Characterising the extent of misreporting of high blood pressure, high cholesterol, and diabetes using the Australian Health Survey

BACKGROUND: Measuring and monitoring the true prevalence of risk factors for chronic conditions is essential for evidence-based policy and health service planning. Understanding the prevalence of risk factors for cardiovascular disease (CVD) in Australia relies heavily on self-report measures from surveys, such as the triennial National Health Survey. However, international evidence suggests that self-reported data may substantially underestimate actual risk factor prevalence. This study sought to characterise the extent of misreporting in a large, nationally-representative health survey that included objective measures of clinical risk factors for CVD.

METHODS: This study employed a cross-sectional analysis of 7269 adults aged 18 years and over who provided fasting blood samples as part of the 2011-12 Australian Health Survey. Self-reported prevalence of high blood pressure, high cholesterol and diabetes was compared to measured prevalence, and univariate and multivariate logistic regression analyses identified socio-demographic characteristics associated with underreporting for each risk factor.

RESULTS: Approximately 16 % of the total sample underreported high blood pressure (measured to be at high risk but didn't report a diagnosis), 33 % underreported high cholesterol, and 1.3 % underreported diabetes. Among those measured to be at high risk, 68 % did not report a diagnosis for high blood pressure, nor did 89 % of people with high cholesterol and 29 % of people with high fasting plasma glucose. Younger age was associated with underreporting high blood pressure and high cholesterol, while lower area-level disadvantage and higher income were associated with underreporting diabetes.

CONCLUSIONS: Underreporting has important implications for CVD risk factor surveillance, policy planning and decisions, and clinical best-practice guidelines. This analysis highlights concerns about the reach of primary prevention efforts in certain groups and implications for patients who may be unaware of their disease risk status.

Increased blood pressure later in life may be associated with perinatal n-3 fatty acid deficiency

Hypertension is a major risk factor for cardiovascular and cerebrovascular disease. Previous work in both animals and humans with high blood pressure has demonstrated the antihypertensive effects of n−3 polyunsaturated fatty acids (PUFA), although it is not known whether these nutrients are effective in preventing hypertension. The predominant n−3 PUFA in the mammalian nervous system, docosahexaenoic acid (DHA), is deposited into synaptic membranes at a high rate during the perinatal period, and recent observations indicate that the perinatal environment is important for the normal development of blood pressure control. This study investigated the importance of perinatal n−3 PUFA supply in the control of blood pressure in adult Sprague-Dawley rats. Pregnant rat dams were fed semisynthetic diets that were either deficient in (DEF) or supplemented with (CON) n−3 PUFA. Offspring were fed the same diets as their mothers until 9 wk; then, half of the rats from each group were crossed over to the opposite diet, creating four groups, i.e., CON-CON; CON-DEF; DEF-DEF, DEF-CON. Mean arterial blood pressures (MAP) were measured directly, at 33 wk of age, by cannulation of the femoral artery. The phospholipid fatty acid profile of the hypothalamic region was determined by capillary gas-liquid chromatography. The tissue phospholipid fatty acid profile reflected the diet that the rats were consuming at the time of testing. Both groups receiving DEF after 9 wk of age (i.e., DEF-DEF and CON-DEF) had similar profiles with a reduction in DHA levels of 30%, compared with rats receiving CON (i.e., CON-CON and DEF-CON). DEF-DEF rats had significantly raised MAP compared with all other groups, with differences as great as 17 mm Hg. DEF-CON rats had raised MAP compared with CON-CON rats, and DEF-DEF rats had higher MAP than CON-DEF rats, despite the fact that their respective fatty acid profiles were not different. These findings indicate that inadequate levels of DHA in the perinatal period are associated with altered blood pressure control in later life. The way in which these long-term effects are produced remains to be elucidated.

Organized blood pressure control programs to prevent stroke in Australia : would they be cost-effective?

Background and Purpose—: High blood pressure (BP) is the most important modifiable stroke risk factor. Worldwide high BP in many people is uncontrolled or people are unaware of their BP status. We aimed to assess whether a program of organized multidisciplinary care and medication would be cost-effective for improving BP control for the prevention of stroke.

