Parathyroid hormone concentration and risk of cardiovascular diseases: the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

According to a recent meta-analysis, parathyroid hormone (PTH) excess is associated with increased cardiovascular disease (CVD) risk, but existing studies are limited. We examined in a prospective study the association of PTH with the incidence of CVD, taking into account vitamin D and other confounding variables.

METHODS

The ARIC study measured PTH using a second-generation assay (Roche, Indianapolis, IN) in stored serum samples from 1990 to 1992 and related levels in 10,392 adults to incident cardiovascular outcomes (coronary heart disease [n = 808], heart failure [n = 1,294], stroke [n = 586], peripheral artery disease [n = 873], atrial fibrillation [n = 1,190], and CVD mortality [n = 647]) through 2010 (median follow-up 19 years).

RESULTS

Contrary to the hypothesis, PTH level was not associated positively with any CVD outcome. The associations of incident heart failure, peripheral artery disease, and CVD mortality with PTH actually were weakly inverse (P trend = .02-.04) in the most fully adjusted models. For example, the hazard ratios across PTH quartiles were 1.00, 1.07, 1.07, and 0.96 (P trend = .74) for coronary heart disease incidence and were 1.00, 0.69, 0.74, and 0.74 (P trend = .02) for CVD mortality. Patterns were similar when restricted to participants with normal baseline kidney function.

CONCLUSIONS

This large prospective study failed to support the hypothesis that elevated PTH is an independent risk marker for incident CVD. When our data were added to the previous meta-analysis, the pooled hazard ratio remained statistically significant but weakened.

Serum 25-hydroxyvitamin D and risk of venous thromboembolism: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Some evidence suggests that an inadequate vitamin D level may increase the risk for atherosclerotic cardiovascular disease. Whether a low vitamin D level plays a role in venous thromboembolism (VTE), that is, venous thrombosis and pulmonary embolism, is largely unexplored.

OBJECTIVES

We tested prospectively, in the Atherosclerosis Risk in Communities (ARIC) cohort, whether the serum level of 25-hydroxyvitamin D (25[OH]D) is inversely associated with VTE incidence, and whether it partly explains the African American excess of VTE in the ARIC Study.

PATIENTS AND METHODS

We measured 25(OH)D by using mass spectroscopy in stored samples of 12 752 ARIC Study participants, and followed them over a median of 19.7 years (1990-1992 to 2011) for the incidence of VTE (n = 537).

RESULTS

The seasonally adjusted 25(OH)D level was not associated with VTE incidence. In a model adjusted for age, race, sex, hormone replacement therapy, and body mass index, the hazard ratios of VTE across 25(OH)D quintiles 5 (high) to 1 (low) were: 1 (ref.), 0.84 (95% confidence interval [CI] 0.65-1.08), 0.88 (95% CI 0.68-1.13), 1.04 (95% CI 0.78-1.38), and 0.90 (95% CI 0.64-1.27). The lowest 25(OH)D quintile contained 59% African Americans, whereas the highest quintile contained 7% African Americans. However, lower 25(OH)D levels explained little of the 63% greater VTE risk of African Americans over whites in this cohort.

CONCLUSIONS

A low 25(OH)D level was not a risk factor for VTE in this prospective study. However, the totality of the literature (three studies) suggests that a low 25(OH)D level might modestly increase VTE risk in whites, but this needs further confirmation.

Temporal trends in the occurrence and outcomes of atrial fibrillation in patients with acute myocardial infarction (from the Atherosclerosis Risk in Communities Surveillance Study)

Atrial fibrillation (AF) frequently coexists in the setting of myocardial infarction (MI), being associated with increased mortality. Nonetheless, temporal trends in the occurrence of AF complicating MI and in the prognosis of these patients are not well described. We examined temporal trends in prevalence of AF in the setting of MI and the effect of AF on prognosis in the community. We studied a population-based sample of 20,049 validated first-incident nonfatal hospitalized MIs among 35- to 74-year old residents of 4 communities in the Atherosclerosis Risk in Communities (ARIC) Study from 1987 through 2009. Prevalence of AF in the setting of MI increased from 11% to 15% during the 23-year study period. The multivariable adjusted odds ratio for prevalent AF, per 5-year increment, was 1.11 (95% confidence interval 1.04 to 1.19). Overall, in patients with MI, AF was associated with increased 1-year case fatality (odds ratio 1.47, 95% confidence interval 1.07 to 2.01) compared with those without AF. However, there was no evidence that the impact of AF on MI survival changed over time or differed over time by sex, race, or MI classification (all p values >0.10). In conclusion, co-occurrence of AF in MI slightly increased between 1987 and 2009. The adverse impact of AF on survival in the setting of MI was consistent throughout. In the setting of MI, co-occurrence of AF should be viewed as a critical clinical event, and treatment needs unique to this population should be explored further.

Serum magnesium, phosphorus, and calcium are associated with risk of incident heart failure: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Heart failure (HF) is a major source of morbidity and mortality, particularly among the elderly. Magnesium, phosphorus, and calcium are micronutrients traditionally viewed in relation to bone health or chronic kidney disease. However, they also may be associated with risk of cardiovascular disease through a broad range of physiologic roles.

OBJECTIVE

With the use of data from the Atherosclerosis Risk in Communities (ARIC) cohort, we tested the hypotheses that the incidence of HF is greater among individuals with low serum magnesium and those with high serum phosphorus and calcium.

