Chapter 3 At The Heart of Public Health: Prevention

Prevention - a core population health concept

• concerned with creating the healthiest possible populations

• prevention of disease

• creating conditions suitable for keeping us all healthy for as a long as possible

• tries to ensure that we do not get sick to begin with

Dramatic gains in life expectancy:

• accelerating economic growth

• recognition of infectious diseases

• improved sanitation practices

Preventing Disease

• actions that ward off or forestall the occurrence of disease in populations

• a cornerstone of public health

• investing in disease prevention is one of the most effective and commonsense methods to improve health

Prevention:

• spares people from developing preventable illnesses

• reduces healthcare costs

• improves productivity

• enhances quality of life

Prevention Basics: Types of prevention

• primordial prevention - actions that affect the systems which determine the risk factors of disease

  • precedes primary, aims to completely prevent the expression of risk factor

    • far “upstream”

    • lowers disease incidence

      • the proportion of people developing new-onset disease

• primary prevention - detection and management of risk factors for future disease

  • actions that keep people from becoming ill or injured in the first place

    • focuses on

      • immunizing the population against infectious diseases

      • ensuring safe water supplies and sanitation

      • improving the nutritional status of population

      • decreasing or eliminating hazardous exposures

      • diminishing health-compromising behaviors

    • examples - vaccination, seat-belt legislation, asbestos ban

• secondary prevention - screening for asymptomatic early disease

  • aims to reduce the impact of a disease or injury in the earliest stages

    • focuses on

      • detecting and treating subclinical disease or injuries asap

      • reduce the number of people living with disease or disease prevalence

      • restore a person to full health when possible

    • examples - screening tests (mammograms), regular exams to detect medical conditions or diseases

    • common screening tests and detection targets

      • pap smear for cervical cancer

      • prostate specific antigen (PSA) measurement for prostate cancer

      • colonoscopy for colon cancer

      • cholesterol measurement for cardiovascular disease

    • key performances measures of screening tests

      • sensitivity - % of persons with disease who screen positive

      • specificity - % pf persons without disease who screen negative

      • false-positive fraction - % of persons without disease who screen positive

      • false-negative fraction - % of persons with disease who screen positive

    • rules of thumb from the WHO

      • should be done only for diseases with serious consequences

      • be reliable enough and not harmful in itself

      • must be an effective treatment for disease detection at an early state

      • unbiased information should be made public to help people decide to be screened or not

      • benefits outweigh the risks

• tertiary prevention - improved management of patients with established disease

  • actions that reduce the impact of a diagnosed, ongoing injury or disease

  • aims to increase the individuals ability to function, quality of life, and life expectancy

  • approaches

    • rehabilitation

    • managing complex, long-term health issues such as chronic diseases and disabilities

  • examples

    • cardiac rehab programs for people who have had a heart attack

    • interventions to promote weight loss in individuals who develop type 2 diabetes

• upstream

  • intervening to prevent the occurrence of risk factors (primordial)

  • adopting risk reducing behaviors (primary)

• midstream

  • secondary prevention strategies that operate throughout the lifetime — detecting and intervening on identified risk factors and subclinical conditions

• downstream

  • tertiary prevention when health has already been compromised

  • restore health, improve stamina, and well-being

  • averted or delayed severe diseases

Alternative Terminology

• universal prevention - general population

• selective prevention - subgroups with biological, psychological, and/or social risk factors

• indicated prevention - those with detectable signs/symptoms of disease or subclinical diseases

Applying Notions of Prevention to Local, National, and Global populations

• Local - local governments providing preventative services

• National - national screening and surveillance programs

• Global - WHO and others support countries to develop national prevention protocols

Public health vs. Medical Care Approach

• clinical medicine

  • concerned with diagnosis, understanding the pathology, identifying the optional treatment for individual patients

  • curing and caring for the patient are top priorities for the healthcare system

• prevention-based public health approach

  • concerned with populations

  • aims to minimize the need for clinical interventions

  • means

    • identifying potential causes or determinants of disease

    • reducing the risk of exposure to these causes

    • reducing the risk of disease through a wise array of interventions

      • policies that promote health

      • altering the social conditions people live in

      • individual education

      • behavior change

    • Works through

      • identifying a health problem

      • identifying the cause or determinants

      • developing and testing interventions to prevent or control these determinants

      • implementing and monitoring these interventions to assess their effectiveness

• Public Health

  • 20th century - public health was focused on behavior modification and individual responsibility for health

  • 21st century - focus on the collective health of entire communities and populations

    • social determinants of health

    • cultural and built environments that shape health