Methods—: A novel aspect was to simulate the intervention to match recent primary care initiatives (eg, new Medicare reimbursement items) to ensure policy relevance. Current practice and additional costs of each intervention were included using the best available evidence. The differences in the cost per quality-adjusted life year (QALY) gained for the interventions were compared against current practice. Cost-effectiveness was defined as cost per QALY gained was less than Australian dollars (AUD) 50 000 (societal perspective; reference year 2004). The robustness of estimates was assessed with probabilistic multivariable uncertainty analysis.

Results—: For primary prevention, the median cost per QALY gained was AUD11 068 (95% uncertainty interval AUD5201 to AUD18 696) in those aged 75 years or older and was AUD17 359 (95% uncertainty interval AUD10 516 to AUD26 036) in those aged 55 to 84 years with >=15% absolute risk of stroke. Primary prevention interventions were not cost-effective if aged younger than 50 years. The median cost per QALY gained for secondary prevention was AUD1811 and AUD4704, depending on which medications were modeled.

Conclusions—: Organized care for BP control targeted at specific populations offers excellent value over current practice. Organized care for secondary prevention provided the greatest benefits and strongest cost-effectiveness. Translation into clinical practice requires improved use of relevant Medicare policy in Australia.

Reduced preprandial dipping accounts for rapid elevation of blood pressure and renal sympathetic nerve activity in rabbits fed a high-fat diet

Consumption of a high-fat diet (HFD) by rabbits results in increased blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA) within 1 wk. Here, we determined how early this activation occurred and whether it was related to changes in cardiovascular and neural 24-h rhythms. Rabbits were meal-fed a HFD for 3 wks, then a normal-fat diet (NFD) for 1 wk. BP, HR, and RSNA were measured daily in the home cage via implanted telemeters. Baseline BP, HR, and RSNA over 24 h were 71 ± 1 mm Hg, 205 ± 4 beats/min and 7 ± 1 normalized units (nu). The 24-h pattern was entrained to the feeding cycle and values increased from preprandial minimum to postprandial maximum by 4 ± 1 mm Hg, 51 ± 6 beats/min, and 1.6 ± .6 nu each day. Feeding of a HFD markedly diminished the preprandial dip after 2 d (79–125% of control; p < 0.05) and this reduction lasted for 3 wks of HFD. Twenty-four-hour BP, HR, and RSNA concurrently increased by 2%, 18%, and 22%, respectively. Loss of preprandial dipping accounted for all of the BP increase and 50% of the RSNA increase over 3 wks and the 24-h rhythm became entrained to the light-dark cycle. Resumption of a NFD did not alter the BP preprandial dip. Thus, elevated BP induced by a HFD and mediated by increased sympathetic nerve activity results from a reduction in preprandial dipping, from the first day. Increased calories, glucose, insulin, and leptin may account for early changes, whereas long-term loss of dipping may be related to increased sensitivity of sympathetic pathways.

Association of birth weight and current body size to blood pressure in female twins

It has been proposed that low birth weight is associated with high levels of blood pressure in later life. The aim of this study was to assess the relationship of blood pressure to birth weight and current body size during growth and adulthood. A total of 711 female multiple births, with one group of 244 in their growth phase mean age 12.0 (2.3)(SD) years and the other of 467 adults (mean age 35.2 (12.6) years), had height, weight and both systolic (SBP) and diastolic (DBP) blood pressures measured, and self-reported their birth weight. Regression analyses were performed to assess the cross-sectional and within-pair associations of blood pressure to birth weight, with and without adjustments for current body size. Within-pair analysis was based on 296 twin pairs. Cross-sectionally, a reduction in birth weight of 1 kg was associated with 2 to 3 mm Hg higher age-adjusted SBP, which was of marginal significance and explained about 2% of the population variance. Adjustment for body mass index did not significantly change this association. Within-pair analyses found no association between birth weight and SBP or DBP,even after adjusting for current body size. After age, current body size was the strongest predictor of systolic BP. The weak association of blood pressure to birth weight cross-sectionally is of interest, but any within-pair effect of birth weight on blood pressure must be minimal compared with the effect of current body size.

