHODS: The cross-sectional study included the first 2-year (2000 and 2001) enrollees who were aged > or =65 years (n = 1,519,086). The cohort study included only baseline MI-free enrollees (n = 1445677). MAIN OUTCOME MEASURES: Chronic conditions (AMD and type, history of MI, hypertension, and diabetes) were defined based on any occurrence of relevant International Classification of Diseases 9 codes in relevant diagnosis fields of the baseline Medicare claim files. A total of 56611 incident MI cases were identified from the follow-up data (2002 and 2003). RESULTS: Baseline mean age was 76 years, with 60% women and 88% whites. The prevalence of neovascular AMD was 2.2% (2.3% in women vs. 1.7% in men and 2.3% in whites vs. 1.2% in blacks; P<0.01 for both gender and race differences). The prevalence of nonneovascular AMD was 8.8% (9.9% in women vs. 7.3% in men and 9.5% in whites vs. 4.3% in blacks; P<0.01 for both gender and race differences). Baseline age-, gender-, and race-adjusted prevalences of hypertension, diabetes, and history of MI were 75%, 33%, and 5.00%, respectively, in the neovascular AMD group. In contrast, they were 73%, 27%, and 4.68% in the nonneovascular AMD group, and 65%, 25%, and 4.54% in the non-AMD group (P<0.01 for comparing the prevalence in neovascular and nonneovascular AMD vs. non-AMD groups). Prospectively, baseline age-, gender-, race-, hypertension-, and diabetes-adjusted 2-year incident odds ratios and 95% confidence intervals of MI associated with AMD are 1.19 (1.16-1.22) for all persons with AMD, 1.26 (1.20-1.33) for neovascular AMD, and 1.18 (1.14-1.21) for nonneovascular AMD. CONCLUSIONS: AMD is associated with older age, female gender, being white, and having a history of MI, hypertension, and diabetes. Furthermore, presence of AMD, especially neovascular AMD, is prospectively associated with a higher risk of incident MI. These findings, if confirmed by other studies that control for smoking and other lifestyle covariables, suggest the possibility of shared common antecedents between MI and AMD.

Age Factors↗

PubMed2006

Is early age-related macular degeneration related to carotid artery stiffness? The Atherosclerosis Risk in Communities Study.

BACKGROUND/PURPOSE: Atherosclerosis and vascular stiffness have been implicated in the pathogenesis of age-related macular degeneration (AMD). The association of carotid artery stiffness, a measure of arterial elasticity reflecting early atherosclerosis, with early AMD, was examined in this study. METHODS: A population-based, cross-sectional study of 9954 middle-aged people (age range 51-72 years). The presence of AMD signs was determined from fundus photographs according to the Wisconsin grading protocol. Carotid arterial stiffness was measured from high-resolution ultrasonic echo tracking of the left common carotid artery, and was defined as an adjusted arterial diameter change (AADCmu). A smaller AADC reflects greater carotid artery stiffness. The associations of pulse pressure and carotid artery intima-media thickness (IMT) with early AMD signs were also analysed. RESULTS: In the study population, 454 (4.6%) had early AMD. The mean (SD) AADC was 403 (127) mu. After adjusting for age, sex, race/centre, education, cigarette smoking, fasting glucose, lipid profile and inflammatory markers, a smaller AADC was found to be not associated with early AMD (odds ratio 0.94; 95% confidence interval, 0.71 to 1.25) or its component lesions. Other measures of arterial stiffness (pulse pressure) and atherosclerosis (carotid IMT) were also not associated with early AMD. CONCLUSIONS: Carotid artery stiffness was not associated with signs of early AMD in this middle-aged population. These data provide no evidence of a link between age-related elastoid changes and early atherosclerotic processes in the carotid arteries and early AMD.

Aged↗

PubMed2006

Accuracy of commercial geocoding: assessment and implications.

