Salt and blood pressure in children and adolescents

To study the relationship between salt intake and blood pressure in children and adolescents, we analysed the data of a large cross-sectional study (the National Diet and Nutrition Survey for young people), which was carried out in Great Britain in 1997 in a nationally representative sample of children aged between 4 and 18 years. A total of 1658 participants had both salt intake and blood pressure recorded. Salt intake was assessed by a 7-day dietary record. The average salt intake, which did not include salt added in cooking or at the table, was 4.7+/-0.2 g/day at the age of 4 years. With increasing age, there was an increase in salt intake, and by the age of 18 years, salt intake was 6.8+/-0.2 g/day. There was a significant association of salt intake with systolic blood pressure as well as with pulse pressure after adjusting for age, sex, body mass index and dietary potassium intake. An increase of 1 g/day in salt intake was related to an increase of 0.4 mm Hg in systolic and 0.6 mm Hg in pulse pressure. The magnitude of the association with systolic blood pressure is very similar to that observed in a recent meta-analysis of controlled trials where salt intake was reduced. The consistent finding of our present analysis of a random sample of free-living individuals with that from controlled salt reduction trials provides further support for a reduction in salt intake in children and adolescents.     

Relaxation therapies for the management of primary hypertension in adults: a Cochrane review

The objective of this review was to evaluate the effectiveness of relaxation to lower high blood pressure. We searched electronic bibliographic databases and grey literature to identify randomized controlled trials comparing relaxation therapies with no active treatment or sham therapy, enrolling adult participants with raised systolic blood pressure (SBP) > or = 140 mm Hg or diastolic blood pressure (DBP) > or = 85 mm Hg and follow-up > or = 8 weeks. Twenty-five trials with up to 5 years follow-up, assessing 1198 participants, met our inclusion criteria and were meta-analysed. Overall, relaxation resulted in small, statistically significant reductions in SBP (mean difference: -5.5 mm Hg, 95% CI: -8.2 to -2.8) and DBP (mean difference: -3.5 mm Hg, 95% CI: -5.3 to -1.6) compared to the control. Substantial heterogeneity between trials (I2 > 70%) was not explained by duration of follow-up, type of control, type of relaxation therapy or baseline blood pressure. The 9 trials that reported blinding of outcome assessors found a non-significant net reduction in blood pressure (SBP mean difference: -3.2 mm Hg, 95% CI: -7.7 to 1.4) associated with relaxation, as did the 15 trials comparing relaxation with sham therapy (SBP mean difference: -3.5 mm Hg, 95% CI: -7.1 to 0.2). Adequate randomization was confirmed in only seven trials and concealment of allocation in only one. In view of the poor quality of the included trials and unexplained variation between trials, the evidence in favour of a causal association between relaxation and blood pressure reduction is weak. Some of the apparent benefit of relaxation was probably due to aspects of treatment unrelated to relaxation.     

Effect of cocoa and tea intake on blood pressure: a meta-analysis

BACKGROUND: Epidemiological evidence suggests blood pressure-lowering effects of cocoa and tea. We undertook a meta-analysis of randomized controlled trials to determine changes in systolic and diastolic blood pressure due to the intake of cocoa products or black and green tea. METHODS: MEDLINE, EMBASE, SCOPUS, Science Citation Index, and the Cochrane Controlled Trials Register were searched from 1966 until October 2006 for studies in parallel group or crossover design involving 10 or more adults in whom blood pressure was assessed before and after receiving cocoa products or black or green tea for at least 7 days. RESULTS: Five randomized controlled studies of cocoa administration involving a total of 173 subjects with a median duration of 2 weeks were included. After the cocoa diets, the pooled mean systolic and diastolic blood pressure were -4.7 mm Hg (95% confidence interval [CI], -7.6 to -1.8 mm Hg; P = .002) and -2.8 mm Hg (95% CI, -4.8 to -0.8 mm Hg; P = .006) lower, respectively, compared with the cocoa-free controls. Five studies of tea consumption involving a total of 343 subjects with a median duration of 4 weeks were selected. The tea intake had no significant effects on blood pressure. The estimated pooled changes were 0.4 mm Hg (95% CI, -1.3 to 2.2 mm Hg; P = .63) in systolic and -0.6 mm Hg (95% CI, -1.5 to 0.4 mm Hg; P = .38) in diastolic blood pressure compared with controls. CONCLUSION: Current randomized dietary studies indicate that consumption of foods rich in cocoa may reduce blood pressure, while tea intake appears to have no effect.     

