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Biomedical subjects

R A Hahn

Publications and source records attributed to R A Hahn.

At least 19 recordsLinked to original sources
PubMed2001

Multiple risk factors and population attributable risk for ischemic heart disease mortality in the United States, 1971-1992.

The objective of this study was to assess the associations and population attributable risks (PAR) of risk factor combinations and ischemic heart disease (IHD) mortality in the United States. We used logistic regression models to assess the association of risk factors with IHD in the First National Health and Nutrition Examination Survey (1971-1974) and Epidemiologic Follow-up Study (1982-1992) among white and black men and women. We examined eight modifiable risk factors: hypertension, elevated serum cholesterol, diabetes, overweight, current smoking, physical inactivity, depression, and nonuse of replacement hormones. Risk factors associated with IHD mortality were the same among white and black men (i.e., age, education, smoking, diabetes, hypertension, and serum cholesterol). Age, education, smoking, diabetes, and hypertension were the risk factors among white and black women. Physical inactivity, nonuse of replacement hormones, serum cholesterol, and overweight were the additional risk factors among white women. Adjusted for demographic risk factors, overall PARs for study risk factors were 41.2% for white men, 60.5% for white women (with five risk factors only), 49.2% for black men, and 71.2% for black women. Much IHD mortality attributable to individual risk factors is caused by those factors in combination with other risk factors; relatively little mortality is attributable to each risk factor in isolation. Analysis that does not examine risk factor combinations may greatly overestimate PARs associated with individual risk factors.

Adult↗
PubMed1999

Why race is differentially classified on U.S. birth and infant death certificates: an examination of two hypotheses.

Among U.S. infants who die within a year of birth, classification of race on birth and death certificates may differ. I investigate two hypotheses: (1) The race of infants of different-race parents is more likely to be differentially classified at birth and death than the race of infants of same-race parents. (2) States with a greater proportion of infant deaths of a given race are less likely to differentially classify infants of that race on birth and death certificates than states with a smaller proportion of infant deaths of that race. Using the Linked Birth/Infant Death data tape for 1983-1985, I assessed the first hypothesis by comparing rates of differential classification for infants with different-race parents and same-race parents. To assess the second hypothesis, I examined the correlations between the proportion of infant deaths of each race in each state and the proportion of infants of that race consistently classified. Differential racial classification on birth and death certificates was more than 31 times as likely with different-race than with same-race parents. The second hypothesis was confirmed for white, black, American Indian, and Japanese infants. As the U.S. population becomes more heterogeneous, attention to these methodologic issues becomes increasingly critical for the measurement and redress of differential racial health status.

Birth Certificates↗
PubMed1998

Cardiovascular disease risk factors and preventive practices among adults--United States, 1994: a behavioral risk factor atlas. Behavioral Risk Factor Surveillance System State Coordinators.