BACKGROUND: Published studies of geocoding accuracy often focus on a single geographic area, address source or vendor, do not adjust accuracy measures for address characteristics, and do not examine effects of inaccuracy on exposure measures. We addressed these issues in a Women's Health Initiative ancillary study, the Environmental Epidemiology of Arrhythmogenesis in WHI. RESULTS: Addresses in 49 U.S. states (n = 3,615) with established coordinates were geocoded by four vendors (A-D). There were important differences among vendors in address match rate (98%; 82%; 81%; 30%), concordance between established and vendor-assigned census tracts (85%; 88%; 87%; 98%) and distance between established and vendor-assigned coordinates (mean rho [meters]: 1809; 748; 704; 228). Mean rho was lowest among street-matched, complete, zip-coded, unedited and urban addresses, and addresses with North American Datum of 1983 or World Geodetic System of 1984 coordinates. In mixed models restricted to vendors with minimally acceptable match rates (A-C) and adjusted for address characteristics, within-address correlation, and among-vendor heteroscedasticity of rho, differences in mean rho were small for street-type matches (280; 268; 275), i.e. likely to bias results relying on them about equally for most applications. In contrast, differences between centroid-type matches were substantial in some vendor contrasts, but not others (5497; 4303; 4210) p(interaction) < 10(-4), i.e. more likely to bias results differently in many applications. The adjusted odds of an address match was higher for vendor A versus C (odds ratio = 66, 95% confidence interval: 47, 93), but not B versus C (OR = 1.1, 95% CI: 0.9, 1.3). That of census tract concordance was no higher for vendor A versus C (OR = 1.0, 95% CI: 0.9, 1.2) or B versus C (OR = 1.1, 95% CI: 0.9, 1.3). Misclassification of a related exposure measure--distance to the nearest highway--increased with mean rho and in the absence of confounding, non-differential misclassification of this distance biased its hypothetical association with coronary heart disease mortality toward the null. CONCLUSION: Geocoding error depends on measures used to evaluate it, address characteristics and vendor. Vendor selection presents a trade-off between potential for missing data and error in estimating spatially defined attributes. Informed selection is needed to control the trade-off and adjust analyses for its effects.

Journal Article↗

PubMed2006

GIS approaches for the estimation of residential-level ambient PM concentrations.

Spatial estimations are increasingly used to estimate geocoded ambient particulate matter (PM) concentrations in epidemiologic studies because measures of daily PM concentrations are unavailable in most U.S. locations. This study was conducted to a) assess the feasibility of large-scale kriging estimations of daily residential-level ambient PM concentrations, b) perform and compare cross-validations of different kriging models, c) contrast three popular kriging approaches, and d) calculate SE of the kriging estimations. We used PM data for PM with aerodynamic diameter </= 10 microm (PM10) and aerodynamic diameter </= 2.5 microm (PM2.5) from the U.S. Environmental Protection Agency for the year 2000. Kriging estimations were performed at 94,135 geocoded addresses of Women's Health Initiative study participants using the ArcView geographic information system. We developed a semiautomated program to enable large-scale daily kriging estimation and assessed validity of semivariogram models using prediction error (PE) , standardized prediction error (SPE) , root mean square standardized (RMSS) , and SE of the estimated PM. National- and regional-scale kriging performed satisfactorily, with the former slightly better. The average PE, SPE, and RMSS of daily PM10 semivariograms using regular ordinary kriging with a spherical model were 0.0629, -0.0011, and 1.255 microg/m3, respectively ; the average SE of the estimated residential-level PM10 was 27.36 microg/m3. The values for PM2.5 were 0.049, 0.0085, 1.389, and 4.13 microg/m3, respectively. Lognormal ordinary kriging yielded a smaller average SE and effectively eliminated out-of-range predicted values compared to regular ordinary kriging. Semiautomated daily kriging estimations and semivariogram cross-validations are feasible on a national scale. Lognormal ordinary kriging with a spherical model is valid for estimating daily ambient PM at geocoded residential addresses.

Air Movements↗

PubMed2005

Association of criteria pollutants with plasma hemostatic/inflammatory markers: a population-based study.

