Race, vitamin D-binding protein gene polymorphisms, 25-hydroxyvitamin D, and incident diabetes: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Low 25-hydroxyvitamin D [25(OH)D] is associated with diabetes, but few studies have examined racially diverse populations while also accounting for key vitamin D-binding protein (DBP) gene polymorphisms.

OBJECTIVE

We sought to evaluate whether the association between 25(OH)D and incident diabetes varied by race and important DBP single nucleotide polymorphisms (SNPs).

DESIGN

We studied 10,222 adults (8120 whites, 2102 blacks) aged 46-70 y at baseline (1990-1992) from the ARIC (Atherosclerosis Risk in Communities) Study with follow-up for incident diabetes ascertained during study visits conducted in 1993-1995 and 1996-1998. Adjusted HRs and their 95% CIs for diabetes were estimated according to 25(OH)D status.

RESULTS

During follow-up there were 750 incident cases of diabetes. The association of 25(OH)D with diabetes varied by race (P-interaction = 0.004). Among whites, the adjusted HR for diabetes corresponding to each additional SD higher 25(OH)D concentration (21.3 nmol/L) was 0.95 (95% CI: 0.91, 0.99). No significant association was observed among blacks (HR: 1.06; 95% CI: 0.99, 1.14). There was evidence that the A allele at rs4588 and the T allele at rs7041, which are reported to be associated with high and low DBP concentrations, respectively, modified the association between 25(OH)D and diabetes among whites (P-interaction < 0.05 for both) but not blacks (P-interaction > 0.50 for both).

CONCLUSIONS

In this large, community-based study, low 25(OH)D concentrations were associated with diabetes among whites but not blacks. Interactions by key DBP SNPs varied between genotypes associated with either high or low DBP concentrations among whites but not blacks. Nevertheless, the findings from this prospective study suggest that there are important differences in the association of 25(OH)D with incident diabetes between white and black adults.

Fructosamine and Glycated Albumin and the Risk of Cardiovascular Outcomes and Death

BACKGROUND

Hemoglobin A1c (HbA1c) is the standard measure to monitor glucose control in diabetes mellitus and is a marker of future cardiovascular risk. Fructosamine and glycated albumin are markers of short-term glycemic control, but their associations with cardiovascular outcomes are uncharacterized.

METHODS AND RESULTS

We measured glycated albumin and fructosamine in 11 104 participants with and without diabetes in the community-based Atherosclerosis Risk in Communities (ARIC) Study in 1990 to 1992 (baseline). We evaluated associations of fructosamine and glycated albumin with risk of coronary heart disease, ischemic stroke, heart failure, and mortality. We compared associations with those observed for HbA1c. During two decades of follow-up there were 1096 new cases of coronary heart disease, 605 of ischemic stroke, 1432 of heart failure, and 2860 deaths. Elevated baseline concentrations of fructosamine and glycated albumin were significantly associated with each of the outcomes even after adjustment for traditional cardiovascular risk factors, with especially strong associations in persons with diabetes mellitus. Associations were of similar magnitude to those observed for HbA1c and-as has been previously observed for HbA1c-the associations tended to be J-shaped, with an elevation of risk at the lowest levels of each biomarker.

CONCLUSIONS

The acceptance of new measures of hyperglycemia is partly dependent on establishing their association with long-term outcomes. We found that fructosamine and glycated albumin were associated with vascular outcomes and mortality and that these associations were similar to those observed for HbA1c.

Vitamin D, vitamin D binding protein gene polymorphisms, race and risk of incident stroke: the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND AND PURPOSE

Low vitamin D levels, measured by serum 25-hydroxyvitamin D [25(OH)D], are associated with increased stroke risk. Less is known about whether this association differs by race or D binding protein (DBP) single nucleotide polymorphism (SNP) status. Our objective was to characterize the associations of and interactions between 25(OH)D levels and DBP SNPs with incident stroke. It was hypothesized that associations of low 25(OH)D with stroke risk would be stronger amongst persons with genotypes associated with higher DBP levels.

METHODS

25(OH)D was measured by mass spectroscopy in 12 158 participants in the Atherosclerosis Risk in Communities (ARIC) study (baseline 1990-1992, mean age 57 years, 57% female, 23% black) and they were followed through 2011 for adjudicated stroke events. Two DBP SNPs (rs7041, rs4588) were genotyped. Cox models were adjusted for demographic/behavioral/socioeconomic factors.

