Trends in the prevalence of hypertension, antihypertensive therapy, and left ventricular hypertrophy from 1950 to 1989.

BACKGROUND: Men and women with hypertension are at increased risk for cardiovascular disease, especially when left ventricular hypertrophy is present. We examined temporal trends in the use of antihypertensive medications and studied the relation between their use, the prevalence of high blood pressure, and the presence of electrocardiographic evidence of left ventricular hypertrophy. METHODS: A total of 10,333 participants in the Framingham Heart Study who were 45 to 74 years of age underwent a total of 51,756 examinations from 1950 to 1989. Data were obtained on blood pressure and the use of antihypertensive medications, and electrocardiograms were assessed for left ventricular hypertrophy. The generalized-estimating-equation method was used to test for trends over time. RESULTS: From 1950 to 1989, the rate of use of antihypertensive medications increased from 2.3 percent to 24.6 percent among men and from 5.7 percent to 27.7 percent among women. The age-adjusted prevalence of systolic blood pressure of at least 160 mm Hg or diastolic blood pressure of at least 100 mm Hg declined from 18.5 percent to 9.2 percent among men and from 28.0 percent to 7.7 percent among women. This decline was accompanied by age-adjusted reductions in the prevalence of electrocardiographic evidence of left ventricular hypertrophy, from 4.5 percent to 2.5 percent among men and from 3.6 percent to 1.1 percent among women. CONCLUSIONS: Our findings support the notion that the increasing use of antihypertensive medication has resulted in a reduced prevalence of high blood pressure and a concomitant decline in left ventricular hypertrophy in the general population. Our observations may in part explain the considerable decline in mortality from cardiovascular disease observed since the late 1960s.

Secular trends in long-term sustained hypertension, long-term treatment, and cardiovascular mortality. The Framingham Heart Study 1950 to 1990.

BACKGROUND: Cardiovascular morbidity and mortality result from the chronic processes involved in hypertension. However, long-term sustained (LTS) hypertension has received little attention. METHODS AND RESULTS: Trends in the prevalence of LTS hypertension and its treatment were assessed in 1950, 1960, and 1970 among three cohorts of men and women in the Framingham Heart Study (Mantel-Haenszel test). Cardiovascular disease (CVD) incidence and mortality were compared between patients with LTS hypertension with and without long-term treatment by use of the chi 2 test. Cox proportional hazards regression analysis was used to estimate 10-year risk of death as a function of risk factor levels and treatment. Prevalence of LTS hypertension rose from 138 to 208 per 1000 between the 1950 and 1970 male cohorts (P < .01), while prevalence fell from 253 to 198 per 1000 between the female cohorts (P < .02). Long-term treatment increased 51% between the male cohorts and 45% between the female cohorts (both P < .001). While CVD incidence was similar (26% versus 25%), all-cause mortality was significantly lower among men with long-term treatment (31% versus 43%; P < .05), and CVD mortality was less than half (13% versus 28%; P < .01). Among treated women, all-cause mortality was 21% (versus 34%; P < .01), and CVD mortality was 9% (versus 19%; P < .01). Ten-year risk of CVD death for patients with LTS hypertension with long-term treatment compared with those without was 0.40 (95% CI, 0.27 to 0.60). CONCLUSIONS: This investigation of LTS hypertension, its treatment, and its sequelae in a free-living general population confirms the reduction in CVD mortality demonstrated in more short-term clinical trials of hypertension therapy in select patient groups.

Sex and time trends in cardiovascular disease incidence and mortality: the Framingham Heart Study, 1950-1989.