DESIGN

A total of 14,709 African Americans (27%) and whites from the ARIC cohort [aged 45-64 y at baseline (1987-1989)] were observed through 2009. Proportional hazards regression was used to explore associations between biomarkers and incident HF. Serum calcium was corrected for serum albumin. Models were adjusted for demographics, behaviors, and physiologic characteristics.

RESULTS

A total of 2250 incident HF events accrued over a median follow-up of 20.6 y. Participants in the lowest (≤1.4 mEq/L) compared with the highest (≥1.8 mEq/L) category of magnesium were at greater HF risk (HR: 1.71; 95% CI: 1.46, 1.99). For phosphorus, there appeared to be a threshold whereby only those in the highest quintile were at greater HF risk [HR(Q5 vs Q1): 1.34; 95% CI: 1.16, 1.54]. Higher concentrations of calcium were also associated with greater risk of HF [HR(Q5 vs Q1): 1.24; 95% CI: 1.07, 1.43]. Results were not modified by race, sex, or kidney function and were similar when incident coronary heart disease was included as a time-varying covariate.

CONCLUSIONS

Low serum magnesium and high serum phosphorus and calcium were independently associated with greater risk of incident HF in this population-based cohort. Whether these biomarkers will be useful candidates for HF risk prediction or targets for prevention remains to be seen.

Vitamin D and cognitive function and dementia risk in a biracial cohort: the ARIC Brain MRI Study

BACKGROUND AND PURPOSE

Some recent studies in older, largely white populations suggest that vitamin D, measured by 25-hydroxyvitamin D [25(OH)D], is important for cognition, but such results may be affected by reverse causation. Measuring 25(OH)D in late middle age before poor cognition affects behavior may provide clearer results.

METHODS

This was a prospective cohort analysis of 1652 participants (52% white, 48% black) in the Atherosclerosis Risk in Communities (ARIC) Brain MRI Study. 25(OH)D was measured from serum collected in 1993-1995. Cognition was measured by the delayed word recall test (DWRT), the digit symbol substitution test (DSST) and the word fluency test (WFT). Dementia hospitalization was defined by ICD-9 codes. Adjusted linear, logistic and Cox proportional hazards models were used.

RESULTS

Mean age of participants was 62 years and 60% were female. Mean 25(OH)D was higher in whites than blacks (25.5 vs. 17.3 ng/ml, P < 0.001). Lower 25(OH)D was not associated with lower baseline scores or with greater DWRT, DSST or WFT decline over a median of 3 or 10 years of follow-up (P > 0.05). Over a median of 16.6 years, there were 145 incident hospitalized dementia cases. Although not statistically significant, lower levels of 25(OH)D were suggestive of an association with increased dementia risk [hazard ratio for lowest versus highest race-specific tertile: whites 1.32 (95% confidence interval 0.69, 2.55); blacks 1.53 (95% confidence interval 0.84, 2.79)].

CONCLUSIONS

In contrast to prior studies performed in older white populations, our study of late middle age white and black participants did not find significant associations between lower levels of 25(OH)D with lower cognitive test scores at baseline, change in scores over time or dementia risk.

Social network, social support, and risk of incident stroke: Atherosclerosis Risk in Communities study

BACKGROUND AND PURPOSE

Having a small social network and lack of social support have been associated with incident coronary heart disease; however, epidemiological evidence for incident stroke is limited. We assessed the longitudinal association of a small social network and lack of social support with risk of incident stroke and evaluated whether the association was partly mediated by vital exhaustion and inflammation.

METHODS

The Atherosclerosis Risk in Communities study measured social network and social support in 13 686 men and women (mean, 57 years; 56% women; 24% black; 76% white) without a history of stroke. Social network was assessed by the 10-item Lubben Social Network Scale and social support by a 16-item Interpersonal Support Evaluation List-Short Form.

RESULTS

During a median follow-up of 18.6 years, 905 incident strokes occurred. Relative to participants with a large social network, those with a small social network had a higher risk of stroke (hazard ratio [95% confidence interval], 1.44 [1.02-2.04]) after adjustment for demographics, socioeconomic variables, marital status, behavioral risk factors, and major stroke risk factors. Vital exhaustion, but not inflammation, partly mediated the association between a small social network and incident stroke. Social support was unrelated to incident stroke.

CONCLUSIONS

In this sample of US community-dwelling men and women, having a small social network was associated with excess risk of incident stroke. As with other cardiovascular conditions, having a small social network may be associated with a modestly increased risk of incident stroke.

Chronic stress, depressive symptoms, anger, hostility, and risk of stroke and transient ischemic attack in the multi-ethnic study of atherosclerosis

BACKGROUND AND PURPOSE

This study investigated chronic stress, depressive symptoms, anger, and hostility in relation to incident stroke and transient ischemic attacks in middle-aged and older adults.

METHODS

Data were from the Multi-Ethnic Study of Atherosclerosis (MESA), a population-based cohort study of 6749 adults, aged 45 to 84 years and free of clinical cardiovascular disease at baseline, conducted at 6 US sites. Chronic stress, depressive symptoms, trait anger, and hostility were assessed with standard questionnaires. The primary outcome was clinically adjudicated incident stroke or transient ischemic attacks during a median follow-up of 8.5 years.

