Decline In Stroke Mortality Research Articles

Antihypertensive treatment and US trends in stroke mortality, 1962 to 1980.

This study examines the association between increases in antihypertensive pharmacotherapy and declines in stroke mortality among 96 US groups stratified by race, sex, age, metropolitan status, and region from 1962 to 1980. Data on the prevalence of controlled hypertension and socioeconomic profiles were obtained from three successive national health surveys. Stroke mortality rates were calculated using data from the National Center for Health Statistics and the Bureau of the Census. The association between controlled hypertension trends and stroke mortality declines was assessed with weighted regression. Prior to 1972, there was no association between trends in controlled hypertension and stroke mortality declines (beta = 0.04, P = .69). After 1972, groups with larger increases in controlled hypertension experienced slower rates of decline in stroke mortality (beta = 0.16, P = .003). Faster rates of decline were modestly but consistently related to improvements in socioeconomic indicators only for the post-1972 period. These results do not support the hypothesis that increased antihypertensive pharmacotherapy has been the primary determinant of recent declines in stroke mortality. Additional studies should address the association between declining stroke mortality and trends in socioeconomic resources, dietary patterns, and cigarette smoking.

The US decline in stroke mortality: what does ecological analysis tell us?

We review a study in this issue that concludes, from analyses of ecological associations, that the use of medication to lower high blood pressure has caused at most a small decline in US stroke mortality rates. Our analysis suggests that other possible sources of the decline may be population-wide falls in levels of blood pressure, cigarette smoking, and coronary heart disease mortality, as well as improved treatment of cardiac and respiratory sequelae of stroke. Although the ecological method is powerful for answering questions about medical interventions' population-wide effects on disease, it must be used with care. Of particular concern are variables with meanings that differ between the ecological and the individual levels, the number of ecological units available for analysis, the sample size within the ecological units, and the range of independent variables used in ecological regression.

Stroke incidence rates were unchanged, while fatality rates declined, during 1971-1987 in Göteborg, Sweden.

Stroke risk factors have been shown to change with time in several places; simultaneously, stroke incidence rates have increased in some and decreased in other places. In Göteborg, Sweden, cardiovascular epidemiological research has included stroke registration since 1971. From these data on stroke, incidence and fatality rates from a 17-year period are given. During the period 1971-1987 all cases of stroke occurring in people aged 15-65 years in the city of Göteborg were uniformly recorded, with an estimated case detection rate of 90% or more. Age-adjusted incidence rates of first-ever stroke by sex did not change during the period. Age-specific rates and rates for individual types of stroke (subarachnoid hemorrhage, intracerebral hemorrhage, and cerebral infarction-unspecified stroke combined) were also largely unchanged. A slight increase in the incidence rate of intracerebral hemorrhage may be due to better detection after computed tomography came into use in 1976. Stroke fatality rates declined through the whole period in both sexes and all age groups, markedly so for intracerebral hemorrhage and subarachnoid hemorrhage. This conforms with vital statistics for Göteborg and for Sweden of declining stroke mortality during the period. The decline in stroke fatality rates may be related to decreases in smoking habits and blood pressure together with an increase in the percentage of people on antihypertensive treatment among middle-aged men, and to some extent even middle-aged women, reported from the same population. Why stroke incidence rates did not decline concomitantly is unexplained.

Is stroke mortality on the decline in England?

This paper challenges the assumption that mortality from stroke will remain constant or decline over the next few decades. A decline in stroke mortality could be brought about by changes in factors acting close to the time of death (period effect) or by risk factors determined by the generation into which a person is born (cohort effect). Age-specific death rates for stroke (1931-1985) in England and Wales were analyzed to estimate the influence of these different effects. There were significant effects for age, period, and cohort on mortality from stroke with significantly different age and period effects in each sex. The effect of age was linear, with an increasing mortality with age in both sexes. Cohort analysis demonstrated a deceleration away from the previous trend in the mortality rates associated with birth cohorts born after 1880, followed by an acceleration in the trend of mortality rates in cohorts born after 1910. These relative increases in risk for cohorts born after 1910 were offset by a deceleration in mortality associated with periods from around 1951-1954. Since cohort effects are likely to be associated with a lifetime increase in risk of stroke mortality, it is difficult to predict the extent of any long-term fall in stroke incidence.

Some epidemiological aspects of stroke: mortality/morbidity trends, age, sex, race, socioeconomic status.

