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Statistical Methods in Epidemiology

TL;DR: Review of selected elementary statistics random sampling relative risk and odds ratio attributable risk adjustment of data without use of multivariate models and comparison of numerical results for various methods of adjustment the primacy of data collection.
Abstract: Review of selected elementary statistics random sampling relative risk and odds ratio attributable risk adjustment of data without use of multivariate models adjustment of data without use of multivariate models follow-up studies person years comparison of numerical results for various methods of adjustment the primacy of data collection.
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TL;DR: The strongest factors independently associated with HCV infection were illegal drug use and high-risk sexual behavior, and poverty, having had 12 or fewer years of education, and having been divorced or separated were independently associated.
Abstract: Background Because many persons with chronic hepatitis C virus (HCV) infection are asymptomatic, population-based serologic studies are needed to estimate the prevalence of the infection and to develop and evaluate prevention efforts. Methods We performed tests for antibody to HCV (anti-HCV) on serum samples from 21,241 persons six years old or older who participated in the third National Health and Nutrition Examination Survey, conducted during 1988 through 1994. We determined the prevalence of HCV RNA by means of nucleic acid amplification and the genotype by means of sequencing. Results The overall prevalence of anti-HCV was 1.8 percent, corresponding to an estimated 3.9 million persons nationwide (95 percent confidence interval, 3.1 million to 4.8 million) with HCV infection. Sixty-five percent of the persons with HCV infection were 30 to 49 years old. Seventy-four percent were positive for HCV RNA, indicating that an estimated 2.7 million persons in the United States (95 percent confidence interval, ...

3,014 citations

Journal ArticleDOI
TL;DR: The overweight category is associated with increased relative and population attributable risk for hypertension and cardiovascular sequelae and interventions to reduce adiposity and avoid excess weight may have large effects on the development of risk factors and cardiovascular disease at an individual and population level.
Abstract: Background To our knowledge, no single investigation concerning the long-term effects of overweight status on the risk for hypertension, hypercholesterolemia, diabetes mellitus, and cardiovascular sequelae has been reported. Methods Relations between categories of body mass index (BMI), cardiovascular disease risk factors, and vascular disease end points were examined prospectively in Framingham Heart Study participants aged 35 to 75 years, who were followed up to 44 years. The primary outcome was new cardiovascular disease, which included angina pectoris, myocardial infarction, coronary heart disease, or stroke. Analyses compared overweight (BMI [calculated as weight in kilograms divided by the square of height in meters], 25.0-29.9) and obese persons (BMI ≥30) to a referent group of normal-weight persons (BMI, 18.5-24.9). Results The age-adjusted relative risk (RR) for new hypertension was highly associated with overweight status (men: RR, 1.46; women: RR, 1.75). New hypercholesterolemia and diabetes mellitus were less highly associated with excess adiposity. The age-adjusted RR (confidence interval [CI]) for cardiovascular disease was increased among those who were overweight (men: 1.21 [1.05-1.40]; women: 1.20 [1.03-1.41]) and the obese (men: 1.46 [1.20-1.77]; women: 1.64 [1.37-1.98]). High population attributable risks were related to excess weight (BMI ≥25) for the outcomes hypertension (26% men; 28% women), angina pectoris (26% men; 22% women), and coronary heart disease (23% men; 15% women). Conclusions The overweight category is associated with increased relative and population attributable risk for hypertension and cardiovascular sequelae. Interventions to reduce adiposity and avoid excess weight may have large effects on the development of risk factors and cardiovascular disease at an individual and population level.

1,859 citations

Journal ArticleDOI
TL;DR: Even after controlling for personal income, education, and occupation, it is found that living in a disadvantaged neighborhood is associated with an increased incidence of coronary heart disease.
Abstract: BACKGROUND: Where a person lives is not usually thought of as an independent predictor of his or her health, although physical and social features of places of residence may affect health and health-related behavior. METHODS: Using data from the Atherosclerosis Risk in Communities Study, we examined the relation between characteristics of neighborhoods and the incidence of coronary heart disease. Participants were 45 to 64 years of age at base line and were sampled from four study sites in the United States: Forsyth County, North Carolina; Jackson, Mississippi; the northwestern suburbs of Minneapolis; and Washington County, Maryland. As proxies for neighborhoods, we used block groups containing an average of 1000 people, as defined by the U.S. Census. We constructed a summary score for the socioeconomic environment of each neighborhood that included information about wealth and income, education, and occupation. RESULTS: During a median of 9.1 years of follow-up, 615 coronary events occurred in 13,009 participants. Residents of disadvantaged neighborhoods (those with lower summary scores) had a higher risk of disease than residents of advantaged neighborhoods, even after we controlled for personal income, education, and occupation. Hazard ratios for coronary events in the most disadvantaged group of neighborhoods as compared with the most advantaged group--adjusted for age, study site, and personal socioeconomic indicators--were 1.7 among whites (95 percent confidence interval, 1.3 to 2.3) and 1.4 among blacks (95 percent confidence interval, 0.9 to 2.0). Neighborhood and personal socioeconomic indicators contributed independently to the risk of disease. Hazard ratios for coronary heart disease among low-income persons living in the most disadvantaged neighborhoods, as compared with high-income persons in the most advantaged neighborhoods were 3.1 among whites (95 percent confidence interval, 2.1 to 4.8) and 2.5 among blacks (95 percent confidence interval, 1.4 to 4.5). These associations remained unchanged after adjustment for established risk factors for coronary heart disease. CONCLUSIONS: Even after controlling for personal income, education, and occupation, we found that living in a disadvantaged neighborhood is associated with an increased incidence of coronary heart disease.

1,656 citations

Journal ArticleDOI
TL;DR: It was concluded that malnutrition, as analyzed by a multivariate logistic regression model, is an independent risk factor impacting on higher complications and increased mortality, length of hospital stay and costs.

1,622 citations