Measuring Occurances Of Disease & Standarizing Rates Flashcards
Rate
The frequency of occurrence of same event in s population at risk in a given period of time
What are the two different types of surveillance methods?
Passive and active
What is the difference between a crude rate and a specific rate? Give example of specific rate
Crude - birth or death
Specific - demographic, cause or condition, combo of factors
Ex: gender, age, race, zip code, county, state, country, cause/condition, combination, time
What is the range of values for a proportion?
0 to 1
No time element
Is the case fatality rate a proportion or rate?
Proportion
What are the three main points or questions that one must consider in terms of epidemiology of disease transmission?
Host, agent, environment
What is the range of values for a ratio? Give an example.
They don’t have range values
Ex: 4:1
What does incidence measure? (Formula)
Pop. At risk of disease during that SAME period of time
What does prevalence measure? (Formula)
Pop. of ppl at that specific time
What is the difference between cumulative incidence and incidence density rate?
Cumulative - assumes every person in the pop. Is at risk during that time period
Incidence density rate- assumes ppl in pop. are followed for diff lengths of time
What are some problems with hospital data?
They have countless medical conditions, never a specific type of disease… Can possibly be a little bias. Missing some things as well.
What is the difference between point and period prevalence?
Point - now, at this present day
Period - # of cases that occur during a period of time
Explain the relationship between incidence and prevalence.
They both measure cases of disease at a specific time period but incidence measures new cases and prevalence measures the total cases at that time
If a certain drug helps prolong the life expectancy of a person but doesn’t cure it, what is affected the incidence or prevalence? How?
Prevalence bc they will be country in the pop. And the number of cases in that pop.
Limitations of calculating incidence and prevalence
Who has the disease/doesn’t & hospital data is incomplete
Choice of denominator can be manipulate
Why do we use the midyear pop. To calculate morality rate?
Bc it is the estimate/average of the pop. And usually utilized by census data
Is the proportionate morality rate (PMR) s rate, proportion, or ratio?
Proportion
Of deaths that disease X is responsible for
If the PMR for heart disease is 0.35. What does that mean?
35% of the deaths is due to heart disease in that population
What is years of potential life lost (YPLL)? Who contributes more the young or the old?
Based on life expectancy
The younger bc they have longer to live so they have more life to lose
What are limitations of using mortality rate?
Death certificate is like the birth certificate so:
- not accurate
- underline cause of death is not always known
- quality of data is poor
- change of disease definitions throughout the years
What are the two methods of standardizing data?
Direct - age specific mortality rates for two or more pop is known
Indirect
Why is wrong to only look at the crude rated when comparing two populations? What can we do to correct this?
The crude rates do not reflect the true situational risks and they have confounding factors
To fix this we use standardization
When do we use the indirect method of standardizing tests?
When given an age specific mortality rates from a reference population
