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MD1 > Epidemiology > Flashcards

Epidemiology Flashcards

1
Q

Prevalence

A

Number of EXISTING cases of an outcome at ONE POINT IN TIME

expressed as proportion or percentage

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2
Q

Incidence

A

Number of NEW cases of an outcome DURING A TIME INTERVAL

expressed as rate (denominator includes time component)

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3
Q

Risk

A

Probability of disease occurring in a disease-free population during a specified time period
Risk = N/P
N = new cases in defined period
P = population at risk

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4
Q

Rate

A

Probability of disease occurring in a disease-free population during the sum of individual follow up periods (person-time)
Rate = N/T
N = new cases in defined period
T = total person-time of follow-up

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5
Q

Relative Risk (RR)

A

RELATIVE change in risk/rate of outcome associated with exposure
RR = Re/Ru
Re= Risk/Rate among exposed
Ru = Risk/Rate among unexposed

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6
Q

Attributable Risk (AR)

A

ABSOLUTE change in risk/rate of outcome associated with exposure
AR = Re – Ru
Re= Risk/Rate among exposed
Ru = Risk/Rate among unexposed

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7
Q

Attributable Risk Percent (AR%)

A

AR% = [(Re – Ru) / Re ] * 100

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8
Q

Population Attributable Risk (PAR)

A 
PAR = Rt – Ru
Rt = Risk/Rate in whole population (both exposed and unexposed)
Ru = Risk/Rate among unexposed
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9
Q

Population Attributable Risk Percent (PAR%)

A 
PAR% = [ (Rt – Ru) / Rt ] * 100
Rt = Risk/Rate in whole population (both exposed and unexposed)
Ru = Risk/Rate among unexposed
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10
Q

Bradford Hill Criteria for Causality

A 
Temporal Relationship
Strength
Dose Relationship
Consistency (multiple studies show same results)
Plausibility (makes sense)
Excludes Alternatives
Experimental Evidence
Specificity (lung cancer & smoking study)
Coherence
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11
Q

Odds Ratio

A

Used for case control studies to approximate relative risk

OR = odds of exposure vs non exposure among cases / odds of exposure vs non exposure among controls

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12
Q

Hazard

A

Continuously updated instantaneous rate
Week 1, 10 die, hazard week 1 = 10/1000
Week 2, 15 die, hazard week 2 = 15/990

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13
Q

Relative Rate Reduction

A

Relative Rate Reduction = Rc / Ri
Rc = rate of outcome in control arm
Ri = rate of outcome in intervention arm

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14
Q

Absolute Rate Reduction

A

Absolute Rate Reduction = Rc – Ri
Rc = rate of outcome in control arm
Ri = rate of outcome in intervention arm

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15
Q

Number Needed To Treat

A

NNT = 1 / (absolute risk or rate reduction)

Defines number of people needed to undergo the intervention in order to prevent outcome in one person

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16
Q

PICOT

A 
Population
Intervention
Comparator/Control
Outcome
Timing
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17
Q

Internal Validity

A

Extent to which the results of a study are valid (accurate, robust, sound and complete).

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18
Q

Statistical Significance

A

P-value < 0.05

Probability that the observed result arose from chance

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19
Q

Confidence Interval

A

Interval within there is 95% chance the true value lies

If null value is excluded result is statistically significant

20
Q

External Validity

A

Extent to which the results of a study are applicable to a clinical scenario (using PICOT)

21
Q

Systematic Review

A

Idenitify, appraise,select, synthesize
Focuses on single question
Well defined criteria
Highest NHMRC level of evidence

22
Q

Meta-analysis

A

Statistical Aspect of systematic review
Derived (weighted-average) effect size
Increases power and answers other questions

23
Q

Heterogeneity

A

Whether component studies are similar enough to be pooled

24
Q

Diagnostic Test

A

Confirmation of disease (high pre-test probability of disease)

25
Q

Screening test

A

Identify patients who may have disease (low pre-test probability of disease)

26
Q

Sensitivity

A

True Positive / (True Positive + False Negative)

% of people with disease that test positive

27
Q

Specificity

A

True Negative / (True Negative + False Positive)

% of people without disease that test negative

28
Q

Positive Predictive Value

A

True Positive / (True Positive + False Positive)
% of positive tests that are truly positive
Dependant on prevalence of disease

29
Q

Negative Predictive Value

A

True Negative / (True Negative + False Negative)
% of negative tests that are truly negative
Dependant on prevalence of disease

