Blood pressure monitoring and control by cardiovascular disease status in UK primary care: 10 year retrospective cohort study

Transcription

1 Journal of Public Health Vol. 33, No. 2, pp doi: /pubmed/fdq078 Advance Access Publication 12 October 2010 Blood pressure monitoring and control by cardiovascular disease status in UK primary care: 10 year retrospective cohort study Anthony A. Laverty*, Alex Bottle, Azeem Majeed, Christopher Millett Department of Primary Care and Public Health, Imperial College London, St Dunstan s Road, London W6 8RP, UK *Address correspondence to Anthony Laverty, a.laverty@imperial.ac.uk ABSTRACT Background Strategies to reduce the burden of cardiovascular disease (CVD) in the UK have emphasized improved management of high-risk individuals rather than population-based approaches. Methods This 10-year retrospective cohort study examined blood pressure (BP) monitoring and control among patients with and without CVD in general practices in Wandsworth, London between 1998 and Logistic regression was used to assess associations among age, gender, ethnicity, deprivation and BP control. Results The percentage of patients with elevated BP (.140/90 mm Hg) decreased at a slower rate in patients without CVD ( %) compared with those with CVD ( %) (P, 0.001). Mean systolic BP decreased from to mm Hg in patients with CVD and from to in patients without CVD. Mean diastolic BP decreased from 84.2 to 78.4 mm Hg in patients with CVD and from 80.5 to 79.0 in patients without CVD. Inequalities in BP control decreased among age, ethnic and deprivation groups but increased between men and women without CVD. Conclusions Measurement and control of BP among those with CVD has improved much more rapidly compared with those without CVD. Inequalities in BP control appeared to increase between men and women without CVD, but decreased among age, ethnicity and deprivation groups. Keywords Circulatory disease, population-based and preventative services, primary care Introduction Elevated blood pressure (BP) is responsible for approximately half of the worldwide burden of cardiovascular disease (CVD). 1 Estimates suggest that eliminating poor BP control would prevent deaths from coronary heart disease (CHD) and stroke each year in the UK alone. 2 Moreover, improvements in BP control may reduce health inequalities as mortality from CVD has been shown to be three times higher in the most deprived areas of the UK in comparison to affluent areas. 3 Previous studies suggest that while a combination of strategies are required to reduce CVD mortality, the benefit derived from population-wide reductions in risk factors is greater than that associated with improved management of established cases. 4 While the UK has introduced some promising initiatives to reduce BP at the population level, including the Food Standard Agency s salt reduction strategy, 5 disproportionate emphasis may have been placed on improving the management of BP among high-risk groups. This is reflected in the National Service Frameworks for CHD 6 and Older People 7 and the increased investment in secondary prevention in primary care through the 2004 Anthony A. Laverty, Research Assistant Alex Bottle, Lecturer in Medical Statistics Azeem Majeed, Professor of Primary Care Christopher Millett, Senior Lecturer and Honorary Consultant in Public Health 302 # The Author 2010, Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved.

2 BLOOD PRESSURE CONTROL IN PRIMARY CARE 303 General Practitioner contract. More recently, the government introduced NHS Health Checks, a cardiovascular risk assessment programme, which aims to identify and manage adults at high risk of cardiovascular disease in England. 8 Detailed data on the prevalence of hypertension come from the Health Survey for England (HSE), which focused on cardiovascular disease in 1994, 1998, 2003 and These nationally representative surveys suggest that mean BP values in the population have been falling since 1994, and that there have been significant increases in rates of treatment and control among those with hypertension. 9 While data from the HSE are informative, they have limitations including small numbers of patients with CVD, limited data on ethnicity and possible bias arising from undertaking comparisons of cross-sectional data. Previous studies have used data from primary care to examine inequalities in BP measurement and control by deprivation group after the introduction of the Quality and Outcomes Framework (QOF). 