Low-Sodium DASH reduces oxidative stress and improves vascular function in salt-sensitive humans

Salt induces oxidative stress in salt-sensitive (SS) animals and man. It is not known whether in SS subjects the low-sodium dietary approaches to stop hypertension (LS-DASH) reduces oxidative stress more than DASH, which is high in antioxidants. To assess the effects of DASH and LS-DASH on oxidative stress, 19 volunteers were studied after 3 weeks of a standardized usual low fruits and vegetables diet (ULFV), followed by 3 weeks on DASH (both diets approximately 120 mmol Na(+) per day), then 3 weeks on LS-DASH (60 mmol Na(+) per day). SS was defined as systolic blood pressure >or=5 mm Hg lower on LS-DASH than DASH. In SS subjects (N=9), systolic blood pressure was lower on LS-DASH (111.0+/-2.0 mm Hg) than DASH (118.0+/-2.2, P<0.01) and ULFV (122.3+/-2.7, P=0.002). In salt-resistant (SR) volunteers (N=10), systolic blood pressure was lower on DASH (113.0+/-1.6) than ULFV (119.0+/-1.8, P<0.05) but not LS-DASH (115.7+/-1.8). Urine F2-isoprostanes, a marker of oxidative stress, were lower in SS subjects on LS-DASH (1.69+/-0.24) than ULFV (3.09+/-0.50, P<0.05) and marginally lower than DASH (2.46+/-0.44, P<0.20). F2-isoprostanes were not different among the three diets in SR volunteers (2.18+/-0.29, 2.06+/-0.29, 2.27+/-0.53, respectively). Aortic augmentation index, a measure of vascular stiffness, was lower in SS subjects on LS-DASH than either DASH or ULFV, and lower on DASH than ULFV in SR volunteers. In SS but not SR subjects, LS-DASH is associated with lower values for F2-isoprostanes and the aortic augmentation index. The results suggest that LS-DASH decreases oxidative stress, improves vascular function and lowers blood pressure in SS but not SR volunteers.

The role of sympathetic activation in cardiovascular disease

Activation of the sympathetic nervous system plays an important role in the development and maintenance of essential hypertension and the subsequent development of cardiac hypertrophy, heart failure, and sudden cardiac death. Current research suggests that pharmacologic treatment of hypertension should be aimed not only at lowering blood pressure, but also at inhibiting sympathetic drive.

Prehypertension: should we be treating with pharmacologic therapy?

Prehypertension, defined by Seventh Joint National Committee (JNC 7) as a blood pressure (BP) 120-139/80-89 mm Hg, was controversial. Approximately 31-37% of US adults are prehypertensive, and approximately 12-14% have BP of 130-139/85-89 mm Hg or ;Stage 2' prehypertension, is associated with approximately 3-fold greater likelihood of developing hypertension and roughly twice the cardiovascular events than BP <120/80 mm Hg. Lifestyle change is the only intervention recommended for most prehypertensives. When fully implemented, lifestyle changes lower BP and prevent cardiovascular events, but evidence for community-wide effectiveness is limited. The Trial of Preventing Hypertension (TROPHY) documented that angiotensin receptor blockade safely lowers BP and prevents and/or delays hypertension in Stage 2 prehypertensives. Prehypertensives with diabetes or nephropathy are at high risk and should receive antihypertensive treatment according to JNC 7. Epidemiological data suggest that the number needed to treat to prevent a cardiovascular event in these at-risk Stage 2 prehypertensives is similar to Stage 1 hypertensives when both groups have one or more concomitant risk factors. Clinical trials are urgently needed to address this question. In the absence of clinical trials data, we believe it is prudent for the concerned clinician to consider initiating antihypertensive pharmacotherapy in selected Stage 2 prehypertensive patients at significant absolute risk for progression to hypertension and cardiovascular events.

Dietary salt restriction and blood pressure in clinical trials

Dietary salt has long been recognized as a major factor affecting blood pressure such that sodium intake is a component of lifestyle modification guidelines for control of high blood pressure. These recommendations are based on results from epidemiologic observational studies and clinical trials of various sodium diets among normotensives and hypertensives. Nonetheless, results from the different studies vary such that specific recommendations regarding sodium intake are difficult to interpret. The results from several recent major trials indicated greater associations of blood pressure and sodium intake than earlier studies as well as meta-analyses of numerous clinical trials. The studies of sodium intake and blood pressures are complicated by measurements of intake, salt sensitivity, hypertension treatment, effects of sodium independent of blood pressure, and length of interventions. Limitations in the methodology of different studies have reduced the value of the results to provide specific and reliable sodium intake levels essential for clinical and lifestyle guidelines.