The reasons for decreasing stroke mortality could be related to either decreasing incidence and/or improved prognosis. Thus far, secular trends of stroke have been analyzed either through mortality or morbidity data. This report examines both aspects simultaneously, on a nationwide basis, for the period 1968-1988. Mortality statistics were based on the Compressed Mortality File. Estimates of morbidity were based on the National Hospital Discharge Survey. The Area Resource File was used to obtain county-specific socioeconomic statistics. The decline in stroke mortality continued through the 1970s and 1980s, whereas morbidity remained constant and possibly even increased. Mortality and morbidity rates were similar in both sexes, higher in blacks, and lower in other (primarily Asian) Americans. There was an inverse correlation between death rates and socioeconomic status, which was particularly marked in blacks. Temporal decline occurred in all strata. The observed decrease in stroke mortality rates results most probably from an improved survival rather than from a decline in incidence. The abundance of new drugs and screening programs may not have affected the overall morbidity of stroke, possibly because of inefficient treatment regimens.

Trends in Mortality, Morbidity, and Risk Factor Levels for Stroke From 1960 Through 1990

The Minnesota Heart Survey is a population-based study designed to monitor and explain trends in cardiovascular mortality, morbidity, and risk factors. Surveillance time-trends study. The following trends were examined among men and women aged 25 to 74 years living in Minneapolis-St Paul, Minn: (1) stroke mortality from 1960 through 1990; (2) risk factors in population-based surveys conducted in 1973 through 1974, 1980 through 1982, and 1985 through 1987; and (3) morbidity in a 50% sample of hospitalized discharges for acute-stroke in 1970, 1980, and 1985. Stroke mortality in Minneapolis-St Paul declined slowly from 1960 through 1972 (average fall, 2.4% per year), dropped sharply from 1972 through 1984 (average fall, 6.5% per year), but exhibited little change thereafter (average fall, 1.5% per year). The average level of cardiovascular disease risk factors fell from 1973-1974 to 1985-1987, with the exception of body mass index. In particular, hypertension diagnosis, treatment, and control levels improved substantially between 1973-1974 and 1980-1982, although there was little improvement after 1980-1982. While discharge rates for hospital-coded acute stroke declined substantially between 1970 and 1985 in both sexes, no clear trend was observed in definite stroke rates as validated using standard clinical criteria. Twenty-eight-day case fatality rates of definite stroke improved significantly from 1970 to 1985. The substantial decline in stroke mortality of more than 50% from 1960 through 1990 appears to have been attributable to both primary and secondary prevention. These data suggest that the long decline in stroke mortality and morbidity in Minneapolis-St Paul has plateaued, although improved detection of stroke with computed tomography prevents an unequivocal conclusion.

Evaluation of and controversies in stroke rehabilitation

The decline in stroke mortality, increased longevi­ ty, and modest increases in the incidence of stroke result in more individuals living with physical dis­ ability caused by cerebrovascular disease. This is creating an increasing burden on the facilities and expertise of individuals who are concerned with the rehabilitation of the patient after stroke. The costs of rehabilitation services are considerable, and there is concern about the cost-effectiveness of rehabilitative care for pat ients with stroke. Not every individual following a stroke is a candi­ date for rehabilitative therapy. A number of investi­ gations have been conducted as to who is most likely to benefit from stroke rehabilitation. Third-party reimbursers in the United States have made determi­ nations on this issue and have set guidehnes for ad­ missioncriteria for inpatient rehabihtation. Admission criteria include that the patient must (a) be medically stable, (b) be responsive to verbal or visual stimuli, (c) have sufficient mental alertness to participate in a program, and (d) have a condition that indicates a potential for rehabilitation with a reasonable expecta­ tion of improvement. The patient must be able to enter a program that requires at least 3 h of active participation per day in physical therapy, occupa­ tional therapy, speech therapy, or rehabilitation nursing. A number of attempts have been made to deter­ mine from the large population of patientswithstroke which ones might be the best candidates for rehabil­ itation. Assuming a population of 100 patients follow­ ing an ischemic cerebral infarction 14 days after the ons et of stroke, approximately 14% of the patients will be dead, 13% will be normal, 20% will have hemi­ plegia, 49% will have hemiparesis, and 4% will have monoparesis. Thus, 73% of the total are potential candidates for inpatient rehabilitation. Analyzing this group of 73 patients, approximately 18-24 will be too well to need inpatient rehabilitation and 18-24 will be too neurologically impaired or medically unstable to be able to enter a rehabilitation program, leaving approximately one-quarter to one-third of the total group as good candidates for rehabilitation.

