epidemiology

• Epidemiology


  The study of how often diseases occur in different groups of people and why
• Epidemiological information is used to plan and evaluate strategies to prevent illness and as a guide to the management of patients in whom disease has already developed
• Epidemiology


  • Focuses on frequencies
  • Distributions (Time-Place-Person)
  • Causes/risk factors
• Epidemiology


  (From Greek roots) Epi = upon, Demos = the population, Logy = study of
• Hippocrates used the word epidemic for the first time about 2400 years ago and mentioned the use of epidemiology in the study of epidemics of infectious diseases, environmental hazards and nutritional issues
• Epidemiology (Dictionary of Epidemiology definition)


  The study of the distribution and determinants of health-related states or events in specified populations and the application of this study to control of health problems
• Epidemiology (WHO definition)


  The study of the distribution and determinants of health-related states or events (including disease), and the application of this study to the control of diseases and other health problems
• Various methods can be used to carry out epidemiological investigations: surveillance and descriptive studies can be used to study distribution; analytical studies are used to study determinants
• What can be concluded from the definitions of epidemiology

  • It emphasizes the group, not the individual
  • It is the science of quantities and deals with sizes and measurements
  • It is the study of relationships, differences, and changes in trends and patterns of health and disease in human populations
  • It is the science of comparing and contrasting health and illness in human societies
  • It pays attention to various aspects of prevention
  • It is both Science and Practice
• How is Epidemiology Used

  • Population/community health assessment
  • Decision-making
  • Complete clinical picture
  • Evaluate interventions
  • Search for cause
  • Exposure and relationship to disease
  • Outbreak investigation
• Distribution


  When, where and among whom the health state or event occurs
• Determinants


  Risk factors: The presence or absence of a factor is associated with an increased likelihood that a certain state or event will occur
• Epidemiology Focus


  • Population
  • Sample
  • Statistical Analysis
  • Conclusions
  • Investigation
• The history of epidemiology

  • Ancient Times: Early observations of disease outbreaks and attempts to control them
  • Hippocrates and the Theory of Miasma
  • John Snow and Cholera
  • Development of Germ Theory
  • Epidemiologic Transition
  • Expansion of Epidemiology
  • Modern Epidemiology
• In 400 BC, Hippocrates pointed out the role of factors related to the way of life and factors of the external environment in causing disease in humans. Hippocrates is also known as the father of public health science
• Edward Jenner, born in 1749, the discoverer of the smallpox vaccine, conducted epidemiological studies
• The invention of quarantine in the 14th century by the Venetians, which was done to protect people from plague epidemics, was one of the most important human efforts in the field of epidemiology
• At the beginning of the 17th century, Francis Bacon (1561-1626), an English scientist, founded the principles of thinking and the logical and philosophical attitude of epidemiology
• The emergence of chronic diseases in addition to infectious diseases led to the concept of epidemiologic transition, which describes the shift from a predominance of infectious diseases to chronic diseases as the leading causes of morbidity and mortality in populations
• Expansion of Epidemiology


  Epidemiology continued to evolve and expand in the 20th century, with the development of statistical methods, study designs, and the establishment of epidemiology as a scientific discipline
• Major events, such as the Spanish Flu pandemic in 1918 and the emergence of HIV/AIDS in the 1980s, further highlighted the importance of epidemiology in understanding and controlling disease outbreaks
• In recent decades, epidemiology has become an interdisciplinary field, incorporating advances in genetics, molecular biology, and data science. It plays a crucial role in public health, clinical research, policy development, and disease surveillance
• Hippocrates


  Pointed out the role of factors related to the way of life and factors of the external environment in causing disease in humans. Hippocrates is also known as the father of public health science
• Edward Jenner


  Discoverer of the smallpox vaccine, conducted epidemiological studies
• Quarantine


  Invention in the 14th century by the Venetians to protect people from plague epidemics, one of the most important human efforts in the field of epidemiology
• Francis Bacon


  English scientist who founded the principles of thinking and the logical and philosophical attitude of epidemiology
• John Graunt


  Analyzed the statistics related to birth and death in London and calculated the rates of the disease
• James Lind


  Scottish naval surgeon who conducted the first experimental clinical trial in 1747 for the treatment of scurvy (vitamin C deficiency)
• John Snow


  One of the most prominent scientists in the history of epidemiology, known as the father of modern epidemiology. Conducted the first analytical study of epidemiology in London by testing a hypothesis about cholera and was among the first to understand that cholera is related to the consumption of contaminated water and the importance and role of environmental health in disease control and prevention
• Framingham study


  The first cohort study started in 1948 by the American National Heart Institute on 5209 men aged 30 to 62 living in the city of Framingham, Massachusetts, USA, to identify the most important factors related to coronary heart disease
• Richard Doll and colleagues

  Conducted the first case-control study on the effect of smoking on lung cancer in 1950, finding that there are factors that do not necessarily cause the disease but increase the chance and probability of the disease in the group that faces those factors, which can be called risk factors
• Salk polio vaccine field trial

  The largest field trial conducted in 1954 on about one million children, which tested the effectiveness of the Salk polio vaccine
• Brian McMahon


  Published the first reference book (Text) of epidemiology under the title of Epidemiologic Methods in 1960, working systematically on study design
• Bradford Hill et al.


  Published the causal evaluation criteria in 1964
• Uses of Epidemiology


  • To understand what are the causes and factors in the stability of the disease in the population
  • Disease prevention and control in populations
  • Guiding the planning and policies of health care services
  • Helping to manage and care for the health and illness of people in the community
  • Testing the techniques, such as the correctness of measurements, agreement and how to perform measurements, measurement tools, observations
  • Measuring diseases and health
  • Conducting study designs
  • Determining causal relationships including etiology, identifying risk factors, and risk assessment
  • Carrying out and evaluating interventions and new experiences in the field of treatment methods, control and prevention, policy making, cost effectiveness, and the like
  • Investigating exposure to pathogenic or dangerous agents (including the effects of exposure, dose, duration, manner, consequences)
  • Studying new diseases, epidemics
  • Assessment and evaluation of healthcare services
  • Screening
  • Surveillance and monitoring
• Prevalence can be calculated using cross-sectional studies that collect data on all individuals in a specific area during a particular period.
• Incidence rates are used to measure how quickly a disease spreads or increases over time, while prevalence rates indicate the current burden of disease within a population.
• The incidence rate is the number of new cases per unit time, while the prevalence rate is the proportion of people with the disease at any given point.
• Cross-sectional studies involve collecting information from a sample at a single point in time, allowing researchers to estimate prevalence rates.
• Case-control studies compare individuals with a certain condition (cases) to individuals without the condition (controls), looking for differences in exposures between the two groups.