RESULTS

One hundred ninety-five incident events (147 strokes; 48 transient ischemic attacks) occurred during follow-up. A gradient of increasing risk was observed for depressive symptoms, chronic stress, and hostility (all P for trend ≤0.02) but not for trait anger (P>0.10). Hazard ratios (HRs) and 95% confidence intervals indicated significantly elevated risk for the highest-scoring relative to the lowest-scoring group for depressive symptoms (HR, 1.86; 95% confidence interval, 1.16-2.96), chronic stress (HR, 1.59; 95% confidence interval, 1.11-2.27), and hostility (HR, 2.22; 95% confidence interval, 1.29-3.81) adjusting for age, demographics, and site. HRs were attenuated but remained significant in risk factor-adjusted models. Associations were similar in models limited to stroke and in secondary analyses using time-varying variables.

CONCLUSIONS

Higher levels of stress, hostility, and depressive symptoms are associated with significantly increased risk of incident stroke or transient ischemic attacks in middle-aged and older adults. Associations are not explained by known stroke risk factors.

Intracranial hemorrhage mortality in atrial fibrillation patients treated with dabigatran or warfarin

BACKGROUND AND PURPOSE

In randomized trials, patients with atrial fibrillation (AF) receiving dabigatran, a direct oral anticoagulant, had lower risk of intracranial bleeding (ICB) than those on warfarin. However, concerns exist about potential worse outcomes in dabigatran users if bleeding occurs, given the lack of approved reversal agents. Thus, we examined in-hospital mortality in AF patients with ICB being treated with dabigatran versus warfarin in a real-world population in the United States.

METHODS

We analyzed healthcare utilization claims in the Truven Health Marketscan Research Databases. The study sample included patients with AF admitted to a hospital with a primary diagnosis of ICB. Information on medications, inpatient, and outpatient diagnoses was obtained from available claims. Propensity score-adjusted risk ratios and 95% confidence intervals of in-hospital mortality comparing current users of dabigatran versus warfarin were estimated using relative risk regression.

RESULTS

Among 2391 AF patients admitted with ICB (2290 on warfarin, 101 on dabigatran), 531 died during their admission. In-hospital mortality was similar in those treated with warfarin (22%) or dabigatran (20%). Compared with warfarin users, the propensity score-adjusted risk ratio (95% confidence interval) of mortality in dabigatran users was 0.93 (0.62-1.37). Associations were similar across different ICB subtypes (intracerebral hemorrhage, subarachnoid hemorrhage, and subdural hematoma).

CONCLUSIONS

In this sample of AF patients with ICB on oral anticoagulants, dabigatran was not associated with higher in-hospital mortality compared with warfarin. Hence, reluctance to use dabigatran because of a lack of approved reversal agents is not supported by our results.

Serum fibroblast growth factor-23 is associated with incident kidney disease

Fibroblast growth factor-23 is a bone-derived hormone that increases urinary phosphate excretion and inhibits hydroxylation of 25-hydroxyvitamin D. Recent studies suggest that fibroblast growth factor-23 may be an early biomarker of CKD progression. However, its role in kidney function decline in the general population is unknown. We assessed the relationship between baseline (1990-1992) serum levels of intact fibroblast growth factor-23 and incident ESRD in 13,448 Atherosclerosis Risk in Communities study participants (56.1% women, 74.7% white) followed until December 31, 2010. At baseline, the mean age of participants was 56.9 years and the mean eGFR was 97 ml/min per 1.73 m(2). During a median follow-up of 19 years, 267 participants (2.0%) developed ESRD. After adjustment for demographic characteristics, baseline eGFR, traditional CKD risk factors, and markers of mineral metabolism, the highest fibroblast growth factor-23 quintile (>54.6 pg/ml) compared with the lowest quintile (<32.0 pg/ml) was associated with risk of developing ESRD (hazard ratio, 2.10; 95% confidence interval, 1.31 to 3.36; trend P<0.001). In a large, community-based study comprising a broad range of kidney function, higher baseline fibroblast growth factor-23 levels were associated with increased risk of incident ESRD independent of the baseline level of kidney function and a number of other risk factors.

Vitamin D and subclinical cerebrovascular disease: the Atherosclerosis Risk in Communities brain magnetic resonance imaging study

IMPORTANCE

Vitamin D deficiency has been associated with hypertension, diabetes mellitus, and incident stroke. Little is known about the association between vitamin D and subclinical cerebrovascular disease.

OBJECTIVE

To examine the relationship of 25-hydroxyvitamin D (25[OH]D) levels with cerebrovascular abnormalities as assessed on brain magnetic resonance imaging (MRI) among participants of the Atherosclerosis Risk in Communities (ARIC) Brain MRI study.

DESIGN, SETTING, AND PARTICIPANTS

Participants were white and black adults aged 55 to 72 years with no history of clinical stroke who underwent a cerebral MRI at ARIC visit 3 (n = 1622) and a second cerebral MRI approximately 10 years later (n = 888).

EXPOSURES

The 25(OH)D level was measured by mass spectrometry at visit 3, with levels adjusted for calendar month and categorized using race-specific quartiles.

MAIN OUTCOMES AND MEASURES

The cross-sectional and prospective associations of 25(OH)D levels with white matter hyperintensities (WMHs) and MRI-defined infarcts were investigated using multivariable regression models.

RESULTS

The mean age of the participants was 62 years, 59.6% were women, and 48.6% were black. Lower 25(OH)D levels were not significantly associated with WMH score of severity, prevalent high-grade WMH score (≥3), or prevalent infarcts in cross-sectional, multivariable-adjusted models (all P > .05). Similarly, no significant prospective associations were found for lower 25(OH)D levels with change in WMH volume, incident high WMH score (≥3), or incident infarcts on the follow-up MRI, which occurred approximately 10 years later.

