1. Evidence Based Screening
Prof. Shlomo Vinker MD, MHA,
Vice Dean, Sackler Faculty of Medicine, Tel Aviv Univ. Chairman, Israeli Association of Family Physicians Chief Medical Director, Leumit Health Services Executive member EGPRN

2. Independence 1991
Area – 603,500 km2
Population – 42,500,000
Human Development Index – 0.75
Annual pop. Growth – negative
Fertility rate – 1.5
Independence 1948
Area - 22,072 km2
Population - 8,462,000
Human Development Index -0.89
Annual pop. Growth – 1.8%
Fertility rate – 2.9

3. THE ICEBEERG PHENOMENON
The Biggest Challenge in Preventive Medicine is to distinguish between
people who have the disease and those who do not.
CLINICAL DISEASE
HIDDEN BURDEN
OF DISEASE
The disease progress from its subclinical stages to overt disease
HIDDEN DISEASE: Subclinical cases, carriers,
undiagnosed cases.

4. Prevention and the Natural history of disease

5. CRITERIA FOR CHOOSING A SCREENING TEST
DISEASE
Significant burden of disease
Detectable and long preclinical stage of disease
Adequately understood natural history of disease
Appropriate test available for early detection of disease
Facilities for diagnosis of disease
Early detection of disease has outcome benefit and expected benefits must exceed risks and costs
Effective treatment available for disease
Policy of screening program for disease

6. SCREENING TEST
Inexpensive
Acceptable
Valid
Reliable
Yielding

7. POSSIBLE BIAS Lead time bias
- the systematic error of apparent increased survival from detecting disease in an early stage.

9. SCREENING TEST vs. DIAGNOSTIC TEST
Done on apparently healthy individuals
Applied to groups
Results are arbitrary and final
Based on one criteria and cut-off
Less accurate
Less expensive
Not a basis for treatment
Initiative comes from investigator
Diagnostic test
Done on sick or ill individuals
Applied on single patient
Diagnosis is not final
Based on evaluation of a no. of signs/symptoms & lab findings
More accurate
More expensive
Used as a basis for treatment
Initiative comes from a patient

10. TYPES OF SCREENING MASS SCREENING
Application of screening test to large, unselected population. Everyone in the group is screened regardless of the probability of having the disease or condition.
a) Visual defects in all school children
Mammography in women
c) Colonoscopy or occult blood.

11. OPPORTUNISTIC / CASE FINDING SCREENING
There is no accurate or precise diagnostic test for the disease and where the frequency of its occurrence in the population is small. The main objective is to detect disease and bring patients to treatment.
Example: a) measuring blood pressure in a physician visit
b) measuring BMI in a nurse visit

12. HIGH RISK / SELECTIVE / TARGETED SCREENING
The screening of selected high-risk groups in the population.
a) Screening fetus for Down’s syndrome in a mother who already has a baby with Down’s syndrome
b) Screening for familial cancers, HTN and DM
c) Screening for CA Cervix in low SES women
d) Screening for HIV in risk groups.

13. WHAT IS VALID AND RELIABLE?
VALIDITY IS THE ACCURACY OF A TEST.
RELIABILITY IS THE PRECISION OF A TEST.
ACCURACY: “how close is result of a test to its true value?”
PRECISION: “how close are the results of a test on repetition?”

14. HA,LP
LA,HP
HA,HP
LA,LP

16. Calculating
An Ideal Screening Test should have 100% Sensitivity, and 100%
Specificity. (Not Practically Possible)

17. PREDICITVE ACCUARCY
Positive Predictive Value:
The Proportion of the people who is screened positive
that actually have the disease. (Are the people with disease
correctly identified?)
Negative Predictive Value:
The Proportion of the people who is screened negative
that are actually FREE of the disease. (Are the people without
disease correctly identified?)
These Values are not fixated for a particular test.

18. Calculating…
PPV= TP/TP+FP
NPV= TN/TN+FN

20. Analytic framework for screening for a disease

21. Wording of recommendations
A - Strongly recommend
benefits substantially outweigh harms
B - Recommend
benefits outweigh harms
C - USPSTF makes no recommendation
benefits and harms closely balanced
D - Recommend against routine use
ineffective interventions or harms outweigh potential benefits
I - In sufficient evidence

22. Ukrainian Screening Program
Conducting clinical examination of the adult population.
Anamnesis according to medical history questionnaires
Anthropometric measurements (blood pressure,height,
Palpation of the breast, gynecological examination of women of 18 years (in the absence of pathology - 1 in every 3 years
Measuring of hearing;
Measurement of visual acuity;

23. Ukrainian Screening Program
Conducting clinical examination of the adult population - No
Anamnesis according to medical history questionnaires - Partial
Anthropometric measurements (blood pressure, BMI) - Partial
Palpation of the breast, gynecological examination of women of 18 years (in the absence of pathology - 1 in every 3 years -No
Measuring of hearing - No
Measurement of visual acuity - No
U.S. Preventive Services Task Force

24. Coronary Heart Disease (Electrocardiography)

25. Cervical Cancer

26. High Blood Pressure in Adults
Recommendation: Screen for high blood pressure. Grade: A
The optimal interval for screening adults for hypertension is not known.
The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) recommends:
● Screening every 2 years with BP <120/80.
● Screening every year with SBP of mmHg or DBP of mmHg.

27. Lipid Disorders in Adults

28. The situation
Most Ukrainian screening recommendations are not according to the most acceptable international guidelines - USPSTF

29. The Solution Not just “copy – paste” Adaptation to disease prevalence
Health problems
Health resources
Health care structure