The decline of mortality due to stroke

Although stroke mortality has been declining since the first part of this century, the rate of decline increased sharply during the early 1970s. The basis for the fall in stroke mortality is often attributed to effective management of risk factors, particularly hypertension. However, some investigators have questioned whether risk factor reduction alone can adequately account for the magnitude of the recent decline in stroke mortality. When viewed from the perspective of competitive and deterministic mortality dynamics, the major force decreasing stroke mortality is the decreasing deterministic competitiveness of stroke and the increasing deterministic competitiveness of various malignant neoplasms and degenerative diseases as causes of mortality. These reciprocal trends are a natural consequence of the competitive deterministic mortality dynamics which describe these diseases in an environment that is becoming more conducive to human survival. The competitive nature of human mortality makes drawing etiopathogenic conclusions based upon single disease mortality data hazardous.

Slowdown in the decline of stroke mortality in the United States, 1978-1986.

The gradual decline in stroke mortality rates observed in the United States since 1900 accelerated markedly around 1973 for whites and around 1968 for blacks. During the next decade stroke mortality rates decreased by almost 50% so that the United States now experiences one of the lowest stroke mortality rates in the world. Beginning in 1979, however the annual rate of decline in stroke mortality began to slow considerably. Comparing the period 1979-1986 with the previous decade, a 57% slowing in the absolute rate of decline (as estimated by the slope of the linear portion of the mortality curve) was observed for white men; the corresponding slowdowns in the rate of decline were 58% for white women, 44% for black men, and 62% for black women. If the decline during the 1980s had continued at the rate observed for the period 1968/73-1978, there would have been 131,000 fewer stroke deaths during the period 1979-1986, 28,000 fewer in 1986 alone. This slowdown in the rate of decline in stroke mortality is occurring while mortality rates for both coronary heart disease and all causes are leveling off. The reasons for this change in the mortality trend remain unknown, and corresponding trends in the treatment and control of hypertension do not provide an entirely satisfactory explanation.

Longitudinal Gompertzian analysis of stroke mortality in the U.S., 1951–1986: Declining stroke mortality is the natural consequence of competitive deterministic mortality dynamics

Age-adjusted mortality rates for stroke in the United States from 1951 to 1986 were subjected to longitudinal Gompertzian analysis. Age-adjusted stroke mortality rate distributions were determined by a variable environmental factor and a constant Gompertz slope. Compared to 1951 values, the environmental factor in 1986 had declined (improved) 49.8% for men and 59.1% for women. This was associated with a 51.9% and 31.4% decrease in the annual crude mortality rate from stroke for men and women respectively. However, the Gompertz slope remained remarkably constant from 1951 to 1986; 0.050152 for men and 0.048341 for women. The constant Gompertz slope for age-adjusted mortality rate distributions for stroke is in sharp contrast to the increasing Gompertz slope which occurs with an improving environment in ‘degenerative’ diseases and aging in general. These findings suggest that the recent dramatic decline in overall stroke mortality is the natural consequence of competitive deterministic mortality dynamics. As the overall environment becomes more conducive to human survival, Gompertzian diseases with converging mortality rate distributions must increase as causes of human mortality at the expense of diseases with constant Gompertz slopes.

International trends in stroke mortality: 1970-1985.

We compared the pattern of cerebrovascular disease (stroke) mortality in men and women aged 40-69 years in 27 countries during 1970-1985 with the decline in coronary heart disease mortality during the same period. Stroke mortality rates declined in 21 and 25 countries for men and women, respectively. In 23 countries the decline in stroke mortality in women was greater than that in men. Countries with the highest rates of stroke mortality are also those with the least favorable secular trend. The rate of decline for stroke mortality is greater than that for coronary heart disease mortality in those countries that experienced a decline in both categories. International comparisons of risk factor levels over time are required to explain the striking differences between countries.

Increased treatment of hypertension does not explain the decline in stroke mortality in the United States, 1970-1980.

The steady decline in mortality from stroke in the United States accelerated markedly in the 1970s. It has been widely assumed that an increase in the rate of treatment of hypertension is the most likely explanation for this major public health achievement. An analysis of available information, however, suggests that improvements in the community control of hypertension in the United States in the period 1970-1980 have contributed in only a minor way. There were 45,357 fewer deaths from stroke in 1980 among those aged 35-74 years than might have been expected if the death rates had stayed the same as in 1970. Data from the National Health and Nutrition Surveys indicate that six million more people received antihypertensive medication in 1980 than in 1970. Results from a pooled analysis of randomized controlled trials of the treatment of hypertension suggest that between 6% and 16% of the reduction in stroke mortality was due to the increased treatment of hypertension. Epidemiological observations indicate that between 16% and 25% of the overall decline in stroke mortality can be attributed to the treatment of hypertension, suggesting that clinical trials probably underestimate the community-wide benefits of treatment. These results also suggest that at least three quarters of the decline in stroke mortality in the United States in the period 1970-1980 is due to factors other than antihypertensive treatment.

