Home / Subjects / Public Health

Public Health

The science of protecting and improving the health of people and their communities through education, policy, disease prevention, and health promotion.

Epidemiology

Epidemiology is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

Health Promotion

Health Promotion is a fundamental physics concept explaining the behavior of matter and energy, with formulas and real-world applications.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

Disease Prevention

Disease Prevention is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Structure and function, clinical presentation, diagnostic criteria, and evidence-based management.

Health Policy & Management

Health Policy & Management is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Legal framework, key precedents, statutory interpretation, and practical application.

Social Determinants of Health

Social Determinants of Health is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

Global Health

Global Health is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

Environmental Health

Environmental Health is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

Health Equity

Health Equity is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

Key Formulas & Equations

Incidence Rate: IR = (New cases / Population at risk) × K
Prevalence: P = (Total cases / Total population) × K
K = 100, 1000, 10,000, or 100,000
Mortality Rate: MR = (Deaths / Population) × K
Case Fatality Rate: CFR = (Deaths / Cases) × 100%
Age-Specific Rate: ASR = (Events in age group / Population in age group) × K
Standardized Rate: SMR = Observed deaths / Expected deaths
Vaccine Efficacy: VE = (ARU - ARV) / ARU × 100%
Herd Immunity Threshold: HIT = 1 - 1/R₀
Number Needed to Treat: NNT = 1/ARR
Attributable Risk: AR = Ie - Iu
Odds Ratio: OR = (a×d)/(b×c)
Relative Risk: RR = [a/(a+b)] / [c/(c+d)]
Population Attributable Risk: PAR = It - Iu
Disability-Adjusted Life Years: DALY = YLL + YLD
Years of Life Lost: YLL = N × L
Quality-Adjusted Life Years: QALY = years × quality weight

Core Concepts

Epidemiology

The study of disease distribution and determinants in populations. Uses descriptive and analytic methods to identify risk factors and causes of disease.

Health Promotion

Process of enabling people to increase control over their health. Includes education, community development, advocacy, and policy change.

Disease Prevention

Primary (prevent disease onset), secondary (early detection), tertiary (reduce impact). Includes screening, immunization, and lifestyle interventions.

Health Policy & Management

The planning, organization, and evaluation of health systems. Includes healthcare financing, workforce planning, and quality improvement.

Social Determinants of Health

Conditions in which people are born, grow, live, work, and age. Includes income, education, housing, employment, and social support.

Global Health

Health issues that transcend national boundaries. Includes infectious diseases, maternal health, nutrition, and health system strengthening.

Environmental Health

Study of how environmental factors affect human health. Includes air/water quality, sanitation, occupational health, and climate change.

Health Equity

The principle that everyone should have a fair opportunity to attain their health potential. Addresses disparities based on race, income, gender, and geography.

Worked Examples

Example 1: Incidence Rate

Problem: A population of 50,000 has 200 new cases of disease in one year. Calculate incidence rate per 100,000.

Solution:

IR = (200/50,000) × 100,000 = 400 per 100,000 per year

Example 2: Vaccine Efficacy

Problem: In a trial, attack rate in unvaccinated = 10%, attack rate in vaccinated = 2%. Calculate VE.

Solution:

VE = (10% - 2%)/10% × 100% = 80%

Example 3: Herd Immunity Threshold

Problem: Measles has R₀ = 15. Calculate herd immunity threshold.

Solution:

HIT = 1 - 1/15 = 1 - 0.067 = 0.933 = 93.3%

Practice Problems

Problem 1

Calculate prevalence if 500 cases exist in a population of 25,000. Express per 1,000.

Answer: P = (500/25,000) × 1,000 = 20 per 1,000

Problem 2

Calculate CFR if 50 deaths occur among 1,000 cases.

Answer: CFR = 50/1,000 × 100% = 5%

Problem 3

Calculate NNT if absolute risk reduction = 0.05.

Answer: NNT = 1/0.05 = 20

Problem 4

Calculate odds ratio: Exposed cases = 40, exposed non-cases = 60, unexposed cases = 20, unexposed non-cases = 80.

Answer: OR = (40×80)/(60×20) = 3200/1200 = 2.67

Problem 5

Calculate herd immunity threshold for polio (R₀ = 6).

Answer: HIT = 1 - 1/6 = 83.3%

Problem 6

Calculate attributable risk if incidence in exposed = 15/1000 and unexposed = 5/1000.

Answer: AR = 15 - 5 = 10 per 1,000

Problem 7

Calculate SMR if observed deaths = 120 and expected deaths = 100.

Answer: SMR = 120/100 = 1.2 (20% more deaths than expected)

📚 Related Subjects

All Subjects

Categories

Get Premium