Effect of spironolactone on blood pressure in subjects with resistant hypertension

Spironolactone is recommended as fourth-line therapy for essential hypertension despite few supporting data for this indication. We evaluated the effect among 1411 participants in the Anglo-Scandinavian Cardiac Outcomes Trial-Blood Pressure Lowering Arm who received spironolactone mainly as a fourth-line antihypertensive agent for uncontrolled blood pressure and who had valid BP measurements before and during spironolactone treatment. Among those who received spironolactone, the mean age was 63 years (SD: +/-8 years), 77% were men, and 40% had diabetes. Spironolactone was initiated a median of 3.2 years (interquartile range: 2.0 to 4.4 years) after randomization and added to a mean of 2.9 (SD: +/-0.9) other antihypertensive drugs. The median duration of spironolactone treatment was 1.3 years (interquartile range: 0.6 to 2.6 years). The median dose of spironolactone was 25 mg (interquartile range: 25 to 50 mg) at both the start and end of the observation period. During spironolactone therapy, mean blood pressure fell from 156.9/85.3 mm Hg (SD: +/-18.0/11.5 mm Hg) by 21.9/9.5 mm Hg (95% CI: 20.8 to 23.0/9.0 to 10.1 mm Hg; P<0.001); the BP reduction was largely unaffected by age, sex, smoking, and diabetic status. Spironolactone was generally well tolerated; 6% of participants discontinued the drug because of adverse effects. The most frequent adverse events were gynecomastia or breast discomfort and biochemical abnormalities (principally hyperkaliemia), which were recorded as adverse events in 6% and 2% of participants, respectively. In conclusion, spironolactone effectively lowers blood pressure in patients with hypertension uncontrolled by a mean of approximately 3 other drugs. Although nonrandomized and not placebo controlled, these data support the use of spironolactone in uncontrolled hypertension.     

Salt, blood pressure and cardiovascular diseases

The rise in average blood pressure with age seen in Western populations does not occur in isolated traditional nomadic communities. Several factors contribute to the higher blood pressure in the West. Salt is particularly important, however, because its effect on blood pressure is large, the dietary intake by Western populations is high and a large reduction in its intake is realistic. The size of the relationship between salt and blood pressure depends on age and, in trials, the duration of reduction of intake of salt. Results of many of the randomized trials have suggested that reduction of dietary salt exerts only a small effect on average blood pressure; this is because their subjects have been young (average age 26 years) and trials have been of short duration (average 2 weeks). Analysis of observational data concerning various communities indicated that a reduction in dietary intake of sodium of 100 mmol/24 h (3 g of salt, a realistic reduction) lowers systolic blood pressure in subjects aged 50-65 years by 10 mmHg on average. Much evidence corroborates this estimate, including data from the Intersalt study and a randomized controlled trial of reduction of intake of salt by older persons. This reduction in blood pressure would reduce age-specific stroke mortality by an estimated 22% and mortality from heart disease by 16%. Reducing the amount of salt added to manufactured foods is an important public-health target.     

Systematic review and meta-analysis of preterm birth and later systolic blood pressure

