Decreased risk of stroke among postmenopausal hormone users. Results from a national cohort.

OBJECTIVE: To assess the impact of postmenopausal hormone use on the risk of stroke incidence and stroke mortality. DESIGN: Longitudinal study consisting of three data collection waves. The average follow up for cohort members was 11.9 years (maximum, 16.3 years). Cox proportional hazards regression models were used to estimate the relative risk of stroke for postmenopausal hormone ever-users compared with never-users. PARTICIPANTS: A national sample of 1910 (of 2371 eligible) white postmenopausal women who were 55 to 74 years old when examined in 1971 through 1975 as part of the first National Health and Nutrition Examination Survey and who did not report a history of stroke at that time. MAIN OUTCOME MEASURE: The main outcome measure was incident stroke (fatal and nonfatal). Events were determined from discharge diagnosis information coded from hospital and nursing home records and cause of death information coded from death certificates collected during the follow-up period (1971 through 1987). RESULTS: There were 250 incident cases of stroke identified, including 64 deaths with stroke listed as the underlying cause. The age-adjusted incidence rate of stroke among postmenopausal hormone ever-users was 82 per 10,000 woman-years of follow-up compared with 124 per 10,000 among never-users. Postmenopausal hormone use remained a protective factor against stroke incidence (relative risk, 0.69; 95% confidence interval, 0.47 to 1.00) and stroke mortality (relative risk, 0.37; 95% confidence interval, 0.14 to 0.92) after adjusting for the baseline risk factors of age, systolic blood pressure, diabetes, body mass index, smoking, history of hypertension and heart attack, and socioeconomic status. CONCLUSIONS: The results suggest that postmenopausal hormone use is associated with a decrease in risk of stroke incidence and mortality in white postmenopausal women.

Antihypertensive drug therapy and survival by treatment status in a national survey.

The National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study, an investigation of a cohort originally examined during the period 1971-1975, provided an opportunity to assess the frequency of antihypertensive drug therapy in the United States during the period 1982-1984. For most age-sex-race subgroups, the frequency of medication use during 1982-1984 was higher than that observed during 1976-1980 based on the NHANES II. In the interval 1982-1984, diuretic agents were the most frequent medications prescribed (47% of drugs prescribed), and beta-blockers were second (17%). At the time of the initial survey in 1971-1975, participants had their blood pressures measured and a history of diagnosis and treatment of hypertension ascertained. Follow-up for vital status was 93% complete by 1984 (average length of follow-up, 9 years). In white men and women aged 50 years and older, the relative risk of death increased steadily, from those with elevated blood pressure (systolic blood pressure greater than or equal to 160 mm Hg or diastolic blood pressure greater than or equal to 95 mm Hg) but no history of hypertension to those treated for hypertension but whose blood pressure was still elevated. Regardless of history or treatment, those with an elevated blood pressure had about a 25-30% excess risk of death. Evidence from these national studies shows a high frequency of antihypertensive drug therapy in 1982-1984 and suggests the importance of adequate blood pressure control for optimal survival.

Health service areas for the United States.

The objectives of this report are to document methods used to identify health service areas for the United States and to describe and evaluate these areas. A health service area is defined as one or more counties that are relatively self-contained with respect to the provision of routine hospital care. Service areas that include more than one county are characterized by travel between the counties for routine hospital care.

NHANES III for older persons: nutrition content and methodological considerations.

The National Health and Nutrition Examination Surveys (NHANES) are important in the assessment of nutritional status of the population of the United States. The utility of these surveys for assessment of the nutritional status of older Americans has been limited because prior NHANES have not included persons aged greater than or equal to 75 y. This paper reviews the role of the NHANES for nutritional epidemiology, highlighting the unique opportunity NHANES III offers to expand the nutrition database for older persons. Data are presented on consequences of nonresponse in analytic work and mechanisms that have been devised to approach the potential problem of nonresponse within NHANES III.

Postneonatal mortality in the United States: an international perspective.

