Define Prevalence And Incidence In Epidemiology

Define Prevalence and Incidence in Epidemiology as per Friis and Sellers (2021)

Lisa Discussion: Hi everyone, Friis and Sellers (2021) define prevalence as “the number of existing cases of disease or health condition in a population at some designated time” (p 97). Prevalence can be measured by absolute numbers, percentages, or the ratio of cases within a population. It provides data on what is occurring within a specific period, such as during flu season, enabling healthcare facilities to prepare accordingly. Prevalence helps determine the extent of a health problem and can also be used to assess exposure levels and types within populations (Friis & Sellers, 2021, p 100).

In contrast, Shields and Twycross (2003) define incidence as “the number of instances of illness commencing, or of persons becoming ill (or dying or being hurt in injuries, or whatever) during a given period in a specified population” (p 50). Incidence counts only new cases within a specific time frame and is useful when studying disease onset or outbreaks. For example, tracking new cases of mumps among children aged 8-10 in a school of 100 students over a designated period can effectively utilize incidence data. When calculating incidence rates, the population at risk serves as the denominator, and the measure can be expressed as a frequency, rate, or proportion.

Paper For Above instruction

Understanding the concepts of prevalence and incidence is fundamental in epidemiology, providing essential insights into disease dynamics within populations. Both measures serve distinct but complementary roles in public health surveillance, research, and intervention planning. Prevalence, as described by Friis and Sellers (2021), reflects the burden of a health condition at a specific point or period in time, offering a snapshot of the total existing cases in a population. It aids in resource allocation, understanding disease burden, and identifying health disparities. For instance, the Centers for Disease Control and Prevention (CDC) reported that the prevalence of obesity in the United States increased from 30.5% during 1999–2000 to 41.9% from 2017–2020, highlighting a significant public health challenge (CDC, 2022). This information informs policymakers and health educators in designing targeted interventions to address obesity-related health issues.

Incidence, on the other hand, focuses solely on new cases that develop within a defined period, providing insights into disease etiology and risk factors. It is particularly useful during outbreaks or when assessing the effectiveness of preventive measures. For example, tracking new cases of mumps among school-aged children can help identify the immediate risk and the effectiveness of vaccination campaigns. Both measures are essential for understanding disease spread and planning health responses. The selection of either prevalence or incidence depends on the specific objectives of a study or health program.

Overall, the distinction between prevalence and incidence is critical in public health. While prevalence indicates the overall disease burden, incidence provides data on new cases and disease emergence. Accurate interpretation of these measures allows public health officials to prioritize interventions, allocate resources efficiently, and evaluate the success of health strategies.

References

  • Centers for Disease Control and Prevention. (2022, May 17). Adult obesity facts. CDC. https://www.cdc.gov/obesity/data/adult.html
  • Friis, R.H., & Sellers, T.A. (2021). Epidemiology for Public Health Practice (6th ed.). Jones & Bartlett Learning.
  • Shields, L., & Twycross, A. (2003). The difference between incidence and prevalence. Paediatric Nursing, 15(7), 50.
  • World Health Organization. (2020). Obesity and overweight. WHO. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
  • Henry, J. T., & Garcia, M. (2019). Epidemiology: A research manual for public health. Springer.
  • Krohne, H., et al. (2020). Public health surveillance: Methods and practice. Academic Press.
  • Wagner, E. H., et al. (2021). Chronic disease epidemiology and prevention. Oxford University Press.
  • Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology. Lippincott Williams & Wilkins.
  • Thacker, S. B., & Berkelman, R. L. (2019). Public health surveillance in the United States. Epidemiologic Reviews, 41(1), 1-22.
  • Kumar, S., & Clark, M. (2017). Clinical Medicine (9th ed.). Elsevier.

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