10 However, there is currently little information on longer term trends in BP measurement and control and whether known inequalities among age, gender and ethnic groups have persisted. This study examines trends in BP monitoring and control in persons with and without CVD in southwest London between 1998 and It also examines inequalities in BP measurement and control among age, gender, ethnic and socio-economic status (SES) groups over this period. Methods Study setting and data collection The study was conducted in Wandsworth, southwest London, which has a younger, more deprived and more culturally diverse population than is typical for England. 11,12 Twenty-nine of the 34 general practices in the study area participated in the study. Data were extracted directly from individual practice computers using an algorithm applied to each practice to gain all of the relevant data on each patient, including past medical history. We extracted the last BP measurement in each year between 1998 and 2007 from patients aged 45 years, who were registered with practices on the 31 December Our main outcome measures were recording of BP measurement and raised BP. We defined BP as being raised if it was higher than 140/90 mm Hg, as in guidance from the National Institute for Health and Clinical Excellence. 13 Our predictor variables were age, gender, ethnicity, SES and number of comorbid cardiovascular conditions. We categorized age into four groups: 45 54, 55 64, and 75þ years. We categorized ethnicity into four groups (white, black, south Asian and unknown/missing) due to small numbers in individual ethnic subgroups. We assigned each patient to an SES tertile based on their general practice postcode using the Index of Multiple Deprivation (IMD) 2007 (10). The IMD is the most common way to measure arealevel SES in the UK and is composed of several dimensions, such as income, living environment and unemployment. We identified CVD conditions (stroke, diabetes, heart failure, hypertension, CHD, atrial fibrillation or renal failure) in each year using Read and OXMIS codes. Read codes are the clinical classification system used in primary care in the UK; OXMIS codes were used in the past by some general practices but have now been replaced by Read codes. We grouped patients by the number of comorbid CVD conditions (1, 2, 3þ) in each year. Data analysis We calculated the percentage of patients having their BP measured and with raised BP annually by age, gender, ethnic and SES groups. Odds ratios (adjusted for age, sex, IMD of practice and ethnicity) were calculated, with confidence intervals using the Mantel-Haenszel technique. Logistic regression models were used to examine associations among age, sex, ethnicity, deprivation and number of CVD conditions and the measurement and control of BP in 1998 and We used robust standard errors to take account of clustering of patients within general practices. This takes into account that we would expect patients at the same practice to have more similar outcomes than patients from other practices. We fitted an interaction term for year and CVD status to determine whether trends in BP measurement and control differed between patients with and without CVD. Statistical analyses were performed using Stata 10.0 (Stata Corporation, TX, USA). Results Table 1 shows the breakdown of the population in this study. In 2007, there were patients without CVD and with CVD aged 45 years and over in Wandsworth. As expected, the without CVD group was younger than those with CVD with a mean age of 56.0 years in 2007, compared with 66.6 years for the CVD group. There was a much higher percentage with unknown/missing ethnicity among the non-cvd group than among those with CVD (39.9 and 12.4%, respectively), which reflects the high level of ethnicity coding among those with a long-term condition in Wandsworth, as noted elsewhere. 14

3 304 JOURNAL OF PUBLIC HEALTH Table 1 Breakdown of age, ethnic group, deprivation and gender in 2007, by CVD status Total number patients without CVD Percentage of total in this group Total number patients with CVD Percentage of total in this group Overall number of patients in 2007 Age group in years þ Gender Female Male Deprivation group, by practice-level IMD 1 (least deprived) (most deprived) Ethnic background White Black South Asian Unknown/ missing Number of multimorbidities or more Total Trends in BP measurement among individuals with and without CVD The proportion of patients with CVD who have had their BP measured each year increased from 40.3% in 1998 to 91.7% in 2007 (Fig. 1a, Table 2). Older patients were more likely to have their BP measured in 2007 with an adjusted odds ratio (AOR) of 1.39 for those over 75 compared with those between 45 and 54 (95% CI: ), although there was no significant difference between age groups in Men were less likely to have their BP measured in both years (AOR in 2007 of 0.74; 95% CI: ), although the absolute percentage difference