Effect of psyllium fiber supplementation on C-reactive protein: the trial to reduce inflammatory markers (TRIM)

PURPOSE

Recent evidence supports a significant association between the intake of dietary fiber and levels of inflammatory markers. The objective of this study was to determine whether daily fiber supplementation would reduce levels of inflammatory markers.

METHODS

This study was a prospective randomized controlled trial at a single university medical center. Participants were overweight or obese adults with no history of heart disease. The intervention was psyllium supplementation at either 7 or 14 g/d for 3 months compared with no supplements in a control group. The main outcome measure was change in level of high-sensitivity C-reactive protein (hsCRP) concentration; secondary outcomes included changes in interleukin-6 (IL-6) levels, fibrinogen levels, and white blood cell (WBC) count. Protocol completers attended at least 2 visits and took more than 75% of the prescribed fiber dose.

RESULTS

In this intent-to-treat analysis (n = 158), there were no significant differences between either of the 2 treatment groups and the control group in the amount of change in CRP, fibrinogen, or IL-6 levels or in WBC count (P>.05). In the analysis of protocol completers (n = 132), there also were no significant differences between the groups except for a small decrease in fibrinogen level in the high-fiber group (-6 mg/dL [-0.18 micromol/L] compared with 13 mg/dL [0.38 micromol/L] in the control group, P<.05).

CONCLUSION

Psyllium fiber supplementation did not significantly reduce CRP levels in overweight or obese individuals in this trial, and changes in other markers were not consistent. Further research is needed to determine whether other fibers or nutrients can reduce inflammatory markers.

Differences in cardiovascular disease mortality associated with body mass between Black and White persons

We analyzed cardiovascular disease mortality risks associated with obesity using participant-level meta-analysis of data from the Black Pooling Project for Black and White individuals. The adjusted relative risks (ARRs) were stronger among White participants than among Black participants for coronary heart disease AAR=1.21 (95% confidence interval [CI]=1.07, 1.36) versus 0.87 (95% CI=0.69, 1.09), respectively, and cardiovascular disease ARR=1.18 (95% CI=1.07, 1.29) versus 0.91 (95% CI=0.77, 1.05), respectively. The results suggest that obesity is an independent risk factor in White people, and additional study of body size and disease progression is necessary in the assessment of racial disparities.

Use of statins and blood pressure

BACKGROUND

Markers of inflammation such as high-sensitivity C-reactive protein (CRP) were shown to be elevated in patients with hypertension. Small trials using statin therapy showed blood-pressure (BP) reductions, but it is unknown whether this association extends to larger populations. The objective of this study was to determine whether statin use was associated with better blood-pressure control in adults with hypertension and whether inflammation levels mediated this relationship.

METHODS

This was a cross-sectional study of 2584 hypertensive adults aged >or=40 years with no known cardiovascular disease from the National Health and Nutrition Examination Survey 1999-2002. Logistic regression models were calculated to determine whether there was an association between statin use and blood-pressure control. C-reactive protein was added to the full model to determine its impact on the association.

RESULTS

Compared with people not using statin medication, significantly more statin users had their blood pressure under control (52.2% v 38.0%). After adjustment for demographic factors, statin users were two times (95% confidence interval [CI], 1.46 to 2.72) more likely to have their blood pressure under control (<140/90 mm Hg) than nonusers. After further adjustment for body mass index, diabetes, smoking, exercise, low-salt diet, and antihypertensive medications, the likelihood of having blood pressure under control remained more likely among statin users (odds ratio, 1.46; 95% CI, 1.05 to 2.05). The association between statin use and lower BP was most evident among participants who used antihypertensive medication as well as statins and was unchanged with the addition of CRP to the model.

CONCLUSIONS

Statin use was associated with a BP level <140/90 mm Hg in a representative sample of US adults with hypertension. Levels of CRP did not attenuate the association. Further studies are needed to explore the effects of statin use on blood pressure and to determine how best to apply this knowledge in clinical care.

