Risk of stopping high blood pressure medication

Summarized by Robert W. Griffith, MD
January 6, 1999 (Reviewed: January 21, 2005)

Stroke is the third commonest cause of death in the USA. High blood pressure (hypertension) is the most important risk factor for intracerebral (within-brain) hemorrhage (ICH), one form of stroke.¹ About a third of all people having this form of stroke die within 30 days, and many of the rest are left with serious permanent disability. It is thought that raised blood pressure causes weakening of the walls of the small arteries in the brain, so that they are more likely to rupture. A team in Australia has done a study to see what are the important risk factors in hypertensive patients who have such a stroke.²

ICH stroke patients were identified by hospital discharge records and coroner's reports. Age limits were 18 to 80 years, and nursing home patients were excluded. A total of 331 cases were collected.

To form a non-stroke comparison group, 331 people were identified among the patient's near neighbors - they were matched for sex, age (+/- 5 years), and work activities. The same nurse who interviewed the stroke patient (or the closest available informant, if the patient was dead or incapacitated) interviewed the matched control subject. Questions were asked about smoking, alcohol consumption, physical activity and medical history. Details of medication were also obtained, checked in most cases by prescription records.

First, the occurrence of ICH in hypertensive patients was compared with that in people with normal blood pressure. Then, the occurrence in a particular group of hypertensive patients (e.g. smokers) was compared with that in the same group of normal blood pressure subjects. This allowed comparison of the risk involved by the particular grouping or activity.

Overall, it was found that people with hypertension have more than twice the likelihood of having an ICH-type stroke than people with normal blood pressure. When this effect was examined in different age groups it was found that the impact of high blood pressure was greatest among those younger than 55, and decreased in the older age groups.

The most interesting finding was that the risk of ICH-type stroke varied according to patients' current or past use of blood pressure lowering drugs. Hypertensive patients who quit taking their medication were twice as likely to have an ICH than those who continued with their medication. Most of those discontinuing their medication (about 90%) had done so for more than one month.

Smoking played an even greater part as a risk factor. Current smokers with high blood pressure had a six-fold greater occurrence of ICH compared to smokers with normal blood pressure. Hypertensive previous smokers were not at increased risk because of their earlier habit.

There was no evidence that, for patients with high blood pressure, either gender, cardiovascular disease, diabetes, exercise, alcohol use, or serum cholesterol level played a role in the likelihood of ICH.

This study shows that the risk of ICH stroke is more than doubled in patients diagnosed as having hypertension, compared to people with normal blood pressure. Among those treated with antihypertensive drugs, the risk is much higher (doubled again) in those who have discontinued treatment, compared with those who continue on their medication.

Recently there have been reports of successful treatment of high blood pressure by salt restriction and weight loss, to such an extent that drug medication can be discontinued.³ The present study adds a note of caution to this approach. Drug treatment should not be discontinued while the blood pressure is still raised. Those patients who can control their blood pressure adequately without medication should continue their effective lifestyle, without medication; however, they do need to have their blood pressure checked regularly monitored. Otherwise, as the principal author, Dr Thrift, says: "The bottom line is if you have high blood pressure, keep taking those medications, have regular blood pressure checks, and give up smoking".

Source

• Three important subgroups of hypertensive persons at greater risk of intracerebral hemorrhage AG. Thrift, JJ. McNeil, A. Forbes, Hypertension, 1998, vol. 31, pp. 1223--1229

Footnotes
1. The commonest form of stroke is cerebral thrombosis, and another, rarer, form is subarachnoid hemorrhage (bleeding from a congenitally abnormal artery, outside the brain tissue).
2. Three important subgroups of hypertensive persons at greater risk of intracerebral hemorrhage. AG. Thrift, JJ. McNeil, A. Forbes,  et al, for the Melbourne Risk Factor Study., Hypertension, 1998, vol. 31, pp. 1223--1229
3. Sodium reduction and weight loss in the treatment of hypertension in older persons: a randomized controlled trial of nonpharmacologic interventions in the elderly (TONE). PK. Whelton, LJ. Appel, MA. Espeland,  et al., JAMA, 1998, vol. 279, pp. 839--846

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