3. preventative medicine and principles of screening

Preventive medicine definition 1

Practice of promoting preventive health care to improve patient well-being; goal is to prevent disease, disability, and death (American College of Preventive Medicine)

Preventive medicine definition 2

Medicine focused on disease prevention rather than treatment (World Health Organization, 2023)

Preventive medicine examples

Vaccination, lifestyle modification, screening programs (Galea, 2019)

Preventive medicine impact

Saves lives and reduces healthcare costs (Murray et al., 2020)

Global risk factor 1

High blood pressure

Global risk factor 2

Smoking / 2nd hand smoke exposure

Global risk factor 3

High fasting blood sugar

Global risk factor 4

High BMI

Global risk factor 5

Childhood underweight

Global risk factor 6

Ambient particulate matter pollution

Global risk factor 7

High total cholesterol

Global risk factor 8

Household air pollution

Global risk factor 9

Alcohol use

Global risk factor 10

High sodium intake

Global risk factor 11

Low wholegrain intake

Global risk factor 12

Unsafe sex

Global risk factor 13

Low fruit intake

Global risk factor 14

Unsafe water

Global risk factor 15

Low glomerular filtration rate

Primordial prevention

Prevents emergence of risk factors in population; e.g., planning green spaces to encourage physical activity and reduce stress

Primary prevention

Prevents disease before it occurs; e.g., vaccines, diet, exercise (Koh & Sebelius, 2010)

Secondary prevention

Detects early-stage disease; e.g., cancer screening (Wilson & Jungner, 1968)

Tertiary prevention

Limits complications of existing disease; e.g., rehab after stroke (Gofin, 2018)

Quaternary prevention

Prevents over-medicalization; e.g., avoiding unnecessary testing (Jamoulle, 2015)

Legislation banning smoking in public areas

Primordial; reduces exposure to secondhand smoke and discourages smoking initiation

Mammograms for breast cancer screening

Secondary; detects cancer early, improving treatment outcomes

Promoting green energy policies

Primordial; reduces air pollution, lowering risks for respiratory diseases

Limiting antibiotic use in upper respiratory infections

Quaternary; prevents antibiotic resistance by avoiding unnecessary prescriptions

Cardiac rehabilitation after heart attack

Tertiary; helps patients recover function and prevents further cardiac events

Pap smear for cervical cancer screening

Secondary; identifies precancerous changes for timely treatment

Vaccination against influenza

Primary; builds immunity and prevents infection

Speech therapy for patient with aphasia

Tertiary; improves communication skills following brain injury or stroke

Free school meal programs

Primordial; encourages healthy eating habits in children, reducing future obesity risks

Urban planning for active transportation

Primordial; promotes physical activity by creating environments conducive to walking and cycling

Physical therapy after stroke

Tertiary; restores mobility and reduces disability caused by the stroke

Colonoscopy for colorectal cancer screening

Secondary; detects polyps or cancer at early stage, enabling effective treatment

Smoking cessation programs

Primary; prevents lung cancer and other smoking-related diseases

Wilson and Jungner criteria

Basic principles of screening; screening most effective when applied to relatively common disorders that carry large disease burden

Screening benefit 1

Early detection

Screening benefit 2

Reduced mortality

Screening benefit 3

Cost-effective long term

Screening risk 1

False positives

Screening risk 2

Overdiagnosis

Screening risk 3

Unnecessary anxiety

Cancer screening examples

Mammography, Pap smear, Colonoscopy

Infectious disease screening examples

HIV, Hepatitis B

Metabolic disorder screening example

Newborn screening

Cardiovascular screening example

Hyperlipidemia

Ethical principle autonomy

Right to refuse screening

Ethical principle justice

Access for all populations

Ethical principle non-maleficence

Avoiding harm from unnecessary tests

Case scenario 50-year-old woman with family history of breast cancer

Asks for mammogram with no symptoms; provider concerned about emotional impact of false positives

Take home message 1

Prevention saves lives and reduces healthcare costs

Take home message 2

Screening must be evidence-based and ethically sound

Take home message 3

Real-world application is essential for future doctors

Reference American College of Preventive Medicine

What is preventive medicine? Available at: https://www.acpm.org/about-acpm/what-is-preventive-medicine/ (Accessed: March 14, 2025)

Reference Beauchamp and Childress

Principles of biomedical ethics. Oxford University Press, 2013

Reference Wilson and Jungner

Principles and practice of screening for disease. WHO, 1968

Reference Welch et al.

Overdiagnosis in cancer. Journal of the National Cancer Institute, 108(1), pp. 1-8, 2016

Reference WHO 2023

Screening programs: Guidelines and recommendations. Available at: www.who.int

Further reading Harrison's

Harrison's Principles of Internal Medicine 22nd edition, pages 37-41

Further reading Davidson's

Davidson's Principles and Practice of Medicine, 24th edition, pages 93-95