RESULTS

During a median of 20 years follow-up, 804 incident strokes occurred. The lowest quintile of 25(OH)D (<17.2 ng/ml) was associated with higher stroke risk [hazard ratio (HR) 1.34 (1.06-1.71) versus highest quintile]; this association was similar by race (P interaction 0.60). There was weak evidence of increased risk of stroke amongst those with 25(OH)D < 17.2 ng/ml and either rs7041 TG/GG [HR = 1.29 (1.00-1.67)] versus TT genotype [HR = 1.19 (0.94-1.52)] (P interaction 0.28) or rs4588 CA/AA [HR = 1.37 (1.07-1.74)] versus CC genotype [HR = 1.14 (0.91-1.41)] (P interaction 0.11).

CONCLUSIONS

Low 25(OH)D is a risk factor for stroke. Persons with low 25(OH)D who are genetically predisposed to high DBP (rs7041 G, rs4588 A alleles), who therefore have lower predicted bioavailable 25(OH)D, may be at greater risk for stroke, although our results were not conclusive and should be interpreted as hypothesis generating.

Race and Vitamin D Binding Protein Gene Polymorphisms Modify the Association of 25-Hydroxyvitamin D and Incident Heart Failure: The ARIC (Atherosclerosis Risk in Communities) Study

OBJECTIVES

This study sought to determine if low serum 25-hydroxyvitamin D (25[OH]D) is associated with incident heart failure (HF) and if the association is: 1) partly mediated by traditional cardiovascular risk factors; 2) stronger among whites than blacks; and 3) stronger among those genetically predisposed to having high levels of vitamin D binding protein (DBP).

BACKGROUND

Suboptimal 25(OH)D is a potential cardiovascular risk factor.

METHODS

A total of 12,215 ARIC (Atherosclerosis Risk in Communities) study participants free of HF at baseline (1990 to 1992; median age, 56; 24% black) were followed through 2010. Total serum 25(OH)D was measured at baseline using liquid chromatography-mass spectrometry. Incident HF events were identified by a hospital discharge code of ICD9-428 and parallel International Classification of Diseases codes for HF deaths.

RESULTS

During 21 years of follow-up, 1,799 incident HF events accrued. The association between 25(OH)D and HF varied by race (p-interaction = 0.02). Among whites, risk was 2-fold higher for those in the lowest (≤17 ng/ml) versus highest (≥31 ng/ml) quintile of 25(OH)D. The association was attenuated but remained significant with covariate adjustment. In blacks there was no overall association. In both races, those with low 25(OH)D and the rs7041 G allele, which predisposes to high DBP, were at greater risk (p-interaction = 0.01).

CONCLUSIONS

Low serum 25(OH)D was independently associated with incident HF among whites, but not among blacks. However, in both races, low 25(OH)D was associated with HF risk among those genetically predisposed to high DBP. These findings provide novel insight into metabolic differences that may underlie racial variation in the association between 25(OH)D and cardiovascular risk.

The 25-hydroxyvitamin D3 C-3 epimer: distribution, correlates, and reclassification of 25-hydroxyvitamin D status in the population-based Atherosclerosis Risk in Communities Study (ARIC)

BACKGROUND

Little is known about the vitamin D3 epimer [3-epi-25(OH)D3], particularly in adults. We describe characteristics of the D3 epimer within the community-based ARIC cohort.

METHODS

The vitamin D3 epimer, 25(OH)D3, and 25(OH)D2 were measured using LC-MS/MS in stored serum collected in 1990-1992 from 9,887 white and 3,221 black ARIC study participants, aged 46-70years. Cross-sectional characteristics were explored.

RESULTS

Concentrations of the epimer were quantifiable (≥1.41ng/ml) in 33.4% of whites and 15.0% of blacks and made up on average 3.23% and 2.25% of total D3 [epimer+25(OH)D3] concentrations, respectively. Epimer levels were positively correlated with 25(OH)D3 in both whites (r=0.54) and blacks (r=0.36) and were unrelated to 25(OH)D2 concentrations. Overall, epimer levels were associated with participant characteristics in a manner similar to that typically observed for 25(OH)D3. Including the epimer in the calculation of total 25(OH)D resulted in approximately 2% of participants being reclassified from being clinically 25(OH)D deficient to having suboptimal levels.