UNLABELLED: PROBLEM/CONDITIONS: Cardiovascular disease (CVD), including coronary heart disease (CHD) and stroke, is the leading cause of death in the United States, and state rates of CVD vary by state and by region of the country. Several behavioral risk factors (i.e., overweight, physical inactivity, smoking, hypertension, and diabetes mellitus) and preventive practices (i.e., weight loss and smoking cessation) are associated with the development of CVD and also vary geographically. This summary displays and analyzes geographic variation in the prevalences of selected CVD risk factors. REPORTING PERIOD: 1994 (1992 for prevalence of hypertension). DESCRIPTION OF SYSTEM: The Behavioral Risk Factor Surveillance System (BRFSS) is a state-based random-digit-dialing telephone survey of noninstitutionalized adults aged > or =18 years; 50 states and the District of Columbia participated in BRFSS in 1994, and 48 states and the District of Columbia participated in 1992. METHODS: Several different analyses were conducted: a) analysis of state risk factor and preventive practice prevalences by sex and race (i.e., black and white); b) mapping; c) cluster analysis; d) correlations of state prevalence rates by sex and race; and e) regression of state risk factor prevalences on state CHD and stroke mortality rates. RESULTS: Mapping the prevalence of selected CVD risk factors and preventive health practices indicates substantial geographic variation for black and white men and women, as confirmed by cluster analysis. Data for blacks are limited by small sample size, especially in western states. Geographic clustering is found for physical inactivity, smoking, and risk factor combinations. Risk factor prevalences are generally lower in the West and higher in the East. White men and white women are more similar in state risk factor rates than other race-sex pairs; white women and black women ranked second in similarity. State prevalences of physical inactivity and hypertension are strongly associated with state mortality rates of CVD. INTERPRETATION: Geographic patterns of risk factor prevalence suggest the presence (or absence) of sociocultural environments that promote (or inhibit) the given risk factor or preventive behavior. Because the risk factors examined in this summary are associated with CVD, further exploration of the reasons underlying observed geographic patterns might be useful. The BRFSS will continue to provide geographic data about cardiovascular health behaviors with a possible emphasis on more data-based small- area analyses and mapping. This will permit states to more adequately monitor trends that affect the burden of CVD in their regions and the United States. Mapping also facilitates the exploration of patterns of morbidity, health-care use, and mortality, as well as the epidemiology of risk factors. Finally, by identifying those segments of the population with high levels of these risk factors and lower levels of the preventive health practices, public health personnel can better allocate resources and target intervention efforts for the prevention of CVD.

Adult↗
PubMed1998

The prevalence of risk factors among women in the United States by race and age, 1992-1994: opportunities for primary and secondary prevention.

OBJECTIVE: To analyze the prevalence of 11 modifiable behavioral risk factors, including multiple risk factors, among white, black, Asian and Pacific Islander, American Indian, and Hispanic women in the United States. DESIGN: We used Behavioral Risk Factor Surveillance System (BRFSS) data for 1992 to 1994 to examine risk factors (smoking; obesity; diabetes; heavy alcohol consumption; sedentary lifestyle; and inadequate use of seat belts, pap smears, consumption of fruits or vegetables, mammography and colorectal screening, and immunization), among women age 18 to 49, 50 to 64, and 65 and older. We also conducted a multiple regression analysis, comparing the odds of having either 1-2 versus 0 or 3 or more versus 0 risk factors among racial/ethnic groups, controlling for education and family income, to see if racial/ethnic differences can be attributed to socioeconomic differences. RESULTS: US women engage in a variety of behaviors that place them at risk for many causes of morbidity and mortality. Risk profiles vary substantially among racial/ethnic populations: Pacific Islanders have relatively low prevalences of most major risk factors, while blacks and American Indians have relatively high prevalences of many major risk factors. Prevalence differences among racial/ethnic populations are diminished but not eliminated when socioeconomic factors are accounted for. CONCLUSIONS: Appropriately designed programs to help women reduce their behavioral risk factors are needed. Action by health care providers, communities, and policy makers can substantially improve the health of women in the United States.

Adolescent↗
PubMed1997

Reliability of reported age at menopause.

Age at menopause is an important epidemiologic characteristic whose reliability of reporting in the US population is not known. The authors examined four hypotheses about the reliability of reported age at menopause in the United States: 1) women with hysterectomy-induced menopause more reliably report their age at menopause than women who have undergone natural menopause; 2) reliability declines with time since menopause; 3) reliability declines with age; and 4) women with higher educational levels report their age at menopause more reliably than women with less education. The authors used linear regression models among 2,545 women in the First National Health and Nutrition Examination Survey and Followup Study (1971-1984) and compared responses at first and follow-up interviews. Among women who had undergone a natural menopause, 44% reported their age at menopause within one year from the first to second interviews; among women who had undergone a hysterectomy-induced menopause, 59% reported their age at menopause within one year from first to follow-up interviews. Only hysterectomy status and years from menopause to follow-up interview were significantly associated with the absolute difference between age at menopause reported at first and follow-up interviews. The authors conclude that caution in studies involving age at menopause may enhance our understanding of this critical event in the lives of women.