To elucidate the health effects of air pollution, the short-term association of criteria pollutants (particles <10 microm in diameter [PM(10)], O(3), CO, NO(2), and SO(2)) with hemostatic and inflammatory markers were examined using a population-based sample of 10,208 middle-age males and females of the biracial cohort of Atherosclerosis Risk in Communities (ARIC) study. For each participant, we calculated the following pollutant exposures 1-3 days prior to the randomly allocated cohort examination date: PM(10), CO, NO(2), and SO(2) as 24-h averages, and O(3) as an 8-h average of the hourly measures. The hemostatic/inflammatory factors included fibrinogen, factor VIII-C, von Willebrand factor (vWF), albumin, and white blood cell count (WBC). Linear regression models were used to adjust for cardiovascular disease (CVD) risk factors, demographic and socioeconomic variables, and relevant meteorological variables. One standard deviation (SD) increment of PM(10) (12.8 microg/m(3)) was significantly (P < 0.05) associated with 3.93% higher of vWF among diabetics and 0.006 g/dl lower of serum albumin among persons with a history of CVD. One SD increment of CO (0.60 p.p.m.) was significantly (P < 0.01) associated with 0.018 g/dl lower of serum albumin. Significant curvilinear associations, indicative of threshold effects, for PM(10) with factor VIII-C, O(3) with fibrinogen and vWF, and SO(2) with factor VIII-C, WBC, and serum albumin were found. This population-based study suggest that the hemostasis/inmflammation markers analyzed, which are linked to higher risk of CHD, are associated adversely with environmentally relevant ambient pollutants, with the strongest associations in the upper range of the pollutant distributions, and in persons with a positive history of diabetes and CHD.

Air Pollutants↗

PubMed2005

Diabetes, glucose, insulin, and heart rate variability: the Atherosclerosis Risk in Communities (ARIC) study.

OBJECTIVE: To describe the progression of autonomic impairment among individuals with diabetes and pre-diabetic metabolic impairments. RESEARCH DESIGN AND METHODS: We investigated the consequence of diabetes and pre-diabetic metabolic impairments on the 9-year change in heart rate variability (HRV) in a population-based cohort of 6,245 individuals aged 45-64 years at baseline and cross-sectional associations among 9,940 individuals. RESULTS: Diabetic subjects had a more rapid temporal decrease in HRV conditional on baseline HRV than nondiabetic subjects. Adjusted mean annual changes (95% CI) (ms/year) in the SD of all normal-to-normal R-R intervals were -0.65 (-0.69 to -0.61) for those with normal fasting glucose vs. -0.95 (-1.09 to -0.81) for diabetic subjects, in root mean square of successive differences in normal-to-normal R-R intervals -0.35 (-0.39 to -0.30) vs. -0.66 (-0.82 to -0.51), and in R-R interval 6.70 (6.37-7.04) vs. 3.89 (2.72-5.05). While we found cross-sectional associations between decreased HRV and diabetes and nondiabetic hyperinsulinemia and a weak inverse association with fasting glucose, neither impaired fasting glucose nor nondiabetic hyperinsulimenia was associated with a measurably more rapid decline in HRV than normal. CONCLUSIONS: Cardiac autonomic impairment appears to be present at early stages of diabetic metabolic impairment, and progressive worsening of autonomic cardiac function over 9 years was observed in diabetic subjects. The degree to which pre-diabetic metabolic impairments in insulin and glucose metabolism contribute to decreases in cardiac autonomic function remains to be determined.

Arteriosclerosis↗

PubMed2004

Accuracy and repeatability of commercial geocoding.

The authors estimated accuracy and repeatability of commercial geocoding to guide vendor selection in the Life Course Socioeconomic Status, Social Context and Cardiovascular Disease study (2001-2002). They submitted 1,032 participant addresses (97% in Maryland, Minnesota, Mississippi, or North Carolina) to vendor A twice over 9 months and measured repeatability as agreement between levels of address matching, discordance (%) between statistical tabulation areas, and median distance (d, in meters) and bearing (theta;, in degrees) between coordinates assigned on each occasion (H(o):Sigma(i)( = 1 -->) (n) [theta;(i) /n] = 180 degrees ). They also submitted 75 addresses of nearby air pollution monitors (77% urban/suburban; 69% residential/commercial) to vendors A and B and then measured accuracy by comparing vendor- and US Environmental Protection Agency (EPA)-assigned geocodes using the above measures. Repeatability of geocodes assigned by vendor A was high (kappa = 0.90; census block group discordance = 5%; d < 1 m; theta; = 177 degrees ). The match rate for EPA monitor addresses was higher for vendor B versus A (88% vs. 76%), but discordance at census block group, tract, and county levels also was, respectively, 1.4-, 1.9-, and 5.0-fold higher for vendor B. Moreover, coordinates assigned by vendor B were further from those assigned by the EPA (d = 212 m vs. 149 m; theta; = 131 degrees vs. 171 degrees ). These findings suggest that match rates, repeatability, and accuracy should be used to guide vendor selection.

