Principles of Screening (Dr. Hoppe) Flashcards
What is Screening?
Identification of a problem Not a diagnosis Not 100% accurate Should be low cost Should be cost effective Should be quick and easy Not a substitute for regular health care.
True or False: For a screening to be effective, the condition being screened for must be treatable.
True.
There must be a system in place to handle referrals. For what?
To improve quality of life
To improve school performances
To be able to perform job functions
To preserve vision.
True or False: For screening to be effective, you don’t have to identify target population or be familiar with that population’s health risks.
False. You need to know.
Early detection can lead to what?
Early treatment and improve health outcomes.
Which objective is this? Increase the proportion of preschool children aged 5 years and under who receive vision screening from 36% in 2002 to 52% in 2010.
Objective 28-2.
Objective V-1 states to increases the proportion of preschool children aged 5 years and under who receive vision screening to what percentage? What is the baseline? What was the target setting method?
44.1%. 40.1% in 2008. 10% improvement.
In 2007, ___ states did not require children to receive any vision screening or examination before or during school. Only ___ states require a follow-up to the screening.
16; 5.
California Law requires vision be appraised upon (first/second/third) enrollment of a child at a California elementary school, and at least every (first/second/third) year thereafter until the child has completed the (5th/8th/12th) grade. This evaluation shall include tests for visual acuity and color vision; however, color vision shall be appraised of (female/male) pupils once they have reached the (first/second/third) grade. The results of the color vision appraisal shall be entered in the health record of the pupil. Gross external observation of the child’s eyes, visual performance, and perception shall be done by the ________ and the ______________.
First; third; 8th; male; first; school nurse and classroom teacher.
Screenings are an example of what type of prevention?
“Secondary Prevention”.
Preventing or reversing ongoing vision deterioration so that any interference with the patient’s potential would be reversed, and visual performance raised above minimal levels is called what?
Secondary Prevention.
What is the difference between chronic and acute?
Chronic- once your sick it stays
Acute- healthy, sick, healthy, sick.
True of False: We want to screen for acute conditions.
False. Chronic because once you have it, it stays.
Selected screening conditions depend on population characteristics. What are they?
Age Gender Ethnicity Geographic location Health care.
What does prevalence mean?
Common, Frequent.
The portion of persons in a given population that has a particular condition.
What does incidence mean?
Risk of developing.
How do you evaluate a screening?
By using a 2 X 2 table.
What is true positive?
A. Screening says you have it when you actually do have it.
What is true negative?
D. Screening says you don’t have it when you really don’t have it.
What is false positive?
B. Screening says you do have it when really you don’t have it.
What is false negative?
C. Screening says you don’t have it when you actually do have it.
Why may false positive and false negative happen?
Child may be fooling around and doesn’t want to participate. Didn’t do the test correctly. There is a language barrier. Maybe patient does have the conditions just wasn’t showing at that moment.
The accuracy of the screening procedure to correctly identify all individuals in a population who have a particular disorder is known as what?
Sensitivity.
Out of all the people who have the disorder, how many does your screening test correctly identify? What is this question asking for?
Sensitivity.
What percentage is sensitivity expressed as when looking at a 2 X 2 table?
A/ (A + C) X 100
A + C is all the people who actually have the disorder.
A is what you screened to have the disorder that actually have the disorder.
The accuracy of the screening procedure to correctly identify those who do not have the disorder is known as what?
Specificity.
Out of all the people who do not have the disorder, how many does your screening test correctly identify? What is this question asking for?
Specificity.
What percentage is specificity expressed as when looking at a 2 X 2 table?
D/(B + D) X 100
D + B is all the people that don’t have the disorder.
D is what you screened and identified that do not have the disorder.
True or False: As sensitivity rises, specificity declines.
True.
Sensitivity higher over specificity is over-referred or under-referred?
Over-referred.
Specificity higher over sensitivity is over-referred or under-referred?
Under-referred.