CONCLUSIONS AND RELEVANCE

A single measure of 25(OH)D was not cross-sectionally associated with WMH grade or prevalent subclinical infarcts and was not prospectively associated with WMH progression or subclinical brain infarcts seen on serial cerebral MRIs obtained approximately 10 years apart. These findings do not support optimizing vitamin D levels for brain health.

Fibroblast growth factor-23 and incident coronary heart disease, heart failure, and cardiovascular mortality: the Atherosclerosis Risk in Communities study

BACKGROUND

Fibroblast growth factor-23 (FGF-23) is a hormone involved in phosphorous regulation and vitamin D metabolism that may be associated with cardiovascular risk, and it is a potential target for intervention. We tested whether elevated FGF-23 is associated with incident coronary heart disease, heart failure, and cardiovascular mortality, even at normal kidney function.

METHODS AND RESULTS

A total of 11 638 Atherosclerosis Risk In Communities study participants, median age 57 at baseline (1990-1992), were followed through 2010. Cox regression was used to evaluate the independent association of baseline serum active FGF-23 with incident outcomes. Models were adjusted for traditional cardiovascular risk factors and estimated glomerular filtration rate. During a median follow-up of 18.6 years, 1125 participants developed coronary heart disease, 1515 developed heart failure, and 802 died of cardiovascular causes. For all 3 outcomes, there was a threshold, whereby FGF-23 was not associated with risk at <40 pg/mL but was positively associated with risk at >40 pg/mL. Compared with those with FGF-23 <40 pg/mL, those in the highest FGF-23 category (≥ 58.8 pg/mL) had a higher risk of incident coronary heart disease (adjusted hazard ratio, 95% CIs: 1.65, 1.40 to 1.94), heart failure (1.75, 1.52 to 2.01), and cardiovascular mortality (1.65, 1.36 to 2.01). Associations were modestly attenuated but remained statistically significant after further adjustment for estimated glomerular filtration rate. In stratified analyses, similar results were observed in African Americans and among persons with normal kidney function.

CONCLUSIONS

High levels of serum FGF-23 were associated with increased risk of coronary heart disease, heart failure, and cardiovascular mortality in this large, biracial, population-based cohort. This association was independent of traditional cardiovascular risk factors and kidney function.

Glycemia (hemoglobin A1c) and incident venous thromboembolism in the Atherosclerosis Risk in Communities cohort study

Diabetes has been inconsistently associated with increased risk of venous thromboembolism (VTE) and there is little direct evidence on the associations of glycemia levels with VTE. We used data from the Atherosclerosis Risk in Communities study to test the hypothesis that glycemia, as measured by hemoglobin A1c (A1c), is positively associated with VTE. Participants aged 45-64 years (n = 12,298) had A1c measured in 1990 and were followed for incident VTE (n = 345) through 2005. Because A1c is affected by diabetes treatment, analyses were stratified by history of diagnosed diabetes. Owing to evidence of non-linearity, we categorized A1c according to clinical cut-points: <5.7, 5.7-6.4, and ≥ 6.5% in those with no diagnosed diabetes; <7.0 and ≥ 7.0% in those with diagnosed diabetes. After adjustment for potential confounders, the hazard ratios (95% CIs) for VTE across increasing A1c categories were 1 (referent), 1.02 (0.77, 1.35) and 0.72 (0.41, 1.29) for those without diagnosed diabetes, and 1.30 (0.77, 2.17) and 1.41 (0.95, 2.09) for those with diagnosed diabetes. To explore the relation, we employed various models to adjust for potential confounding variables and modeled A1c as tertiles. We consistently found elevated hazard ratios in those with diagnosed diabetes, though the association was not statistically significant in every model. Hazard ratios in those without diagnosed diabetes were close to 1. In conclusion, our results are mildly suggestive that diagnosed diabetes and high levels of glucose, per se, may increase the risk of VTE. Elevated glucose was not related to VTE in those without diagnosed diabetes.

Comparable ascertainment of newly-diagnosed atrial fibrillation using active cohort follow-up versus surveillance of centers for medicare and medicaid services in the atherosclerosis risk in communities study

OBJECTIVE

Increasingly, epidemiologic studies use administrative data to identify atrial fibrillation (AF). Capture of incident AF is not well documented. We examined incidence rates and concordance of AF diagnosis based on active cohort follow-up versus surveillance of Centers for Medicare and Medicaid Services data in the Atherosclerosis Risk in Communities study.

METHODS

Atherosclerosis Risk in Communities cohort participants without prevalent AF enrolled in fee-for-service Medicare, with inpatient and outpatient coverage, for at least 12 continuous months between 1991 and 2009 were included. In active Atherosclerosis Risk in Communities study follow-up, annual telephone calls captured hospitalizations and deaths with incident AF diagnosis codes. For Centers for Medicare and Medicaid Services data, incident AF was defined by billed inpatient and outpatient diagnoses.

