DARM DA study exercise group 3
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For some guidance see the discussion page: D↷
Introduction
Since travel restriction for an indetermined period of time is an unrealistic measure, more feasible tools to control the spreading of the swine flu to Finland are needed. We propose the use of thermal-image scanners combined with a PCR flu test.
The symptoms of swine flu are similar to regular flu symptoms. The most common symptoms include a sudden fever, a sore throat, cough and a runny nose. The incubation period for influenza (the time between infection and appearance of symptoms) is usually 2–3 days, but symptoms may start 1–7 days from contamination. Because the fever is one of the most common symtoms of swine flu, the idea is using the thermal-image scanners to prevent swine spreding with passangers incoming to Finland. The scanners could be set up at airports and other border control points for checking all incoming travellers. Thermal scanning is a quick and non-intrusive system for mass screening of people from a distance of more than one metre. The scanners use thermal imaging to assess the skin temperatures of people as they pass through a checkpoint, and transform that data into a coloured image on a screen. The machines will be set up so that when someone with raised body temperature or the set threshold temperature of scanner (normally above 38(?)C), passes through the testing area, his/hers features will be highlighted in a particular colour. Those who are monitoring the screen would then pull over the person for further investigation and check whether the observed higher body temperature is really because of a fever, or whether the person is just out of breath or agitated.
After the checking and confirming of the fever, person will be quarantined, because the laboratory tests are required to confirm whether a person has been infected with influenza A(H1N1)virus. There are several methods for testing swine flue, but one of the most effective and sensitive is the real-time reverse transcriptase-polymerase chain reaction, co called rRT-PCR technique. It uses a device to amplify copies of genes so researchers can easily compare a sample taken from a sick person to the genetic material of the potentially pandemic infection. Running of PCR-test in laboratory takes few days (48-96 hours: http://www.cdc.gov/h1n1flu/guidance/diagnostic_tests.htm) and during that time person who is tested will be quarantied. Although the accuracy of PCR-test is quite good (sensitivity 86-100%: http://www.cdc.gov/h1n1flu/guidance/diagnostic_tests.htm and specificity:), the test can also provide "false negative" and "false positive" results. "False negative" is in cases where the person actually has the virus and the a negative result does not, by itself, exclude the possibility of swine flu virus infection. Another problem is that a positive result only indicates that the patient is presumptively infected with swine flu virus, but not the stage of infection.
Purpose
Can thermal scanners combined with PCR tests prevent the spreading of swine flu to Finland?
----#: . Part of this purpose statement could be moved below under the boundaries description. Trying to formulate the purpose as an explicit question (at can probably be answered) might be useful for sharpening the focus of the analysis. Perhaps something like: What are the costs and benefits of a thermal scanning + possible PCR flu testing -procedure for all incoming passengers to Finland? (also consider: benefits in terms of what? costs in terms of what? --Mikko Pohjola 15:56, 25 March 2011 (EET) (type: truth; paradigms: science: comment)
Scope
- We want to assess whether the installation of thermal scanners (and performance of PCR flu tests if fever is detected) in the Finnish airports, harbours and other border controls is a good measure to prevent the illness from spreading.
- The purpose of this assessment is to find out if the thermal scanners could be used for preventing the spreding of swine flu to Finland.
Boundaries
- Our assessment takes place in the moment (end of April 2009) when swine flu was starting to spread from Mexico, but no cases had yet been detected in Finland. At that time, The Finnish Ministry of Foreign Affairs was not issued any travel restrictions to the affected areas. The scanners would be placed in the Finnish airports, harbours and other border control points and all the passengers arriving to Finland abroad would be scanned. The scanning would be continued untill the decision about swine flu vaccination campaign in Finland will be made.
Scenarios
- With scanners, individuals with a raised body temperature (normal temperature is 37±0.5 C) are tested for H1N1 virus through a PCR test and quarantined if test is positive
- No scanners are used and travellers can move freely without monitoring
←--#: . Also this looks to me mostly like specifics of boundary definition. --Mikko Pohjola 16:04, 25 March 2011 (EET) (type: truth; paradigms: science: defence)
- ⇤--#: . I would rather say that these are other variables in your causal chain. There are properties related to swine flu, and you need to learn about them to be able to make an assessment. You cannot decide the value of these things, they are what they are. The exception is the temperature threshold for further action, which can be adjusted by the person who uses the scanner. --Jouni 07:37, 27 March 2011 (EEST) (type: truth; paradigms: science: attack)
Intended users
- The Finnish Ministry of Social Affairs and Health
- The Finnish Ministry of Foreign Affairs
- The Finnish Ministry of Transport and Communications
----#: . This seems to state who will be scanned. Describe here who will/should be using the information that is/will produced by this decision analysis. --Mikko Pohjola 15:56, 25 March 2011 (EET) (type: truth; paradigms: science: comment)
Participants
- Group 3 of Darm-course 2011: Bate Shadrak, Carmen Gil, and Minna Ruokolainen
----#: . You can describe both who participate in making the plan and who should be participating in making the actual decision analysis study. --Mikko Pohjola 15:56, 25 March 2011 (EET) (type: truth; paradigms: science: comment)
Definition
- Causal diagram
Decision variables
- Use of thermal scanners combined with PCR test or not
Indicators
Individuals infected with H1N1 get through the passenger control on their arrival to Finland
----#: . What does the scanning have impact on? what do you need to find out in order to answer your assessment question (also see the comment under purpose sub-attribute). --Mikko Pohjola 15:56, 25 March 2011 (EET) (type: truth; paradigms: science: comment)
Other variables
- Swine flu incubation takes 5 days on average (2 to 7 days)
- Symptoms last for XX days on average
- Sensitvity of the PCR swine flu test: 50% (30-70%)
- Specificity of the PCR swine flu test: 99%
- Sensitivity and specificity of thermal scanner
- Number and origin of passengers travelling to Finland
- Prevalence of swine flu in different countries
- Prevalence of fever (background + swine flu)
- Intake of painkillers
Calculation
----#: . Try to identify a) the variables that are needed to make a continuous causal chain from decision variable(s) to indicator(s), b) possible other variables needed to estimate the indicator result(s). Based on this you can consider how the calculation could be done (if you had the numbers) --Mikko Pohjola 15:56, 25 March 2011 (EET) (type: truth; paradigms: science: comment)
Analyses
EXTRA * Analyses: statistical and other analyses that contain two or more variables, e.g. optimizing.
Result
We got no results since we could not have the numbers to calculate and to do the analysis in our work.