Decreasing dietary sodium while following a self-selected potassium-rich diet reduces blood pressure

Reducing dietary sodium reduces blood pressure (BP), a major risk factor for cardiovascular disease, but few studies have specifically examined the effect on BP of altering dietary sodium in the context of a high potassium diet. This randomized, crossover study compared BP values in volunteer subjects self-selecting food intake and consuming low levels of sodium (Na+; 50 mmol/d) with those consuming high levels of sodium (> or =20 mmol/d), in the context of a diet rich in potassium (K+). Sodium supplementation (NaSp) produced the difference in Na+ intake. Subjects (n = 108; 64 women, 44 men; 16 on antihypertensive therapy) had a mean age of 47.0 ± 10.1 y. Subjects were given dietary advice to achieve a low sodium (LS) diet with high potassium intake (50 mmol Na+/d, >80 mmol K+/d) and were allocated to NaSp (120 mmol Na+/d) or placebo treatment for 4 wk before crossover. The LS diet decreased urinary Na+ from baseline, 138.7 ± 5.3 mmol/d to 57.8 ± 3.8 mmol/d (P < 0.001). The NaSp treatment returned urinary Na+ to baseline levels 142.4 ± 3.7 mmol/d. Urinary K+ increased from baseline, 78.6 ± 2.3 to 86.6 ± 2.1 mmol/d with the LS diet and to 87.1 ± 2.1 mmol/d with NaSp treatment (P < 0.001). The LS diet reduced home systolic blood pressure (SBP) by 2.5 ± 0.8 mm Hg (P = 0.004), compared with the NaSp treatment. Hence, reducing Na+ intake from 140 to 60 mmol/d significantly decreased home SBP in subjects dwelling in a community setting who consumed a self-selected K+-rich diet, and this dietary modification could assist in lowering blood pressure in the general population.

Blood pressure response to dietary modifications in free-living individuals 1,2

A diet rich in fruits, vegetables, and low-fat dairy foods has been shown to lower blood pressure (BP) when all foods are provided. We compared the effect on BP (measured at home) of 2 different self-selected diets: a low-sodium, high-potassium diet, rich in fruit and vegetables (LNAHK) and a high-calcium diet rich in low-fat dairy foods (HC) with a moderate-sodium, high-potassium, high-calcium DASH-type diet, high in fruits, vegetables and low-fat dairy foods (OD). Subjects were randomly allocated to 2 test diets for 4 wk, the OD and either LNAHK or HC diet, each preceded by a 2 wk control diet (CD). The changes in BP between the preceding CD period and the test diet period (LNAHK or HC) were compared with the change between the CD and the OD periods. Of the 56 men and 38 women that completed the OD period, 43 completed the LNAHK diet period and 48 the HC diet period. The mean age was 55.6 ± 9.9 (±SD) years. There was a fall in systolic pressure between and the CD and OD [-1.8 ± 0.5 mm Hg (P < 0.001)]. Compared with OD, systolic and diastolic BPs fell during the LNAHK diet period [-3.5 ± 1.0 (P < 0.001) and -1.9 ± 0.7 (P < 0.05) mmHg, respectively] and increased during the HC diet period [+3.1 ± 0.9 (P < 0.01) and +0.8 ± 0.6 (P = 0.15) mm Hg, respectively]. A self-selected low-sodium, high-potassium diet resulted in a greater fall in BP than a multifaceted OD, confirming the beneficial effect of dietary intervention on BP in a community setting.

Blood pressure change with weight loss is affected by diet type in men

Background: Weight loss reduces blood pressure, and the Dietary Approaches to Stop Hypertension (DASH) diet has also been shown to lower blood pressure.

Objective: Our goal was to assess the effect on blood pressure of 2 weight-reduction diets: a low-fat diet (LF diet) and a moderate-sodium, high-potassium, high-calcium, low-fat DASH diet (WELL diet).

Design: After baseline measurements, 63 men were randomly assigned to either the WELL or the LF diet for 12 wk, and both diet groups undertook 0.5 h of moderate physical activity on most days of the week.

Results: Fifty-four men completed the study. Their mean (±SD) age was 47.9 ± 9.3 y (WELL diet, n = 27; LF diet, n = 27), and their mean baseline home systolic and diastolic blood pressures were 129.4 ± 11.3 and 80.6 ± 8.6 mm Hg, respectively. Body weight decreased by 4.9 ± 0.6 kg (±SEM) in the WELL group and by 4.6 ± 0.6 kg in the LF group (P < 0.001 for both). There was a greater decrease in blood pressure in the WELL group than in the LF group [between-group difference (week 12 –baseline) in both SBP (5.5 ± 1.9 mm Hg; P = 0.006) and DBP (4.4 ± 1.2 mm Hg; P = 0.001)].