Variations in cardiovascular disease mortality between sexes, over time, and across regions point to population differences in the biologic, behavioral, and environmental factors influencing cardiovascular health. The authors examined 20-year trends in risk factors, incidence, and mortality among women and men in Framingham, Massachusetts, who were members of the Framingham Heart Study and aged 50-59 years in 1950, 1960, and 1970. The incidence declined 21% between the female cohorts (p < 0.01 for trend) with the greatest decline occurring between the 1950 and 1960 cohorts. The 20-year incidence declined only 6% between the male cohorts despite an 18% decline (p < 0.05 for trend) during the first 10 years of follow-up. Cardiovascular disease mortality declined 59% between the female cohorts and 53% between the male cohorts (both p < 0.001 for trend). The largest mortality declines occurred between the 1950 and 1960 female cohorts during the second 10 years of follow-up and between the 1960 and 1970 male cohorts during both follow-up periods. Obesity, hypercholesterolemia, and high blood pressure were significantly lower at baseline and 10 years later in the 1970 female cohort compared with the 1950 cohort (all p < 0.001). Smoking and high blood pressure were significantly lower at baseline and 10 years later in the 1970 male cohort compared with the 1950 cohort (both p < 0.001). More than half of the 51% decline in coronary heart disease mortality observed in women between 1950 and 1989 and one third to one half of the 44% decline observed in men could be attributed to improvements in risk factors in the 1970 cohorts.

Secular trends in diet and risk factors for cardiovascular disease: the Framingham Study.

OBJECTIVE: In this study we examined changes in dietary intake and risk factors for cardiovascular disease that occurred over three decades in a US-population-based sample. DESIGN: Secular trends in dietary profiles and risk factors were studied in cross-sectional samples of subjects from the Framingham Study in 1957-1960, 1966-1969, and 1984-1988. RESULTS: Dietary levels of cholesterol appeared to have declined considerably, whereas macronutrient and fatty acid intakes appeared to change only slightly. Men appeared to increase their saturated fat intakes from 16.4% in 1966-1969 to 17.0% in 1984-1988 (P < .01). In spite of relatively stable mean total fat intake levels, 35% to 60% of Framingham Study men and women reported decreased consumption of higher-fat animal products over the 10-year period between 1974-1978 and 1984-1988. Framingham subjects who reported modifying their diets by substituting lower-fat foods for high-fat items between 1974-1978 and 1984-1988 were more likely to achieve the guidelines of the National Cholesterol Education Program and Healthy People 2000 for dietary fat and cholesterol intake and for serum total cholesterol level. Levels of systolic and diastolic blood pressure, total and low-density lipoprotein cholesterol, and cigarette smoking were also lower in 1984-1988 than in earlier times. Compared with 1957-1960, mean body mass index and prevalence rates of overweight and hypertension were higher in 1984-1988, despite higher levels of reported physical activity. CONCLUSIONS: The observed secular trends in diet and risk factor levels for cardiovascular disease in the Framingham population are important to guide the development and implementation of population-based strategies for promoting cardiovascular health, including nutrition interventions.

Changes in risk factors and the decline in mortality from cardiovascular disease. The Framingham Heart Study.

A decline in mortality from cardiovascular disease over the past 30 years has been well documented, but the reasons for the decline remain unclear. We analyzed the 10-year incidence of cardiovascular disease and death from cardiovascular disease in three groups of men who were 50 to 59 years old at base line in 1950, 1960, and 1970 (the 1950, 1960, and 1970 cohorts) in order to determine the contribution of secular trends in the incidence of cardiovascular disease, risk factors, and medical care to the decline in mortality. The 10-year cumulative mortality from cardiovascular disease in the 1970 cohort was 43 percent less than that in the 1950 cohort and 37 percent less than that in the 1960 cohort (P = 0.04 by log-rank test). Among the men who were free of cardiovascular disease at base line, the 10-year cumulative incidence of cardiovascular disease declined approximately 19 percent, from 190 per 1000 in the 1950 cohort to 154 per 1000 in the 1970 cohort (0.10 less than P less than 0.20 by chi-square test), whereas the 10-year rate of death from cardiovascular disease declined 60 percent (relative risk for the 1950 cohort as compared with the 1970 cohort, 2.53; 95 percent confidence interval, 1.22 to 5.97). Significant improvements were found in risk factors for cardiovascular disease among the men initially free of cardiovascular disease in the 1970 cohort as compared with those in the 1950 cohort, including a lower serum cholesterol level (mean +/- SD, 5.72 +/- 0.98 mmol per liter [221 +/- 38 mg per deciliter], as compared with 5.90 +/- 1.03 mmol per liter [228 +/- 40 mg per deciliter]) and a lower systolic blood pressure (mean +/- SD, 135 +/- 19 mm Hg, as compared with 139 +/- 25 mm Hg), better management of hypertension (22 percent vs. 0 percent were receiving antihypertensive medication), and reduced cigarette smoking (34 percent vs. 56 percent). We propose that these improvements may have had more pronounced effects on mortality from cardiovascular disease than on the incidence of cardiovascular disease in this population. Our data suggest that the improvement in cardiovascular risk factors in the 1970 cohort may have been an important contributor to the 60 percent decline in mortality in that group as compared with the 1950 cohort, although a decline in the incidence of cardiovascular disease and improved medical interventions may also have contributed to the decline in mortality.

