Drugs 11 (Suppl. 1): 25-27 (1976) © ADIS Press 1976
Session II: Morbidity and Mortality Chairman: Professor R.B. Blacket (Sydney)
Morbidity and Mortality in Hypertension
A.E. Doyle Department of Medicine, Melbourne
Summary
University of Melbourne, Austin Hospital, Heidelberg,
There is substantial evidence of increased mortality and morbidity in hypertension. There is also clear evidence that antihypertensive treatment reduces the incidence of stroke and reduces the· incidence of heart failure, but leaves myocardial infarction as a major cause of death and disability.
1. Morbidity and Mortality in Untreated Hypertension
There is a paucity of reliable data on the effects of high blood pressure on either morbidity or mortality, largely due to the fact that since 1950 intervention in untreated hypertension has become so widespread. Such data as there are come from studies like those of Simpson and Gilchrist (1958) in Scotland and Sokolow and Perloff (1960) in San Francisco, and also from life insurance figures which really represent casual blood pressures. The life insurance statistics (Society of Actuaries, 1959) reveal (as is well known) that as the diastolic blood pressure increases so does the probability of an early demise. In fact, as the diastolic blood pressure decreases below a certain point, expectation of life increases above average. There
is no doubt that modest levels of increase in diastolic or, indeed, of systolic blood pressure are associated with an increased mortality. These are crude data and it is possible to dissect out within ~oups of people with high casual blood pressure, those who have a better or worse prognosis. One of the most significant developments in this has been the work of Smirk and his group; they demonstrated clearly that blood pressure is usually variable and that lack of variability of blood pressure is an important component in mortality (Smirk, 1964). The more fixed the high blood pressure (or the higher the basal blood pressure, to use Smirk's terminology), the worse the prognosis. There are, of course, other factors which affect mortality in relation to hypertension. For any given blood pressure the prognosis is worse in men
Symposium on hypertension
26
than in women. The bigger the heart when the patient is first seen, the worse the outlook. It is also obviously true that patients who have exudative retinopathy with or without papilloedema have a worse prognosis than those who have retinal vascular changes only. Also, the higher the blood pressure the worse the prognosis.
2. Effects of Treatment on Morbidity and Mortality When we get to the question of the effects of treatment on morbidity and mortality it is obviously very much more difficult now to demonstrate exactly what the situation is. It has been known, since the 1950's, that patients with heart failure or patients with malignant hypertension do better if treated. It has been shown also in controlled studies by Hamilton et al. (1964) and Carter (1970) that hypertensive patients who have suffered a stroke are less likely to have recurrences if they are treated. Nevertheless, there is still a substantial incidence of complications in treated hypertensive patients, as illustrated by the following data from our clinic for 250 patients who had attended for at least 5 years. Patients with initial serum creatinine levels greater than l.5mg% have been excluded, but nevertheless hypertension was in general severe. The incidence of complications before treatment was started (table I) was: stroke, 8.5%
Table I. Complications before starting treatment Complication
Males (n=142)
Females (n=105)
Cerebrovascular accidents Myocardial infarction Congestive heart failure Retinal vascular accidents
12 17 8 2
14 7 1 1
Total
39 (27.3%)
(8.5%) (12.0%) (5.6%) (1.5%)
(13.3%) (6.8%) (1.0%) (1.0%)
23 (22%)
Table II. Mortality and morbidity on treatment Males (n=140)
Mortality Stroke Myocardial infarction Other Total
Morbidity Stroke Myocardial infarction Heart failure Total
Females (n=100)
3 16
4 4
20 (14.25%)
9 (9%)
26
2 15 0
33 (23.5%)
17 (17%)
6
for men, 13% for women; myocardial infarction, 12% for men, 7% for women; heart failure, 6% for men, 1% for women; retinal vascular accidents, about 1% in both men and women. In this particular group of severely hypertensive patients treated over 5 years there was an overall mortality of 14.25% for men and 9% for women (table II). So there is still an appreciable mortality in this type of patient, in the men predominantly from myocardial infarction. Similarly, the incidence of morbid events in our clinic is quite considerable: almost a quarter of the patients have had some morbid vascular event; again in the men it is predominantly myocardial infarction, while in women myocardial infarction is also common but the overall morbidity in women is lower. The incidence of stroke is reduced and strokes tended to occur predominantly in patients who were badly controlled. However, myocardial infarction, either fatal or non-fatal, appears to occur with equal frequency in patients whether their blood pressures have been well controlled or not. So there is no evidence from our study, and this applies also to many others, for a reduction in the mortality or incidence of myocardial infarction with treatment.