30
Q

Likelihood Ratio of Positive Test

A

Sensitivity / (1 - Specificity)

31
Q

Likelihood Ratio of Negative Test

A

(1 - Sensitivity) / Specificity)

32
Q

Social Determinants of Health

A
  1. Social Gradient
  2. Stress
  3. Early Start
  4. Social Inclusion
  5. Work
  6. Unemployment
  7. Social Support
  8. Addiction
  9. Food
  10. Clean Transport
33
Q

Observational Studies

A 
case series, case reports
ecological
cross-sectional
case-control
cohort
34
Q

Interventional Studies

A

clinical trials

35
Q

Descriptive Studies

A

case series, case reports
ecological
cross-sectional

e.g. How common is coronary heart disease?

36
Q

Analytical Studies

A

case-control
cohort
clinical trials

e.g. Does dyslypidaemia increase the risk of CHD?
Do lipid-lowering medications decrease the risk of CHD?

37
Q

Cross Sectional Studies

A 
Data collected via questionnaires, examinations, investigations
Mostly descriptive (esp. PREVALENCE)
38
Q

Case Control Studies

A 
Comparison of PREVIOUS exposure between Cases (have outcome) and Controls (without outcome)
Matched by confounders
RETROSPECTIVE
Useful for studying rare outcomes
output: ODDS RATIO
39
Q

Cohort Studies

A

LONGITUDINAL with FOLLOW-UP
collect INCIDENCE data
derive RELATIVE RISKS

40
Q

Clinical Trials

A 
LONGITUDINAL assess if INTERVENTION changes INCIDENCE
outcomes: 
RR
HR
ARR
NNT
41
Q

Death Stats

A

1/5 deaths are children under 5

  • communicable diseases account for 50%
  • malnutrition underlying cause of 30%
  • 37% of deaths are neonates (under 28 days)

out of every 10 deaths

  • 6 non-communicable diseases
  • 3 communicable, reproductive, nutritional
  • 1 injury (males)

Leading causes of death

  • Ischemic Heart Disease
  • Cardiovascular Disease
  • Infections / Parasitic
  • Cancers
42
Q

Millenium Development Goal 4

A

Reduce the under 5 mortality rate by 2/3rds by 2015

43
Q

Leading Global Cause of DALYs

A
  • Unipolar depressive disorders
  • Hearing loss (adult onset)
  • Alcohol use disorders
44
Q

Leading global risk factors for mortality

A
  • High Blood Pressure (13% of deaths)
  • Childhood underweight (2million children)
  • Unsafe water, sanitation, hygiene, indoor smoke (2million children)
  • Unsafe sex
  • Tobacco (1/8 deaths over 30)
  • Obesity (7% of deaths globally)
45
Q

Tobacco Control

A

Tobacco is a risk factor for 6 of the top 8 leading causes of death

Monitor tobacco use and prevention policies
Protect people from tobacco smoke (smoking bans)
Offer help to quit tobacco use (nicotine replacement)
Warn about the dangers of tobacco (packaging & adds)
Enforce bans on tobacco advertising
Raise taxes on tobacco (most effective)

Australia most expensive place to buy Marlboro

Tobacco use declining among teens (alcohol rising)
Lung cancer rates declining in males (females rising)
COPD death rates declining
CHD rates declining
400,000 deaths averted

Tobacco will kill approx 1billion people this century (due to smoking by pre-teens in south east asia and china
WHO FCTC (framework convention on tobacco control) developed to combat worldwide tobacco smoking
46
Q

Leading causes of Blindness and Vision Impairment

A

Blindness (Australia)

  • Age Related Macular Degeneration (48%)
  • Glaucoma (14%)
  • Cataract (12%)

Vision Impairment (Australia)

  • Refractive Error (62%)
  • Cataract (14%)
  • Age Related Macular Degeneration (10%)

Blindness (Worldwide)

  • Cataract (39%)
  • Refractive Errors (18%)
  • Glaucoma (10%)
47
Q

Indigenous Eye Health

A

Aboriginal kids born with better vision (1/5th vision loss c.f mainstream)
Blindness 6x more common in adults than mainstream
Low vision 3x more common

Primary causes

  • Cataract (12x more common, 7 year wait for surgery)
  • Refractive Errors (only 20% wear glasses)
  • Trachoma (Surgery, Antibiotics, Facial cleanliness, Environmental improvements)
  • Diabetes (only 20% have yearly eye exam)

94% of vision impairment avoidable with early intervention

MD1 (11 decks)

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