Adult↗
PubMed1996

Characterization of collagen fibril segments from chicken embryo cornea, dermis and tendon.

The cornea, dermis and tendon have extracellular matrix architectures with differences in fibril diameter, packing and organization. An early step in fibril assembly is the formation of a striated fibril of discrete length (segment). Fibril segments were isolated from developing chicken cornea, dermis and tendon by physical disruption and the structure characterized. In all three tissues, intact but relatively short fibril lengths were isolated. These segments were asymmetric, having long (alpha) and short (beta) tapered ends. They were also centrosymmetric with respect to molecular packing. Segments isolated from 12- to 16-day corneas, dermis and tendons had identical structures, but their lengths and diameters were distinct. We propose that the increase in length is, at least in part, the result of lateral associations of adjacent segments. In the developing tendon, there is a rapid increase in length and diameter between day 16 and 17, while in the dermis the increase is more linear with respect to time. In the cornea, the fibril segments grow longer, but their diameters remain constant. Disruption of corneas in phosphate-buffered saline yielded larger diameter segments than seen in situ, while tendon or dermis maintained tissue-specific diameters. When corneas were disrupted in buffers that stabilized the water layer associated with the collagen molecules or containing the corneal proteoglycans, then tissue-specific diameters were maintained. These data suggest differences in the stabilization of segments during growth in tissues where diameter increases versus those where diameter remains constant, and this may be related to collagen-proteoglycan interactions.

Animals↗
PubMed1996

Use of the terms 'race', 'ethnicity', and 'national origins': a review of articles in the American Journal of Public Health, 1980-1989.

OBJECTIVES: To assess the use of the categories of race, ethnicity, and national origin in recent public health research. METHODS: We reviewed all research articles on human populations published in the American Journal of Public Health from January 1980 through December 1989. Articles were classified by (1) mention of the categories, (2) use of the categories, (3) presence of explicit definitions, and (4) definitional criteria. RESULTS: Specific categories (e.g. 'black', 'Chinese', 'Hispanic') or generic categories (e.g. 'race', 'ethnicity', 'national origin') were mentioned in 461 (50.4%) of 914 articles on human populations. In most studies (65.1%), single categories (e.g. race or ethnicity) were considered; in 1.3% of studies, two terms (e.g. both race and ethnicity) were examined independently; in 1.3%, categories were used interchangeably; in 5.6% of the studies, combined categories (e.g. race-ethnicity) were used; and in 27.5% of the studies, specific population groups were named without reference to a generic category. Explicit definitions of categories were present in only 8.4% of the articles in which the categories were considered. Absence of explicit definitions and use of combined and interchangeable categories suggest a lack of clarity and conceptual consistency in research on race, ethnicity, and national origin-related topics. CONCLUSION: To improve our assessment of differences in health status among racial, ethnic, and national origin groups, research involving these categories should assess their validity and should define concepts clearly, explicitly, and consistently. Such research would minimize misclassification, improve the interpretation of findings, facilitate comparison among studies, and enhance the understanding of causes underlying differences in health status among populations of different racial, ethnic, and national origins.

Ethnicity↗
PubMed1996

Reduction of type V collagen using a dominant-negative strategy alters the regulation of fibrillogenesis and results in the loss of corneal-specific fibril morphology.