Age and race impact the association between BMI and CVD mortality in women

OBJECTIVES

In previous studies, we have shown that obesity is associated with increased cardiovascular disease (CVD) mortality in white women but not in black women. Earlier research suggests that body mass index (BMI) has a greater effect on CVD mortality in younger white females than older white females, whereas this relationship in black women is not as clear. This study examines the effect of age on the association of BMI to CVD in black and white women.

METHODS

The Black Pooling Project includes data on 2,843 black women with 50,464 person-years of follow-up, and 12,739 white women with 214,606 person-years of follow-up. A Cox proportional hazards model was used to examine the association between BMI and CVD mortality for specific age/race groups. The younger group was < 60 years of age and the older group was > 60 years of age.

RESULTS

In younger white women, the relative risk (95% confidence interval [CI]) for CVD mortality was significant in obese women (BMI > 30 kg/m2) vs. women of normal weight (BMI 18.5-24.9 kg/m2) (1.59 [CI 1.20, 2.09]). Similarly, in older white women, the relative risk for CVD mortality in obese women vs. women of normal weight was significant (1.21 [CI 1.04, 1.41]). There were no such associations for black women. Overweight (BMI 25-29.9 kg/m2) was not associated with increased risk in black or white women.

CONCLUSION

These findings indicate that obesity is associated with a significantly greater risk of CVD mortality among white women, with the strongest association among white women < 60 years of age.

A Statewide Primary Care Approach to Cardiovascular Risk Factor Control in High‐Risk Diabetic and Nondiabetic Patients With Hypertension

Patients with multiple cardiovascular risk factors benefit from having them all controlled, but this rarely occurs. Fifty-seven primary care providers were enrolled in a program to monitor cardiovascular risk factor control. Data were obtained on 7315 hypertensives. This analysis focuses on 3460 high-risk hypertensives including 2199 with diabetes and 1261 with clinical cardiovascular disease. Blood pressures were <140/90 mm Hg and <130/80 mm Hg in only 44.3% and 20.4% of diabetics and 49.6% and 26.6% nondiabetics, respectively, despite the use of an average of 2.7+/-1.8 antihypertensive medications. Among high-risk dyslipidemic hypertensives, the low-density lipoprotein cholesterol level was <100 mg/dL in only 34% of diabetic and 33% of nondiabetic patients. Among 1696 diabetic hypertensives, the most recent glycosylated hemoglobin value averaged 7.5%, with 46.6% less than 7%. Among 805 diabetic, dyslipidemic hypertensives, all three risk factors were controlled to goal in only 6.6% with higher rates in whites than in African Americans (14.8% vs. 1.6%, p<0.001). An angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, or both were prescribed in 89.9% of diabetic and 70.8% of nondiabetic patients, p<0.05. Primary care providers use evidence-based combination therapy in high-risk hypertensive patients with and without diabetes. These findings confirm the low rates of multiple risk factor control and highlight challenges of reaching evidence-based goals in primary care.

Platelet and White Blood Cell Counts Are Elevated in Patients With the Metabolic Syndrome

Platelet and white blood cell counts are higher among some insulin-resistant patients and may contribute to atherothromboembolic complications. Metabolic syndrome patients are insulin resistant, often hypertensive, and at high cardiovascular disease risk, yet the relationship of platelets to the metabolic syndrome is unknown. Platelet and white blood cell counts were obtained from 135 volunteers who had measurements of blood pressure, fasting triglycerides, high-density lipoprotein cholesterol, and glucose. A body mass index >30 kg/m2 served as a surrogate for increased waist circumference. Subjects were subdivided into three groups by the number of metabolic syndrome criteria, i.e., no metabolic syndrome risk factor (MS-0; n = 40), one or two metabolic syndrome risk factors (MS1-2; n = 61), and three to five metabolic syndrome risk factors (MS3-5; n = 34). Platelet counts were increased significantly from 226+/-8 to 257+/-8 and 276+/-10 (x10(3)/mm3) in the MS-0, MS1-2, and MS3-5 groups, respectively (p < 0.01), after adjustment for age, gender, ethnicity, total cholesterol, and low-density lipoprotein cholesterol. White blood cell counts were also increased across the three groups (5.4+/-0.2, 6.2+/-0.2, and 6.6+/-0.3 [x10(3)/mm3]; p < 0.01) after multivariate adjustment. Compared with patients with zero to two metabolic syndrome risk factors, metabolic syndrome patients have higher platelet and white blood counts, which may serve as markers of a prothrombotic and proinflammatory state and contributors to atherothromboembolic risk.