Aged↗

PubMed2004

Association of higher levels of ambient criteria pollutants with impaired cardiac autonomic control: a population-based study.

An association between air pollution and increased cardiovascular disease (CVD) mortality has been reported, but underlying mechanisms are unknown. The authors examined short-term associations between ambient pollutants (particulate matter less than 10 microm in aerodynamic diameter (PM10), ozone, carbon monoxide, nitrogen dioxide, and sulfur dioxide) and cardiac autonomic control using data from the fourth cohort examination (1996-1998) of the population-based Atherosclerosis Risk in Communities Study. For each participant, the authors calculated PM10 and gaseous pollutant exposures as 24-hour averages and ozone exposure as an 8-hour average 1 day prior to the randomly allocated examination date. They calculated 5-minute heart rate variability indices and used logarithmically transformed data on high-frequency (0.15-0.40 Hz) and low-frequency (0.04-0.15 Hz) power, standard deviation of normal R-R intervals, and mean heart rate. Linear regression was used to adjust for CVD risk factors and demographic, socioeconomic, and meteorologic variables. Regression coefficients for a one-standard-deviation increase in PM10 (11.5 microg/m3) were -0.06 ms2 (standard error (SE), 0.018), -1.03 ms (SE, 0.31), and 0.32 beats/minute (SE, 0.158) for log-transformed high-frequency power, standard deviation of normal R-R intervals, and heart rate, respectively. Similar results were found for gaseous pollutants. These cross-sectional findings suggest that higher ambient pollutant concentrations are associated with lower cardiac autonomic control, especially among persons with existing CVD, and highlight a putative mechanism through which air pollution is associated with CVD.

Air Pollutants↗

PubMed2004

Relationship between carotid artery stiffness and retinal arteriolar narrowing in healthy middle-aged persons.

BACKGROUND AND PURPOSE: Both carotid atherosclerosis and cerebral arteriolosclerosis are associated with stroke. However, the relationship between carotid atherosclerosis and cerebral arteriolosclerosis is unknown. We examined the association between carotid artery stiffness, a marker of early atherosclerosis, and retinal arteriolar narrowing, a marker of arteriolosclerosis, in healthy middle-aged people. METHODS: This population-based, cross-sectional study involved 8031 men and women 45 to 64 years of age. Carotid arterial stiffness was estimated from high-resolution ultrasonic echo tracking of the left common carotid artery and was defined as adjusted arterial diameter change (AADC, micro, adjusted for diastolic blood pressure, pulse pressure and pulse pressure squared, and diastolic arterial diameter and height, with smaller AADC reflecting greater arterial stiffness). Generalized retinal arteriolar narrowing was estimated from measurements of diameters of retinal vessels from digitized retinal photographs and summarized as the arteriole-to-venule ratio (AVR, with smaller AVR indicating greater retinal arteriolar narrowing). RESULTS: After controlling for age, sex, ethnicity, hypertension, diabetes, and cigarette smoking, decreasing AADC was associated with decreasing AVR. The mean AADCs, comparing the lowest and highest quartiles of AVR, were 394 (SE, 4) and 409 (SE, 4) micro, respectively (P<0.01). The pattern of the graded association between carotid arterial stiffness and generalized retinal arteriolar narrowing was similar among persons with and without hypertension. CONCLUSIONS: Greater stiffness of the carotid arteries is related to generalized narrowing of the retinal arterioles independent of blood pressure and other vascular factors. This supports a relationship between macrovascular and microvascular disease processes important in stroke pathogenesis.

Arterioles↗

PubMed2003

Lung function and incident coronary heart disease: the Atherosclerosis Risk in Communities Study.