A number of factors have been implicated in the regulation of tissue-specific collagen fibril diameter. Previous data suggest that assembly of heterotypic fibrils composed of two different fibrillar collagens represents a general mechanism regulating fibril diameter. Specifically, we hypothesize that type V collagen is required for the assembly of the small diameter fibrils observed in the cornea. To test this, we used a dominant-negative retroviral strategy to decrease the levels of type V collagen secreted by chicken corneal fibroblasts. The chicken alpha 1(V) collagen gene was cloned, and retroviral vectors that expressed a polycistronic mRNA encoding a truncated alpha 1(V) minigene and the reporter gene LacZ were constructed. The efficiency of viral infection was 30-40%, as determined by assaying beta-galactosidase activity. To assess the expression from the recombinant provirus, Northern analysis was performed and indicated that infected fibroblasts expressed high steady-state levels of retroviral mRNA. Infected cells synthesized the truncated alpha 1(V) protein, and this was detectable only intracellularly, in a distribution that colocalized with lysosomes. To assess endogenous alpha 1(V) protein levels, infected cell cultures were assayed, and these consistently demonstrated reductions relative to control virus-infected or uninfected cultures. Analyses of corneal fibril morphology demonstrated that the reduction in type V collagen resulted in the assembly of large-diameter fibrils with a broad size distribution, characteristics similar to fibrils produced in connective tissues with low type V concentrations. Immunoelectron microscopy demonstrated the amino-terminal domain of type V collagen was associated with the small-diameter fibrils, but not the large fibrils. These data indicate that type V collagen levels regulate corneal fibril diameter and that the reduction of type V collagen is sufficient to alter fibril assembly so that abnormally large-diameter fibrils are deposited into the matrix.

Animals↗
PubMed1996

Identifying ancestry: The reliability of ancestral identification in the United States by self, proxy, interviewer, and funeral director.

We examined consistency in the classification of ancestry by self, proxy, interviewer, and funeral director (on a death certificate) in a sample of the U.S. population--the First National Health and Nutrition Examination Survey and Epidemiologic Follow-up. Among study subjects for whom comparable ethnic identity options were available at both interviews, 58% of subjects specified the same identity at two times. Persons who specified four different ethnic backgrounds were 3.4 times as likely to change their identity over time as persons specifying only one background. Self-classification of ancestry at initial interview was consistent with proxy reports at follow-up for 55% of subjects for whom proxy information was available. Comparison of the self-classification of ancestry with the classification of race by interviewers and by funeral directors indicates high consistency for Whites and Blacks and low consistency for American Indians. The "measurement" of ancestry (that is, race or ethnicity) is critical to the understanding and elimination of differences in health status among racial/ethnic populations, but the low reliability of these measures over time and across observers complicates the analysis and interpretation of health statistics by ancestry, particularly for populations other than White or Black.

Adult↗
PubMed1996

Poverty and death in the United States.

The authors conducted a survival analysis to determine the effect of poverty on mortality in a national sample of blacks and whites, 25 to 74 years of age (the first National Health and Nutrition Examination Survey (NHANES-1) and NHANES-1 Epidemiologic Follow up Study). They estimated the proportion of mortality associated with poverty during 1971-1984 and in 1991 by calculating population attributable risk and assessed confounding by major known risk factors (e.g., smoking, cholesterol levels, and physical inactivity). In 1973, 6.0 percent of U.S. mortality among black and white persons 25 to 74 years of age was attributable to poverty; in 1991, the proportion was 5.9 percent. In 1991, rates of mortality attributable to poverty were lowest for white women, 2.2 times as high for white men, 8.6 times as high for black men, and 3.6 times as high for black women. Adjustment for all these potential confounders combined had little effect on the hazard ratio among men, but reduced the effect of poverty on mortality among women by 42 percent. The proportion of mortality attributable to poverty among U.S. black and white adults has changed only minimally in recent decades. The effect of poverty on mortality must be largely explained by conditions other than commonly recognized risk factors.

Adult↗
PubMed1996

Evaluation of activated protein C on canine infarct size in a nonthrombotic model of myocardial reperfusion injury.

