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Epidemiological Methods in Studies of Symptoms in Advanced Disease
Author Bios
Why Study Advanced Disease?
Why Epidemiology?
Incidence and Prevalence
Using Incidence and Prevalence
Currently selected selection: Definition of a Case
Defining Time, Place, Person
Types of Study Design
Cross-Sectional Studies
Longitudinal Studies
Measurement
Bias
Selection Bias
Measurement Bias
Presenting and Interpreting Results
Practical Example
Calculating Prevalence
Conclusion


Chapter 19: Epidemiological Methods in Studies of Symptoms in Advanced Disease: Defining of a Case
        
 
Figure 5.1: Cases of Breathlessness
Graphic depiction of cases of breathlessness

 

As in the hypothetical study of breathlessness in Problem 3.1, consider five patients followed for 6 days before and after admission in a palliative care program. This time, however, you are given the severity of breathlessness in terms of a Likert scale from 1 (mild breathlessness) to 4 (overwhelming breathlessness). For this exercise a "case" of severe breathlessness is defined as a score of 3 or 4.

Question 5.1 The incidence of severe breathlessness in the first two days is three patients out of five, or 60%.

Question 5.2 The point prevalence of severe breathlessness at the beginning of day two is three patients out of five, or 60%.

Question 5.3 The period prevalence of severe breathlessness in the first two days is three patients out of five, or 60%.

Question 5.4 The incidence is 20% (one patient) because patient #5 goes from mild breathlessness to severe breathlessness at this time.

Question 5.5
The period prevalence of severe breathlessness between days three and five is 20% (one patient).

Question 5.6
The point prevalence of severe breathlessness at the beginning of day six is 20% (one patient).

 

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