RESULTS

Of 10,134 eligible cohort participants, 738 developed AF according to both Atherosclerosis Risk in Communities and Centers for Medicare and Medicaid Services data; an additional 93 and 288 incident cases were identified using only Atherosclerosis Risk in Communities and Centers for Medicare and Medicaid Services data, respectively. Incidence rates per 1,000 person-years were 10.8 (95% confidence interval: 10.1-11.6) and 13.6 (95% confidence interval: 12.8-14.4) in Atherosclerosis Risk in Communities and Centers for Medicare and Medicaid Services, respectively; agreement was 96%; kappa was 0.77 (95% confidence interval: 0.75-0.80). Earlier AF ascertainment by one system versus the other was not associated with any cardiovascular disease risk factors, after accounting for sociodemographic factors. Additional Centers for Medicare and Medicaid Services events did not alter observed associations between risk factors and AF.

CONCLUSION

Among fee-for-service enrollees, AF incidence rates were slightly lower for active cohort follow-up than for Centers for Medicare and Medicaid Services surveillance, because the latter included outpatient atrial fibrillation. Concordance was high and combining the two approaches could provide a more complete picture of newly-diagnosed AF.

Racial and regional differences in venous thromboembolism in the United States in 3 cohorts

BACKGROUND

Blacks are thought to have a higher risk of venous thromboembolism (VTE) than whites. However, prior studies are limited to administrative databases that lack specific information on VTE risk factors or have limited geographic scope.

METHODS AND RESULTS

We ascertained VTE from 3 prospective studies: the Atherosclerosis Risk in Communities Study (ARIC), the Cardiovascular Health Study (CHS), and the Reasons for Geographic and Racial Differences in Stroke study (REGARDS). We tested the association of race with VTE using Cox proportional hazard models adjusted for VTE risk factors. Over 438 090 person-years, 916 incident VTE events (302 in blacks) occurred in 51 149 individuals (17 318 blacks) who were followed up. In risk factor-adjusted models, blacks had a higher rate of VTE than whites in the CHS (hazard ratio, 1.81; 95% confidence interval, 1.20-2.73) but not ARIC (hazard ratio, 1.21; 95% confidence interval, 0.96-1.54). In REGARDS, there was a significant region-by-race interaction (P=0.01): Blacks in the Southeast had a significantly higher rate of VTE than blacks in the rest of the United States (hazard ratio, 1.63; 95% confidence interval, 1.08-2.48) that was not seen in whites (hazard ratio, 0.83; 95% confidence interval, 0.61-1.14).

CONCLUSIONS

The association of race with VTE differed in each cohort, which may reflect the different time periods of the studies or different regional rates of VTE. Further studies of environmental and genetic risk factors for VTE are needed to determine which underlie racial and perhaps regional differences in VTE.

Physical activity and cardiovascular disease in African Americans in Atherosclerosis Risk in Communities

PURPOSE

Although there is substantial evidence that physical activity reduces a person's risk of cardiovascular disease (CVD), few of these studies have included African Americans. The studies that have included African Americans offer inconclusive evidence on the association, and none studied heart failure separately. We used data from the Atherosclerosis Risk in Communities study cohort to examine, in African Americans, the association of physical activity with the incidence of CVD and its major components-stroke, heart failure, and CHD.

METHODS

Participants age 45-64 yr (3707 African Americans and, for comparison, 10,018 Caucasians) had physical activity assessed via questionnaire in 1987 and were followed for incident CVD (n = 1039) through 2008.

RESULTS

After adjustment for potential confounders, physical activity was inversely related to CVD, heart failure, and CHD incidence in both races (P values for trend <0.0001), and with stroke in African Americans. Hazard ratios (95% confidence intervals) for CVD for each higher physical activity category were similar by race: 1.0, 0.65 (0.56-0.75), and 0.59 (0.49-0.71) for African Americans and 1.0, 0.74 (0.66-0.83), and 0.67 (0.59-0.75) for Caucasians (P value for interaction = 0.38).

CONCLUSIONS

Our findings reinforce recommendations that regular physical activity is important for CVD risk reduction in African Americans as well as Caucasians and support the idea that some physical activity is better than none.

A comparative analysis of risk factors for stroke in blacks and whites: the Atherosclerosis Risk in Communities study

OBJECTIVE

Previous studies have speculated that the higher stroke incidence rate (IR) in blacks compared with whites may be due, in part, to stroke risk factors exerting a more adverse effect among blacks than whites. To determine whether such racial differences exist we compared the prospective associations between novel, traditional, and emerging stroke risk factors in blacks and whites.

DESIGN

Baseline characteristics on risk factor levels were obtained on 15,407 participants from the Atherosclerosis Risk in Communities Study. Stroke incidence was ascertained from 1987 to 2008. Adjusted Cox proportional hazard models were used to compute hazard ratios (HRs) and their 95% confidence intervals (CIs) for stroke in relation to stroke risk factor levels stratified by race.

RESULTS

During follow-up, 988 stroke events occurred: blacks had higher stroke incident rates compared with whites with the greatest difference in those aged <60 years: 4.34, 3.24, 1.20, and 0.84 per 1000 person-years, in black men, black women, white men, and white women, respectively. Associations between risk factors with incident stroke were similar in blacks and whites excluding diabetes which was more strongly associated with the risk of stroke in blacks than in whites: HR 2.54 (95% CI: 2.03-3.18) versus 1.74 (1.37-2.21), respectively; p for race interaction=0.02.

CONCLUSIONS

At all ages, blacks are at a considerably higher risk of incident stroke compared with whites, although the effect is most marked in younger age groups. This is most likely due to blacks having a greater burden of stroke risk factors rather than there being any substantial race differences in the associations between risk factors and stroke outcomes.