The authors examined the association between lung function, as measured by forced expiratory volume in 1 second (FEV1) and forced vital capacity, and the 10-year incidence of coronary heart disease among 14,480 participants in the Atherosclerosis Risk in Communities Study (1987-1998). Separate proportional hazards models were used for FEV1 and forced vital capacity, with gender-specific lung function quartiles and lung function x gender interaction terms. An association between lung function and coronary heart disease was observed in both genders and was stronger among women. After adjustment for age, race, study center, height, height squared, smoking, and cardiovascular disease risk factors, the hazard ratios for the first (lowest), second, and third quartiles of FEV1 were 3.70 (95% confidence interval (CI): 2.19, 6.24), 2.54 (95% CI: 1.49, 4.32), and 2.25 (95% CI: 1.31, 3.87) for women and 1.51 (95% CI: 1.07, 2.13), 1.59 (95% CI: 1.15, 2.20), and 1.52 (95% CI: 1.10, 2.09) for men. After stratification by smoking status, associations were observed in each smoking group for women, while those in men were weaker and less consistent. Similar results were obtained for forced vital capacity. This analysis indicates an association between lung function and incident coronary heart disease that may be stronger in women than in men.

Black or African American↗

PubMed2003

Hypertension, blood pressure, and heart rate variability: the Atherosclerosis Risk in Communities (ARIC) study.

Dysregulation of the autonomic nervous system has been implicated in the development of hypertension. Heart rate variability is a noninvasive tool to quantitatively estimate cardiac autonomic activity and has been used to document decreased cardiac autonomic activity in hypertension. The ability of decreased heart rate variability to predict incident hypertension has not been well studied, and there are no studies of whether hypertension leads to changes in heart rate variability. We investigated the temporal sequence linking hypertension, blood pressure, and heart rate variability in a population-based cohort of 11 061 individuals aged 45 to 54 years at baseline. Individuals with hypertension had decreased heart rate variability at baseline, and this association was present across the full blood pressure range. Among 7099 individuals without hypertension at baseline, low heart rate variability predicted greater risk of incident hypertension over 9 years of follow-up. The hazard ratio (95% confidence interval [CI]) for the lowest compared with the highest quartile of the standard deviation of normal-to-normal R-R intervals was 1.24 (95% CI, 1.10-1.40), for the root mean square of successive differences in normal-to-normal R-R intervals was 1.36 (95% CI, 1.21-1.54), and for R-R interval was 1.44 (95% CI, 1.27-1.63). Over 9 years, there was no measurable difference in the rate of change in heart rate variability among those with and without hypertension, although the differences in heart rate variability at follow-up were smaller than those at baseline. These findings thus support the thesis that the autonomic nervous system is involved in the development of hypertension, yet suggest that differences in the autonomic profile of hypertensives and normotensives do not increase with time.

Blood Pressure↗

PubMed2003

Prospective investigation of autonomic nervous system function and the development of type 2 diabetes: the Atherosclerosis Risk In Communities study, 1987-1998.

BACKGROUND: Autonomic nervous system (ANS) dysfunction has been correlated with fasting insulin and glucose, independent of clinically diagnosed diabetes. We tested whether men and women (aged 45 to 64 years) from the Atherosclerosis Risk In Communities study (n=8185) with ANS dysfunction, estimated by high heart rate (HR) and low HR variability (HRV), were at increased risk for developing type 2 diabetes. METHODS AND RESULTS: Supine HR and HRV indices were measured for 2 minutes at baseline; indices were divided into quartiles for analyses. From 1987 to 1998 (mean follow-up 8.3 years), there were 1063 cases of incident diabetes. The relative risk (RR) of developing diabetes for participants with low-frequency (LF) power (0.04 to 0.15 Hz) HRV in the lowest quartile (<7.7 ms2) compared with the highest quartile (> or =38.9 ms2) was 1.2 (95% CI 1.0-1.4) after adjustment for age, race, sex, study center, education, alcohol drinking, current smoking, prevalent coronary heart disease, physical activity, and body mass index. Participants in the uppermost (>72.7 bpm) versus the lowest (< or =60.1 bpm) quartile of HR had a 60% increased risk (95% CI 33%-92%) of developing diabetes. Results were similar when the sample was restricted to participants with normal fasting glucose (glucose <6.1 mmol/L) at baseline (n=7192) or when adjusted for baseline glucose (HR quartile 4 versus quartile 1, RR=1.4, 95% CI 1.2-1.7). CONCLUSIONS: These findings suggest that ANS dysfunction may be associated with the development of diabetes in healthy adults.