Lower birth weight because of fetal growth restriction is associated with higher blood pressure later in life, but the extent to which preterm birth (<37 completed weeks' gestation) or very low birth weight (<1500 g) predicts higher blood pressure is less clear. We performed a systematic review of 27 observational studies that compared the resting or ambulatory systolic blood pressure or diagnosis of hypertension among children, adolescents, and adults born preterm or very low birth weight with those born at term. We performed a meta-analysis with the subset of 10 studies that reported the resting systolic blood pressure difference in millimeters of mercury with 95% CIs or SEs. We assessed methodologic quality with a modified Newcastle-Ottawa Scale. The 10 studies were composed of 1342 preterm or very low birth weight and 1738 term participants from 8 countries. The mean gestational age at birth of the preterm participants was 30.2 weeks (range: 28.8-34.1 weeks), birth weight was 1280 g (range: 1098-1958 g), and age at systolic blood pressure measurement was 17.8 years (range: 6.3-22.4 years). Former preterm or very low birth weight infants had higher systolic blood pressure than term infants (pooled estimate: 2.5 mm Hg [95% CI: 1.7-3.3 mm Hg]). For the 5 highest quality studies, the systolic blood pressure difference was slightly greater, at 3.8 mm Hg (95% CI: 2.6-5.0 mm Hg). We conclude that infants who are born preterm or very low birth weight have modestly higher systolic blood pressure later in life and may be at increased risk for developing hypertension and its sequelae.     

Effect of nocturnal nasal continuous positive airway pressure on blood pressure in obstructive sleep apnea

Obstructive sleep apnea (OSA) is a very common risk factor for hypertension, and continuous positive airway pressure (CPAP) has been widely used to treat OSA. We conducted a meta-analysis of randomized, controlled trials to evaluate the effects of CPAP on blood pressure, reported as either a primary or secondary end point, among patients with OSA. Studies were retrieved by searching Medline (January 1980 to July 2006), the Cochrane Database of Systematic Reviews, conference abstracts, and bibliographies of review and original articles. From 255 relevant reports, 16 randomized clinical trials were selected that compared CPAP to control among participants with OSA, had a minimum treatment duration of 2 weeks, and reported blood pressure changes during the intervention or control period. Data on sample size, participant characteristics, study design, intervention methods, duration, and treatment results were independently abstracted by 2 investigators using a standardized protocol. Data from 16 trials representing 818 participants were examined using a random-effects model. Mean net change in systolic blood pressure for those treated with CPAP compared with control was -2.46 mm Hg (95% CI: -4.31 to -0.62); mean net change in diastolic blood pressure was -1.83 mm Hg (95% CI: -3.05 to -0.61); and mean net change in mean arterial pressure was -2.22 mm Hg (95% CI: -4.38 to -0.05). Net reductions in blood pressure were not statistically different between daytime and nighttime. These results indicate that CPAP decreases blood pressure among those with OSA and may help prevent hypertension.     

Individual blood pressure responses to changes in salt intake: results from the DASH-Sodium trial

Although group characteristics are known to influence average blood pressure response to changes in salt intake, predictability of individual responses is less clear. We examined variability and consistency of individual systolic blood pressure responses to changes in salt intake in 188 participants who ate the same diet at higher, medium, and lower (140, 104, 62 mmol/d) sodium levels for 30 days each, in random order, after 2 weeks of run-in at the higher sodium level. Regarding variability in systolic blood pressure changes over time, changes from run-in to higher sodium (no sodium level change) ranged from -24 to +25 mm Hg; 8.0% of participants decreased > or =10 mm Hg. Regarding variability in systolic blood pressure response to change in sodium intake, with higher versus lower sodium levels (78-mmol sodium difference), the range of systolic blood pressure change was -32 to +17 mm Hg; 33.5% decreased > or =10 mm Hg. Regarding consistency of response, systolic blood pressure change with run-in versus lower sodium was modestly correlated with systolic blood pressure change with higher versus medium sodium; systolic blood pressure change with higher versus lower sodium was similarly correlated with run-in versus medium sodium (combined Spearman r=0.27, P=0.002). These results show low-order consistency of response and confirm that identifying individuals as sodium responders is difficult. They support current recommendations for lower salt intake directed at the general public rather than "susceptible" individuals as one of several strategies to prevent and control adverse blood pressures widely prevalent in the adult population.     