Conclusions: For a comparable 5-kg weight loss, a diet high in low-fat dairy products, vegetables, and fruit (the WELL diet) resulted in a greater decrease in blood pressure than did the LF diet. This dietary approach to achieving weight reduction may confer an additional benefit in reducing blood pressure in those who are overweight.

Effect of a low sodium DASH diet, including red meat on blood pressure in post-menopausal women

Background – The DASH type dietary pattern which consists of high fruit, vegetable and dairy products and low saturated fat, is “base-producing” but restricts red meat with no clear justification.
Objective – To compare the BP-lowering effect of Vitality diet (VD), a moderately low sodium, “base” producing modified DASH diet, containing 6 serves/week of lean red meat to a “ high carbohydrate, low fat diet (HCLF diet), with a higher dietary acid load in post-menopausal women.
Design – Ninety-five hypertensive post-menopausal women (46 VD and 49 HCLF) completed a 14-wk randomised parallel study. Home BP was measured daily. Repeat 24-h dietary records and 24-h urine samples were collected fortnightly. Dietary acid load, expressed as potential renal acid load (PRAL), was calculated from nutrient intakes.
Outcomes – During the intervention, the VD group had an average daily consumption of 85 g cooked red meat. They had a mean (± SEM) reduction of 38 ± 7 mmol/d in urinary sodium excretion (P <0.0001), and a 7 ± 4 mmol/d increase in urinary potassium (P = 0.0681), with an estimated 23.1± 2.3 mEq/d lower PRAL than the HCLF group (P <0.0001). The fall in systolic pressure in the VD group tended to be greater by 3 ± 2 mmHg (P = 0.08) than the fall in systolic pressure seen with the HCLF diet. A greater BP-lowering effect of VD was observed among those taking anti-hypertensive medication (n = 17) with a greater 5.5 ± 2.7 mm Hg (P = 0.0518) reduction of systolic BP and greater reduction in diastolic BP by 3.6 ± 1.7 mm Hg (P = 0.0388) compared to the HCLF diet. However, no relationship between BP and PRAL was observed.
Conclusions – A low sodium DASH type dietary pattern with the inclusion of lean red meat was effective in reducing BP in post-menopausal women, particularly in those taking anti-hypertensive medication. This dietary pattern could be recommended for this group who are at increased risk of cardiovascular disease.
This study was funded by Meat & Livestock Australia.

Long-term effect of calcium-vitamin D3 fortified milk on blood pressure and serum lipid concenstrations in healthy older men

Background/Objectives:
Some epidemiological and clinical studies have shown that increased dairy consumption or calcium and/or vitamin D supplementation can have a beneficial effect on blood pressure, and lipid and lipoprotein concentrations. The aim of this study was to assess the long-term effects of calcium-vitamin D3 fortified milk on blood pressure and lipid-lipoprotein concentrations in community-dwelling older men.

Subjects/Methods:
This is a substudy of a 2-year randomized controlled trial in which 167 men aged >50 years were assigned to receive either 400 ml per day of reduced fat (approx1%) milk fortified with approximately 1000 mg of calcium and 800 IU of vitamin D3 or to a control group receiving no additional fortified milk. Weight, blood pressure, lipid and lipoprotein concentrations were measured every 6 months. Participants on lipid-lowering (n=32) or antihypertensive medication (n=39) were included, but those who commenced, increased or decreased their medication throughout the intervention were excluded (n=27).

Results:
In the 140 men included in this study (milk, n=73; control, n=67), there were no significant effects of the calcium-vitamin D3 fortified milk on weight, systolic or diastolic blood pressure, total cholesterol, high-density lipoprotein or low-density lipoprotein cholesterol or triglyceride concentrations at any time throughout the intervention. Similar results were observed after excluding men taking antihypertensive or lipid-lowering medication or limiting the analysis to those with baseline calcium intakes <1000 mg per day and/or with hypovitaminosis D (25(OH)D <75 nmol/l).