27
Hypertension and strokes
A further point relates to the probability of a patient who has had a morbid event before treatment developing one subsequently. As far as men are concerned, there was no difference in incidence of subsequent stroke or myocardial infarction between those who had previously had such an event and those who had not. However, of the women who presented without a previous stroke or myocardial infarction, almost none subsequently developed these complications. Almost all the women who developed subsequent myocardial infarction or stroke were those who had had some similar event before treatment.
References Carter, A.: Hypotensive therapy in stroke survivors. Lancet 1: 485 (1970). Hamilton, M.; Thompson, E.N. and Wisniewski, T.K.M.: The role of blood pressure control in preventing complications of hypertension. Lancet I: 235 (1964). Simpson, F.O. and Gilchrist, A.R.: Prognosis in untreated hypertensive vascular disease. Scottish Medical Journal 3: 1 (1958). Smirk F.H.: Observations on the mortality of 270 treated and 199 untreated retinal Grade I and II hypertensive
patients followed in all instances for five years. New Zealand Medical Journal 63: 413 (1964). Society of Actuaries: Build and Blood Pressure Study, Chicago (1959). Sokolow, M. and Perloff, D.: The prognosis of essential hypertension treated conservatively. Circulation 23: 697 (1961). Author's address: Professor A.E Doyle, Department of Medicine, University of Melbourne, Austin Hospital, Heidelberg, Victoria 3084 (Australia).
Discussion Prof. Blacket: Could you speculate on why you are so unsuccessful at preventing myocardial infarction? Prof. Doyle: Prof. Blacket, I know, has beliefs about the role of fats in myocardial infarction. I suspect, and most of the evidence appears to be, that altering fats makes no difference. Maybe it is not so surprising that lowering blood pressure makes no difference either. Ijust don't think we know what causes myocardial necrosis. Dr Reader: Could I ask what the age group of that survey was? Prof. Doyle: The mean age of that group was 52. The great majority of the patients were between 40 and 60.
Drugs 11 (Suppl. 1): 27-34 (1976) © ADIS Press 1976
Hypertension and Strokes
J. L. Corbett Neuropsychiatric Institute, Sydney
Summary
Strokes are the third major cause of death in developed countries and are probably the major cause of severe chronic disability. Hypertension is the most important condition predisposing to strokes, and treatment of hypertension is of great importance in stroke prevention. The relationship of strokes to the degree of hypertension, and to age, sex, race and drug treatment is discussed.
Session II: Morbidity and Mortality Chairman: Professor R.B. Blacket (Sydney)
Morbidity and Mortality in Hypertension
A.E. Doyle Department of Medicine, Melbourne
Summary
University of Melbourne, Austin Hospital, Heidelberg,
There is substantial evidence of increased mortality and morbidity in hypertension. There is also clear evidence that antihypertensive treatment reduces the incidence of stroke and reduces the· incidence of heart failure, but leaves myocardial infarction as a major cause of death and disability.
1. Morbidity and Mortality in Untreated Hypertension
There is a paucity of reliable data on the effects of high blood pressure on either morbidity or mortality, largely due to the fact that since 1950 intervention in untreated hypertension has become so widespread. Such data as there are come from studies like those of Simpson and Gilchrist (1958) in Scotland and Sokolow and Perloff (1960) in San Francisco, and also from life insurance figures which really represent casual blood pressures. The life insurance statistics (Society of Actuaries, 1959) reveal (as is well known) that as the diastolic blood pressure increases so does the probability of an early demise. In fact, as the diastolic blood pressure decreases below a certain point, expectation of life increases above average. There
is no doubt that modest levels of increase in diastolic or, indeed, of systolic blood pressure are associated with an increased mortality. These are crude data and it is possible to dissect out within ~oups of people with high casual blood pressure, those who have a better or worse prognosis. One of the most significant developments in this has been the work of Smirk and his group; they demonstrated clearly that blood pressure is usually variable and that lack of variability of blood pressure is an important component in mortality (Smirk, 1964). The more fixed the high blood pressure (or the higher the basal blood pressure, to use Smirk's terminology), the worse the prognosis. There are, of course, other factors which affect mortality in relation to hypertension. For any given blood pressure the prognosis is worse in men
Symposium on hypertension
26
than in women. The bigger the heart when the patient is first seen, the worse the outlook. It is also obviously true that patients who have exudative retinopathy with or without papilloedema have a worse prognosis than those who have retinal vascular changes only. Also, the higher the blood pressure the worse the prognosis.