Self-monitoring of home blood pressure with estimation of daily salt intake using a new electrical device

We investigated a simple device to monitor daily salt intake at home and examined the relationship between salt excretion and morning blood pressure in order to enable patients to better manage daily salt intake and hypertension. The correlation between 24-h urinary salt excretion and measured value with salt monitor from overnight urine was significant (n = 224, r = 0.72, P < 0.001). A total of 46 volunteers participated for more than 3 weeks by measuring daily salt intake and morning blood pressure. The relationship between predicted daily salt excretion and blood pressure was examined with use of 3-day moving average. Mean salt excretion and systolic blood pressure (SBP) significantly decreased by the end of the trial (i.e., salt excretion decreased from 158+/-31 to 149+/-30 mmol/day and SBP from 137+/-17 to 133+/-16 mm Hg). Of 46 participants, 18 (39%) had a significant correlation between predicted daily salt excretion and blood pressure (r > 0.4, P < 0.05, n > 21), indicating sodium sensitivity. An additional 17% had a positive correlation that did not reach statistical significance (0.2 < r < or = 0.4), and the remaining 44% had no correlation (r < or = 0.2). Mean decrease in blood pressure per decrease in salt (g) (17 mmol) intake in the 18 participants with a significant correlation was 3.3 mm Hg (SBP) and 1.5 mm Hg (diastolic blood pressure), which was higher than that reported for other studies. Hypertensive patients not using medication showed the largest decrease. We conclude that daily monitoring of salt intake and morning blood pressure will be useful for management of hypertension.     

Influence of weight reduction on blood pressure: a meta-analysis of randomized controlled trials

Increased body weight is a strong risk factor for hypertension. A meta-analysis of randomized controlled trials was performed to estimate the effect of weight reduction on blood pressure overall and in population subgroups. Twenty-five randomized, controlled trials (comprising 34 strata) published between 1966 and 2002 with a total of 4874 participants were included. A random-effects model was used to account for heterogeneity among trials. A net weight reduction of -5.1 kg (95% confidence interval [CI], -6.03 to -4.25) by means of energy restriction, increased physical activity, or both reduced systolic blood pressure by -4.44 mm Hg (95% CI, -5.93 to -2.95) and diastolic blood pressure by -3.57 mm Hg (95% CI, -4.88 to -2.25). Blood pressure reductions were -1.05 mm Hg (95% CI, -1.43 to -0.66) systolic and -0.92 mm Hg (95% CI, -1.28 to -0.55) diastolic when expressed per kilogram of weight loss. As expected, significantly larger blood pressure reductions were observed in populations with an average weight loss >5 kg than in populations with less weight loss, both for systolic (-6.63 mm Hg [95% CI, -8.43 to -4.82] vs -2.70 mm Hg [95% CI, -4.59 to -0.81]) and diastolic (-5.12 mm Hg [95% CI, -6.48 to -3.75] vs -2.01 mm Hg [95% CI, -3.47 to -0.54]) blood pressure. The effect on diastolic blood pressure was significantly larger in populations taking antihypertensive drugs than in untreated populations (-5.31 mm Hg [95% CI, -6.64 to -3.99] vs -2.91 mm Hg [95% CI, -3.66 to -2.16]). This meta-analysis clearly shows that weight loss is important for the prevention and treatment of hypertension.     

The effect of magnesium supplementation on blood pressure: a meta-analysis of randomized clinical trials

BACKGROUND: An increased intake of magnesium might lower blood pressure (BP), yet evidence from clinical trials is inconsistent, perhaps as a result of small sample size or heterogeneity in study design. METHODS: We performed a meta-analysis of randomized trials that tested the effects of magnesium supplementation on BP. Twenty trials meeting the inclusion criteria were identified. Random effects models and meta-regression methods were used to pool study results and to determine the dose-response relationship of magnesium to BP. RESULTS: The 20 studies included 14 of hypertensive and 6 of normotensive persons totaling 1220 participants. The doses of magnesium ranged from 10 to 40 mmol/day (median, 15.4 mmol/day). Magnesium supplementation resulted in only a small overall reduction in BP. The pooled net estimates of BP change (95% confidence interval [CI]) were -0.6 (-2.2 to 1.0) mm Hg for systolic BP and -0.8 (-1.9 to 0.4) mm Hg for diastolic BP. However, there was an apparent dose-dependent effect of magnesium, with reductions of 4.3 mm Hg systolic BP (95% CI 6.3 to 2.2; P < .001) and of 2.3 mm Hg diastolic BP (95% CI 4.9 to 0.0; P = .09) for each 10 mmol/day increase in magnesium dose. CONCLUSIONS: Our meta-analysis detected dose-dependent BP reductions from magnesium supplementation. However, adequately powered trials with sufficiently high doses of magnesium supplements need to be performed to confirm this relationship.     