The international standing of the United States in postneonatal mortality has deteriorated from third in 1950 to sixteenth in 1986. The high rate among United States blacks is not the reason for the poor United States standing: ten other countries had lower rates than that for United States whites. Recent trends show a slowdown in the decline in postneonatal mortality between 1970 to 1981 and 1981 to 1986 in Canada, England and Wales, Netherlands, and the United States. Norway actually experienced increases during the latter period. Only France showed an acceleration in its decline during the 1980s. Canada has maintained the most rapid rate of decline between 1950 and 1986. Although all countries examined here reported Sudden Infant Death Syndrome as the leading cause of postneonatal deaths, there was twofold variation among the countries in the Sudden Infant Death Syndrome rate. Similarly, congenital anomalies, the second leading cause of death, showed a 50% range in mortality rates. Infections accounted for less than 10% of all postneonatal deaths. A reasonable approach to assessing the magnitude of preventable mortality in the postneonatal period is to use mortality from all causes except congenital anomalies among normal birth weight infants. United States whites had a lower "preventable" postneonatal mortality rate than Denmark, England and Wales, and Scotland, but a higher rate than Sweden. United States blacks, on the other hand, had by far the highest rates. Disaggregating the United States rates further into three broad maternal risk groups, there was a doubling of rates with increasing level of maternal risk. About half the postneonatal deaths among normal birth weight infants could be prevented if the entire population experienced the rates of the lowest maternal risk group.

Is weight loss a modifier of the cholesterol-heart disease relationship in older persons? Data from the NHANES I Epidemiologic Follow-up Study.

The relationship between cholesterol and 14-year incidence of coronary heart disease was compared for men and women of two age groups, 25 to 64 years and 65 to 74 years. While cholesterol levels of 6.2 mmol/L or higher were associated with a risk of coronary heart disease in the younger group, this was not true for either men or women aged 65 to 74. Further analyses for older persons showed that weight loss modified the cholesterol-heart disease relationship. Those with stable weight showed a positive relationship between cholesterol and coronary heart disease, similar to the younger age group (relative risk [RR] = 1.8 [95% confidence interval: 1.1, 2.9] for men; RR = 1.6 [.7, 3.4] for women). Among those with a weight loss of 10% or more, the relationship of cholesterol to heart disease was inverse (RR = .8 [.5, 1.2] for men; RR = .6 [.3, 1.0] for women). These data suggest that the relationship of cholesterol to coronary disease in healthier older persons may be similar to that in younger persons, and that health status should be considered in analyses of cholesterol risk in old age.

Regional variation in ischemic heart disease incidence.

This study examines the relationship between cardiovascular risk factors and regional variation in IHD incidence among white males 55-74 years of age from the NHANES I Epidemiologic Followup Study. The age-adjusted IHD incidence rate was lowest in the west (31.3 per 1000 persons years of followup). The rates in the northeast, midwest, and south were similar and so they were combined into one region, the non-west, with a rate of 42.4. Differences in risk factors (smoking, educational level, hypertension, serum cholesterol, diabetes mellitus, and body mass index) did not explain the regional differences in IHD incidence. After adjusting for baseline risk factors using proportional hazards model, the risk of IHD incidence was still 38% higher in the non-west compared to the west. However, the effect of hypertension, diabetes, and body mass index on IHD incidence varied by region.

The low cholesterol-mortality association in a national cohort.

The relationship of low serum cholesterol and mortality was examined in data from the NHANES I Epidemiologic Followup Study (NHEFS) for 10,295 persons aged 35-74, 5833 women with 1281 deaths and 4462 men with 1748 deaths (mean (followup = 14.1 years). Serum cholesterol below 4.1 mmol/l was associated with increased risk of death in comparison with serum cholesterol of 4.1-5.1 mmol/l (relative risk (RR) for women = 1.7, 95% confidence interval (CI) = (1.2, 2.3); for men RR = 1.4, CI = (1.1, 1.7)). However, the low serum cholesterol-mortality relationship was modified by time, age, and among older persons, activity level. The low serum cholesterol-mortality association was strongest in the first 10 years of followup. Moreover, this relationship occurred primarily among older persons (RR for low serum cholesterol for women 35-59 = 1.0 (0.6, 1.8), for women 70-74, RR = 2.1 (1.2, 3.7); RR for low serum cholesterol for men 35-59 = 1.2 (0.8, 2.0), for men 70-74, RR = 1.9 (1.3, 2.7)). Among older persons, however, the low serum cholesterol-mortality association was confined only to those with low activity at baseline. Factors related to underlying health status, rather than a mortality-enhancing effect of low cholesterol, likely accounts for the excess risk of death among persons with low cholesterol. The observed low cholesterol-mortality association therefore should not discourage public health programs directed at lowering serum cholesterol.

Indirect standardization of neonatal mortality for birth weight.

