Epidemiology Flashcards
Triad of epidemiological questions?
How does pattern of disease vary over time?
How does place in which population lives affect disease pattern?
How do personal characteristics of people in a population affect disease pattern?
What does descriptive epidemiology do?
Describe pattern of disease
What does analytical epidemiology do?
Make associations of observed patterns to make inferences in hypothesis driven manner
What is genetic epidemiology?
Epidemiological evaluation of role of inherited causes of disease in families and populations
What did Morton define genetic epidemiology as?
Science which deals with etiology, distribution and control of disease in groups of relatives and with inherited causes of disease in populations
Define incidence
Number of new cases diagnosed in specified time interval for specified size of population at risk
What determines population size for incidence?
Mid-interval population
Give formula for incidence
Number of newly diagnosed cases/mid-2014 population at an area
What must new cases include for incidence calculation?
Newly diagnosed patients whether cured or dead
What is the advantage of cumulative incidence?
Valid in cohort studies where attrition is low
When is cumulative incidence not helpful?
High attrition rate - as dropouts are excluded from being counted as new cases
What is used if high attrition rate and need to calculate incidence?
Incidence rate
What is incidence rate?
Number of new cases per person-year of observation
What is the unit of incidence rate?
Time-1
When are incident rate ratios used?
When reporting results that compare two groups incidence rates
What is prevalence?
Number of existing cases in specified population for period of observation
What is point prevalence?
Prevalence in cross-sectional observation
What is period prevalence?
Prevalence in longitudinal observation
Which cases are counted in prevalence?
New cases
Diagnosed before observation but still suffering disease
What does prevalence not count re cases?
Previously diagnosed but now cured or dead
Calculation of point prevalence
Number of existing cases/cross sectional population at an area on 11/11/2018
Calculation of period prevalence
Number of existing cases/mid year population at an area
Which illnesses will have higher prevalence?
Chronic
What formula expresses relationship between incidence and prevalence?
Prevalence = incidence x duration of illness
What is lifetime prevalence?
Proportion of individuals in the population who have ever manifested a disease who are alive on a given day.
What is lifetime morbid risk?
Probability of a person developing the disorder during the entire period of their life (often a specified period)
What does lifetime morbid risk include?
Entire lifetime of a birth cohort both past and future
Includes those deceased at time of survey
What is used to calculate lifetime morbid risk for low incidence disorders?
Summation of age-specific incidence rates live approximate LMR
What is baseline prevalence?
Usual prevalence of a disease in a community
When is a disease said to be endemic?
If baseline is low to moderate and continues without significant fluctuation
What is hyperendemic occurrence?
A persistent but high baseline