What is Screening? Basic Health promotion Concepts Health promotion national conference 2010 Poster Presentation supervised by Dr Aidah Al Kaissi, RN,BSN,MD,PhD

What is Screening?

Basic Health promotion Concepts

Health promotion national conference 2010

Poster Presentationsupervised by

Dr Aidah Al Kaissi , RN,BSN,MD,PhD

Prepared by :

Mohammed Salahat

&others

Contents

04/19/23 Working to promote health in Palestine “ call for national action “

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SCREENING: DEFINITION

• “The PRESUMPTIVE identification of UNRECOGNIZED disease or defect by the application of tests, exams or other procedures which can be applied RAPIDLY to sort out apparently well persons who PROBABLY have a disease from those who PROBABLY do not”*

• Key Elements:

• disease/disorder/defect

• screening test

Screening and prevention

• The actual process of screening is a form of secondary prevention , whether the health education about screening comes under primary prevention .

• The primary objective of screening is the detection of a disease in its early stages to treat and deter its progression .

• Early asymptomatic period in any health condition allows treatment and prevention .


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Advantages & disadvantages

• Screening tests offer several advantages and disadvantages :-

• Advantages :- • 1 – Simplicity and cost effectiveness of

the screening tests & this means :-

A – Time save ( serving more and more populations )

B – low cost ( available to all )• 2 – Ability to serve screening

programs to both individual and large populations .


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Cont’ed Disadvantages

• Disadvantages majorly appear in imperfection of modern science , which results in a margin of error for most instruments and tests .

• Effectiveness depends on the test’s ability to distinguish those who probably do have the disease from those do not .

• This errors and malfunctions lead to :-• 1- Individuals anxiety .• 2- Time wasting and cost of follow up diagnostic

tests .• 3- Lose opportunity to receive early treatment and

prevent irreversible .damage .

•


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Selection of a screenable disease

• GOLDEN ROLE :-

( The Greater the physical and psychological harm experienced by the population , the greater the need to designate the disease as a priority health problem ) .


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Issues in Screening

• -Disease/disorder should be an important public health problem

• High prevalence• Serious outcome

• -Early Detection in asymptomatic (pre-clinical) individuals is possible

• -Early detection and treatment can affect the course of disease (or affect the public health problem?)


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Screening Test Concerned with a Functional Definition of Normality versus Abnormality


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Screening Test

Normal Abnormal

High Priority health problems – need screening

• The following information is indicates recent articles and researches up to 2010 studies .

• PKU Phenylketonuria :- ( Leads to brain damage and CNS dimension which ends with mental retardation resulting from genetic lack of phenylalanine hydroxylase , which is an enzyme necessary to metabolize an important amino acid “phenylalanine” , in its absence , blood level of phenylalanine increase causing previous irreversible damage .


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Cont’ed PKU Phenylketonuria

• PKU is a paradigm of a disease that can be identified by proper screening of newborns and medical follow-up in order to prevent serious complications.

• The following study about PKU screening done recently by the end of June of 2010 in Gaza Strip .


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Screening Programme for Phenylketonuria in the Gaza Strip• Data about the screening of PKU in the

Gaza Strip were obtained from the records of the healthcare centers of the Palestinian Ministry of Health

(MOH) during the year 2010. In addition, PKU patients and families

were interviewed.• The results showed that the

prevalence of PKU in the Gaza Strip varied considerably between the different regions with an overall prevalence of 6.35/100 000


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Cont.

• while the maximum prevalence of 28.3/100 000 occurred in the rural areas. Coverage of PKU testing in the Gaza Strip is limited to about 35.3 % of the total newborns, who are delivered and receive health care at the government clinics.


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Cont.

• Among those newborns delivered at the government clinics, the percentage of PKU screening is about 87.8 %. However, PKU testing is not carried

out at UNRWA clinics where about two-thirds of newborn deliveries take place.


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Cont.

• On average, 61 % of PKU testing is made in the infant’s second week, ranging between 11 and 17 days, and the remaining (39 %) are tested thereafter. Approximately 60 % of PKU patients had consanguine parents (first cousins), while 7.7 % had no consanguinity.


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Cont.

• Only 43.1 % of PKU patients were fed on the specialized low phenylalanine milk. An inverse correlation was reported between the use of low phenylalanine milk and age. A total of 35.4 % of the PKU patients were

regularly monitored by blood tests each month .


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Cont.

• 47.7 % had not been tested for the previous year. It was concluded that the PKU screening programme has to be improved, the screening methods should be reviewed, and the screening coverage should include all the newborns in the Gaza Strip .


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Done By :-

• This Study Done By :

• 1 Biology Department, Al-Azhar University, Gaza

• 2 College of Public Health, Gaza

• 3 Gaza Central Laboratories,

• Ministry of Health, Gaza


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Second Screenable disease Breast Cancer

• Breast Cancer is indicated As a lesion in the breast indicates the disease , severity is based on the size of the lesion and the length of time that it has been present .

• Screening for asymptomatic cases and findings unnoticed and presumably smaller masses permit more successful and conservative treatment because the stage is less service .


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Breast Cancer Incidence among Palestinian Women

• BC incidence < other populations. Still, it is the most common malignancy among Palestinians.

• 2nd leading cause of cancer morbidity & mortality among Palestinian women.