Association of ideal cardiovascular health metrics and retinal microvascular findings: the Atherosclerosis Risk in Communities Study

Background

This study evaluated the prevalence of ideal cardiovascular (CV) health in the Atherosclerosis Risk in Communities Study and determined its relationship with prevalent retinopathy, wider retinal venular diameters, and narrower arteriolar diameters, which are risk markers for subclinical cerebrovascular disease and are associated with increased stroke and coronary heart disease (CHD) morbidity and mortality.

Methods and Results

We used gradings of fundus photography measurements from the Atherosclerosis Risk in Communities Study to examine the association of retinopathy and retinal arteriolar and venular calibers to the number of ideal CV health metrics. Prevalent retinopathy showed a graded relationship with the CV health categories and number of ideal CV health metrics present: retinopathy prevalence was 2.1% among those with ≥5 ideal CV health metrics compared with 13.1% among those with zero ideal CV health metrics (odds ratio [CI]), 4.8 [2.5 to 8.9]). Central retinal venule equivalent and central retinal arteriolar equivalent diameters also showed graded relationships with CV health categories and number of ideal CV health metrics: after adjustment for age, race, sex, and education, mean central retinal venular equivalent was 187.8 μm (95% CI, 186.9 to 188.6 μm) among those with ≥5 ideal CV health metrics compared with 201.1 μm (95% CI, 199.1 to 203.1 μm) among those with zero ideal CV health metrics. Mean central retinal arteriolar equivalent was 163.8 μm (95% CI, 163.0 to 164.5 μm) among those with ≥5 ideal CV health metrics compared with 157.9 μm (95% CI, 156.1 to 159.7 μm) among those with zero ideal CV health metrics.

Conclusions

Few adults had ideal cardiovascular health. Those with the best level of health were less likely to have retinopathy signs, wide retinal venules, and narrow retinal arterioles, which are associated with increased stroke and coronary heart disease risk.

Lipoprotein-associated phospholipase A2 and venous thromboembolism: a prospective study

INTRODUCTION

Plasma lipoprotein-associated phospholipase A2 (Lp-PLA2) is an inflammatory marker associated positively with atherothrombotic risk. Whether Lp-PLA2 is related to risk of venous thromboembolism (VTE) is incompletely studied.

METHODS

We assessed Lp-PLA2 activity in 10,687 Atherosclerosis Risk in Communities (ARIC) Study participants and followed them a median of 8.3 years (from 1996-98 through 2005) for VTE occurrence (n=226).

RESULTS

There was no significant association between baseline Lp-PLA2 quartiles and risk of VTE, neither overall nor stratified as provoked or unprovoked. Adjusted for other risk factors, the hazard ratios (95% confidence interval) of total VTE across quartiles of Lp-PLA2 were 1.0 (reference), 0.95 (0.64, 1.42), 1.03 (0.69, 1.56), and 1.26 (0.83, 1.91). In the subset of participants with LDL-cholesterol ≥130 mg/dL, hazard ratios of total VTE were 1.00, 1.39 (0.44, 4.44), 2.45 (0.84, 7.11), and 2.84 (0.99, 8.14).

CONCLUSION

Our study does not support the overall hypothesis that elevated Lp-PLA2 contributes to VTE occurrence in the general population. However, in the presence of high LDL-cholesterol there was some evidence that Lp-PLA2 may increase VTE risk.

Statin therapy and levels of hemostatic factors in a healthy population: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

HMG-CoA reductase inhibitors (statins) reduce the risk of venous thromboembolism (VTE) in healthy people. Statins reduce levels of inflammation biomarkers; however, the mechanism for the reduction in VTE risk is unknown.

AIM

In a large cohort of healthy people, we studied associations of statin use with plasma hemostatic factors related to VTE risk.

METHODS

Cross-sectional analyses were performed in the Multi-Ethnic Study of Atherosclerosis (MESA), a cohort study of 6814 healthy men and women aged 45-84 years, free of clinical cardiovascular disease at baseline; 1001 were using statins at baseline. Twenty-three warfarin users were excluded. Age, race and sex-adjusted mean hemostatic factor levels were compared between statin users and non-users, and multivariable linear regression models were used to assess associations of statin use with hemostatic factors, adjusted for age, race/ethnicity, education, income, aspirin use, hormone replacement therapy (in women), and major cardiovascular risk factors.

RESULTS

Participants using statins had lower adjusted levels of D-dimer (- 9%), C-reactive protein (- 21%) and factor VIII (- 3%) than non-users (P < 0.05). Homocysteine and von Willebrand factor levels were non-significantly lower with statin use. Higher fibrinogen (2%) and plasminogen activator inhibitor-1 (22%) levels were observed among statin users than among non-users (P < 0.05). Further adjustment for LDL and triglyceride levels did not attenuate the observed differences in these factors with statin use.

CONCLUSIONS

Findings of lower D-dimer, FVIII and C-reactive protein levels with statin use suggest hypotheses for mechanisms whereby statins might lower VTE risk. A prospective study or clinical trial linking these biochemical differences to VTE outcomes in statin users and non-users is warranted.

Estimating mean annual 25-hydroxyvitamin D concentrations from single measurements: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

The seasonal variation in circulating 25-hydroxyvitamin D [25(OH)D] concentrations is large relative to mean values. Single measurements may misclassify annual exposure, which may lead to bias in research and complicate clinical decision making.

OBJECTIVE

We aimed to develop and validate a model for adjusting a single measurement of a serum 25(OH)D concentration to the time of year it was measured.