Increased insulin resistance in salt sensitive essential hypertension

OBJECTIVE: To determine the possible relationship between insulin resistance and salt sensitivity in essential hypertension. DESIGN AND METHODS: We studied 17 non-obese, essential hypertensive patients (24-h blood pressure: 149 +/- 15/94 +/- 5 mm Hg) with normal glucose tolerance. Salt sensitivity was diagnosed in the presence of a significant increase (P < 0.05, more than 4 mm Hg) in 24-h mean blood pressure (MBP) when patients switched from a low-salt intake (50 mmol/day of Na(+)) to a high-salt intake (240 mmol/day of Na(+)), each period lasting 7 days. The insulin sensitivity index was determined by the euglycaemic hyperinsulinaemic clamp. RESULTS: Six patients were classified as salt sensitive (24-h MBP increase: 6.2 +/- 1.1 mm Hg), and 11 as salt resistant (24-h MBP increase: -1.2 +/- 3.8 mm Hg). No significant differences were observed between salt sensitive and salt resistant patients regarding baseline characteristics, fasting serum insulin, fasting serum glucose, glycosylated haemoglobin, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, uric acid and microalbuminuria. Salt sensitive patients exhibited a reduced insulin sensitivity index compared with salt resistant patients (1.7 +/- 1.1 vs 3.5 +/- 1.2 mg/kg/min; P = 0.009). An inverse relationship (r -0.57; P = 0.016) between the insulin sensitivity index and 24-h MBP increase with high salt intake was found. CONCLUSION: Salt sensitive essential hypertensive patients are more insulin resistant than salt resistant patients when both salt sensitivity and insulin resistance are accurately measured. Indirect measures of both insulin and salt sensitivity and/or the presence of modifying factors, such as obesity or glucose intolerance, may account for differences in previous studies.     

Effect of modest salt reduction on blood pressure: a meta-analysis of randomized trials. Implications for public health

Two recent meta-analyses of randomised salt reduction trials have concluded that there is little purpose in reducing salt intake in the general population. However, the authors, as with other previous meta-analyses, included trials of very short duration (eg 1 week or less) and trials of acute salt loading followed by abrupt reductions to very low salt intake (eg from 20 to less than 1 g of salt/day). These acute salt loading and salt depletion experiments are known to increase sympathetic tone, and with salt depletion cause a rise in renin release and, thereby, plasma angiotensin II. These trials are not appropriate, therefore, for helping to inform public health policy, which is for a more modest reduction in salt intake, ie, from a usual intake of approximately 10 to approximately 5 g of salt per day over a more prolonged period of time. We carried out a meta-analysis to assess the effect of a modest salt reduction on blood pressure. Our data sources were MEDLINE, EMBASE, Cochrane library, CINAHL, and the reference lists of original and review articles. We included randomised trials with a modest reduction in salt intake and a duration of 4 or more weeks. Meta-analysis, meta-regression, and funnel plots were performed. A total of 17 trials in hypertensives (n=734) and 11 trials in normotensives (n=2220) were included in our study. The median reduction in 24-h urinary sodium excretion was 78 mmol (equivalent to 4.6 g of salt/day) in hypertensives and 74 mmol in normotensives. The pooled estimates of blood pressure fall were 4.96/2.73+/-0.40/0.24 mmHg in hypertensives (P<0.001 for both systolic and diastolic) and 2.03/0.97+/-0.27/0.21 mmHg in normotensives (P<0.001 for both systolic and diastolic). Weighted linear regression analyses showed a dose response between the change in urinary sodium and blood pressure. A reduction of 100 mmol/day (6 g of salt) in salt intake predicted a fall in blood pressure of 7.11/3.88 mmHg (P<0.001 for both systolic and diastolic) in hypertensives and 3.57/1.66 mmHg in normotensive individuals (systolic: P<0.001; diastolic: P<0.05). Our results demonstrate that a modest reduction in salt intake for a duration of 4 or more weeks does have a significant and, from a population viewpoint, important effect on blood pressure in both hypertensive and normotensive individuals. This meta-analysis strongly supports other evidence for a modest and long-term reduction in population salt intake, and would be predicted to reduce stroke deaths immediately by approximately 14% and coronary deaths by approximately 9% in hypertensives, and reduce stroke and coronary deaths by approximately 6 and approximately 4%, in normotensives, respectively.     

