Preventive medicine

Preventive medicine is the branch of medicine that deals not only with preventing disease from occurring, but also with halting disease progression and averting complications after disease onset. Disease prevention occurs on five levels, with measures ranging from health policies that affect the general population to specific treatments for particular patient groups: primordial prevention (actions that address environmental, socioeconomic, behavioral risk factors; e.g., smoking cessation campaigns), primary prevention (actions that inhibit the occurrence of specific diseases; e.g., immunization), secondary prevention (actions that inhibit the progress of specific diseases at an early stage to prevent or limit complications; e.g., screening), tertiary prevention (actions that inhibit the progress of specific diseases at an advanced stage to prevent or limit complications; e.g., blood pressure management in patients with hypertension), and quartenary prevention (actions that prevent over-medicalization and offer ethically acceptable interventions; e.g., pursuing nonaddictive strategies to managing chronic pain rather than prescribing opioids). One of the greatest challenges to preventive medicine is the “prevention paradox,” which states that preventive measures that benefit large populations have little impact on most people (e.g., even without measles immunization, only a relatively small proportion of the population would contract the disease). This leads to the common misconception that preventive measures provide no benefit to the individual as part of a larger population. Another challenge is poor medical adherence, i.e., the extent to which an individual follows prescribed drug regimens and medical advice, especially in patients who do not feel ill and, therefore, perceive the burden of prevention rather than its long-term benefits. Strategies to encourage adherence include a patient-centered approach, frequent follow-ups, and education regarding long-term consequences of medical conditions, behaviors, and lifestyle.

• Definition: actions that address environmental, socioeconomic, and behavioral risk factors that affect a population as a whole to prevent potential disease or injury.
• Measures ^[1][2]
  • Target: entire population
  • Health promotion beginning in childhood to encourage positive and discourage negative lifestyle habits
  • Mass education
  • Legislation
• Examples
  • Programs on food safety and nutrition guidelines
  • Campaigns discouraging tobacco and drug use (e.g., smoke-free air laws in public buildings)
  • Building bicycle and sidewalks to promote physical activity

Primordial prevention aims to prevent risk factors from developing in the first place, whereas primary prevention targets existing risk factors to prevent the onset of a disease.

• Definition: actions targeted at preventing specific diseases from occurring to decrease the incidence and, subsequently, the prevalence of those diseases
• Measures ^[2][3]
  • Target: entire population and select groups (healthy individuals)
  • Decrease incidence and, in turn, prevalence of a specific disease
  • Primarily done through
    • Health promotion (health interventions, lifestyle modifications)
    • Environmental modifications (e.g., work safety)
    • Specific protection interventions (immunizations, chemoprophylaxis, safety of drugs and food)
• Examples
  • Immunization
  • Lifestyle modification; (e.g., smoking cessation to reduce lung cancer risk, exercise to reduce the risk of heart disease, dental care to reduce the risk of tooth loss)
  • Fortification of salt with iodine to prevent iodine deficiency
  • Fluoridation of toothpaste, water, and salt to reduce the risk of dental conditions
  • Fortification of food with folic acid to reduce the prevalence of neural tube defects
  • Health legislation (e.g., seat belt laws, food safety standards, traffic laws)
  • Ocular prophylaxis for all newborns to prevent neonatal gonococcal conjunctivitis

• Definition: actions targeted at early detection of disease in asymptomatic patients (or while the symptoms of the condition are still mild) to promote early intervention
• Measures ^[2]
  • Target: patient groups
  • Prevent further progression and complications from the disease
  • Consists of a two-step process: screening test to identify disease and follow-up for disease management

Screening complements diagnostics, but it is not a substitute.

• Definition: actions taken to optimize care of patients with an existing disease to improve well-being and prevent complications
• Measures ^[2]
  • Target: select patient groups
  • Decrease the risk of relapse
  • Decrease morbidity and mortality after the onset of symptoms
• Examples
  • Adjuvant therapy (e.g., tamoxifen in breast cancer) to reduce risk of cancer recurrence
  • Blood pressure management (e.g., antihypertensives) to decrease risk of a cardiovascular event
  • Diabetes management (e.g., antidiabetic medication) to decrease risk of chronic kidney disease and/or cardiovascular events
  • Measures to prevent restenosis following myocardial infarction (e.g., low-dose aspirin)

• Definition: actions taken to avoid unnecessary medical interventions by identifying actions that might cause harm rather than benefit patients
• Measures ^[2][12][13]
  • Target: patient groups
  • Prevent overmedicalization (e.g., overdiagnosis, overtreatment)
  • Avoid unnecessary diagnostic studies or treatments without proven efficacy (e.g., only offer ethically acceptable interventions, use treatments previously assessed by randomized controlled trial with low risk of bias)
  • Avoid disease mongering, i.e., widening the definition of certain medical illnesses, to expand markets for those who deliver and/or sell medical treatments.
• Examples ^[14]
  • Avoid hormone replacement therapy after menopause in order to reduce risk of cardiovascular events (e.g., stroke, thromboembolism).
  • Avoid prescribing antibiotics if uncertain that the disease has a bacterial cause (may lead to antibiotic resistance).
  • Avoid overdiagnosis (e.g., recurrent PSA testing in men without high risk for prostate cancer, MRI or CT scan for lower back pain of < 6 weeks duration or without red flags).

• Definition: the degree to which an individual follows prescribed medication regimens and medical advice ^[15]
• Common reasons for poor adherence ^[16][17]
  • Medication
    • Forgetfulness (mostly occurs in older patients or patients with cognitive disabilities)
    • Financial burden (e.g., cost of medications)
    • Polypharmacy (e.g., multiple comorbidities, complex treatment regimen)
    • Poor education by healthcare provider regarding medication use, side effects, and consequences of poor adherence
  • Lifestyle modification: lack of motivation
  • Cultural and personal beliefs
    • Personal health care beliefs (e.g., homeopathy)
    • Personal health care misconceptions (e.g., vaccine hesitancy)
    • Distrust of health care system
• Strategies to encourage adherence
  • Identify potential barriers (e.g., disease-related knowledge)
  • A patient-centered approach
  • Communication about treatment options
  • Provide patient education
    • Written instructions regarding medication
    • Discuss medication side effects
  • Reminder system
    • Regular follow-up visits
    • Email reminder programs
    • Electronic alerts
    • Phone call reminders

• Definition ^[18][19]
  • A preventive measure that benefits a population as a whole will offer little benefit to each individual member of that population (population approach to prevention; primordial and primary prevention)
  • A preventive measure that benefits a group of individuals susceptible to a particular disease will offer little benefit to the population as a whole (high-risk approach to prevention; secondary and tertiary prevention).
  • The high-risk approach and the population approach to prevention are complementary, but preventive medicine should prioritize preventing the underlying causes of disease (primordial and primary prevention) over reducing the impact of disease after it occurs (secondary and tertiary prevention).
  • The prevention paradox may lead to the misconception that a measure that provides no immediate benefit to the individual, provides no benefit to the entire population and that a small risk involved in a measure (e.g., vaccination) outweighs the benefits of that measure.
    • Misconceptions derived from the prevention paradox may negatively affect epidemiological policy as well as adherence in the population.
    • Primordial and primary prevention require consistent, long-term education programs for health care professionals as well as the general population to be effective.
• Examples
  • While heavy drinking carries a greater risk than moderate drinking, moderate drinking has a greater negative impact on the general population because the number of moderate drinkers is greater than that of heavy drinkers.
  • Seatbelt laws have prevented many severe injuries, yet the overall risk of dying in an accident due to not wearing a seatbelt is still low.

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