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Epidemiologists emphasize that the "one cause – one effect" understanding is a simplistic mis-belief. [53] Most outcomes, whether disease or death, are caused by a chain or web consisting of many component causes. [54] Causes can be distinguished as necessary, sufficient or probabilistic conditions.
The crude death rate is defined as "the mortality rate from all causes of death for a population," calculated as the "total number of deaths during a given time interval" divided by the "mid-interval population", per 1,000 or 100,000; for instance, the population of the United States was around 290,810,000 in 2003, and in that year, approximately 2,419,900 deaths occurred in total, giving a ...
Smoking is the leading cause of preventable death in the United States. It is an underlying cause of many cancers, cardiovascular diseases, stroke, and respiratory diseases. [43] Smoking usually refers to smoking of tobacco products. E-cigarettes also pose large risks to health. [44]
In epidemiology, case fatality rate (CFR) – or sometimes more accurately case-fatality risk – is the proportion of people who have been diagnosed with a certain disease and end up dying of it. Unlike a disease's mortality rate, the CFR does not take into account the time period between disease onset and death. A CFR is generally expressed ...
One of the first to refine the idea of the epidemiological transition was Preston, who in 1976 proposed the first comprehensive statistical model relating mortality and cause-specific mortality. Preston used life tables from 43 national populations, including both developed countries such as United States and England and developing countries ...
The Plague of Athens (c. 1652 –1654) by Michiel Sweerts, illustrating the devastating epidemic that struck Athens in 430 BC, as described by the historian Thucydides. The United States Centers for Disease Control and Prevention defines epidemic broadly: "Epidemic refers to an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in ...
In epidemiology and actuarial science, the term morbidity (also morbidity rate or morbidity frequency) can refer to either the incidence rate, the prevalence of a disease or medical condition, or the percentage of people who experience a given condition within a given timeframe (e.g., 20% of people will get influenza in a year). [18]
Epidemiological (and other observational) studies typically highlight associations between exposures and outcomes, rather than causation. While some consider this a limitation of observational research, epidemiological models of causation (e.g. Bradford Hill criteria) [7] contend that an entire body of evidence is needed before determining if an association is truly causal. [8]