Biostatistics and Epidemiology – Week 1 Comprehensive Notes

Learning Outcomes

  • LO1 – Origins & Developments

    • Recall historical milestones in epidemiology for continuous learning & professional growth.

    • Connect past discoveries to modern practice, reinforcing critical thinking about evolving methods (CLO1).

  • LO2 – Core Functions

    • Describe & apply central epidemiologic functions (surveillance, investigation, analytic assessment, program evaluation, policy development) in evidence-based public-health practice (CLO2).

  • LO3 – Real-World Application & Ethics

    • Evaluate how epidemiologic principles solve current health problems, stressing ethical decision-making, scientific responsibility, & community welfare (CLO3).

Introduction to Epidemiology

  • Epidemiology – Dual Definition

    • "Method used to find causes of health outcomes & diseases in populations."

    • More formally, "the study (scientific, systematic, data-driven) of the distribution (frequency, pattern) & determinants (causes, risk factors) of health-related states/events in specified populations, & the application of this study to control health problems."

  • Etymology

    • Greek roots: epi = "upon/among", demos = "people/district", logos = "study/word/discourse" ⇒ literally, "study of what is upon the people" (applies only to human populations).

  • Patient Perspective

    • In epidemiology the “patient” is the community; individuals are examined collectively.

  • Application Domains

    • Clinical research, disease prevention, health promotion, health protection.

Core Epidemiologic Questions (“Disease Detective” Approach)

  • Who? – Identify cases & populations at risk.

  • What? – Characterize symptoms, diagnoses, health events.

  • When? – Determine onset & temporal patterns.

  • Where? – Map exposure sources & geographic distribution.

  • Why/How? – Uncover causal agents, risk factors, & modes of transmission.

  • Data analyzed statistically to trace introduction & propagation of health problems.

Events & Problems Investigated

  • Environmental Exposures

    • Air pollutants, asthma triggers, lead, heavy metals.

  • Infectious Diseases

    • Food-borne illness, influenza, pneumonia.

  • Injuries & Violence

    • Localized homicide spikes, national surge in domestic violence.

  • Non-Infectious / Chronic Diseases

    • Cancer clusters, increase in major birth defects.

  • Natural Disasters

    • Hurricanes Katrina & Rita (2005), Haiti earthquake (2010).

  • Terrorism / Intentional Events

    • World Trade Center attacks (2001), anthrax release (2001).

  • Health-Services Research

    • System performance, access, costs, quality indicators.

Roles & Skills of Epidemiologists

  • Often trained physicians, veterinarians, scientists, or allied-health professionals.

  • Nickname: “Disease Detectives.” Responsibilities include:

    • Rapid field investigation during outbreaks/threats.

    • Identification of at-risk groups & sources of exposure.

    • Design & implementation of control / prevention strategies.

    • Communication of findings to health authorities & the public.

Historical Pioneers & Contributions

  • Hippocrates (≈400 BCE)

    • Work: On Airs, Waters and Places.

    • Proposed that disease relates to external & personal environment; considered Father of Modern Medicine.

  • John Graunt (1662)

    • London haberdasher; published first quantitative analysis of mortality data.

    • Identified sex disparities, high infant mortality, urban vs. rural differences, seasonal variation.

    • Founder of the Science of Demography.

  • James Lind (1747)

    • Naval physician; conducted first clinical trial aboard HMS Salisbury.

    • Discovered citrus fruit cures scurvy, shifting focus from “bad air” theories to nutritional deficiency.

  • William Farr (1807–1883)

    • Built on Graunt; systematized collection/analysis of Britain’s vital statistics.

    • Regarded as Father of Modern Vital Statistics & Surveillance; advocated for data-driven public health.

  • John Snow (1813–1858)

    • London anesthetist; mapped 1854 Broad Street cholera outbreak, removed pump handle, halted transmission.

    • Dubbed Father of Modern Epidemiology; pioneered natural experiment & geographic mapping.

  • Wade Hampton Frost (1880–1938)

    • First Professor of Epidemiology (Johns Hopkins).

    • Arrested U.S. yellow-fever epidemic; studied poliomyelitis, influenza, diphtheria, tuberculosis.

  • Sir Austin Bradford Hill (1897–1991)

    • Proposed nine criteria ("Bradford Hill Criteria") to infer causal relationships (e.g., strength, consistency, temporality, biological gradient).

    • Demonstrated link between cigarette smoking & lung cancer.

  • Sir Richard Doll (1912–2005)

    • Collaborated with Hill; produced definitive evidence that smoking increases risk of lung cancer & heart disease.

Scope of Epidemiology

  1. Causation of Disease – Identify etiologic agents & risk factors.

  2. Natural History & Spectrum – Track progression from exposure to outcome, including pre-clinical stages.

  3. Health Status of Populations – Measure incidence, prevalence, mortality, morbidity.

  4. Evaluation of Interventions – Assess effectiveness, efficiency, equity of preventive, therapeutic & policy measures.

Ultimate Aim

  • Promote community health & well-being by eliminating or reducing health problems.

Specific Aims & Objectives

  • Descriptive

    • Describe distribution    (person, place, time)\text{Describe distribution \; (person, place, time)} of health & disease.

    • Quantify magnitude (e.g., rates, ratios, proportions).

  • Analytic / Etiologic

    • Identify risk factors & elucidate pathogenesis.

    • Employ cohort, case–control, cross-sectional, experimental study designs.

  • Programmatic / Evaluative

    • Provide data essential for planning, implementing & evaluating prevention, control, treatment services.

Connections to Biostatistics

  • Statistical tools (hypothesis testing, regression, survival analysis) underpin measurement of association & effect.

  • Epidemiologic reasoning guides study design, data collection, analysis, & interpretation.

Ethical & Practical Considerations

  • Maintain confidentiality of subjects & communities.

  • Balance rapid public-health response with rigorous scientific standards.

  • Uphold transparency & accuracy when communicating risks.

  • Comply with intellectual-property laws (e.g., Republic Act No. 8293, Philippines) when using data/materials.

Engagement Exercise – “Who Is That Man?” (Matching)

  • Clues & Answers

    • "Assisted in first successful arrest of yellow fever" → Wade Hampton Frost.

    • "Father of modern epidemiology / solved cholera outbreak" → John Snow.

    • "Studied poliomyelitis, influenza, diphtheria, tuberculosis" → Wade Hampton Frost (again).

    • "Science of demography" → John Graunt.

    • "Discovered citrus fruit to treat scurvy" → James Lind.

    • "Pioneered research linking smoking to health problems" → Richard Doll.

Key Takeaways

  • Epidemiology integrates systematic inquiry, statistical expertise, and field investigation to safeguard population health.

  • Historical breakthroughs—from Lind’s scurvy trial to Snow’s cholera map—underscore the discipline’s reliance on observation, experimentation, and data visualization.

  • Modern challenges (chronic disease, disasters, terrorism) expand epidemiology’s scope, demanding interdisciplinary collaboration & stringent ethical oversight.

  • Mastery of epidemiologic principles is foundational for medical-laboratory scientists, enabling evidence-based diagnostics, surveillance, and public-health leadership.