Conclusions:
Supplementation with reduced-fat calcium-vitamin D3 fortified milk did not have a beneficial (nor detrimental) effect on blood pressure, lipid or lipoprotein concentrations in healthy community-dwelling older men.

Low-sodium dietary approaches to stop hypertension-type diet including lean red meat lowers blood pressure in postmenopausal women

Low-sodium Dietary Approaches to Stop Hypertension (DASH) diets are base producing but restrict red meat without clear justification. We hypothesized that a vitality diet (VD), a low-sodium DASH-type diet with a low dietary acid load containing 6 servings of 100 g cooked lean red meat per week, would be more effective in reducing blood pressure (BP) compared with a higher acid load reference healthy diet (RHD) based on general dietary guidelines to reduce fat intake and increase intake of breads and cereals. A randomized, parallel dietary intervention study was conducted to compare the BP-lowering effect of these 2 diets in postmenopausal women with high/normal BP. Women were randomly assigned to follow either VD or RHD for 14 weeks. Home BP was measured daily with an automated BP monitor under standard conditions. Of 111 women commencing the study, 95 completed (46 VD, 49 RHD). Systolic BP (SBP) throughout the intervention was lower in the VD group compared to the RHD group (repeated-measures analysis of variance time by diet, P = .04), such that at the end of the study, the VD had a fall of SBP by 5.6 ± 1.3 mm Hg (mean ± SEM) compared with a fall of 2.7 ± 1.0 mm Hg in the RHD (group difference, P = .08). When only those taking antihypertensive medications were assessed, the VD (n = 17) had a significant fall of 6.5 ± 2.5 mm Hg SBP (P = .02) and 4.6 ± 1.4 mm Hg diastolic BP (P = .005) after 14 weeks, and their BP was lower than that of the RHD group (n = 18) throughout the study (P < .05). We concluded that a low-sodium DASH diet with a low dietary acid load, which also included lean red meat on most days of the week, was effective in reducing BP in older women, particularly in those taking antihypertensive medications.

Influence of dietary modifications on the blood pressure response to antihypertensive medication

Identifying dietary modifications that potentiate the blood pressure (BP)-lowering effects of antihypertensive medications and that are practical for free-living people may assist in achieving BP reduction goals. We assessed whether two dietary patterns were effective in lowering BP in persons on antihypertensive therapy and in those not on therapy. Ninety-four participants (38/56 females/males), aged 55.6 (sd 9.9) years, consumed two 4-week dietary regimens in random order (Dietary Approaches to Stop Hypertension (DASH)-type diet and low-Na high-K (LNAHK) diet) with a control diet before each phase. Seated home BP was measured daily for the last 2 weeks in each phase. Participants were grouped based on antihypertensive drug therapy. The LNAHK diet produced a greater fall in systolic BP (SBP) in those on antihypertensive therapy ( - 6.2 (sd 6.0) mmHg) than in those not on antihypertensive therapy ( - 2.8 (sd 4.0) mmHg) (P = 0.036), and this was greatest for those on renin-angiotensin system (RAS) blocker therapy ( - 9.5 (sd 6.4) mmHg) (interaction P = 0.007). The fall in SBP on the DASH-type diet, in those on therapy (overall - 1.1 (sd 6.2) mmHg; renin-angiotensin blocker therapy - 4.2 (sd 4.7) mmHg), was not as marked as that observed on the LNAHK diet. Dietary modifications are an important part of all hypertension management regimens, and a low-Na and high-K diet enhances the BP-lowering effect of antihypertensive medications, particularly those targeting the RAS.