Modest salt reduction lowers blood pressure in isolated systolic hypertension and combined hypertension

Many randomized trials have shown that a reduction in salt intake lowers blood pressure in hypertensive individuals. However, few have looked at the effects according to hypertension category. A recent analysis of the third and fourth National Health and Nutrition Examination Survey suggests that salt intake may not be related to blood pressure in isolated systolic or combined hypertension. To look at this further, we reanalyzed the data of our previous salt reduction trials. Hypertensive individuals were studied in randomized double-blind crossover studies: 1 month of usual salt intake compared with 1 month of reduced salt intake. In isolated systolic hypertension (n=24), blood pressure was reduced from 166+/-19/86+/-7 to 156+/-20/85+/-7 mm Hg (systolic P<0.001; diastolic P=0.459) with a reduction in urinary sodium from 175+/-51 to 87+/-38 mmol per 24-hour period (10.3 to 5.1 g per day of salt). In combined hypertension (n=88), blood pressure was reduced from 161+/-16/100+/-9 to 154+/-17/96+/-9 mm Hg (P<0.001) with a reduction urinary sodium from 176+/-65 to 98+/-51 mmol per 24-hour period (10.4 to 5.8 g per day of salt). These results demonstrate that salt reduction has a significant effect on blood pressure in isolated systolic and combined hypertension. The fall in systolic observed in isolated systolic hypertension would be predicted to reduce stroke by approximately one third, ischemic heart disease by one quarter, and heart failure by one quarter in the population between 60 and 80 years of age, in whom isolated systolic hypertension is the predominate form of hypertension and carries the highest risk. These results provide strong support for universal salt reduction in all hypertensives.     

Stop Hypertension with the Acupuncture Research Program (SHARP): results of a randomized, controlled clinical trial

Case studies and small trials suggest that acupuncture may effectively treat hypertension, but no large randomized trials have been reported. The Stop Hypertension with the Acupuncture Research Program pilot trial enrolled 192 participants with untreated blood pressure (BP) in the range of 140/90 to 179/109 mm Hg. The design of the trial combined rigorous methodology and adherence to principles of traditional Chinese medicine. Participants were weaned off antihypertensives before enrollment and were then randomly assigned to 3 treatments: individualized traditional Chinese acupuncture, standardized acupuncture at preselected points, or invasive sham acupuncture. Participants received < or = 12 acupuncture treatments over 6 to 8 weeks. During the first 10 weeks after random assignment, BP was monitored every 14 days, and antihypertensives were prescribed if BP exceeded 180/110 mm Hg. The mean BP decrease from baseline to 10 weeks, the primary end point, did not differ significantly between participants randomly assigned to active (individualized and standardized) versus sham acupuncture (systolic BP: -3.56 versus -3.84 mm Hg, respectively; 95% CI for the difference: -4.0 to 4.6 mm Hg; P=0.90; diastolic BP: -4.32 versus -2.81 mm Hg, 95% CI for the difference: -3.6 to 0.6 mm Hg; P=0.16). Categorizing participants by age, race, gender, baseline BP, history of antihypertensive use, obesity, or primary traditional Chinese medicine diagnosis did not reveal any subgroups for which the benefits of active acupuncture differed significantly from sham acupuncture. Active acupuncture provided no greater benefit than invasive sham acupuncture in reducing systolic or diastolic BP.     

