Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
22 Cards in this Set
- Front
- Back
|
What is the difference between ratio and proportion? (x and y variable example)
|
Ratio : x and y are independent (ex. 4 males to 6 females = 4/6 ratio)
Proportion : percent where x is included in y (ex. 4 males of 10 total people = 40%) |
|
|
Define RATE.
|
Rate is a proportion with time dimension, or the (# of cases or events occurring during a given time period) / population at risk during the same time period x10^n
|
|
|
Define INCIDENCE.
|
the occurrence of NEW CASES in a population.
Incidence rate refers to the occurrence of new cases in a population over a period of time. |
|
|
Cumulative Incidence is...
|
the proportion of people who become diseased during a specified period of time.
|
|
|
Incidence density is...
(a) the occurrence of new cases in a population over a period of time (b) the proportion of people who become diseased during a specified period of time (c) measure of risk in a changing population where people are free of disease at start and observed for disease onset over different time periods. |
(c) measure of risk in a changing population where people are free of disease at start and observed for disease onset over different time periods. This includes the concept of person-years where person years = # of people x # of years followed up.
|
|
|
___________ is the proportion of persons in a population who have a particular disease or attribute at a specified point in time or over a specified period of time.
(a) Incidence (b) Incidence Density (c) Prevalence |
(d) Prevalence
|
|
|
True or False:
If incidence is high but the disease duration is short then the prevalence will be low relative to the incidence. |
True.
|
|
|
If a disease is short-lived, there will be [ high / low ] prevalence in the population.
|
low
|
|
|
If incidence is low but those affected have the condition for long, the prevalence will be [ high / low ] to the incidence.
|
high
|
|
|
If a disease lasts a long time, there will be [ high / low ] prevalence in the population.
|
high
|
|
|
Which of the following statements are correct?
(a) Both incidence density and cumulative incidence assume equal observation periods (b) Incidence density assumes that the population has been followed for the entire specified time interval (c) Cumulative incidence assumes that individuals in the population have been followed for different time periods (d) Incidence density measures risk in a changing population where subjects are observed for disease onset for different time periods |
D! example: : In a cohort study, 600 contraceptive users were followed over the course of three years as follows:100 women for 1year, 200 women for 2 years, 300 women for 3 years. The number of person-years of observation in this study is:
100 women x 1 = 100 person-years 200 women x 2 = 400 person-years 300 women x 3 = 900 person-years Total = 1400 person-years Of these, 600 people, 10 developed outcome. Incidence rate of outcome is 10/1400 = 7.1 per 1000 person years of follow up. |
|
|
Prevalence
(a) gives an indication of the “burden” of disease in a population - numerator is existing cases (b) measure of risk in a changing population where people are free of disease at start and observed for disease onset over different time periods (c) is the proportion of people who become diseased during a specified period of time |
(a) gives an indication of the “burden” of disease in a population - numerator is existing cases. Specifically, it Is the proportion of persons in a population who have a particular disease or attribute at a specified point in time or over a specified period of time
|
|
|
There are two types of prevalence: point prevalence and period prevalence. differentiate
|
Point prevalence is the presence of a disease at a single point in time (snap shot) whereas period prevalence is the presence of disease at a particular time interval.
|
|
(a) Attack Rate
(b) Incidence Density (c) Cumulative Incidence |
(a) Attack Rate
Example: Of 75 persons who attended a church picnic, 46 subsequently developed gastroenteritis. The attack rate of gastroenteritis is: 46/75 *100 = 61% |
|
|
What is the secondary attack rate?
(a) the proportion of persons in a population who have a particular disease or attribute at a specified point or period in time (b) measure of risk in a changing population where people are free of disease at start and observed for disease onset over different time periods (c) a measure of the frequency of new cases of a disease among the contacts of known cases. |
(c) a measure of the frequency of new cases of a disease among the contacts of known cases.
|
|
|
________ is a measure of the frequency of occurrence of death in a defined population during a specified interval i.e. for a defined population over a specified period of time.
(a) Crude Mortality Rate (b) Case Mortality Rate (c) Adjusted Rate |
(a) Crude Mortality Rate
Crude is among the population at large whereas Case is among the people who have that disease. |
|
|
__________ is the proportion of persons with a particular condition (cases) that die from the condition. It is usually expressed in percent.
(a) Age-Specific Mortality Rate (b) Case Fatality Rate (c) Crude Mortality Rate |
(b) Case Fatality Rate
|
|
|
Infant mortality rate numerator is...
(a) Number of infant deaths less than one year of age (b) Number of infant deaths with the first 28 days (c) No. of deaths in children between 28 days and 1 yr. of age |
(a) Number of infant deaths less than one year of age
(b) is called Neonatal mortality rate (c) is called post neonatal mortality rate |
|
|
Years of Potential Life Lost (YPLL) is a measure of premature death, or when a death occurs earlier than expected if disease were not present. This is set at years lost before age _____.
|
75
|
|
|
_______ give more valuable information when comparing rates between sub-groups but does not provide accurate comparison with other populations whereas ________ correct for differences in age or other factors in populations – making comparisons possible between different populations.
(a) Adjusted rates ; specific rates (B) Specific rates ; adjusted rates |
Specific rates : for between sub-groups
Adjusted rates: corrections for making comparisons between diff populations. Two types of adjustment: indirect and direct. |
|
|
List the steps to calculate an adjusted rate. (4) Use the clinic operation example in class if you want.
|
Step 1: Calculate age-specific rates in the populations you want to compare.
Step 2: Choose a reference population whose age composition is known. Step 3: Calculate Expected deaths in reference population if the Clinic A- or Clinic B-specific rates were the true rates Step 4. Add up the total number of deaths expected in the reference population under each clinic's set of rates. Step 5. Calculate the age-adjusted operative mortality rate for each study group by dividing the sum of expected deaths by the total size of the reference population: |
|
|
Adjusted mortality rates are useful because…..
(a) They minimize the effects of outliers in the data (b) They allow for comparisons between heterogeneous populations (differences in age, ethnicity, gender etc) (c) They allow for corrections in low quality data |
(b) allow for comparisons between heterogeneous populations
|