Changes in survival following stroke in five North Carolina counties observed during two different periods.

We evaluated survival following stroke for patients from a five-county area of rural North Carolina enrolled in either of two community hospital-based stroke survey programs. In this area, the first program enrolled 843 stroke patients between 1970 and 1973 and the second program enrolled 786 stroke patients between 1979 and 1980. One-year survival increased from 49% in the first program to 62% in the second for all stroke patients, from 54% to 68% for patients with cerebral infarction, and from 18% to 55% for patients with cerebral hemorrhage. While other reports have attributed declining stroke mortality to a decline in the incidence of stroke, our study suggests that increased survival after stroke may account for a large portion of the decrease in stroke mortality.

Decline in US stroke mortality. Demographic trends and antihypertensive treatment.

Stroke mortality has been falling rapidly in this country since 1973. To investigate age-race-sex effects on stroke mortality, we studied US vital statistics during 1950-1972 and 1973-1981 in 55-64-, 65-74-, and 75-84-year-old race-sex groups. The accelerated rate of decline in stroke mortality since 1973 has had a substantial public health impact, with greater than 200,000 fewer stroke deaths than would otherwise have occurred. For all groups, stroke mortality declined at a greater rate (p less than 0.05) in 1973-1981 than during 1950-1972. The rates of decline during 1973-1981 were greater with increasing age (p less than 0.05) and were more substantial for younger blacks. There were no consistent differences in the rate of decline by sex. The greater rate of decline in absolute stroke mortality in the older age groups and blacks was explained by higher baseline mortality in these groups. Overall, stroke mortality decreased by approximately 2%/yr in 1950-1972 and by approximately 7%/yr after 1973. Rank order of average annual percent decline after 1973 by age-race-sex groups did not correspond to rates of change in treatment or control of hypertension obtained from three national surveys. The accelerated rate of decline after 1973 may have resulted from improved antihypertensive therapy, but our findings fail to confirm this hypothesis and suggest that treatment of hypertension may not be the principal reason for the decline in stroke mortality.

New approaches to a first-line treatment of hypertension

Stepped-care treatment of hypertension has been widely adopted, and improvement in control of high blood pressure is probably responsible for the decline in stroke mortality rates in the past 15 years. Yet many trials of the efficacy of the treatment of high blood pressure have failed to demonstrate that lowering blood pressure using stepped care will prevent coronary heart disease. Recent evidence suggests that the benefit of stepped care based on the use of diuretics and beta-blockers may be diminished by simultaneous harm from the drugs used. This includes hypokalemia, hypomagnesemia, hyperglycemia, hyperurlcemia, elevation of total and low-density lipoprotein cholesterol levels, elevation of triglyceride levels, and a decrease in high-density lipoprotein cholesterol levels. Awareness of this has led to the development of alternative choices for first-line treatment of mild high blood pressure. A new approach enlarges the number of options for initial treatment to include calcium blockers, angiotensin-converting enzyme inhibitors, alpha-blockers, diuretics, and beta-blockers. Selection of the most appropriate drug is individualized according to the characteristics of the patient. Demographic considerations of age and race are only partially helpful because of frequent exceptions to the rules. Of greater importance are considerations of concurrent disease such as coronary heart disease, diabetes, gout, and hyperlipidemia, for these conditions are powerful determinants of the best first-line drug. Substitution, rather than addition, of another drug should be used when the first choice is not successful.

Stroke in blacks.

In an attempt to answer unresolved questions and to suggest directions for future research concerning stroke in black populations, data from the National Center for Health Statistics were examined and published studies were reviewed. Stroke was the third leading cause of death among U.S. blacks in 1982, accounting for 18,698 deaths, 8.25% of the total. Black men aged 35-74 years were 2.5 times and black women 2.4 times as likely as whites to die of stroke. A long-term decline in stroke mortality rates continued through 1982, with the declines since 1968 probably due to improved hypertension control. Data on morbidity trends are lacking. About 7% of black men and 11% of black women in the U.S. noninstitutionalized population aged 65 and over reported having had a stroke in 1977, black women having the highest prevalence of any group. In several studies, black women had higher incidence rates of stroke than white women in each age group. Black men had higher incidence rates than whites up to age 75 years. Survivorship and outcome following stroke may have been poorer in blacks than in whites. Advanced age and elevated blood pressure were the only putative risk factors for stroke for which published data were adequate to firmly establish the association in blacks. Thus, data are needed to examine trends in stroke incidence and survivorship in blacks and to assess the relation of many variables to the risk of stroke.