has narrowed from 5.6 to 1.9%. Patients with an unknown/missing ethnicity were less likely to have their BP measured in 2007 (AOR, 0.41; 95% CI: ) than white patients, (a) 100 % Meausred during year (b) % With raised Bp 140/ % Measured without CVD % Measured with CVD % Raised BP with CVD % Raised BP without CVD Fig. 1 (a) Improvements in BP measurements among those with and without CVD. (b) Decline in raised BP (140/90) among those with and without CVD. although there was no significant ethnic group difference in In both 1998 and 2007, patients with multiple CVD conditions were more likely to have their BP measured, although the absolute difference between those with one condition and three or more narrowed over this period from 12.6 to 7.2%. The percentage of patients without CVD who had their BP measured in the previous 12 months increased from 13.0 to 36.6% between 1998 and 2007 (Fig. 1a, Table 2). The percentage with their BP measured over the previous 5 years increased from 62.0 to 83.7% between 2002 and Older patients were more likely to have their BP measured, while the absolute difference between patients over 75 years and those between 45 and 54 years increased from 7.5 to 25.9% between 1998 and 2007 (AOR, 2.51; 95% CI: in 2007). The percentage difference for measurement of BP between men and women increased from 6.4 to

4 BLOOD PRESSURE CONTROL IN PRIMARY CARE 305 Table 2 Measurement of BP among those with and without CVD in 1998 and 2007 Characteristic With CVD Without CVD 1998 (%, AOR) 2007 (%, AOR) 1998 (%, AOR) 2007 (%, AOR) Overall % (n) 40.3 (2080/5163) 91.7 (17 863/19 486) 13.0 (2181/16 808) 36.6 (13 337/36 407) Age in years (1) 87.8 (1) 11.4 (1) 31.2 (1) (0.93) 91.1 (1.32)* 14.0 (1.14)* 37.0 (1.27)* (1.05) 93.6 (1.68)* 14.8 (1.12) 49.8 (2.01)* 75þ 46.5 (1.25) 93.0 (1.39)* 18.9 (1.42)* 57.1 (2.51)* Sex Female 42.8 (1) 92.6 (1) 16.1 (1) 45.2 (1) Male 37.2 (0.80)* 90.7 (0.74)* 9.7 (0.62)* 28.9 (0.57)* IMD tertile (1) 90.9 (1) 9.5 (1) 33.2 (1) (2.54) 93.3 (1.41)* 18.0 (2.00) 38.6 (1.21) (2.61) 91.2 (0.98) 12.9 (1.35) 39.7 (1.30) Ethnic group White 41.8 (1) 93.0 (1) 16.2 (1) 46.7 (1) Black 43.6 (1.11) 92.8 (0.98) 17.5 (1.16) 45.8 (1.05) South Asian 34.5 (0.94) 92.7 (0.97) 12.1 (0.89) 43.8 (0.97) Unknown/missing 31.3 (0.66) 83.0 (0.41)* 7.1 (0.46)* 22 (0.37)* Number of CVD conditions (1) 89.6 (1) (1.41)* 95.5 (2.25)* 3 or more 50.9 (1.60)* 96.8 (2.80)* Note that values are adjusted for age, sex, IMD, ethnicity, number of CVD conditions (in patients with CVD only) and practice-level clustering. IMD(1, least deprived; IMD 3, most deprived). *Significant difference at P %. The percentage of patients with an unknown/ missing ethnicity with a BP measurement was significantly lower than among white patients in both 1998 and 2007 (AOR, 0.46; 95% CI: in 1998, and AOR, 0.37; 95% CI: in 2007). Trends in BP control among individuals with and without CVD The percentage of patients with CVD who had raised BP decreased from 56.8 to 36.0% between 1998 and 2007 (Fig. 1b, Table 3). Mean systolic BP decreased from (SD 18.7) to (16.7) mm Hg and mean diastolic BP decreased from 84.2 (10.7) to 78.4 (10.5) mm Hg over the study period. Older patients were more likely to have raised BP in both years, although the absolute difference between those over 75 and those between 45 and 54 has narrowed from 16.1 to 6.1%. South Asian patients with CVD were significantly less likely to have raised BP in both years than their white counterparts, although this difference has narrowed from 13.6 to 9.3%. Patients with multiple CVD conditions were significantly less likely to have raised BP than those with a single CVD condition in The percentage of patients without CVD with raised BP has declined from 31.0 to 25.3% (Fig. 1b, Table 3). Mean systolic BP decreased from (19.1) to (16.6) mm Hg and mean diastolic BP decreased from 80.5 (10.0) to 79.0 (9.6) mm Hg over the study period. Older patients were more likely to have a raised BP (AOR, 4.95; 95% CI: in 1998 and 2.75, 95% CI: in 2007), although the absolute difference here has narrowed from 35.3 to 19.2%. Men were also more likely to have a raised BP in 2007 (AOR, 1.30; 95% CI: ) among this group. Black patients were significantly more likely than white patients to have raised BP in both years (AOR, 1.63;