2. Effects of Treatment on Morbidity and Mortality When we get to the question of the effects of treatment on morbidity and mortality it is obviously very much more difficult now to demonstrate exactly what the situation is. It has been known, since the 1950's, that patients with heart failure or patients with malignant hypertension do better if treated. It has been shown also in controlled studies by Hamilton et al. (1964) and Carter (1970) that hypertensive patients who have suffered a stroke are less likely to have recurrences if they are treated. Nevertheless, there is still a substantial incidence of complications in treated hypertensive patients, as illustrated by the following data from our clinic for 250 patients who had attended for at least 5 years. Patients with initial serum creatinine levels greater than l.5mg% have been excluded, but nevertheless hypertension was in general severe. The incidence of complications before treatment was started (table I) was: stroke, 8.5%
Table I. Complications before starting treatment Complication
Males (n=142)
Females (n=105)
Cerebrovascular accidents Myocardial infarction Congestive heart failure Retinal vascular accidents
12 17 8 2
14 7 1 1
Total
39 (27.3%)
(8.5%) (12.0%) (5.6%) (1.5%)
(13.3%) (6.8%) (1.0%) (1.0%)
23 (22%)
Table II. Mortality and morbidity on treatment Males (n=140)
Mortality Stroke Myocardial infarction Other Total
Morbidity Stroke Myocardial infarction Heart failure Total
Females (n=100)
3 16
4 4
20 (14.25%)
9 (9%)
26
2 15 0
33 (23.5%)
17 (17%)
6
for men, 13% for women; myocardial infarction, 12% for men, 7% for women; heart failure, 6% for men, 1% for women; retinal vascular accidents, about 1% in both men and women. In this particular group of severely hypertensive patients treated over 5 years there was an overall mortality of 14.25% for men and 9% for women (table II). So there is still an appreciable mortality in this type of patient, in the men predominantly from myocardial infarction. Similarly, the incidence of morbid events in our clinic is quite considerable: almost a quarter of the patients have had some morbid vascular event; again in the men it is predominantly myocardial infarction, while in women myocardial infarction is also common but the overall morbidity in women is lower. The incidence of stroke is reduced and strokes tended to occur predominantly in patients who were badly controlled. However, myocardial infarction, either fatal or non-fatal, appears to occur with equal frequency in patients whether their blood pressures have been well controlled or not. So there is no evidence from our study, and this applies also to many others, for a reduction in the mortality or incidence of myocardial infarction with treatment.
27
Hypertension and strokes
A further point relates to the probability of a patient who has had a morbid event before treatment developing one subsequently. As far as men are concerned, there was no difference in incidence of subsequent stroke or myocardial infarction between those who had previously had such an event and those who had not. However, of the women who presented without a previous stroke or myocardial infarction, almost none subsequently developed these complications. Almost all the women who developed subsequent myocardial infarction or stroke were those who had had some similar event before treatment.
References Carter, A.: Hypotensive therapy in stroke survivors. Lancet 1: 485 (1970). Hamilton, M.; Thompson, E.N. and Wisniewski, T.K.M.: The role of blood pressure control in preventing complications of hypertension. Lancet I: 235 (1964). Simpson, F.O. and Gilchrist, A.R.: Prognosis in untreated hypertensive vascular disease. Scottish Medical Journal 3: 1 (1958). Smirk F.H.: Observations on the mortality of 270 treated and 199 untreated retinal Grade I and II hypertensive
patients followed in all instances for five years. New Zealand Medical Journal 63: 413 (1964). Society of Actuaries: Build and Blood Pressure Study, Chicago (1959). Sokolow, M. and Perloff, D.: The prognosis of essential hypertension treated conservatively. Circulation 23: 697 (1961). Author's address: Professor A.E Doyle, Department of Medicine, University of Melbourne, Austin Hospital, Heidelberg, Victoria 3084 (Australia).
Discussion Prof. Blacket: Could you speculate on why you are so unsuccessful at preventing myocardial infarction? Prof. Doyle: Prof. Blacket, I know, has beliefs about the role of fats in myocardial infarction. I suspect, and most of the evidence appears to be, that altering fats makes no difference. Maybe it is not so surprising that lowering blood pressure makes no difference either. Ijust don't think we know what causes myocardial necrosis. Dr Reader: Could I ask what the age group of that survey was? Prof. Doyle: The mean age of that group was 52. The great majority of the patients were between 40 and 60.
Drugs 11 (Suppl. 1): 27-34 (1976) © ADIS Press 1976
Hypertension and Strokes
J. L. Corbett Neuropsychiatric Institute, Sydney
Summary
Strokes are the third major cause of death in developed countries and are probably the major cause of severe chronic disability. Hypertension is the most important condition predisposing to strokes, and treatment of hypertension is of great importance in stroke prevention. The relationship of strokes to the degree of hypertension, and to age, sex, race and drug treatment is discussed.