Arteriosclerosis↗

PubMed2003

Prospective association between hormone replacement therapy, heart rate, and heart rate variability. The Atherosclerosis risk in communities study.

Hormone replacement therapy is universally associated with coronary heart disease (CHD) in observational studies, but it is unknown whether this association is mediated by the autonomic nervous system. We tested the hypothesis that postmenopausal hormone replacement therapy was associated with more favorable heart rate (HR) and heart rate variability (HRV) in a population sample of women (n=2,621). Hormone therapy use was measured at four examinations beginning in 1987. Supine HR and HRV indices were measured for 6 minutes at the final examination (1996-1998). In unadjusted linear regression models, hormone therapy was associated with lower HR (hormone use=64.7 vs. never=65.7 beats/min, P=.01) and higher HRV. However, following adjustment for age and CHD risk factors, both associations were eliminated. Results from this observational study suggest that hormone therapy is not associated with HR or HRV. These analyses should be replicated in a randomized trial.

Autonomic Nervous System↗

PubMed2003

A prospective evaluation of the risk of QT prolongation with hormone replacement therapy: the atherosclerosis risk in communities study.

PURPOSE: Prolongation of the QT interval is associated with an increased risk of arrhythmia, coronary heart disease (CHD), and mortality. Estrogens and androgens have been proposed as a causal factor in QT lengthening. We tested whether postmenopausal hormone replacement therapy was associated with prolonged QT intervals in a healthy population sample of women (mean age=54). METHODS: Women (n=3103) were asked about estrogen (ERT) and progestin plus estrogen (PERT) replacement therapy use at 4 examinations over 9 years. Electrocardiographic QT intervals were measured and corrected for heart rate using the QT Index (QTI) and Bazett's correction. QT prolongation was defined as QTI>110% and a change from baseline of >or=4%. RESULTS: Heart rate corrected QT length was moderately but significantly (p<0.01) greater, and the risk of QT prolongation was nearly twice (Odds Ratio=1.9, 95% Confidence Interval: 1.2-2.0) that in women who used ERT compared with never users. PERT use was not significantly associated with QT length. CONCLUSIONS: The potential for slight increases in QT length over time, and an increased risk of QT prolongation with ERT use identified in this observational study, are important concerns that should be further explored in randomized trials.

Arteriosclerosis↗

PubMed2002

Does the cardiac autonomic response to postural change predict incident coronary heart disease and mortality? The Atherosclerosis Risk in Communities Study.

This study evaluated whether small shifts in cardiac autonomic balance with standing, as measured by heart rate variability (HRV), were prospectively associated with incident coronary heart disease (CHD) and mortality. Both Black and White men and women aged 45-64 years from the Atherosclerosis Risk in Communities Study (n = 9,267) were followed from 1987 to 1997 for myocardial infarction (n = 296), fatal CHD (n = 63), and non-CHD mortality (n = 533). HRV indices and mean R-R interval length (inverse of heart rate) were measured in the supine and standing positions for 2 minutes each; HRV shift was calculated as the difference between positions. After adjustment for demographic characteristics and medication use, HRV in each position was significantly inversely related to events in Cox proportional hazards models. With the exception of R-R interval length shift and myocardial infarction (hazard ratio = 1.42, 95% confidence interval: 1.02, 1.98 for the smallest vs. the largest quartile), there was no association between HRV shift and the other events. Despite clinical research suggesting that HRV shift with standing is a more sensitive measure of autonomic balance than is HRV in one position, simple measures such as heart rate change and supine and standing HRV were better predictors of events.

Autonomic Nervous System↗

PubMed2002

Correlates of the shift in heart rate variability with an active postural change in a healthy population sample: The Atherosclerosis Risk In Communities study.

