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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
Definition of a Case
Defining Time, Place, Person
Types of Study Design
Cross-Sectional Studies
Longitudinal Studies
Measurement
Bias
Selection Bias
Measurement Bias
Currently selected selection: Presenting and Interpreting Results
Practical Example
Calculating Prevalence
Conclusion


Chapter 19: Epidemiological Methods in Studies of Symptoms in Advanced Disease: Calculating Prevalence of a Problem
         


Multiplying these percentages by the number of deaths estimates the number of patients who will have each different symptom in the last year of life. For example, if there are 250 cancer deaths, and pain is found in 84% of cancer patients, there will be 210 patients with cancer and pain each year. If there are 750 people who die from conditions other than cancer, and 67% have pain in the last year of life, then the district will have around 500 people who die from diseases other than cancer and have pain in their last year of life. The next example for London Region demonstrates how this is done for each district, across a wide range of symptoms.

Example from the London Region: Prevalence of Problems in the Last Year of Life Where Palliative Care Would Improve the Quality of Life

Consider the data presented in this table:

Click here to view a larger text version of Table 16.1

Small, non-text version of table

These estimates suggest that in the London Region there are, each year, about 13,300 cancer patients who experience pain that requires treatment in the last year of life, about 8,000 who experience nausea and/or vomiting, and about 7,400 who experience trouble breathing or breathlessness. Many other symptoms are also present. Note that in these data, one patient may have several symptoms.

Among patients who have conditions other than cancer, estimates suggest that in London region each year 30,200 experience pain that requires treatment in the last year of life, 12,200 experience nausea and/or vomiting, 22,100 experience trouble breathing or breathlessness. As for cancer patients, many other symptoms are also present. The table below shows the estimates for each health district. Again, remember that a single patient may have several symptoms. However, the total number of patients with symptoms is roughly double that of cancer patients.

Click here to view a larger text version of Table 16.2

Small, non-text version of table

The next important steps in the epidemiologically-based needs assessment is to compare need and experience. Thus we can contrast the numbers of people who "need" care -- as indicated by the number with symptoms or problems -- with the numbers of people who actually receive care, as indicated by the numbers of people known to be receiving care from different services. Data on those receiving care might be available from individual services, or medicare and medicaid files, or nationally collected data.

Once this is complete then special surveys to further investigate the needs of particular groups of patients and families, about whom there is not yet sufficient information, can begin. It might then also be appropriate to run focus groups of patients and surveys of professionals to examine need and possible solutions.


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