The probability that someone who fails the screening really does have the disorder is called what?
Positive predictive value.
What is the formula when trying to calculate for positive predictive value?
A/ (A + B) X 100
What’s a good way of describing positive predictive value?
Out of all of the people who you refer from the screening, how many actually have the condition?
The probability that someone who passes the screening really does not have the disorder is called what?
Negative predictive value.
What is the formula when trying to calculate for negative predictive value?
D/ (C + D) X 100
What’s a good way of describing negative predictive value?
Out of all of the people who you pass from the screening, how many actually do not have the condition?
A measure of the previously unrecognized cases that are treated as a result of implementing the screening procedure is called what?
Yield.
True or False: Yield requires tracking and follow-up of referrals and is very difficult to accurately measure.
True.
True or False: Yield is related to specificity.
False. Sensitivity and prevalence.
If the screening has a low sensitivity, the yield will be high or low?
Low.
If the population being screened has a low prevalence of the condition, the yield will be high or low?
Low.
1,000 children aged 11 – 15 are screened for myopia.
Expected prevalence is 17% (Grosvenor)
Retinomax Auto-refractor is used
Sensitivity = 0.64
Specificity = 0.90 (Hatch)
How many of the children referred from the screening will have myopia?
Myopia Myopia
+ -
Screening 109 83 192
+
Screening 61 747 808
-
Totals 170 830 1,000
Positive Predictive Value
True Positives
A/ A+B
109/192=56.7%
Slightly more than half of the referrals will have myopia
1,000 children aged 11 – 15 are screened for myopia.
Expected prevalence is 17% (Grosvenor)
Retinomax Auto-refractor is used
Sensitivity = 0.64
Specificity = 0.90 (Hatch)
How many of the children who are not referred from the screening will have myopia?
Myopia Myopia
+ -
Screening 109 83 192
+
Screening 61 747 808
-
Totals 170 830 1,000
False negatives
C/ C + D
61/808= 7.5%
1,000 children aged 5 and 6 are screened for myopia.
Expected prevalence is 1.5% (Grosvenor)
Retinomax Auto-refractor is used
Sensitivity = 0.64
Specificity = 0.90 (Hatch)
How many of the children referred from the screening will have myopia?
Myopia Myopia
+ -
Screening 10 98 108
+
Screening 5 887 892
-
Totals 15 985 1,000
Positive Predictive Value
True Positives
A/ A + B
10/108 X 100= 9%
1,000 children aged 5 and 6 are screened for myopia.
Expected prevalence is 1.5% (Grosvenor)
Retinomax Auto-refractor is used
Sensitivity = 0.64
Specificity = 0.90 (Hatch)
How many of the children who are not referred from the screening will have myopia?
Myopia Myopia
+ -
Screening 10 98 108
+
Screening 5 887 892
-
Totals 15 985 1,000
False Negatives
C/ C + D
5/892 X 100=0.6%
1,000 children aged 11 – 15 are screened for myopia.
Expected prevalence is 17% (Grosvenor)
Sure Sight Vision Screener is used
Sensitivity = 0.85
Specificity = 0.62 (Hatch)
How many of the children referred from the screening will have myopia?
Myopia Myopia
+ -
Screening 145 315 460
+
Screening 25 515 540
-
Totals 170 830 1,000
Positive Predictive Value
True Positive
A/ A + B
145/460 = 32 %
About 1/3 of the referrals will have myopia
1,000 children aged 11 – 15 are screened for myopia.
Expected prevalence is 17% (Grosvenor)
Sure Sight Vision Screener is used
Sensitivity = 0.85
Specificity = 0.62 (Hatch)
How many of the children who are not referred from the screening will have myopia?
Myopia Myopia
+ -
Screening 145 315 460
+
Screening 25 515 540
-
Totals 170 830 1,000
False Negatives
C/ C + D
25/540= 5%
Of all of the screening methods that have been studied, which method has the worst sensitivity?
Nurse observation.