Recent advances in perinatal medicine, together with the proliferation of regionalized perinatal networks, have increased the need for monitoring of trends and variations in birth weight-specific perinatal mortality rates. Since the United states has no national system of linked birth and death records, the only available method for comparing weight-specific mortality among geographic areas or medical care facilities in through indirect standardization of mortality for birth weight. This paper investigates the characteristics of the Standardized Mortality Ratio (SMR) obtained by indirect standardization using 1974-77 neonatal mortality and birth weight data for 202 geographic areas across the United States. The results show that the SMR is not sensitive to the choice of standard rates even when the area's birth weight-specific mortality rates are not a constant multiple of standard rates. A method for estimating the standard error of the SMR without knowledge of the weight-specific rates is presented and shown to be nearly unbiased. There is also a substantial amount of variation among geographic areas in both neonatal mortality rates, SMRs, and birth weight distributions. Thus, despite certain limitations, the SMR provides a useful summary measure for monitoring trends and variations among geographic areas or medical care facilities in birth outcome.

Is the serum cholesterol-coronary heart disease relationship modified by activity level in older persons?

Although coronary heart disease remains a leading cause of death and disability in old age, the relationship of serum cholesterol level to risk of coronary heart disease in old age is controversial. Data for 2,388 white persons aged 65-74 who participated in the National Health and Nutrition Examination Survey (NHANES) I Epidemiologic Follow-up Study (NHEFS) were examined to determine the relationship of serum cholesterol level to coronary heart disease incidence and whether activity level would modify this relationship. While there was no overall relationship between serum cholesterol level and coronary heart disease risk in either men or women, the relationship between serum cholesterol level and coronary heart disease differed within activity groups. For persons who were more active, serum cholesterol level was associated with a graded increase in risk of coronary heart disease, from 1.3 (95% CI 0.7, 2.3) in those with serum cholesterol level of 4.7-5.1 to 1.7 in those with serum cholesterol level of 6.2 mmol/L or more (95% CI 1.0, 2.7), when compared with those with serum cholesterol level below 4.7. For the least active persons, all levels of cholesterol were associated with a significant inverse relative risk, including cholesterol of 6.2 mmol/L or more (Relative risk = 0.4 (95% CI 0.2, 0.7]. These data suggest that factors such as activity level may modify the serum cholesterol-coronary heart disease association in old age. The serum cholesterol-coronary heart disease association in more active older persons resembles that seen in younger populations, whereas the association in less active persons is that of serum cholesterol level and risk of cancer or death. The modification of the serum cholesterol-coronary heart disease association by activity level may have implications for appropriate clinical management as well as appropriate design of research studies of this association.

Are "medically underserved areas" medically underserved?

A comparison of medically underserved areas (MUAs) and adequately served areas (ASAs) is presented. Nonmetropolitan areas represented in the Health Interview Survey (HIS) are classified as MUAs or ASAs by the official criterion of their scores on the Index of Medical Underservice (IMU), and HIS data from the two types of areas are examined for differences. Standard metropolitan statistical areas are also compared with the nonmetropolitan MUAs and ASAs. Results show no difference between MUA and ASA residents in number of physician visits per year or proportion with at least one visit in the past year, although MUA residents reported poorer health status, used some preventive services less, and used nonsurgical hospitalization more than did ASA residents. In gereral, most MUA-ASA differences tend to be similar in size to differences between ASAs and SMSAs. An alternative to the IMU, using HIS data to identify underserved areas, is discussed.

Service areas for ambulatory medical care.

This article evaluates three alternative definitions of physician service areas using data from the 1978 National Health Interview Survey. The three types of areas are county aggregations based on different data sources: the Bureau of Economic Analysis Economic Areas (BEAAs), Ranally Basic Trading Areas (RBTAs), and Health Care Commuting Areas (HCCAs). The three types of areas differ substantially in size, population, urbanization, and the availability of physicians. The overall percentage of physician visits outside each of the three areas was small, ranging from 3 percent for BEAAs to 5 percent for RBTAs and HCCAs. Visits by nonmetropolitan residents were about four times as likely as those by metropolitan residents to occur outside of each area. The results suggest that HCCAs are the most appropriate primary care physician service areas because they are the smallest in size and population and have the greatest variability in physician supply, yet they exhibit an amount of outside-area travel for care similar to that of the two larger types of areas.

Use of out-of-plan services by Medicare members of HIP.

Use of out-of-plan services in 1972 by Medicare members of the Health Insurance Plan of Greater New York (HIP) is examined in terms of the demographic and enrollment characteristics of out-of-plan users, types of services received outside the plan, and the relationship of out-of-plan to in-plan use. Users of services outside the plan tended to be more seriously ill and more frequently hospitalized than those receiving all of their services within the plan. The costs to the SSA of providing medical care to HIP enrollees are compared with analogous costs for non-HIP beneficiaries, and the implications for the organization and financing of health services for the aged are discussed.

Injury fatalities among young children.