DESIGN

We measured serum 25(OH)D concentrations by using mass spectrometry in 6476 participants from the Multi-Ethnic Study of Atherosclerosis at baseline and again in a subset of 368 participants at a median of 17 mo later. We estimated a cosinor model to describe the seasonal variability in 25(OH)D concentrations and evaluated this model by using follow-up 25(OH)D measurements.

RESULTS

The mean age of subjects was 62.1 y, 61.2% of participants were nonwhite, and 53.3% of participants were women. The cosinor model predicted follow-up 25(OH)D concentrations better than a single measurement [difference in root mean squared error (RMSE): 1.3 ng/mL; P< 0.001]. The cosinor model also better predicted the measured annual mean 25(OH)D concentration (difference in RMSE: 1.0 ng/mL; P< 0.001). Annual mean 25(OH)D concentrations estimated from the cosinor model reclassified 7.1% of participants with regard to 25(OH)D deficiency, which was defined as <20 ng/mL. An estimated annual mean 25(OH)D concentration <20 ng/mL was significantly associated with lower bone mineral density, whereas an untransformed 25(OH)D concentration <20 ng/mL was not.

CONCLUSIONS

Cross-sectional data can be used to estimate subject-specific mean annual 25(OH)D concentrations from single values by using a cosinor model. The tool we developed by using this approach may assist research and clinical care of adults in North America by reducing the misclassification of 25(OH)D deficiency.

Relation of serum phosphorus levels to the incidence of atrial fibrillation (from the Atherosclerosis Risk In Communities [ARIC] study)

High serum phosphorus levels have been linked with vascular calcification and greater cardiovascular morbidity and mortality. We assessed whether serum phosphorus was associated with the atrial fibrillation (AF) incidence in a large community-based cohort in the United States. Our analysis included 14,675 participants (25% black, 45% men) free of AF at baseline (1987 to 1989) and with measurements of fasting serum phosphorus from the Atherosclerosis Risk In Communities (ARIC) study. The incidence of AF was ascertained through the end of 2008 from study visit electrocardiograms, hospitalizations, and death certificates. Cox proportional hazard models were used to estimate the hazard ratios of AF by the serum phosphorus levels, adjusting for potential confounders. During a median follow-up of 19.7 years, we identified 1,656 incident AF cases. Greater serum phosphorus was associated with a greater AF risk: the hazard ratio of AF with a 1-mg/dl increase in serum phosphorus was 1.13 (95% confidence interval 1.02 to 1.26). No significant interaction was seen by race (p = 0.88) or gender (p = 0.51). The risk of AF was increased in association with greater serum phosphorus in those with an estimated glomerular filtration rate of ≥90 ml/min/1.72 m(2) but not among those with an estimated glomerular filtration rate of <90 ml/min/1.72 m(2). The total corrected calcium levels were not related to AF risk; however, greater levels of the calcium-phosphorus product were associated with greater AF risk. In conclusion, in the present large population-based study, greater levels of serum phosphorus and the related calcium-phosphorus product were associated with a greater incidence of AF.

Troponin T, N-terminal pro-B-type natriuretic peptide, and incidence of stroke: the atherosclerosis risk in communities study

BACKGROUND AND PURPOSE

Increased levels of plasma troponins and natriuretic peptides are associated with increased risk of cardiovascular disease, but only limited information exists on these biomarkers and stroke occurrence. In a prospective epidemiological study, we tested the hypothesis that high-sensitivity troponin T (TnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are associated positively with incidence of stroke.

METHODS

The Atherosclerosis Risk in Communities (ARIC) Study measured plasma TnT and NT-proBNP in 10 902 men or women initially free of stroke and followed them for a mean of 11.3 years for stroke occurrence (n=507).

RESULTS

Both biomarkers were associated positively with total stroke, nonlacunar ischemic, and especially cardioembolic stroke, but not with lacunar or hemorrhagic stroke. For example, after adjustment for prevalent risk factors and cardiac diseases, the hazard ratios (95% CIs) for jointly high values of TnT and NT-proBNP (versus neither biomarker high) were 2.70 (1.92-3.79) for total stroke and 6.26 (3.40-11.5) for cardioembolic stroke. Associations with stroke appeared somewhat stronger for NT-proBNP than TnT. Strikingly, ≈ 58% of cardioembolic strokes occurred in the highest quintile of prestroke NT-proBNP, and 32% of cardioembolic strokes occurred in participants who had both NT-proBNP in the highest quintile and were known by ARIC to have atrial fibrillation sometime before their cardioembolic stroke occurrence.

CONCLUSIONS

In the general population, elevated plasma TnT and NT-proBNP concentrations are associated with increased risk of cardioembolic and other nonlacunar ischemic strokes.