Myocardial infarct size has been measured after 1 hr of mechanical occlusion of the circumflex coronary artery and 5 hr of reperfusion in control dogs infused with saline, and in dogs infused with activated protein C (aPC) (1mg/kg/hr i.v.). Infusion of aPC during reperfusion produced a sustained doubling of activated partial thromboplastin time and no change in thrombin time at a final plasma parent drug concentration of 1.25 +/- 0.11 mug/ml. aPC infusion did not alter systolic arterial pressure, cardiac rate or the rate pressure product when compared to time-related alterations observed in control dogs. ST-segment deviation and the intensity and duration of cardiac arrhythmias associated with reperfusion of ischemic myocardium also were similar between groups. Resultant infarct sizes were 34.8 +/- 3.9 and 33.2 +/- 6.2% of the left ventricular mass placed at risk of necrosis in control and aPC-treated dogs. respectively. aPC infusion was associated with a small reduction in leukocytosis in response to myocardial ischemic injury, but did not alter the localization of leukocytes within ischemic and infarcted myocardium. In vitro concentrations of aPC (0.3, 1 and 3 mug/ml), comparable to the plasma concentration that inhibited blood coagulation in dogs, did not alter superoxide production or CD11b/CD18-mediated adhesion of chemotactic factor f-Met-Leu-Phe-stimulated neutrophils. Present data indicate that aPC lacks cardioprotectant activity at an infusion rate inhibiting coagulation. Apart from inhibition of thrombin generation, no evidence of an anti-inflammatory effect of aPC was observed.

Animals↗
PubMed1995

Life expectancy in four U.S. racial/ethnic populations: 1990.

Previous estimates of life expectancy in the United States have not corrected for biases in population and mortality data, and no study has examined life expectancy in U.S. Asian/Pacific Islander and American Indian populations. We used information on population undercounts by race/ethnicity in the census and on misclassification of race/ethnicity on death certificates to calculate life expectancy for black, white, American Indian, and Asian men and women in the United States in 1990. Correction for undercount and misclassification had little effect on life expectancy estimates for whites, but it substantially decreased estimates for American Indians and Asians. Asian men had life expectancies of 82.0 years and Asian women 85.8 years--the highest life expectancies reported for any population in the world and beyond the limit predicted by some current theories.

Adolescent↗
PubMed1995

Poverty and death in the United States--1973 and 1991.

We conducted a survival analysis to determine the effect of poverty on mortality in a national sample of blacks and whites 25-74 years of age (in the First National Health and Nutrition Examination Survey and National Health Examination Follow-up Survey). We estimated the proportion of mortality associated with poverty from 1973 through 1984 and in 1991 by calculating the population attributable risk. We assessed confounding by major known risk factors, such as smoking, serum total cholesterol, and inactivity. In 1973, 16.1% of U.S. mortality among black and white persons 25-74 years of age was attributable to poverty; in 1991, the proportion increased to 17.7%. In 1991, the population attributable risk of poverty on mortality was lowest for white women, 1.7 times higher for white men, 2.6 times higher for black women, and 3.6 times higher for black men. Potential confounders explained 40% of the effect of poverty on mortality among women. The proportion of mortality attributable to poverty among U.S. black and white adults has increased in recent decades and is comparable to that attributable to cigarette smoking. The effect of poverty on mortality must be explained by conditions other than commonly recognized risk factors.

Adult↗
PubMed1993

Mammography use and outcomes in a community. The Greater Lansing Area Mammography Study.

BACKGROUND: Mammography is widely known to reduce morbidity and mortality from breast cancer, but a population-based assessment of mammography use and follow-up of mammography findings has not been reported previously. METHODS: An observational, population-based, follow-up study was conducted of all women having mammograms in the Greater Lansing, Michigan, metropolitan area, between June 1987 and June 1988. A total of 17,811 Greater Lansing women participated. The adherence of women to mammography screening guidelines was estimated, and mammography's utility to detect breast cancer was assessed through follow-up review of breast biopsy results. RESULTS: Thirty-seven percent of the expected number of women 35 years of age and older had mammograms. Adherence to screening guidelines declined with age, and less than 5% (302 of 6700) of women 55 years of age and older reporting having annual mammograms. Seventy-six percent of women reported that their physicians prompted the examination. The predictive value of a positive mammogram was 21.9% for women without symptoms and 32.4% for women with symptoms. Mammography's sensitivity and specificity for breast cancer detection were 71% and 98%, respectively. CONCLUSIONS: The study highlights the need to target mammography to women 50 years of age and older, underscores the importance of physicians in promoting mammography, and demonstrates the analytic value and limitation of mammography in clinical decision-making.