CONCLUSIONS

Low concentrations of the D3 epimer were present in adult serum and overall the epimer concentration is moderately correlated with the 25(OH)D3 concentration. The reclassification of participant's clinical 25(OH)D status upon inclusion of the epimer was minimal.

Prospective study of sickle cell trait and venous thromboembolism incidence

BACKGROUND

Sickle cell trait may increase risk of venous thromboembolism, but this is not fully established.

OBJECTIVES

We sought to determine the association of sickle cell trait with deep vein thrombosis and pulmonary embolism.

METHODS

Middle-aged African Americans participating in a prospective, population-based cohort investigation, the Atherosclerosis Risk in Communities Study, were followed from 1987 through 2011 for incident hospitalized pulmonary embolism (n = 111) or isolated deep vein thrombosis (n = 138), verified by physician review of medical records. Sickle cell trait (heterozygosity for hemoglobin S, n = 268) was compared with no sickle cell trait (n = 3748).

RESULTS

Over a median of 22 years of follow-up, 249 participants had an incident venous thromboembolism. The hazard ratio of venous thromboembolism was 1.50 (95% confidence interval [CI] 0.96-2.36) for participants with vs. without sickle cell trait, after adjustment for age, sex, ancestry, hormone replacement therapy (women), body mass index, diabetes, and estimated glomerular filtration rate. This hazard ratio was 2.05 (95% CI 1.12-3.76) for pulmonary embolism and 1.15 (95% CI 0.58-2.27) for deep vein thrombosis without pulmonary embolism.

CONCLUSIONS

Sickle cell trait in African Americans carries a 2-fold increased risk of pulmonary embolism but does not elevate deep vein thrombosis risk. Because neonatal screening for sickle hemoglobin is being conducted in the United States, consideration should be paid to the increased pulmonary embolism risk of individuals with sickle cell trait.

Inflammation markers and incident venous thromboembolism: the REasons for Geographic And Racial Differences in Stroke (REGARDS) cohort

BACKGROUND

Inflammation biomarkers are associated with the venous thromboembolism (VTE) risk factors obesity and age; however, the relationships of inflammation with VTE risk remain controversial.

OBJECTIVES

To examine associations of four inflammation biomarkers, i.e. C-reactive protein (CRP), serum albumin, white blood cell (WBC) count, and platelet count (PLTC), with incident VTE, and to determine whether they mediate the association of age or obesity with VTE.

PATIENTS/METHODS

Hazards models adjusted for VTE risk factors were used to calculate the prospective association of each biomarker with incident VTE in 30,239 participants of the REasons for Geographic And Racial Differences in Stroke (REGARDS) study. Mediation of the associations of obesity and age with VTE were examined by bootstrapping. Over a period of 4.6 years, there were 268 incident VTE events. After adjustment for VTE risk factors, the hazard ratios (HRs) were 1.25 (95% confidence interval [CI] 1.09-1.43) per standard deviation (SD) higher log-CRP and 1.25 (95% CI 1.06-1.48) per SD lower albumin; there were no associations for WBC count or PLTC. The association of body mass index (BMI), but not age, with VTE was partially mediated by CRP and albumin. In risk factor-adjusted models, the percentage attenuations of the BMI HR for VTE after introduction of CRP or albumin into the models were 15.4% (95% CI 7.7-33.3%) and 41.0% (95% CI 12.8-79.5%), respectively.

CONCLUSION

Higher CRP levels and lower serum albumin levels were associated with increased VTE risk, and statistically mediated part of the association of BMI with VTE. These data suggest that inflammation may be a potential mechanism underlying the relationship between obesity and VTE risk.

Troponin T, NT-proBNP, and venous thromboembolism: the Longitudinal Investigation of Thromboembolism Etiology (LITE)

Increased levels of plasma troponins and natriuretic peptides are markers of cardiac dysfunction associated with increased risk of cardiovascular disease. Little information exists on cardiac dysfunction and occurrence of venous thromboembolism (VTE). In two prospective epidemiological cohorts, we tested the hypothesis that high-sensitivity troponin T (TnT) and N-terminal pro B-type natriuretic peptide (NT-proBNP) are associated positively with VTE occurrence. The Atherosclerosis Risk in Communities (ARIC) study and the Cardiovascular Health Study (CHS) measured plasma TnT and NT-proBNP in 13,719 men or women with no history of venous thrombosis, coronary heart disease, or heart failure and followed them for approximately 10 years for VTE occurrence (n = 348 VTEs). In both ARIC and CHS, TnT was associated positively with incidence of total VTE and provoked VTE, but not with unprovoked VTE: age, race, and sex-adjusted hazard ratios for total VTE in the pooled analysis were 1.00, 0.85, 1.36, 1.51, and 1.98 (p-trend <0.0001) across five categories of TnT. In contrast, the association of NT-proBNP with VTE was positive in ARIC (hazard ratios approximately 2.5-fold for the highest versus lowest NT-proBNP quintiles), but non-existent in CHS.