5 306 JOURNAL OF PUBLIC HEALTH Table 3 Raised BP (.140/90 mm Hg) among those with and without CVD in 1998 and 2007 Characteristic With CVD Without CVD 1998 (%, AOR) 2007 (%, AOR) 1998 (%, AOR) 2007 (%, AOR) Overall % (n) 56.8 (1182/2080) 36.0 (6433/17 863) 31.0 (676/2181) 25.3 (3372/13 337) Age in years (1) 33.1 (1) 19.1 (1) 19.2 (1) (1.38)* 34.2 (1.08) 34.3 (2.12)* 25.7 (1.51)* (1.47)* 36.4 (1.21)* 47.0 (3.57)* 34.1 (2.25)* 75þ 64.1 (1.79)* 39.2 (1.37)* 54.4 (4.95)* 38.4 (2.75)* Sex Female 58.3 (1) 36.3 (1) 31.0 (1) 23.5 (1) Male 54.7 (0.90) 35.7 (1.02) 31.1 (1.07) 27.9 (1.30)* IMD third (1) 38.1 (1) 28.3 (1) 25.5 (1) (1.08) 34.6 (0.81) 31.3 (0.99) 25.5 (0.99) (1.51)* 34.6 (0.83) 33.9 (1.20) 24.8 (1.00) Ethnic group White 58.4 (1) 36.9 (1) 31.8 (1) 24.7 (1) Black 58.9 (1.04) 37.7 (1.09) 41.8 (1.63)* 28.5 (1.34)* South Asian 44.8 (0.65)* 27.6 (0.67)* 25.2 (0.78) 20.9 (0.84) Unknown/missing 53.0 (0.76) 38.8 (1.09) 23.6 (0.79) 26.7 (1.21) Number of CVD conditions (1) 37.2 (1) (0.94) 34.1 (0.85)* 3 or more 55.4 (0.93) 33.5 (0.81)* Note that values are adjusted for age, sex, IMD, ethnicity, number of CVD conditions (in patients with CVD only) and practice-level clustering. IMD (1, least deprived; IMD 3, most deprived). *Significant difference at P % CI: , and 1.34; 95% CI: ), although this absolute difference has narrowed from 10.0 to 3.8%. Differences between the with and without CVD groups Fitting an interaction term for year and CVD status showed that BP measurement [1.20 (95% CI: )] and control [0.93 (95% CI: )] improved at a significantly faster rate over the study period among patients with CVD compared with those without CVD. We can see that there is a multiplicative effect between time and both measurement and control, with the difference in these increasing over time between those with and without CVD. Discussion Main findings of this study This population-based study shows that there have been large improvements in both the measurement and control of BP over the past decade among persons with CVD. Much of this improvement occurred before the implementation of the QOF in Comparatively modest improvements were found among individuals without CVD, although our data indicate that (QOF) targets for BP monitoring in this group (80% having their BP measured every 5 years) are being met. Inequalities in BP control decreased among age, ethnic and SES groups over the study period. But some inequalities were still apparent. For example, black patients without CVD remained more likely to have their BP raised than white patients. Also south Asian patients with CVD were less likely to have raised BP than white patients. Differences between men and women without CVD appeared to increase over the study period, with men being less likely to be measured and more likely to have raised BP than women in Among those with CVD, men were less likely to be measured but were not more likely to have raised BP. This study also found that patients with multiple CVD conditions

6 BLOOD PRESSURE CONTROL IN PRIMARY CARE 307 were both more likely to have their BP measured and controlled than those with a single CVD condition. This suggests that recent quality improvement initiatives in England may have improved risk factor control more in high-risk patients. What is already known on this topic? The relative benefits of population-based strategies, in comparison with high-risk strategies, on cardiovascular health and associated mortality are well established. 15,16 For example, previous work suggests that equivalent reductions in diastolic BP confer a 10-fold greater decrease in coronary heart disease (CHD) mortality among the general population relative to patients with existing CHD. 17 A comparison of primary and secondary prevention strategies recommended in the National Service Framework for CHD also concluded that over CHD per year more cardiovascular events would be prevented by meeting public health and primary prevention targets, compared with events prevented by focusing on those with established disease. 18 Our study builds on previous research that has identified important inequalities in BP control between population groups in the UK. Our finding that black patients were more likely to have raised BP than white patients partly fits in with data from the HSE 2004, which found that black women were more likely to have high BP than the general population, and that black Caribbean men had higher mean systolic BP than the general population. 19 The increasing differences between men and women are consistent with the latest data from the HSE, which cites a particularly large improvement in treatment and control of BP among women which was not mirrored in men. 20 Finally, our finding that patients with multiple conditions are more likely to have their BP both measured and controlled is consistent with previous UK and US evidence on the relationship between number of medical conditions and quality of care generally, 21 among patients with hypertension 22 and those with diabetes. 