Adult↗
PubMed1992

Years of potential life lost before age 65, by race, Hispanic origin, and sex--United States, 1986-1988.

A substantial proportion of mortality among young persons is preventable. National vital statistics were used to establish a baseline for the surveillance of rates of years of potential life lost before age 65 (YPLL < 65) in the United States. Rates of YPLL < 65 were calculated for 1986 through 1988 for leading causes of preventable death, by race, Hispanic origin, and sex. U.S. racial and ethnic populations differed widely in YPLL < 65. Among males, the rate (per 1,000 population < 65 years) of YPLL < 65 was highest for non-Hispanic blacks (140.0), followed by American Indians/Alaskan Natives (100.9), Hispanics (74.3), non-Hispanic whites (68.3), and Asians/Pacific Islanders (38.2). Among females, the rate was highest for non-Hispanic blacks (73.7), followed by American Indians/Alaskan Natives (52.0), non-Hispanic whites (35.7), Hispanics (32.9), and Asians/Pacific Islanders (23.2). For non-Hispanic blacks, the high rate of YPLL < 65 was due to increased rates for all causes of death considered, particularly homicide. The high rate for American Indians/Alaskan Natives was due principally to deaths from four causes: unintentional injuries, cirrhosis, suicide, and diabetes. Asians/Pacific Islanders had low rates for most causes of death. In setting health-care priorities and prevention strategies to reduce the large racial-ethnic gap in early deaths, it is essential to recognize the differences in causes of premature mortality among sex, racial, and ethnic populations. Periodic reassessment of YPLL < 65 among these groups provides a simple, timely, and representative means of conducting surveillance to measure the impact of intervention strategies on a national basis.

Age Factors↗
PubMed1992

Inconsistencies in coding of race and ethnicity between birth and death in US infants. A new look at infant mortality, 1983 through 1985.

OBJECTIVE: To ascertain the consistency of the racial and ethnic classification of US infants between birth and death and its impact on infant mortality rates. SUBJECTS: All US infants born from 1983 through 1985 who died within a year. DESIGN: We used the national linked birth/infant-death computer tape, augmented with information on infants' race and ethnicity at death, to compare the coding of race and Hispanic ethnicity at birth and at death. We also assessed infant mortality rates by race and ethnicity as defined (1) by the standard algorithm and (2) by the rule that, beginning in published tabulations for 1989, assigns newborns the race of their mothers. Finally, we estimated infant mortality rates based on consistent coding of race and ethnicity at birth and death. RESULTS: Inconsistency in the coding of race is low for whites (1.2%), greater for blacks (4.3%), and greatest for races other than white or black (43.2%). Most infants reclassified at death (87.3%) are classified as white at death. Inconsistency in coding is lower for non-Hispanic whites (3.5%) and non-Hispanic blacks (3.3%) than for Hispanic populations (30.3%). Compared with the standard algorithm for calculation of infant mortality, consistent definition at birth and death produces rates 2.1% lower for whites, and higher for all other groups--3.2% for blacks, 46.9% for American Indians, 33.3% for Chinese, 48.8% for Japanese, 78.7% for Filipinos, and 8.9% for Hispanics. CONCLUSIONS: The coding of race and ethnicity of infants at birth and death is remarkably inconsistent, with substantial impact on the estimation of infant mortality rates. A need exists to reconsider the nature and definition of race and ethnicity in public health.

Ethnicity↗