Combination Therapy Versus Monotherapy in Reducing Blood Pressure: Meta-analysis on 11,000 Participants from 42 Trials

Objective

To quantify the incremental effect of combining blood pressure-lowering drugs from any 2 classes of thiazides, beta-blockers, angiotensin-converting enzyme inhibitors, and calcium channel blockers over 1 drug alone and to compare the effects of combining drugs with doubling dose.

Methods

Meta-analysis of factorial trials in which participants were randomly allocated to 1 drug alone, another drug alone, both drugs together, or a placebo.

Results

We identified 42 trials (10,968 participants). With a thiazide used alone, the mean placebo-subtracted reduction in systolic blood pressure was 7.3 mm Hg and 14.6 mm Hg combined with a drug from another class. The corresponding reductions were 9.3 mm Hg and 18.9 mm Hg with a beta-blocker, 6.8 mm Hg and 13.9 mm Hg with an angiotensin-converting enzyme, and 8.4 mm Hg and 14.3 mm Hg with a calcium channel blocker. The expected blood pressure reduction from 2 drugs together, assuming an additive effect, closely predicted the observed blood pressure reductions. The ratios of the observed to expected incremental blood pressure reductions from combining each class of drug with any other over that from 1 drug were, respectively, for thiazides, beta-blockers, angiotensin-converting enzyme inhibitors, and calcium channel blockers: 1.04 (95% confidence interval [CI], 0.88-1.20), 1.00 (95% CI, 0.76-1.24), 1.16 (95% CI, 0.93-1.39), and 0.89 (95% CI, 0.69-1.09); the overall average was 1.01 (95% CI, 0.90-1.12). Comparison of our results with those of a published meta-analysis of different doses of the same drug showed that doubling the dose of 1 drug had approximately one fifth of the equivalent incremental effect (0.22 [95% CI, 0.19-0.25]).

Conclusion

Blood pressure reduction from combining drugs from these 4 classes can be predicted on the basis of additive effects. The extra blood pressure reduction from combining drugs from 2 different classes is approximately 5 times greater than doubling the dose of 1 drug.     

Blood pressure response to changes in sodium and potassium intake: a metaregression analysis of randomised trials

The objective of the study was to assess the blood pressure response to changes in sodium and potassium intake and examine effect modification by age, gender, blood pressure, body weight and habitual sodium and potassium intake. Randomised trials of sodium reduction or potassium supplementation and blood pressure were identified through reference lists of systematic reviews and an additional MEDLINE search (January 1995-March 2001). A total of 40 sodium trials and 27 potassium trials in adults with a minimum duration of 2 weeks were selected for analysis. Data on changes in electrolyte intake and blood pressure during intervention were collected, as well as data on mean age, gender, body weight, initial electrolyte intake and initial blood pressure of the trial populations. Blood pressure effects of changes in electrolyte intake were assessed by weighted metaregression analysis, overall and in strata of trial population characteristics. Analyses were repeated with adjustment for potential confounders. Sodium reduction (median: -77 mmol/24 h) was associated with a change of -2.54 mmHg (95% CI: -3.16, -1.92) in systolic blood pressure and -1.96 mmHg (-2.41, -1.51) in diastolic blood pressure. Corresponding values for increased potassium intake (median: 44 mmol/24 h) were -2.42 mmHg (-3.75, -1.08) and -1.57 mmHg (-2.65, -0.50). Blood pressure response was larger in hypertensives than normotensives, both for sodium (systolic: -5.24 vs -1.26 mmHg, P < 0.001; diastolic: -3.69 vs -1.14 mmHg, P < 0.001) and potassium (systolic: -3.51 vs -0.97 mmHg, P=0.089; diastolic: -2.51 vs -0.34 mmHg, P=0.074). In conclusion, reduced intake of sodium and increased intake of potassium could make an important contribution to the prevention of hypertension, especially in populations with elevated blood pressure.     

