Ch. 3 Measuring the occurrence of disease: Morbidity Flashcards
When gathering information about a patients illness what possible methods can be used ?
If hospitalized, medical,physicians, and hospital records are useful. Information about the illness prior to medical care being sought can be obtained using a patient questionnaire or interviews may be conducted.
How can rates and proportions be used to measure the occurrence of disease in a population?
Rates- tells us how fast the disease is occurring within a population.
Proportions- signifies the fraction of the population that is being affected by the disease.
Define the incidence rate
Incidence rate is the # of new cases of a disease that occur during a specific period of time in a population at risk of developing a disease.
What is the formula for the incidence rate per 1,000
(#of new cases of a disease occurring in a population during a specified time period/ # of persons who are at risk of developing the disease during that time period) X1,000
T or F The denominator for incidence rate is defined only by the people who were observed throughout a defined time period.
False- The incidence rate can have 2 denominators people who are at risk throughout a defined time period; or when not all the individuals have been observed for the entire time period the unit of time when each individual was observed.
When not all individuals are observed for the entire time which denominator is used for the incidence rate?
When not all the individuals are observed for different lengths of time, we calculate the incidence rate in which the denominator consists of the unit of time that each individual has successfully observed.
How do you identify new cases in order to calculate an incidence rate?
In order to identify new cases in a population for an incidence rate first a population is identified and screened for the disease at baseline then followed for a specified time and re-screened to identify new cases.
What is the definition and formula for prevalence?
of cases present at a specific time/ # of persons in the population at a specific time
*The important point is that every person represented by the numerator had the disease at the specified time.
What is the difference between the incidence rate and prevalence of the disease?
Prevalence is a snapshot of the # of people who have the disease and those who don’t during a given time period; while the incidence rate is a measure of the risk because it only includes the number of new cases or events during a specified time period.
Define the use of the word prevalence in medical and public health where point prevalence and period prevalence is used.
Point prevalence is the the prevalence of the disease at a certain point in time
Period prevalence is how many people have had the disease at any point in time during a certain time period.
- As the death or cure of the disease can lower the prevalence and the continual addition of new cases increased the prevalence of the disease.
What are some of the issues that can arise when figuring out the denominator and the numerator for disease prevalence ?
For the numerator, first it is figuring out who has the disease and the criteria for determining what constitutes the diagnosis of the disease. Second,it is determining which of those cases should be allowed to be included in the numerator based on the gathering of information.
For the Denominator, the most important thing in any study must be that the working definition be clearly stated so that the reader can judge whether the results are truly comparable.
When conducting interviews what are some issues that can arise when trying to obtain information from the patient?
1) The respondent may have the disease, but may not have the symptoms of and may not be aware of the disease.
2) The respondent may have the disease and may have the symptoms, but may not have had medical attention and therefore may not know the name of the disease.
3) The respondent may have the disease and have had medical attention, but the diagnosis may not have been made or conveyed to the person or the person may have misunderstood.
4) The respondent may not accurately recall an episode of illness and may choose not to respond or may his or her response.
5) The respondent may be involved in litigation about the illness and may choose not to respond or may alter his or her response.
6) The respondent may provide information the information, but the interviewer may not record it or may record it incorrectly.
7) The interviewer may not ask the question he or she is suppose to ask or may ask them incorrectly .
8) The interviewer may be biased by knowing the hypothesis being tested and may probe for more intensively in one group f residents than another.
9) Problems of election bias may occur, possibly including significant nonresponse rates.
When obtaining information from hospitals to gather research what problems can arise?
1) Hospital admissions are selective and vary from hospital to hospital on things such as severity of diseases, associated medical conditions, and admissions policies
2) Designed for patient care rather than research and records can be incomplete or illegible.
What is the relationship between Prevalence and Incidence rate?
Prevalence = Incidence X Duration the disease
Define the purpose of Spot Maps
Spot Maps is an approach used to examine the geographic or spatial differences in incidence by plotting them onto a map with each point representing a case.
*Which may or may not offer important clues to the etiology of the disease