Trends in CHD and risk factors at age 55-64 in the Framingham Study.

In a preliminary analysis to assess secular changes in cardiac morbidity, mortality, and risk factors in the Framingham Heart Study, there is a suggestion of decline in coronary heart disease (CHD) mortality in women but not in men. For subjects age 55 to 64 in 1953, 1963 and 1973, the ten-year CHD mortality rates per 1000 were 93, 84 and 99 for men; and 34, 39, and 24 for women, respectively. In contrast, CHD prevalence rates have increased significantly for men (102, 134 and 159 per 1000) and marginally for women (55, 65 and 69 per 1000). Incidence of CHD increased slightly in men (187, 210 and 208 per 1000 over the three decades) and decreased in women (131, 132, 110). Some coronary risk factors improved, while others changed unfavourably.

A predictive instrument to improve coronary-care-unit admission practices in acute ischemic heart disease. A prospective multicenter clinical trial.

Each year 1.5 million patients are admitted to coronary-care units (CCUs) for suspected acute ischemic heart disease; for half of these, the diagnosis is ultimately "ruled out." In this study, conducted in the emergency rooms of six New England hospitals ranging in type from urban teaching centers to rural nonteaching hospitals, we sought to develop a diagnostic aid to help emergency room physicians reduce the number of their CCU admissions of patients without acute cardiac ischemia. From data on 2801 patients, we developed a predictive instrument for use in a hand-held programmable calculator, which requires only 20 seconds to compute a patient's probability of having acute cardiac ischemia. In a prospective trial that included 2320 patients in the six hospitals, physicians' diagnostic specificity for acute ischemia increased when the probability value determined by the instrument was made available to them. Rates of false-positive diagnosis decreased without any increase in rates of false-negative diagnosis. Among study patients with a final diagnosis of "not acute ischemia," the number of CCU admissions decreased 30 per cent, without any increase in missed diagnoses of ischemia. The proportion of CCU admissions that represented patients without acute ischemia dropped from 44 to 33 per cent. Widespread use of this predictive instrument could reduce the number of CCU admissions in this country by more than 250,000 per year.

Testing a model that evaluates options for rural Emergency Medical Service development.

The authors developed a model that relates survival from myocardial infarction or cardiac arrest to four classes of interactive variables describing the rural community, the patient, Emergency Medical Service (EMS) system inputs, and EMS system process in caring for the suspected cardiac patient. Using data from 92 EMS systems in three geographically distinct and physically dissimilar regions, the authors found a consistent and significant relationship between the probability of patient survival and cardiac disease severity, age, sex, the presence of a life-threatening arrhythmia, health care resources available to the EMS system, citizen-initiated cardiopulmonary resuscitation, EMS response time, and the presence of a paramedic on the ambulance responding to the call. The model affords the opportunity to enumerate those factors with the greatest influence on cardiac survival within the community and to test expected increases in survival gained through incremental changes in these factors.

An aid for diagnosing acute ischemic heart disease in the emergency room.

A five-year study was undertaken to develop a valid mathematical model that could aid in diagnosing acute ischemic heart disease in the emergency room, thus reducing inappropriate admissions to the coronary care unit. The study was divided into two substudies. In the first, variables significantly predictive of ischemic heart disease were identified and a logistic function was developed and tested. In the second, a six-hospital study, the variables of the first substudy were validated and a final logistic regression was developed and tested prospectively. This model's availability proved to be successful in improving diagnostic accuracy and specificity and in reducing false positive predictive rates and admissions to coronary care units.

Emergency medical personnel training: II. Components of training.