Cocoa intake, blood pressure, and cardiovascular mortality: the Zutphen Elderly Study

BACKGROUND: Small, short-term, intervention studies indicate that cocoa-containing foods improve endothelial function and reduce blood pressure. We studied whether habitual cocoa intake was cross-sectionally related to blood pressure and prospectively related with cardiovascular mortality. METHODS: Data used were of 470 elderly men participating in the Zutphen Elderly Study and free of chronic diseases at baseline. Blood pressure was measured at baseline and 5 years later, and causes of death were ascertained during 15 years of follow-up. Habitual food consumption was assessed by the cross-check dietary history method in 1985, 1990, and 1995. Cocoa intake was estimated from the consumption of cocoa-containing foods. RESULTS: One third of the men did not use cocoa at baseline. The median cocoa intake among users was 2.11 g/d. After adjustment, the mean systolic blood pressure in the highest tertile of cocoa intake was 3.7 mm Hg lower (95% confidence interval [CI], -7.1 to -0.3 mm Hg; P = .03 for trend) and the mean diastolic blood pressure was 2.1 mm Hg lower (95% CI, -4.0 to -0.2 mm Hg; P = .03 for trend) compared with the lowest tertile. During follow-up, 314 men died, 152 of cardiovascular diseases. Compared with the lowest tertile of cocoa intake, the adjusted relative risk for men in the highest tertile was 0.50 (95% CI, 0.32-0.78; P = .004 for trend) for cardiovascular mortality and 0.53 (95% CI, 0.39-0.72; P < .001) for all-cause mortality. CONCLUSION: In a cohort of elderly men, cocoa intake is inversely associated with blood pressure and 15-year cardiovascular and all-cause mortality.     

The relationship of salt intake and arterial blood pressure in salted-tea drinking Kashmiris

In this study we attempted to explore the relationship between salt and blood pressure in a salted-tea drinking population of Northern Kashmir which has not been exposed to a Western way of life. All the available family members of randomly selected houses in 14 villages were studied. Dietary intake was documented for the whole month of the study period to estimate the daily salt consumption in 281 subjects (193 males, 88 females), whose ages were reliably known. Their age ranged from 15 to 85 years (median 35) and their mean daily salt intake was 150 +/- 52 mmol (range 80-440). Both the systolic and diastolic blood pressures showed a significant increase with the salt intake and age; multiple regression analysis suggested an independent effect of salt intake on blood pressure after adjusting for age. Twenty-six subjects (9.3%) had hypertension (blood pressure greater than or equal to 160/95 mm Hg); their daily salt intake was significantly higher than that of normotensive subjects (mean 167 +/- SD 53 vs 142 +/- 46 mmol; P less than 0.001). These studies suggest a relationship between habitual high salt intake and blood pressure.     

Isolated diastolic hypotension and incident heart failure in older adults

Aging is often associated with increased systolic blood pressure and decreased diastolic blood pressure. Isolated systolic hypertension or an elevated systolic blood pressure without an elevated diastolic blood pressure is a known risk factor for incident heart failure in older adults. In the current study, we examined whether isolated diastolic hypotension, defined as a diastolic blood pressure <60 mm Hg and a systolic blood pressure ≥100 mm Hg, is associated with incident heart failure. Of the 5795 Medicare-eligible community-dwelling adults age ≥65 years in the Cardiovascular Health Study, 5521 were free of prevalent heart failure at baseline. After excluding 145 individuals with baseline systolic blood pressure <100 mm Hg, the final sample included 5376 participants, of whom 751 (14%) had isolated diastolic hypotension. Propensity scores for isolated diastolic hypotension were calculated for each of the 5376 participants and used to match 545 and 2348 participants with and without isolated diastolic hypotension, respectively, who were balanced on 58 baseline characteristics. During >12 years of median follow-up, centrally adjudicated incident heart failure developed in 25% and 20% of matched participants with and without isolated diastolic hypotension, respectively (hazard ratio associated with isolated diastolic hypotension: 1.33 [95% CI: 1.10-1.61]; P=0.004). Among the 5376 prematch individuals, multivariable-adjusted hazard ratio for incident heart failure associated with isolated diastolic hypotension was 1.29 (95% CI: 1.09-1.53; P=0.003). As in isolated systolic hypertension, among community-dwelling older adults without prevalent heart failure, isolated diastolic hypotension is also a significant independent risk factor for incident heart failure.