Elevated hepatic enzymes and incidence of venous thromboembolism: a prospective study

PURPOSE

Approximately 10% of the general population has elevated blood concentrations of hepatic enzymes, which are linked to increased coagulation markers. We tested whether elevated hepatic enzymes are associated with increased risk of venous thromboembolism (VTE).

METHODS

We followed 12,604 adults with measurements of alanine transaminase, aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGT) prospectively for VTE occurrence.

RESULTS

AST and GGT above the laboratory normal values were associated over two decades of follow-up with increased risk of total (n = 532) and provoked VTE (n = 332), but with not unprovoked VTE (n = 200). In a model adjusted for age, race, sex, hormone replacement, alcohol intake, diabetes, body mass index, estimated glomerular filtration rate, and C-reactive protein, the hazard ratios (HR) (95% confidence interval) for high versus normal AST were 1.46 (1.00-2.11) for total VTE and 1.83 (1.21-2.79) for provoked VTE. For high GGT, the HR were 1.34 (1.06-1.69) for total VTE and 1.43 (1.07-1.91) for provoked VTE. When follow-up was limited to the first 10 years, associations were even stronger (HR ≈ 1.7 for total VTE).

CONCLUSIONS

Elevated concentrations of two hepatic enzymes (AST and GGT) in this general middle-aged population are associated with a modestly increased risk of VTE.

Impact of atrial fibrillation on healthcare utilization in the community: the Atherosclerosis Risk in Communities study

Background

Atrial fibrillation (AF) is associated with increased risk of hospitalization. Little is known about the impact of AF on utilization of noninpatient health care or about sex or race differences in AF‐related utilization. We examined rates of inpatient and outpatient utilization by AF status in the Atherosclerosis Risk in Communities study.

Methods and Results

Participants with incident AF enrolled in fee‐for‐service Medicare for at least 12 continuous months between 1991 and 2009 (n=932) were matched on age, sex, race and field center with up to 3 participants without AF (n=2729). Healthcare utilization was ascertained from Medicare claims and classified by primary International Classification of Diseases, ninth revision code. The average annual numbers of days hospitalized were 13.2 (95% CI 11.6 to 15.0) and 2.8 (95% CI 2.5 to 3.1) for those with and without AF, respectively. The corresponding numbers of annual outpatient claims were 53.3 (95% CI 50.5 to 56.3) and 22.9 (95% CI 22.1 to 23.8) for those with and without AF, respectively. Most utilization among AF patients was attributable to non‐AF conditions. The adjusted rate ratio for annual days hospitalized for other cardiovascular disease–related reasons was 4.58 (95% CI: 3.41 to 6.16) for those with AF versus those without AF. The association between AF and healthcare utilization was similar among men and women and among white and black participants.

Conclusions

Participants with AF had considerably greater healthcare utilization, and the difference in utilization for other cardiovascular disease–related reasons was substantial. In addition to rate or rhythm treatment, AF management should focus on the accompanying cardiovascular comorbidities.

Periodic limb movements during sleep and prevalent hypertension in the multi-ethnic study of atherosclerosis