Injuries and violence are the primary causes of death among young children in the United States. In particular, in 1982-84 motor vehicle injuries, fires, drowning, and homicide were the leading external causes of death at ages 1-4 years and 5-9 years, accounting for nearly 80 percent of all deaths from external causes. The purpose of this article is to analyze race and sex differentials in injury fatalities among young children. Race and sex differentials in injury mortality were measured in terms of relative risks, that is, race (black to white) and sex (male to female) mortality ratios. Race ratios for external causes ranged from 1.7 to 1.9 for children 1-4 and 5-9, while sex ratios were somewhat lower, 1.4 to 1.8. Although race and sex ratios were relatively small for passenger-related motor vehicle fatalities (0.8 to 1.2) the ratios for pedestrian-related injuries were considerably greater (1.5 to 2.0). Race ratios for deaths caused by fires and homicide were particularly large (3.4 to 4.3). Mortality differences were also measured in terms of excess mortality. For each age-race group more than 65 percent of the overall excess deaths among males were due to external causes of death. Pedestrian-related motor vehicle injuries and drownings accounted for the largest proportion of excess deaths among males. At ages 1-4, 53 percent of the overall excess deaths among blacks were due to external causes. Deaths caused by fires and homicide accounted for more than two-fifths of the excess in this age group. At ages 5-9, 81 percent of excess mortality among black males and 69 percent among black females were accounted for by external causes. Fires, pedestrian-related motor vehicle fatalities, and homicides accounted for nearly 65 percent of excess mortality among black children.There has been a 30 percent decline in death rates from all external causes between 1972-74 and 1982-84. Pedestrian-related motor vehicle death rates declined the most in both age groups.Mortality also declined in each age-race-sex group for passenger-related motor vehicle injuries, for drownings, and for fires except among black males ages 5-9. Homicide, in contrast, increased in both age groups. There has been little change, however,in the incidence of injuries among children. Thus,it appears that declines in fatalities accounted for a major portion of the mortality reduction.

Birth weight-specific infant mortality, United States, 1960 and 1980.

National statistics on the risk of infant mortality by birth weight were collected most recently in 1980 and 1960. (Infant mortality risk is the number of deaths of infants under 1 year of age per 1,000 live births.) In this 20-year period, the infant mortality risk (IMR) for single-delivery infants declined 53 percent, from 23.3 deaths per 1,000 live births to 11.0; 91 percent of this decline was due to lower IMRs within birth weight categories, and 9 percent was due to reduced frequency of low birth weight. The greatest reduction in neonatal mortality (under 28 days)--73 percent--occurred among infants of 1,500-1,999 grams (g) birth weight, whereas the greatest reductions in postneonatal mortality (28 days to under 1 year)--51 percent to 54 percent--occurred among infants of 3,500 g or more birth weight. Trends in IMR for black and white infants were similar, and the twofold gap between the races in IMR persisted from 1960 to 1980. For whites, reductions in the frequency of low birth weights contributed to the decline in the IMR. For blacks, the percentage of infants with birth weights of less than 1,500 g increased, and the total reduction in the IMR was attributable to lower birth weight-specific mortality risks. In some regions of the United States, failure to observe an increase in birth weight for blacks may be a reporting artifact, reflecting improved reporting of births of very small black infants in 1980. Examination of changes in perinatal mortality risks (from 20 weeks gestation to less than 28 days of life) did not suggest that infant mortality trends were substantially affected by changes in the distinction between fetal and neonatal deaths over the 20-year period. Reducing the number of low birth weight infants remains the greatest potential for future reductions in infant mortality.

Planning for emergency medical services in Boston.

The results of a survey of 10,200 visits to 11 Boston hospital emergency rooms during a 9-day period in March 1972 are presented. The survey was designed to provide data on emergency room use to permit more informed planning by public agencies concerned with improving areawide emergency medical services. The 11 institutions surveyed provided virtually all of the emergency medical services in the city of Boston. A majority are teaching hospitals affiliated with one or more of the three medical schools in the area. Of the 11 hospitals, 3 accounted for 60% of all emergency room visits. Survey data were extracted from emergency room log sheets and hospital medical records of individual patients. Information collected included the residence pattern of patients within the geographic area, the patient mix by degree of urgency based on presenting complaints, mode of transportation to the hospital, and age and sex of the patients. Only 15 percent of the 10,200 visits were true emergencies. Fifty-seven percent were classified as urgant and 28% nonurgent. The mix among the 11 hospitals ranged from 7 to 22 percent in the emergency category, and 11 to 61 percent in the nonurgent classification. Trauma accounted for 19 percent of all admissions, with 3 percent attributed to fractures and 4 percent to head injuries. Fifty-six percent of the emergency cases required the services of an internist or pediatrician, 38 percent a surgeon, and 1 percent an obstetrician. The highest utilization rate--27 per 1,000 population--was recorded for the under 5 age group. Although the 65 and older age group had the lowest utilization rate of 6 per 1,000, this group had the highest rate of visits classified as emergencies. Children under 5 accounted for the highest proportion of nonurgent visits. The survey revealed that 30 percent of all hospital admissions were from the emergency room. One in four emergency patients lived outside the city of Boston. A neighborhood health center and a hospital general practice unit reduced hospital emergency room workloads appreciably, even when they were open only during daytime hours. Eighty-eight percent of all patients arranged for their own transportation, usually by private automobile. Of those arriving by ambulance, only 35 percent were classified as emergencies. The survey data reinforce the conclusion that major planning efforts should be concentrated on the management of the nonemergency patient. The data also emphasize the need for a single agency to be responsible for overall planning for emergency medical services on an area wide basis.