Ethnic Differences in the Treatment and Control of Hypertension in Patients With Diabetes

Among diabetic hypertensive patients, ethnic differences in blood pressure control and outcomes have been attributed in part to greater reluctance of providers to prescribe combination antihypertensive regimens to African Americans than to Caucasians. African Americans purportedly receive fewer angiotensin-converting enzyme inhibitors (ACEIs) and/or angiotensin receptor blockers (ARBs), which reduce target organ complications. To assess these issues, cross-sectional data were analyzed from 19,864 diabetic hypertensives from 62 primary care clinics. Among diabetic hypertensives, African Americans (N=6230) were less likely than Caucasians (N=8041) to have blood pressure (BP) <130/80 mm Hg at their last clinic visit (23.1% [23.0%-23.2%] vs. 30.7% [30.6%-30.9%]) despite a greater number of prescriptions for antihypertensive medications (2.67 [2.63-2.70] vs. 2.23 [2.20-2.26]). African Americans were more likely than Caucasians to have an ACEI and/or ARB prescribed and to receive prescriptions for at least two antihypertensive medications that included an ACEI or ARB (64.1% [63.8%-64.4%] vs. 53.1% [52.8%-53.4%]). Among diabetic hypertensives, African Americans are less likely than Caucasians to attain BP <130/80 mm Hg, despite receiving more antihypertensive medication prescriptions. African Americans receive more ACEIs and/or ARBs than Caucasians for target organ protection and/or BP control. The data suggest provider prescribing patterns are not a major contributor to ethnic differences in BP control and outcomes in diabetic hypertensives.

Cardioprotection: The Role of β‐Blocker Therapy

Randomized controlled clinical trials document that beta blockers reduce cardiovascular morbidity and mortality, particularly sudden death, in patients with hypertension, heart failure, and post-myocardial infarction. The benefits of beta blockers extend across the boundaries of age, gender, and ethnicity, and include diabetic patients with heart failure and/or previous myocardial infarction. Unfortunately, beta blockers remain underutilized in many high-risk patients who would likely benefit from their use. This paper reviews the protective role of beta blockade in the primary and secondary prevention of cardiovascular events and examines some of the potential barriers to appropriate beta blocker use in patients with compelling indications.

Inverse associations of Helicobacter pylori with asthma and allergy

BACKGROUND

Acquisition of Helicobacter pylori, which predominantly occurs before age 10 years, may reduce risks of asthma and allergy.

METHODS

We evaluated the associations of H pylori status with history of asthma and allergy and with skin sensitization using data from 7663 adults in the Third National Health and Nutrition Examination Survey. Adjusted odds ratios (ORs) for currently and ever having asthma, allergic rhinitis, allergy symptoms in the previous year, and allergen-specific skin sensitization were computed comparing participants seropositive for cagA(-) or cagA(+) strains of H pylori with those without H pylori.

RESULTS

The presence of cagA(+) H pylori strains was inversely related to ever having asthma (OR, 0.79; 95% confidence interval [CI], 0.63-0.99), and the inverse association of cagA positivity with childhood-onset (age </=15 years) asthma was stronger (OR, 0.63; 95% CI, 0.43-0.93) than that with adult-onset asthma (OR, 0.97; 95% CI, 0.72-1.32). Colonization with H pylori, especially with a cagA(+) strain, was inversely associated with currently (OR, 0.77; 95% CI, 0.62-0.96) or ever (OR, 0.77; 95% CI, 0.62-0.94) having a diagnosis of allergic rhinitis, especially for childhood onset (OR, 0.55; 95% CI, 0.37-0.82). Consistent inverse associations were found between H pylori colonization and the presence of allergy symptoms in the previous year and sensitization to pollens and molds.

CONCLUSION

These observations support the hypothesis that childhood acquisition of H pylori is associated with reduced risks of asthma and allergy.

Effect of a High-Fiber Diet vs a Fiber-Supplemented Diet on C-Reactive Protein Level

BACKGROUND

Diets high in fiber are associated with lower levels of inflammatory markers. This study examined the reduction in inflammation from a diet supplemented with fiber compared with a diet naturally high in fiber.