Periodic limb movements during sleep (PLMS) are associated with immediate increases in blood pressure. Both PLMS and hypertension have different distributions across racial/ethnic groups. We sought to determine whether PLMS is associated with hypertension among various racial/ethnic groups. A total of 1740 men and women underwent measurement of blood pressure and polysomnography with quantification of PLMS. Hypertension was defined as systolic blood pressure (SBP) ≥140, diastolic BP ≥90, or taking antihypertensive medication. For those taking antihypertensives, an estimated pretreatment SBP value was derived based on observed SBP and medication type/dose. Measures of PLMS, PLMS index, and PLMS arousal index were the main explanatory variables. Hypertension and SBP were modeled with logistic and multivariable regression adjusted for age, sex, body mass index, cardiovascular risk factors, lifestyle/habitual factors, apnea-hypopnea index, and race/ethnicity. In the overall cohort, prevalent hypertension was modestly associated with PLMS index (10 U; odds ratio, 1.05; 95% confidence interval, 1.00-1.10) and PLMS arousal index (1 U; 1.05; 1.01-1.09) after adjusting for confounders. Association in the overall cohort was influenced by large effect sizes in blacks, in whom the odds of prevalent hypertension increased by 21% (1%-45%) for 10 U PLMS index increase and 20% (2%-42%) for 1-U PLMS arousal index increase. In blacks, every 1-U PLMS arousal index increase was associated with SBP 1.01 mm Hg higher (1.01; 0.04-1.98). Associations between PLMS and blood pressure outcomes were also suggested among Chinese-Americans but not in whites or Hispanics. In a multiethnic cohort of community-dwelling men and women, prevalent hypertension and SBP are associated with PLMS frequency in blacks.

Obstructive sleep apnea and progression of coronary artery calcium: the multi-ethnic study of atherosclerosis study

Background

Obstructive sleep apnea (OSA) is a common condition associated with cardiovascular disease. Its potential effect on progression of subclinical atherosclerosis is not well understood. We tested the hypothesis that self‐reported OSA is associated with progression of coronary artery calcium (CAC). We also evaluated whether traditional cardiovascular risk factors accounted for the association.

Methods and Results

In the Multi‐Ethnic Study of Atherosclerosis (MESA) prospective cohort, we studied 2603 participants who at baseline (2002–2004) completed a sleep questionnaire and underwent coronary computed tomography (CT) and, then 8 years later (2010–2011), a repeat coronary CT. Participants were categorized by symptoms of habitual snoring or reported physician diagnosis of OSA. At baseline, 102 (3.9%) reported diagnosed OSA; 666 (25.6%) reported diagnosed habitual snoring; and 1835 (70.5%) reported neither habitual snoring nor OSA (“normal”). At baseline, CAC prevalence was highest among those with OSA but similar for those with and without habitual snoring. During 8 years of follow‐up, greater progression of CAC was observed among those with OSA versus normal (mean increase of 204.2 versus 135.5 Agatston units; P=0.01), after accounting for demographics, behaviors, and body habitus. Modest attenuation was observed after adjustment for cardiovascular risk factors (188.7 versus 138.8; P=0.06). CAC progression among habitual snorers was similar to that observed in the normal group.

Conclusions

OSA was associated with CAC score progression after adjustment for demographics, behaviors, and body mass index. However, the association was not significant after accounting for cardiovascular risk factors, which may mediate the association between OSA and CAC.

Circulating fibroblast growth factor-23 and the incidence of atrial fibrillation: the Atherosclerosis Risk in Communities study

Background

Increased concentrations of circulating fibroblast growth factor 23 (FGF‐23) have been associated with higher risk of cardiovascular disease. The association between FGF‐23 and the risk of atrial fibrillation (AF), a common arrhythmia, is less defined. Thus, we explored whether FGF‐23 concentration was associated with AF incidence in a large community‐based cohort.

Methods and Results

We studied 12 349 men and women enrolled in the Atherosclerosis Risk in Communities (ARIC) study, without prevalent AF at baseline in 1990–1992. Serum intact FGF‐23 concentration was measured with the Kainos 2‐site ELISA. Incident AF through 2010 was ascertained from study ECGs and hospital discharge codes. Cox proportional hazards models adjusted for potential confounding factors, including kidney function, were used to estimate the association between FGF‐23 and AF risk. We identified 1572 AF events during a mean follow‐up of 17 years. In multivariable analysis, a difference of 1 SD (16 pg/mL) in baseline FGF‐23 was not associated with the risk of AF (hazard ratio [HR], 1.04; 95% confidence interval [CI], 0.99, 1.09). Results were similar when FGF‐23 was modeled in quartiles (HR, 1.09; 95% CI, 0.94, 1.26, comparing extreme quartiles). Reduced kidney function was associated with increased AF risk across quartiles of FGF‐23 levels.

Conclusion

In this large community‐based cohort, baseline FGF‐23 levels were not associated with AF risk independently of kidney function. Our results do not support a major role for FGF‐23 as a risk factor for AF or as a mediator of the association between chronic kidney disease and AF.

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.