Abstract 79: Troponin T, NT-proBNP, and Incidence of Stroke: The Atherosclerosis Risk in Communities (ARIC) Study

Increased levels of plasma troponins and natriuretic peptides in the general population are associated with increased future risk of cardiovascular disease, but only limited information exists on these biomarkers and stroke occurrence. In a prospective epidemiological study, the Atherosclerosis Risk in Communities (ARIC) Study, we tested the hypothesis that high-sensitivity troponin T (TnT) and N-terminal pro B-type natriuretic peptide (NT-proBNP) are associated positively with incidence of stroke. We measured plasma high-sensitivity TnT and NT-proBNP in 10,902 men or women initially free of stroke and followed them for a mean of 11.3 years for stroke occurrence (n=507). Analyses were performed using proportional hazards modeling. Both biomarkers were associated positively with total stroke, nonlacunar ischemic, and especially, cardioembolic stroke, but not with lacunar or hemorrhagic stroke. After adjustment for other stroke risk factors, the hazard ratio (95% CI) per one SD greater increment of natural log-transformed TnT was 1.23 (1.13, 1.35) for total stroke, 1.27 (1.15, 1.40) for total ischemic stroke, and 1.36 (1.14, 1.62) for cardioembolic stroke. Likewise, the hazard ratio per one SD greater natural log-transformed NT-proBNP, was 1.37 (1.26, 1.49) for total stroke, 1.39 (1.27, 1.53) for total ischemic stroke, and 1.95 (1.67, 2.28) for cardioembolic stroke. The hazard ratios for jointly high values of TnT (≥0.013 ug/L) and NT-proBNP (≥155.2 pg/mL), versus neither biomarker high, were 2.70 (1.92, 3.79) for total stroke and 6.26 (3.40, 11.5) for cardioembolic stroke, and somewhat stronger for NT-proBNP than TnT. Strikingly, approximately 58% of cardioembolic strokes occurred in the highest quintile of pre-stroke NT-proBNP (versus 3% occurring in the lowest quintile), and 32% of cardioembolic strokes occurred in participants who had both NT-proBNP in the highest quintile and were known by ARIC to have atrial fibrillation sometime before their cardioembolic stroke occurrence. In conclusion, in the general population, elevated plasma TnT and NT-proBNP concentrations are associated with increased risk of cardioembolic and other nonlacunar ischemic strokes.

Troponin T, B-type natriuretic peptide, C-reactive protein, and cause-specific mortality

PURPOSE

We sought to evaluate the associations of high-sensitivity troponin T (Hs-TnT), N-terminal pro-brain natriuretic peptide (NT-proBNP), and high sensitivity C-reactive protein (Hs-CRP) with mortality from any cause, cardiovascular disease (CVD), coronary heart disease (CHD), stroke, cancer, and respiratory disease in the Atherosclerosis Risk in Communities cohort.

METHODS

We included 11,193 participants aged 54 to 74 years, initially free of the conditions being studied, and who had biomarkers measured. Participants were followed for a mean of 9.9 years.

RESULTS

Hazard ratios (HR), adjusted for multiple risk factors, for mortality in participants in the highest Hs-TnT category compared with those with undetectable levels were: Total 3.42 (95% confidence interval [CI], 2.75-4.26); CVD, 7.34 (95% CI, 4.64-11.6); CHD, 6.06 (95% CI, 2.91-12.6); stroke, 3.31 (95% CI, 1.26-8.66); cancer, 1.60 (95% CI, 1.08-2.38); and respiratory, 3.85 (95% CI, 1.39-10.7). Comparing the highest NT-proBNP quintile with those in the lowest quintile, the adjusted HRs for mortality were: Total, 3.05 (95% CI, 2.46-3.77); CVD, 7.48 (95% CI, 4.67-12.0); CHD, 4.07 (95% CI, 2.07-7.98); and stroke, 10.4 (95% CI, 2.26-47.7). Comparing extreme Hs-CRP quintiles, the adjusted HRs for mortality were: Total, 1.61 (95% CI, 1.32-1.97); CVD, 1.76 (95% CI, 1.19-2.62); and respiratory, 3.36 (95% CI, 1.34-8.45). Having multiple markers elevated simultaneously greatly increased cause-specific mortality risks.

CONCLUSIONS

Greater levels of Hs-TnT, NT-proBNP and Hs-CRP are associated with increased risk of death, not just from CVD, but also from some noncardiovascular causes.

Associations among lung function, arterial elasticity, and circulating endothelial and inflammation markers: the multiethnic study of atherosclerosis

A parallel physiological pathway for elastic changes is hypothesized for declines in arterial elasticity and lung function. Endothelial dysfunction and inflammation could potentially decrease elasticity of both vasculature and lung tissue. We examined biomarkers, large arterial elasticity and small arterial elasticity (SAE), and forced vital capacity (FVC) in a period cross-sectional design in the multiethnic study of atherosclerosis, which recruited 1823 women and 1803 men, age range 45 to 84 years, black, white, Hispanic, and Chinese, free of clinically recognized cardiovascular disease. Radial artery tonometric pulse waveform registration was performed and large arterial elasticity and SAE were derived from diastole. Spirometric data and markers of endothelial dysfunction and inflammation (soluble intracellular adhesion molecule-1, fibrinogen, hs-C-reactive protein, and interleukin-6) were obtained. Mean large arterial elasticity was 13.7 ± 5.5 mL/mm Hg × 10 and SAE was 4.6 ± 2.6 mL/mm Hg × 100. Mean FVC was 3192 ± 956.0 mL and forced expiratory volume in 1 second was 2386 ± 734.5 mL. FVC was about 40 ± 5 mL higher per SD of SAE, stronger in men than women. The association was slightly weaker with large arterial elasticity, with no sex interaction. After regression adjustment for demographic, anthropometric, and cardiovascular risk factors, the biomarkers tended to be related to reduced SAE and FVC, particularly in men. These biomarker associations suggest important cardiovascular disease risk alterations that occur concurrently with lower arterial elasticity and lung function. The observed positive association of SAE with FVC and with forced expiratory volume in 1 second in middle-aged to older free-living people is consistent with the hypothesis of parallel physiological pathways for elastic changes in the vasculature and in lung parenchymal tissue.