METHODS

Randomized crossover intervention trial of 2 diets, a high-fiber (30-g/d) Dietary Approaches to Stop Hypertension (DASH) diet or fiber-supplemented diet (30 g/d), after a baseline (regular) diet period of 3 weeks. There were 35 participants (18 lean normotensive and 17 obese hypertensive individuals) aged 18 to 49 years.

RESULTS

The study included 28 women and 7 men; 16 (46%) were black, the remainder white. The mean (SD) fiber intake on baseline diets was 11.9 (0.3) g/d; on the high-fiber DASH diet, 27.7 (0.6) g/d; and on the supplemented diet, 26.3 (0.4) g/d. Overall, the mean C-reactive protein (CRP) level changed from 4.4 to 3.8 mg/L (-13.7%; P = .046) in the high-fiber DASH diet group and to 3.6 mg/L (-18.1%) in the fiber-supplemented diet group (P = .03). However, CRP levels decreased in the 18 lean normotensive participants in either intervention diet group (2.0 mg/L [baseline] vs 1.4 mg/L [high-fiber DASH] vs 1.2 mg/L [supplemented]); P<.05) but did not change significantly (7.1 mg/L [baseline] vs 6.2 mg/L [high-fiber DASH] vs 6.5 mg/L [supplemented]; P>.05) in obese hypertensive participants. Neither age nor race influenced the response of CRP levels to the diets. No evidence of a crossover effect was detected.

CONCLUSIONS

The results demonstrate that fiber intake of about 30 g/d) from a diet naturally rich in fiber or from a supplement can reduce levels of CRP. Further research is needed to more clearly elucidate the differential effect seen in lean vs obese individuals and whether modification of dietary fiber may be helpful in modulating inflammation and its consequent cardiovascular consequences.

Geographical patterns of end-stage renal disease incidence and risk factors in rural and urban areas of South Carolina

To assess the geographical patterns of end-stage renal disease (ESRD) incidence and to identify the risk factors on the regional differences, the authors conducted an ecological study on incidence of ESRD and related risk factors in the 46 counties of South Carolina (SC). Age and gender adjusted, race specific incidence rates for each county in SC were calculated for the 11,346 ESRD patients of all ages who registered in the United States Renal Data Systems Network 6 from 1990 to 1999. County level exposure measures on population physician density, hospitalization rates of diabetes and hypertension, per capita income, percent college degree, and percent below poverty were evaluated. There was a significant increase in mean incidence rates of ESRD from 1990 to 1999 in SC (p<0.0001). The incidence rates were consistently higher in rural than in urban counties. Population physician density (relative risk (RR) 0.49, 95% confidence interval (95%Cl, 0.41-0.58) and rural residence (adjusted RR 1.66, 95%Cl 1.59-1.74) were significantly associated with ESRD incidence. The strong relationship between ESRD and physician density suggests that access to adequate treatment of diabetes and hypertension is of paramount importance for ESRD prevention, and has important public policy implications.

Cardiovascular risk factor control in communities--update from the ASH Carolinas-Georgia Chapter, the Hypertension Initiative, and the Community Physicians' Network

The prevalence of hypertension dictates that blood pressure must be managed effectively in primary care. The American Society of Hypertension (ASH) regional chapters and clinical hypertension specialists represent a positive response by ASH to the growing problems of hypertension and metabolic syndrome-related risks and disease. To have a significant public health effect, the impact of clinical hypertension specialists must be leveraged. Key activities in the community include educating other providers locally, delivering care for complex referral patients, and fostering growth of a practice network with a central database in collaboration with academic partners. The database supports practice audit and feedback reports to enhance quality improvement, identify continuing medical education topics, and facilitate clinical trials to test new therapeutic and best-practice approaches to risk factor management. The ASH regional chapters serve as a forum for community and academic hypertension specialists to collaborate with like-minded individuals and organizations. The collaboration among the ASH Carolinas-Georgia chapter, the Hypertension Initiative, and the Community Physicians' Network provides a model for other ASH chapters and health delivery groups to partner in delivering continuing medical education programs focused on cardiovascular risk factor management, recruiting practices into the network, and developing and maintaining a centralized patient database. Evidence suggests that this collaboration is facilitating application of evidence-based medicine and risk factor control.