10 years after NHANES I: report of initial followup, 1982-84.

The NHANES I Epidemiologic Followup Study (NHEFS) was jointly initiated by the National Center for Health Statistics and the National Institute on Aging in collaboration with other National Institutes of Health and Public Health Service agencies. The goal of NHEFS is to examine the relationship of baseline clinical, nutritional, and behavioral factors assessed in the first National Health and Nutrition Examination Survey (NHANES I-1971-75) to subsequent morbidity and mortality. Data collection for the initial phase of followup took place between 1982 and 1984 and included tracing of all NHANES I participants, determining their vital status, conducting in-depth interviews with surviving participants or with proxies for those who were deceased or incapacitated, conducting selected physical measurements, obtaining facility records for stays in hospitals or nursing homes that occurred during the period of followup, and obtaining death certificates for decedents. Ninety-three percent of the original cohort was successfully traced. Interviews were conducted for 93 percent of traced, surviving participants and 84 percent of traced, surviving participants and 84 percent of traced, deceased subjects. Physical measurements were obtained for approximately 95 percent of surviving, interviewed subjects. Death certificates are available for more than 95 percent of the decedents, and 18,136 facility records were received for 6,477 subjects.

10 years after NHANES I: mortality experience at initial followup, 1982-84.

The NHANES I Epidemiologic Followup Study (NHEFS) was initiated jointly by the National Center for Health Statistics and the National Institute on Aging in collaboration with other National Institutes of Health and Public Health Service agencies. The goal of NHEFS is to examine the relationship of baseline clinical, nutritional, and behavioral factors assessed in the first National Health and Nutrition Examination Survey (NHANES I-1971-75) to subsequent morbidity and mortality. Tracing for the initial followup began in 1981 and ended in 1984. This article compares the mortality experience of the NHEFS cohort with survival probabilities and cause-of-death distributions derived from U.S. vital statistics data. The analysis was done for 28 age-race-sex specific subgroups. The survival of each group of the NHEFS cohort corresponds quite closely to that expected on the basis of the U.S. life table survival probabilities. Mortality differentials by age, race, and sex are also quite similar between NHEFS and U.S. vital statistics. In addition, the cause-of-death distributions among NHEFS participants are quite similar to those expected based on national vital statistics. Thus, there do not seem to be any serious biases in the mortality data. The NHEFS, therefore, provides a unique resource for assessing the effects of baseline sociodemographic, health, and nutritional factors on future mortality in a large, heterogeneous sample that is representative of the nation's population.

National health and nutrition examination I--epidemiologic follow-up survey.

An epidemiologic follow-up of the first National Health and Nutrition Examination Survey (NHANES I), being conducted from 1982 to 1984, is expected to provide estimates of the risks of certain health conditions for a sample of the U.S. population and to make it possible to relate these conditions to the nutritional, social, demographic, and behavioral characteristics of the sample. As part of the followup study, the baseline data obtained in NHANES I have been reviewed to define hypotheses and to identify pertinent variables that can be used in studying changes over time and the relationships of these variables to outcome measures. Because the followup study provides cohort data on a large sample of the U.S. population, it presents a unique opportunity for epidemiologists.

Racial differences in pregnancy outcomes.

Black mothers in the United States are twice as likely as their white counterparts to experience a wide variety of adverse pregnancy outcomes, including prematurity, low birth weight, and infant and fetal death. Although blacks have higher proportions of births with maternal risk factors such as young age, high birth order, low education, and unmarried mothers, these differences do not account for their higher rates of adverse outcomes; the reasons for the excess remain largely unknown. To develop effective interventions to reduce the racial disparities in pregnancy outcome, we must further our understanding of the mechanisms underlying premature onset of labor and intrauterine growth.