23 This finding may reflect greater contact with primary care among these patients and the impact of the QOF, a pay for performance programme that incentivises improved management of all of the conditions examined in our study. What this study adds Our findings indicate that the current emphasis on secondary prevention within UK health policy has led to a more rapid reduction in BP levels among patients with CVD than in the general population. While reductions in BP at the population level are undoubtedly more difficult to achieve, the very modest reductions seen in our study over the past decade indicate that important health gains may be being missed. Our study therefore further highlights the importance of increasing investment in primary prevention initiatives known to reduce BP. These initiatives include efforts to halt and then reverse the obesity epidemic and increase physical activity levels. 24 Despite recent positive trends suggesting increased levels of physical activity in England, improvements have been slow and in 2008 only 39% of adult men and 29% of adult women met the Chief Medical Officer s recommendations for physical activity. 25 Finally, while the UK is considered as a world leader in its efforts to reduce population salt intake, it is of concern that the Food Standards Agency s target for reducing population salt intake to 6 g has now been delayed until 2012, as population-based salt reduction has the potential to deliver BP and mortality reductions to large numbers of people, 26 both with and without hypertension. 27 Our findings finally highlight the importance of ongoing assessment of the impact of population and high-risk strategies on inequalities in BP control. Limitations of this study Data were collected on all adult patients registered with 29 of 34 practices in the study area providing a comprehensive picture of BP measurement and control in this urban, ethnically diverse area. However, because we were only able to extract historical data on patients registered in 2007, we lacked information on patients who moved from the area or died during the study period and our sample may be biased towards healthier surviving patients. Further, this meant that the sample size was considerably smaller at the beginning of the study and we may not have had adequate power to detect clinically meaningful differences in BP management. Whilst we had high levels of ethnicity recording among patients with CVD conditions (88%), this was considerably lower among patients without CVD (60%). Our findings relating to ethnic group differences in BP control among patients without CVD should therefore be treated with some caution. We assigned an area-based deprivation score to patients using their general practice postcode. While it would be preferable to employ patient level measures of socio-economic circumstances, such as income or occupational status, these are not routinely recorded in UK general practice. Factors other than the measurement and control of BP would also have been of interest. For example, we do not know whether some of the differences observed in our study are due to prescribing patterns of local doctors, differing adherence to medications or other

7 308 JOURNAL OF PUBLIC HEALTH lifestyle interventions. It would have been informative to examine trends in other risk factors for CVD, such as cholesterol and BMI. However, these remain poorly recorded in general practice information systems at present, i.e. 70% of all patients did not have BMI recorded in We employed a cut point of 140/90 mm Hg for raised BP based on NICE 13 and other guidance for the diagnosis and management of hypertension. 28 This may not reflect the optimal treatment target for individual conditions. The proportion of patients overall with a valid BP reading in 1998 was 19.4% (4621 patients) while by 2007 this had risen to 55.8% ( patients). Part of the improvement in BP control seen in the CVD group may be due to improved ascertainment of cases with borderline hypertension because of this increased measurement of BP over the study period. Conclusion BP control has improved more markedly among those with CVD, compared with those without CVD, in the UK over the past decade. This finding highlights a need to re-evaluate the focus on secondary prevention in the current UK health policy. Inequalities in BP control decreased among age, ethnic and SES groups over the study period. However, differences in BP control between black and white patients have persisted and have increased between men and women. Acknowledgments We thank the 29 practices that took part in this study and Dr Jeremy Gray for his help in planning the data collection, and Dr Simon de Lusignan and his team for carrying out the data extraction. Funding A.L. is funded by the National Institute for Health Research. C.M. is funded by the Higher Education Funding