Guidelines from the British Hypertension Society
Author’s reply
Department of Cardiovascular Sciences, Clinical Sciences Building, Leicester Royal Infirmary, University of Leicester, Leicester bw17{at}leicester.ac.uk
Bryan Williams
guideline working party chairman

On behalf of the British Hypertension Society, with the authors listed below

The latest guidelines from the British Hypertension Society (BHS IV) were produced after a thorough review of new and old evidence from observational and clinical trial data relating to hypertension, cardiovascular risk and its treatment. The initial drafts were available for review by a number of stakeholder organisations, including the Royal College of General Practitioners, the Primary Care Cardiovascular Society, and relevant patients’ associations such as the Blood Pressure Association.

We take this opportunity to respond to the letters that have been critical of the guidance. The epidemiological evidence emphasising the importance of elevated blood pressure as a major cause of cardiovascular disease is overwhelming, and the evidence base for the safety and effectiveness of treatment of high blood pressure is the largest and most consistent in medicine. Communicating this risk:benefit equation to doctors and their patients is a major challenge—the implementation of optimal intervention is even more formidable. However, it is not the role of health professionals to collude in the provision of poor quality advice and care by pretending the evidence does not exist. Nor should we adjust the conclusions of what needs to be done because the funding implications and systems of care currently in place may restrict optimal implementation. On the contrary, the evidence base is a much needed stimulus for a complete change in the way we approach the clinical management of cardiovascular risk at a population level in the United Kingdom. We agree that this cannot be delivered by primary care working in the way it does today. The whole approach to preventive medicine needs to be changed, with greater use of multidisciplinary teams, pharmacists, evolving technologies, and patients themselves. This shift in emphasis from treating disease to prevention is key to improving the nation’s health.

In response to Burns, the optimal lipid targets are a total cholesterol concentration of <4.0 mmol/l or a reduction of 25% from baseline. The percentage reduction approach is needed for those patients starting statin treatment for secondary prevention or because of their high cardiovascular risk, but whose total cholesterol value is already close to the target—for example, for such patients starting statin treatment with a total cholesterol of 4.1 mmol/l, lowering cholesterol to 3.9 mmol/l is clearly not sufficient and a 25% reduction is required.

We agree with Green that there are many people in the United Kingdom are unaware that they have a raised blood pressure and are therefore at increased risk. Most of these will develop more serious hypertension over time. How will that be detected without a programme of monitoring? We agree that it may not be cost effective for Green to do it, but somebody should. We agree that the “real world of general practice” cannot meet the challenges of modern health care; that is why changes in service delivery are needed.

Duerden’s comments are more perplexing. The ALLHAT study is just one of many reviewed by the BHS. People 55 years of age or over were recruited, and no data on initial therapy for younger people are therefore provided. BHS-IV guidelines recommend diuretics as one of two evidence based options for initial treatment for people aged 55 years and above. Below this age other drugs have been proved to be more effective at lowering blood pressure—the key objective of treatment . Hence the AB/CD algorithm provides a simple template for selecting the first and subsequent drugs to facilitate and encourage reaching blood pressure targets based on age and ethnic group. With regard to lipid lowering targets, we have suggested an audit standard of total cholesterol <5.0mmol/l and an optimal target of 4 mmol/l. The former reflects guidance that was already in place, the latter reflects increasing awareness, endorsed by clinical trials, that lower achieved cholesterol levels further reduce cardiovascular risk. ASCOT-LLA was a primary prevention study that recruited patients with an average 10 year cardiovascular risk similar to the 20% risk threshold suggested by the guidelines for primary prevention. In this study the addition of a statin for people with well controlled blood pressure (138/80 mm Hg) clearly showed an additional 36% reduction in fatal and non-fatal coronary events and a 27% reduction in stroke. This fully justifies the recommendation for consideration of statin treatment as a complementary means of further reducing cardiovascular risk in people with treated hypertension whose baseline 10 year cardiovascular disease risk is estimated to be ³20%, irrespective of baseline cholesterol values.

Sackin is correct, most older people have high blood pressure—75% of UK adults over the age of 65 years (³140/90 mm Hg). However, BHS-IV has taken a more conservative approach to treatment than other international guidelines. It does not recommend treatment for all people with stage 1 (mild) hypertension (blood pressure 140-159/90-99 mm Hg). Instead, for primary prevention, it recommends treating only patients at high risk of cardiovascular disease (10 year risk ³20%). The cost effectiveness of treating hypertension was recently analysed by the National Institute for Clinical Excellence (NICE) as part of its guideline development process. This revealed that treating hypertension alone is one of the most cost effective medical interventions thus far evaluated—hence the incorporation of hypertension as one of the key targets in the new general medical services contract.

Davies is correct in stating that it is not possible to be certain that a specific patient will benefit from a particular intervention, only that reducing blood pressure and cholesterol will on average reduce cardiovascular disease risk. The size of absolute benefit will depend on the absolute risk and relative risk reduction. The former can be estimated for an individual using the risk tables provided in the guidelines and the latter is known. Extensive trial evidence is available to confirm that treatment benefits outweigh any harm across the treatment range recommended.

Many doctors have been reluctant to acknowledge the success of healthcare policies in the United Kingdom that are directed at reducing the risk of cardiovascular disease. This success has not occurred by chance, and primary care has played a central part. Much more remains to be done, and service redesign, coupled with even more effective implementation of current guidance, will continue to improve the nation’s cardiovascular health.

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6. Sever PS, Dahlof B, Poulter NR, Wedel H, Beevers G, Caulfield M; ASCOT investigators. Prevention of coronary and stroke events with atorvastatin in hypertensive patients who have average or lower-then- average cholesterol concentrations, in the Anglo Scandinavian cardiac outcomes trial-lipid lowering arm (ASCOT-LLA): A multicentre randomised controlled trial. Lancet 2003;361:1149-58.

Additional authors are: guideline working party members—Neil R Poulter, International Centre for Circulatory Health, Imperial College London and St Mary’s Hospital, London; Morris J Brown, Clinical Pharmacology Unit, Addenbrooke’s Hospital, University of Cambridge, Cambridge; Mark Davis, general practitioner, Moorfield House Surgery, Garforth, Leeds; Gordon T McInnes, Section of Clinical Pharmacology and Stroke Medicine, Division of Cardiovascular and Medical Sciences, Gardiner Institute, Western Infirmary, University of Glasgow, Glasgow; John F Potter, Ageing and Stroke Medicine Section, Department of Cardiovascular Sciences, Glenfield Hospital, University of Leicester, Leicester; Peter S Sever, International Centre for Circulatory Health, Imperial College London & St Mary’s Hospital, London. British Hypertension Society member—Simon McG Thom, International Centre for Circulatory Health, Imperial College London and St Mary’s Hospital, London.