Treating hypertension: an evidence based case report

Case history

A 66 year old retired publican, Mr C, was admitted to hospital with a sudden onset of weakness affecting his right arm and right leg. His wife had been unable to get her husband out of bed earlier that morning. She had noted that his speech was very slurred and initially had thought that he was very confused. The day before he had knocked his head against a car door but had seemed all right at the time. There was no history of transient ischaemic attacks. A diagnosis of essential hypertension had been made four years previously, and angina pectoris had been diagnosed two years previously. Although his general practitioner had prescribed antihypertensive treatment, Mr C did not like the side effects of the drug and stopped taking it three and half years ago. His only other current medication was sublingual glyceryl trinitrate as required. He smoked 20 cigarettes a day, having started at age of 20, and consumed 40 units of alcohol per week. Mr C's father had died of a myocardial infarction at age 69, and his mother had died of a stroke at age 70. He had no siblings.

Physical examination revealed power to be reduced at 3/5 in his right arm and right leg with an expressive dysphasia. Tone was increased on the right with a right extensor plantar response and hyperreflexia on the right compared to the left. He was continent and had reasonable sitting balance.

A 12 lead electrocardiogram confirmed him to be in sinus rhythm with left ventricular hypertrophy and an old inferior myocardial infarction. His full blood count, erythrocyte sedimentation rate, random blood glucose, troponin T, urea creatinine, and electrolytes were all within the normal range. A fasting lipid profile revealed a cholesterol concentration of 7.2 mmol/l. A computed tomography scan of the brain showed a cerebral infarct in the internal capsule. Doppler studies showed no sig- nificant stenosis of the carotid arteries. An echocardiogram showed good left ventricular function with an ejection fraction of 59% and mild mitral regurgitation. After rehabilitation Mr C was discharged home, independently mobile with a Zimmer frame.

When he was reviewed in the outpatient department eight weeks later, his general practitioner sent a letter with him, expressing concern at his continued raised blood pressure, which in clinic was 182/102 sitting. On further enquiry it transpired that although Mr C had been discharged home taking aspirin, pravastatin, and atenolol he had taken only aspirin after discharge. He had not experienced any adverse effects from the drugs but was very reluctant to take any medication and wanted to know exactly what evidence existed that he would benefit from taking regular medication, especially as he was totally free of symptoms.

Searching for evidence

With increasing access to the internet and media publication patients are becoming more knowledgeable about their own illnesses and some will want to discuss the information they obtain from these sources with their doctor. It is impossible for doctors to keep abreast of every new development in every field of medicine, but it is important that they develop skills to allow them to seek new information that they can then assess, enabling them to make an informed decision.

Mr C wants to know what evidence exists that would support him taking antihypertensive medication and lipid lowering medication. Although most of the standard medical textbooks will clearly state that hypertension is a risk factor for stroke (see Box) and should be treated, few will quote the exact evidence on which this conclusion is based.

Haemorrhagic stroke in the right occipital lobe(SCIENCE PHOTO LIBRARY)

What evidence do I need to convince Mr C to take antihypertensive drugs? Ideally, large randomised controlled trials showing a significant benefit in those patients who received treatment. One of the easiest sources to start with is Medline, which is readily available to all medical students in their libraries. To start with I need to decide which words to use in my search and how far back to extend the search. Although initially I was going to use hypertension and stroke, by using the thesaurus on Medline I learn that cerebrovascular disorders is a better term to use than stroke. I decide to go back as far as 1990 for the search. When I use the terms hypertension and cerebrovascular disorders, Medline provides 970 records, but when I limit the search to randomised controlled trials only and in English, Medline gives 43 references. Although it might be possible to restrict the search further I prefer to print off the references and look at the title of the study and the journal the study was published in. By doing this I have selected three references^1,2,3 that may answer Mr C's question. I am fortunate to find that someone has already done an overview¹ of 14 randomised controlled trials looking at blood pressure, stroke, and coronary heart disease. These trials give a total of 37 000 individuals randomised to antihypertensive treatment (mainly diuretics or ß blockers), mean duration of treatment five years. For most of these trials a cut-off of 140/90 was taken for determining hypertension. The results indicate that a decrease in diastolic blood pressure of 5-6 mm Hg reduces the risk of stroke by 42% and coronary heart disease by 14%. The systolic hypertension in the elderly programme (SHEP) study,² in which 4736 people from 447 921 screened participants aged 60 years and above were randomised to either active or placebo treatment, showed that treatment of isolated systolic hypertension in elderly people decreases the risk for stroke by 36%. In another study³ 4396 patients aged 65-74 with mild to moderate hypertension were randomised to receive either diuretic, ß blocker, or placebo. Patients in the treat- ment group had a 25% reduction in stroke and 19% reduction in coronary events. In this study, and supported by others,⁴ diuretics seem to be superior to ß blockers in reducing the risk of stroke in older people with hypertension. None of the trials included very elderly patients, as a consequence of which there is some uncertainty whether they will benefit (a trial is under way at present, however, which will answer this).⁵

There is firm evidence that treating hypertension in individuals at risk is beneficial and will substantially reduce the risk of both stroke and to a lesser extent coronary heart disease. The information is relayed back to Mr C, who is now agreeable to taking his antihypertensive drugs. I have decided to prescribe a ß blocker, given the findings on the electrocardiogram of an old myocardial infarction and history of angina. If these were absent, however, the avail- able evidence would support a thiazide diuretic as the first line treatment. If on subsequent review blood pressure is not adequately controlled with a ß blocker I would then add in a thiazide diuretic.

Mr C would like further information on the use of lipid lowering agents before he agrees to take pravastatin on a regular basis. May I suggest that you adapt the same approach as above and review the evidence for treatment yourself.

Rosemary Morgan, consultant physician in medicine for the elderly, Department of Medicine for the Elderly, Wirral Hospital, Merseyside


studentBMJ 2000;08:217-258 July ISSN 0966-6494

1. Collins R, Peto R, MacMahon B, Hebert P, Fiebach NH, Eberlein KA, et al. Blood pressure, stroke and coronary heart disease, part 2: short term reductions in blood pressure: overview of randomised drug trials in their epidemiological context. Lancet 1990;335:827-8.
2. SHEP Cooperative Research Group. Prevention of stroke by antihypertensive drug treatment in older per- sons with isolated systolic hypertension: final results of the systolic hypertension in the elderly program (SHEP). JAMA 1991;265:3255-64.
3. MRC Working Party. Medical Research Council trial of treatment of hypertension in older adults: principal results. BMJ 1992;304:405-12.
4. Messerli F, Grossman E, Goldbourt U. Are beta block- ers efficacious as first line therapy for hypertension in the elderly? a systematic review. JAMA 1998;279:1903-7.
5. Bulpitt C, Fletcher A, Amery A. The hypertension in the very elderly trial (HYVET). Drugs Aging 1994;5:171-83.