Type of gallstones and deaths from stroke and coronary heart disease among cholecystectomized patients.

A total of 841 Japanese patients who had undergone cholecystectomy for choleithiasis (550 for cholesterol stones and 291 for pigment stones) from 1951 to 1970 were investigated on death from stroke, coronary heart disease (CHD) and heart disease other than CHD in relation to the type of gallstones. Compared to patients with pigment stones, those having cholesterol stones had a 50% lower risk of dying from stroke which was statistically significant. The findings support the idea that westernization of Japanese diets may be responsible both for the decline in stroke mortality and for the changing pattern of gallstones in this country. The risk of CHD among cholesterol-stone patients was higher, but not significantly so, than that of pigment-stone patients whereas mortality from heart disease other than CHD did not differ much between the two groups. There were, however, few deaths from these diseases and the findings were therefore not conclusive.

Acute stroke in a metropolitan area 1970 and 1980: The Minnesota heart survey

Mortality rates for stroke, and hospitalization and case fatality rates for acute stroke in 1970 and 1980 were obtained for residents aged 30–74 of the Twin Cities (Minneapolis—St Paul) metropolitan area to determine whether improved hospital care contributed to the decline in stroke mortality. Age-adjusted mortality rates per 100,000 declined significantly in that decade for men (1970, 89.4; 1980, 47.5; p < 0.01) and women (1970, 72.6; 1980, 40.9; p < 0.01). Age-adjusted hospitalization rates per 100,000 population also declined significantly for men (1970, 438; 1980, 323; p < 0.01) and women (1970, 331; 1980, 203; p < 0.01). Age-adjusted mean length of hospital stay did not change significantly. Hospital case fatality declined for men aged 30–64 years (1970, 22.5%; 1980, 15.1%; p < 0.01) but did not change significantly for 65 to 74 year-old men (1970, 16.5%; 1980, 20.0%; p = 0.09) or for all women (age-adjusted rates: 1970, 13.6%; 1980, 16.0%; p = 0.17). There was no change in the distribution of severity of hospitalized cases between years. Therefore, the decline in stroke mortality is consistent with a decreased incidence of stroke resulting from improved hypertension control. Improvements in hospital medical care appear not to have contributed substantially to the decline in stroke mortality.

Recent trends in coronary heart disease and other cardiovascular diseases in Italy.

Trends in death rates from coronary heart disease (CHD) in Italy in the period 1970-1979 suggest a continuous rising of mortality in males until 1976-1977 followed by a plateau or a slight decrease in the next 2 years; whereas an 11.5% decrease has been observed in females aged 35-74. Looking at the whole group of cardiovascular diseases it appears that a continuous and clear decline in stroke mortality (-14.6% in males and -22.0% in females aged 35-74) explains almost completely the overall decrease of cardiovascular mortality observed during the period 1970-1979 which corresponds to -8.4% in males and -24.3% in females. Limited and unrepresentative data from population samples studied between 1960 and 1980 suggest an increasing incidence of CHD which is compatible with parallel changes of some risk factor levels. In the 1970s a continuous increase of fat consumption and of cigarette consumption has been balanced by an increase of prevalence of controlled hypertensives, by an increase of leisure physical activity, by an increasing availability of coronary care units and consumption of beta-blockers. It is likely that in the late 1970s a plateau was reached in the coronary epidemic.

Recent changes in salt use and stroke mortality in England and Wales. Any help for the salt-hypertension debate?

This analysis attempts to fill the gap in the epidemiological evidence about the relation between dietary salt and hypertension. Changes in the purchase of salt in England and Wales are compared with changes in mortality from cerebrovascular disease (1958-78). Stroke mortality, a major sequel of hypertension, has declined in this period. Consumer purchases of salt have decreased also, as suggested by the National Food Survey. While these trends are consistent with the salt-hypertension hypothesis, the picture is confused by an increase in meals eaten outside the home, by the consumption of more processed food, and by a higher prevalence of refrigerators. Other events, such as medical treatment of hypertension or changes in the case fatality rate, could have contributed to the decline in stroke mortality. This secular trend analysis, using available data, does not clarify the salt-hypertension debate.