Blood pressure modifies retinal susceptibility to intraocular pressure elevation

Primary open angle glaucoma affects more than 67 million people. Elevated intraocular pressure (IOP) is a risk factor for glaucoma and may reduce nutrient availability by decreasing ocular perfusion pressure (OPP). An interaction between arterial blood pressure and IOP determines OPP; but the exact contribution that these factors have for retinal function is not fully understood. Here we sought to determine how acute modifications of arterial pressure will affect the susceptibility of neuronal function and blood flow to IOP challenge. Anaesthetized (ketamine:xylazine) Long-Evan rats with low (~60 mmHg, sodium nitroprusside infusion), moderate (~100 mmHg, saline), or high levels (~160 mmHg, angiotensin II) of mean arterial pressure (MAP, n = 5–10 per group) were subjected to IOP challenge (10–120 mmHg, 5 mmHg steps every 3 minutes). Electroretinograms were measured at each IOP step to assess bipolar cell (b-wave) and inner retinal function (scotopic threshold response or STR). Ocular blood flow was measured using laser-Doppler flowmetry in groups with similar MAP level and the same IOP challenge protocol. Both b-wave and STR amplitudes decreased with IOP elevation. Retinal function was less susceptible to IOP challenge when MAP was high, whereas the converse was true for low MAP. Consistent with the effects on retinal function, higher IOP was needed to attenuated ocular blood flow in animals with higher MAP. The susceptibility of retinal function to IOP challenge can be ameliorated by acute high BP, and exacerbated by low BP. This is partially mediated by modifications in ocular blood flow.

Lower protein-to-carbohydrate ratio in maternal diet is associated with higher childhood systolic blood pressure up to age four years

The prenatal environment can influence development of offspring blood pressure (BP), which tracks into adulthood. This prospective longitudinal study investigated whether maternal pregnancy dietary intake is associated with the development of child BP up to age four years. Data are from 129 mother-child dyads enrolled in the Women and Their Children's Health study. Maternal diet was assessed using a validated 74-item food frequency questionnaire at 18 to 24 weeks and 36 to 40 weeks, with a reference period of the previous three months. Child systolic and diastolic BP were measured at 3, 6, 9, 12, 24, 36 and 48 months, using an automated BP monitor. Using mixed-model regression analyses adjusted for childhood growth indices, pregnancy intakes of percentage of energy (E%) polyunsaturated fat (β coefficient 0.73; 95% CI 0.003, 1.45; p = 0.045), E% omega-6 fatty acids (β coefficient 0.89; 95% CI 0.09, 1.69; p = 0.03) and protein-to-carbohydrate (P:C) ratio (β coefficient -14.14; 95% CI -27.68, -0.60; p = 0.04) were associated with child systolic BP trajectory up to 4 years. Child systolic BP was greatest at low proportions of dietary protein (<16% of energy) and high carbohydrate (>40% of energy) intakes. There may be an ideal maternal macronutrient ratio associated with optimal infant BP. Maternal diet, which is potentially modifiable, may play an important role in influencing offspring risk of future hypertension.

Origin of aberrant blood pressure and sympathetic regulation in diet-induced obesity

High fat diet (HFD)-induced hypertension in rabbits is neurogenic and caused by the central action of leptin, which is thought to be dependent on activation of α-melanocortin-stimulating hormone (α-MSH) and neuropeptide Y-positive neurons projecting to the dorsomedial hypothalamus (DMH) and ventromedial hypothalamus (VMH). However, leptin may act directly in these nuclei. Here, we assessed the contribution of leptin, α-MSH, and neuropeptide Y signaling in the DMH and VMH to diet-induced hypertension. Male New Zealand white rabbits were instrumented with a cannula for drug injections into the DMH or VMH and a renal sympathetic nerve activity (RSNA) electrode. After 3 weeks of an HFD (13.3% fat; n=19), rabbits exhibited higher RSNA, mean arterial pressure (MAP), and heart rate compared with control diet-fed animals (4.2% fat; n=15). Intra-VMH injections of a leptin receptor antagonist or SHU9119, a melanocortin 3/4 receptor antagonist, decreased MAP, heart rate, and RSNA compared with vehicle in HFD rabbits (P<0.05) but not in control diet-fed animals. By contrast, α-MSH or neuropeptide Y injected into the VMH had no effect on MAP but produced sympathoexcitation in HFD rabbits (P<0.05) but not in control diet-fed rabbits. The effects of the leptin antagonist, α-MSH, or neuropeptide Y injections into the DMH on MAP or RSNA of HFD rabbits were not different from those after vehicle injection. α-MSH into the DMH of control diet-fed animals did increase MAP, heart rate, and RSNA. We conclude that the VMH is the likely origin of leptin-mediated sympathoexcitation and α-MSH hypersensitivity that contribute to obesity-related hypertension.