• In Palestine (2009 ) 116 cases of BC were recorded ( 23%of all cancer cases)

• Average of 222 new BC in 2008-2009

• Crude incidence rate-ASR : 28.8 /100.000 West Bank 34.5/100.000 Gaza Strip


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Young age & Advanced stage at presentation of BC patients in

Palestine

• 64%< 50 years at the time of diagnosis • Survival, Age & Stage at diagnosis

among Palestinian

– Mean age at diagnosis=51.5 years • 11% of the Palestinian patients were <

age of 35

• Survival, Age & Stage at diagnosis Jewish :

– Mean age at diagnosis=55.9 years

– 5% of the Jewish patients were < age of 35


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Age Distribution In Palestine

• Age under 5 years: 12.1%• Age under 15 years: 38%• Age over 65 years: 3.6%

In many countries, 15 to 25% of the population is above 65 years of age

• Increasing age of the population Increase incidence of cancer


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Recommendation

Raise the need for:( Development of Screening Programs )to:

1-Early detection 2-Defining of high risk group


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Third Screenable diseaseProstate Cancer

• Prostate Cancer , the second leading cause of death in U.S ( U.S Dept. of human services ,2000) ,

• Risk increases with age beginning at 50 years and higher among black men

• Three principle screening for this Disease : -

1. Analysis for the serum tumor maker Prostate specific antigen PSA .

2. Transrectal Ultrasound TRUS

3. DRE


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Good News

• In United States the recent decade approved the effect of breast cancer screening in reducing incidence from 56% in women to 25% .

• Italian Association of Breast Cancer approved that the incideince of 62% of women with breast cancer decreased by 20% to 42% in 3 years indue of applying National program of breast cancer screening


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Breaking News

• In Palestine incidence of breast cancer increased among women in the last 5 years from 22% to 25 % which let us really call for National action .

• Palestinian Ministry of health – 2008 study of breast cancer prevalence , Study and research Dept , Jothor Centre , Ramallah


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High Priority health problems – need screening

• In Addition to previous Diseases there are a lot of Diseases and issues of high public health priority which include :-

1- Cervical Cancer

2- Cholestrol Levels

3- Hypertension


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Criteria & instruments for Evaluating a Screening Test

• Validity: provide a good indication of who does and does not have disease

• -Sensitivity of the test :- refers to the proportion of persons with a condition who correctly test positive when screened .

• A test with poor sensitivity will miss individuals with the condition and there will be a large number of false negative test result ( Individuals who actually have the condition but were told they are disease free ) .


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Cont’ed

• Specificity of the test :- measures the test’s ability to recognize negative reactions or no diseased individuals who actually have a condition , a false positive, when in actually they do not .

• Reliability: (precision): gives consistent results when given to same

person under the same conditions.

• Yield: Amount of disease detected in the population, relative to the effort

• Prevalence of disease/predictive value


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Validity of Screening Test (Accuracy)

- Sensitivity: Is the test detecting true cases of disease? (Ideal is 100%: 100% of cases are detected)

-Specificity: Is the test excluding those without disease? (Ideal is 100%: 100% of non-cases are negative)


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Screening for Glaucoma using IOP


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IOP > 22 Yes No

Yes 50 100

No 50 1900

Total 100 2000

True Cases of Glaucoma

Sensitivity = 50% (50/100) False Negative=50%Specificity = 95% (1900/2000) False Positive=5%

Where do we set the cut-off for a screening test?


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Consider:

• -The impact of high number of false positives:

• anxiety, cost of further testing

• -Importance of not missing a case:

• seriousness of disease, likelihood of re-screening


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Reliability (reproducibility) Agreement within and between examiners


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Validity versus Reliability of Screening Test

Examiner 1 Examiner 2 Examiner 3

True cases

Good Reliability

Low Validity


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Yield from a Screening Test for Disease X

Predictive Value

X

X

Screening Test

Negatives Positives

X

X

X

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Yield from the Screening Test: Predictive Value


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•Relationship between Sensitivity, Specificity, and Prevalence of DiseasePrevalence is low, even a highly specific test will give large numbers of False Positives .

•Predictive Value of a Positive Test (PPV): Likelihood that a person with a positive test has the disease .•Predictive Value of a Negative Test (NPV): Likelihood that a person with a negative test does not have the disease .


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IOP > 22 Yes No

Yes 50 100

No 50 1900

Total 100 2000

True Cases of Glaucoma

Specificity = 95% (1900/2000) False Positive=5%Positive Predictive Value =33%

Screening for Glaucoma using IOP

How Good does a Screening Test have to be?

• IT DEPENDS• -Seriousness of disease,

consequences of high false positivity rate:

• -Rapid HIV test should have >90% sensitivity, 99.9% specificity.

• -Screen for nearsighted children proposes 80% sensitivity, >95% specificity.

• -Pre-natal genetic questionnaire could be 99% sensitive, 80% specific .


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Principles for Screening Programs

1. Condition should be an important health problem

2. There should be a recognizable early or latent stage

3. There should be an accepted treatment for persons with condition

4. The screening test is valid, reliable, with acceptable yield

Cont’ed

1. The test should be acceptable to the population to be screened

2. The cost of screening and case finding should be economically balanced in relation to medical care as a whole


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Nursing Role in Screening

• Intervention and implementation of screening process on target groups and individuals .

• Decision making and planning :

1. Criteria

2. Ethics

3. Community resources


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Summary • Rapid administration of a simple test to

distinguish individuals do not have a condition .

• A unique characteristic and significant advantage of screening is that it can be applied to individuals or groups .

• Three questions provide a means of analyzing the screenability of a disease :-

• 1- Is the condition significant ?

2- Can the condition be screened ?

3- Should the condition be screened ?


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References

• Alberti, K.G.M.M.,DeFronzo, R.A.&Zimmet,P.

• Burnam,M.A.,Hough,R.L.,Karno,M., Escobar,J.,&Telles,C.A.


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Documents

What is Screening? Basic Health promotion Concepts Health promotion national conference 2010 Poster Presentation supervised by Dr Aidah Al Kaissi, RN,BSN,MD,PhD