BACKGROUND: The heart rate variability (HRV) response to postural change is a sensitive measure of the shift in autonomic balance from parasympathetic to sympathetic predominance that, when attenuated or absent, has been correlated with prevalent disease in patient populations. In a healthy population sample, we evaluated whether the shift in HRV with postural change differed by demographic characteristics as well as whether it differed between participants with established coronary heart disease (CHD) risk factors and their counterparts. METHODS: HRV was measured for 2 minutes in the supine and standing positions in a biracial sample of men and women (aged 45-64 years) without clinical CHD from the Atherosclerosis Risk In Communities Study (n = 7686). Mean differences among supine and standing mean R-R interval lengths, the SD of R-R intervals, and high-frequency power (HF) were compared by demographic characteristics (age, race, and sex) and CHD risk factors (smoking, obesity, physical activity, hypertension, and diabetes). Multivariable linear regression models were used to adjust for demographic characteristics. RESULTS: Smaller changes in R-R intervals and larger changes in SD of R-R intervals with standing were found among participants who were obese, less physically active than their counterparts, hypertensive, and diabetic. Smaller changes in HF were identified in male and white participants, but there were no differences in HF by CHD risk factors once models were adjusted for demographic characteristics. CONCLUSIONS: These simple noninvasive measures can be used to detect differences in cardiac autonomic balance that may be markers for autonomic impairment in healthy adults.

Age Factors↗

PubMed2002

Lower heart rate variability is associated with the development of coronary heart disease in individuals with diabetes: the atherosclerosis risk in communities (ARIC) study.

The objective of this study was to test prospectively in a population sample whether individuals with impaired heart rate variability (HRV) are at increased risk of developing coronary heart disease (CHD) and of non-CHD mortality and to test whether this relationship is more pronounced among individuals with diabetes. We examined the association between HRV and incident CHD and non-CHD mortality in a cohort of 11,654 men and women aged 45-64 years at intake, from the biracial, population-based Atherosclerosis Risk in Communities Study. Supine, resting, 2-min beat-to-beat heart rate data were collected at the baseline examination. High frequency (HF; 0.15-0.40 Hz) and low frequency (LF; 0.04-0.15 Hz) spectral powers, LF/HF ratio, normalized HF and LF, the standard deviation of all normal R-R intervals (SDNN), and the mean of the sum of the squared differences between adjacent normal R-R intervals (MSSD) were used as the conventional indexes of HRV to measure cardiac autonomic control. From this cohort, 635 cases of incident CHD (including 346 cases of incident myocardial infarction [MI] and 82 cases of fatal CHD), and 623 non-CHD deaths were identified and validated after an average of 8 years of follow-up. Among individuals with diabetes, the multivariable adjusted proportional hazards ratios (95% CI) were 2.03 (1.28-3.23), 1.60 (1.12-2.27), 1.50 (0.65-3.42), and 1.27 (0.84-1.91) for incident MI, incident CHD, fatal CHD, and non-CHD deaths, respectively, comparing the lowest quartile to the upper most three quartiles of HF. A similar pattern of associations was found for LF, SDNN, and MSSD. By contrast, there was no consistent pattern of associations among individuals without diabetes. At the population level, a lower HRV (reflective of impaired cardiac autonomic control) is statistically significantly related to the development of CHD among individuals with diabetes, independent of markers of the duration/severity of the glucose metabolism impairment. These data suggest a contribution of an impaired cardiac autonomic control to the risk of CHD among individuals with diabetes.

Autonomic Nervous System↗

PubMedDate not supplied

Lung function and long-term exposure to air pollutants in middle-aged American adults.

The authors examined the association of long-term exposure to ozone (03) and ambient particulate matter <10 microm in diameter (PM10) with pulmonary function by using cross-sectional data of 10,240 middle-aged adults who participated in the Atherosclerosis Risk in Communities study. Air-pollution data came from the US Environmental Protection Agency's Aerometric Information Retrieval System. After an adjustment for important covariates, the inverse associations with forced vital capacity or forced expiratory volume in 1 second were observed separately for 03 and PM10). These associations were stronger among smokers than among the nonsmokers; among users of respiratory medications than among nonusers; and among participants currently experiencing respiratory symptoms than among those without symptoms. However, an additional adjustment for the study center eliminated the PM10 association. Moreover, center-specific associations between PM10 and pulmonary function were not significant, possibly as a result of the homogeneity of within-center exposures.

Air Pollutants↗