Nationwide Emergency Medical Technician (EMT) training programs at both basic and advanced levels are in flux, confronting similar challenges in design and implementation. There currently exist the 81-hour Department of Transportation course of instruction as the basis for EMT-Ambulance (EMT-A) certification and the National Standard Training Curriculum (NSTC) 15-module course for training the EMT-Paramedic (EMT-P). The National Registry of EMTs has established examination and recertification guidelines as well as requirements for both levels of training. The two national training courses reflect a difference in disease focus (ie, trauma vs cardiac) and thus a difference in care rendered by the two EMT levels. Variations in both EMT-A and EMT-P training programs at the state level in areas such as length of training and requirements for certification point out a need for greater consistency in training of emergency medical personnel. Evaluation of current training programs based on the NSTC has resulted in updating the EMT-P curriculum. The proposed curriculum includes new course material with behavioral and performance objectives. An ongoing system of training, evaluation, and incorporation of new techniques found clinically relevant is recommended.

Emergency medical personnel training: I. An historical perspective.

The status of Emergency Medical Technicians has evolved from an undefined role with few rules, regulations, or standards to an established health care profession and a nationally administered program. The evolution of this profession received major impetus from the 1966 report by the National Academy of Science/National Research Council that provided recommended training standards. Development of a training course curriculum for basic life support (BLS) followed. The need for coordinated training of Emergency Medical Technical Technicians was recognized, and funds became available to aid in the national standardization of education, examination, certification, and recertification procedures for EMTs. Concomitant with the attempt to standardize BLS training, advanced life support (ALS) programs grew in number. By 1977 the National Standard Training Curriculum became available and was soon followed by a national certification exam. As states have the option to accept or reject the federal standards embodied in the national training course, there remains variation among programs offered by each state. Because of the difference in need for specific emergency services among the states at a time of increased professional mobility, arguments still exist regarding the desirability of federally mandated training and certification programs.

An analytic method for the evaluation of rural Emergency Medical Service development.

An analytic method is presented for assessing the marginal impact of incremental changes in rural Emergency Medical Services (EMS) on cardiac mortality, morbidity, EMS system process and performance, and health care system utilization. The method incorporates a model of the EMS system. This model specifies five sets of interactive variables characterizing EMS system development and effectiveness. The analytic method quantifies the contribution of each of these sets of interactive variables on the outcome variables (cardiac mortality, morbidity, EMS process/performance, and health care system utilization) for three target populations: those who utilize the EMS system, all hospitalized patients with acute ischemic heart disease independent of EMS system use, and the population of all patients dying from acute ischemic heart disease on a communitywide basis. By including in the model those factors unique to rural areas, such as scarcity of fiscal and health care system resources, geographical constraints, and the skewed severity of case mix due to the clinical and socioeconomic conditions found among rural patients, the analytic method is able to quantify and help explain the impact of these factors on the EMS system and the limitations which they impose. The analytic method affords planners and administrators and rational basis for decisions regarding future rural EMS system development through its identification of those system characteristics amenable to change and worth pursuing from a health policy perspective.

Effectiveness of a prehospital medical control system: an analysis of the interaction between emergency room physician and paramedic.

Medical control for paramedics by means of radio and ECG telemetry is costly, time consuming, and of unproved value. We assessed the interaction between emergency room physicians and paramedics during ambulance transport of "seriously ill" cardiac patients (cardiac arrest, acute myocardial infarction, or new onset of crescendo angina pectoris) with paramedics in service. Thirty-five percent of all arrhythmias and 35% of potentially life-threatening arrhythmias were misclassified. Correct treatment was rendered in 74% of the cases, although only 65% were correctly diagnosed (p < 0.01). The principal predictive variable for misdiagnosing or incorrectly treating a patient was the presence of a potentially life-threatening arrhythmia, precisely the condition for which medical control and the paramedic system has the most to offer. Only 39% of patients with life-threatening arrhythmias were correctly diagnosed and correctly treated, whereas 64% of patients without life-threatening arrhythmias were correctly diagnosed and correctly treated (p < 0.001). Mortality reflected correct diagnosis and treatment. In-hospital and overall mortalities were 12% and 33%, respectively, for patients who were correctly diagnosed and treated (p < 0.06), compared with 20% and 43%, respectively, for patients who were incorrectly diagnosed or incorrectly treated (p < 0.04). More rigorous medical control is needed to improve the quality of patient care and outcome and to further integrate the advanced life support program into the health care system.