Council for England and the National Institute for Health Research. A.B. and the Dr Foster Unit are largely funded by Dr Foster Intelligence, a joint venture with the NHS Information Centre. The Department of Primary Care and Public Health at Imperial College is grateful for support from the National Institute for Health Research Biomedical Research Centre scheme, the National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care scheme, and the Imperial Centre for Patient Safety and Service Quality; we are also grateful for past support from the Medical Research Council and the Engineering and Physical Sciences Research Council. References 1 Ezzati M., Lopez AD, Rodgers A et al. Selected major risk factors and global and regional burden of disease. Lancet 2002;360(9343): He FJ, MacGregor GA. Cost of poor blood pressure control in the UK: 62,000 unnecessary deaths per year. J Hum Hypertens 2003; 17(7): British Heart Foundation. Statistics Online (27 May 2010, date last accessed). 4 Capewell S, O Flaherty M. What explains declining coronary mortality? Lessons and warnings. Heart 2008;94(9): Food Standards Agency. Food Standards Agency Salt Reduction Strategy (13 April 2010, date last accessed). 6 Department of Health. The Coronary Heart Disease National Service Framework: Building on Excellence, Maintaining Progress. Department of Health Department of Health, National Service Framework for Older People. Department of Health Department of Health, Putting Prevention First Vascular Checks: Risk Assessment and Management. Department of Health Primatesta P, Poulter NR. Improvement in hypertension management in England: results from the Health Survey for England J Hypertens 2006;24(6): Ashworth M, Medina J, Morgan M. Effect of social deprivation on blood pressure monitoring and control in England: a survey of data from the quality and outcomes framework. BMJ 2008;337:a Department of Communities and Local Government. Index of Multiple Deprivation communities/neighbourhoodrenewal/deprivation/deprivation07/ (12 April 2010, date last accessed). 12 Office for National Statistics. The Census in England and Wales (2010 April 12th, date last accessed). 13 National Institute for Health and Clinical Excellence. NICE Clinical Guideline 34: Hypertension: Management of Hypertension in Adults in Primary Care cg034quickrefguide.pdf (3 March 2010, date last accessed). 14 Millett C, Gray J, Bottle A, Majeed A. Ethnic disparities in blood pressure management in patients with hypertension after the introduction of pay for performance. Ann Fam Med, 2008;6(6): Rose G. The Strategy of Preventive Medicine. Oxford: Oxford University Press Lawes CMM, Bennett DA, Feigin VL, Rodgers A. Blood pressure and stroke an overview of published reviews. Stroke 2004;35(3): Unal B, Critchley JA, Capewell S. Modelling the decline in coronary heart disease deaths in England and Wales, : comparing contributions from primary prevention and secondary prevention. Br Med J 2005;331(7517): Gemmel IH, Heller RF, Payne KK et al. Potential population impact of the UK government strategy for reducing the burden of

8 BLOOD PRESSURE CONTROL IN PRIMARY CARE 309 Coronary Heart Disease in England: comparing primary and secondary prevention strategies. Qual Saf Health Care, 2006;15: Sproston K, Mindell J. (eds). Health Survey for England 2004 The Health of Ethnic Minority Groups. The NHS Information Centre for health and social care Falaschetti E, Chaudhury M, Mindell J, Poulter N. Continued improvement in hypertension management in England: results from the Health Survey for England Hypertension 2009;53(3): Higashi T, Wenger NS, Adams JL et al. Relationship between number of medical conditions and quality of care. N Engl J Med 2007;356(24): Petersen LA, Woodard LD, Henderson LM et al. Will hypertension performance measures used for pay-for-performance programs penalize those who care for medically complex patients? Circulation 2009;119(23): Millett C, Bottle A, Ng A et al. Pay for performance and the quality of diabetes management in individuals with and without co-morbid medical conditions. J R Soc Med 2009;102(9): Rennie KL, Jebb SA. Prevalence of obesity in Great Britain. Obes Rev 2005;6(1): Information Centre. Health Survey for England 2008: Physical Activity and Fitness. The NHS Information Centre for health and social care Bibbins-Domingo K, Chertow GM, Coxson PG et al. Projected effect of dietary salt reductions on future cardiovascular disease. NEnglJ Med 2010;362(7): He FJ, MacGregor GA. How far should salt intake be reduced? Hypertension 2003;42(6): Graham I, Atar D, Borch-Johnsen K et al. European guidelines on cardiovascular disease prevention in clinical practice: executive summary. Eur Heart J 2007;28(19):