screening

Question 1

definition:
early detection of
-
-
-

Answer 1

• disease
• precursors of disease (increase the likelihood of developing a particular disease)
• susceptibility to disease (developing a disease but do not show any signs of disease)

Question 2

what is the goal of early detection

Answer 2

identify the disease early on before symptoms arise

Question 3

briefly explain early detection according to WHO

Answer 3

the presumptive identification of those who probably have disease from those who do not have by means of rapidly applied test in apparently healthy individuals (screening test)

[screening of large populations to detect and implement measures]

Question 4

briefly explain the iceberg of disease

Answer 4

it is the relationship between different levels or stages of a disease within a population

visible tip - clinically apparent cases of the disease that have been diagnosed and treated

submerged portion - many undiagnosed, asymptotic or pre-clinical cases that are not yet visible

in conclusion, the no. of undetected cases in the early stages is much larger than the diagnosed cases. submerged portion is important for prevention, early detection and controlling the overall burden of disease.

Question 5

briefly explain the pyramid of health and disease

Answer 5

top
(1) diseased, diagnosed and controlled
(2) diagnosed, uncontrolled
(3) undiagnosed, misdiagnosed disease
(4) risk factors for disease [increase their susceptibility to developing disease]
(5) free of risk factors
bottom

Question 6

when is screening test conducted

Answer 6

the start of preclinical phase - biological onset of disease

Question 7

briefly explain the pre clinical phase

Answer 7

incubation period - communicable period
latency period - noncommunicable period

[incubation period is the time from exposure to symptom onset, while the latency period is the time from exposure to becoming contagious or infectious to others]

Question 8

define diagnosis

Answer 8

symptoms has not showed yet but is identified in the screening process

Question 9

true or false:
there is symptoms during preclinical phase

Answer 9

false - no symptoms

Question 10

true or false:
in screening test, there is no symptoms and it does not have pathological changes

Answer 10

false - have pathological changes

Question 11

what is the difference between prescriptive screening and proscriptive screening

Answer 11

detection of disease

prescriptive screening - high risk patient
proscriptive screening - entire population

Question 12

what are the objectives of screening programs

Answer 12

describe natural history of disease of a condition
prevention of contagion and protection of public’s health
detect of disease precursor of disease a guide to medical care of individual (prescriptive screening)

Question 13

what are the uses of screening

Answer 13

1. case detection - popu tht has high cases (men = prostate cancer, women = breast cancer)
2. case/ disease control (covid)
3. research (vaccination, development of drugs)
4. health edu - for awareness
5. prescriptive screening - screening to those who are exposed aka high risk (family history of cancer = screening for that type of cancer)
6. proscriptive screening - all the ppl in the community for the benefit of other ppl (covid-19, test kits )
7. natural history of disease
8. public awareness

Question 14

briefly explain screening process (based on the diagram)

Answer 14

identify the indiv who potentially have a particular disease from an apparently well population

the process:
1. applied to healthy populations (all)
2. -ve test = dont have disease under study at that time
3. +ve test = potentially have disease or risk at developing in the future
4.+ve cases then undergo diagnostic procedureed to confirm presence or absence of disease
5. those confirmed = implement interventions
6. -ve cases = no diseases, intervention not required

Question 15

positive on test, no disease =
positive on test, disease present =

Answer 15

positive on test, no disease = false positive
positive on test, disease present = true positive

Question 16

briefly explain diagnostic and screening test

Answer 16

diagnostic - provide yes/no answer about the presence of a disease (gives final confirmation)
screening - identify indiv who may need further diagnostic evaluation for a suspected condition

Question 17

identify whether if it is screening test or diagnostic test:
large grp -
single subject -

Answer 17

large grp - screening
single subject - doagnostic

Question 18

identify whether if it is screening test or diagnostic test:
asymptomatic -
suggestive clinical picture -

Answer 18

asymptomatic - screening
suggestive clinical picture - diagnostic

Question 19

identify whether if it is screening test or diagnostic test:
it is not costly

Answer 19

screening

Question 20

identify whether if it is screening test or diagnostic test:
it is for the basis for treatment

Answer 20

diagnostic

Question 21

identify whether if it is screening test or diagnostic test:
it is conclusive

Answer 21

diagnostic

Question 22

identify whether if it is screening test or diagnostic test:
it is not accurate

Answer 22

screening

Question 23

briefly explain the types of screening test

Answer 23

1. mass
   non selective, large scale, whole population grp covid)
2. high risk
   selective screening, only those who are at high risk
3. multiphasic
   multiple screening, application of 2 or more screening test in combination to a large no. of ppl at one time (blood test, physical examination, nutritional evaluation, cancer screening test)

Question 24

briefly explain the population approach and high risk strategy

Answer 24

popu approach
- not cost effective: every1 is required as long as u r with the infected person
- large chance to reduce disease incidence
- potential to alter the root cause of disease
- small benefit to indiv
- poor subject motivation

high risk strategy
- cost effective
- fails to deal w root cause of disease
- intervention appropriate to indiv (to find how we got hawa)
- subject motivates
- small chance in reducing the disease incidence

Question 25

benefits and limitations of screening

Answer 25

benefits
- improve prognosis for some cases detected
- less radical treatment which cures early cases
-reassurance for those w -ve results

limitations
- hazards of screening (venipuncture, radiation)
- resources cost
- false assurance for those with false negative results
- anxiety to those with false positive results

Question 26

define:
prognosis -
increase of prognosis -

Answer 26

prognosis - improvement of patient
increase of prognosis - patient will get well

Question 27

briefly explain the criteria for successful screening test

Answer 27

1. disease criteria
   - present in population screened
   - high burden and of high public health concern
   - screening and intervention must improve outcome
   - known natural history of the disease
2. test criteria
   - simple and inexpensive
   - cost effective
   - acceptable to subjects and providers
   - reliable
   - exit strategy
   - valid
   - v. safe

Question 28

briefly explain
criteria for successful screening test: reliability

Answer 28

repeatability, reducibility, precision - results r repeated

same results when test repeated in same target indiv in the same setting

Question 29

briefly explain
criteria for successful screening test: cause of unreliability

Answer 29

own SOP/ protocol:
Standard Operating Procedures or testing protocols = intro inconsistencies and errors

observer variation:
diff in how technicians/ observes interpret, perform or score the screening test = variations in same subject

subject variation:
fluctuations in biomarker levels, physiological response or disease progression rates

technical method error variation:
errors or variation in the technical methods (sample collection, handling process, calibration, machine, temp fluctuations)

Question 30

briefly explain
criteria for successful screening test: acceptability

Answer 30

test shld not be
- painful
- unsafe
- discomforting/ embarrassing
- socially/ believes not accepted

Question 31

briefly explain
criteria for successful screening test: validity

Answer 31

able to distinguish btwn who has the disease and who does not

yield
sensitivity
specificity
predictive value

Question 32

briefly explain the efficiency of a screening test

Answer 32

POSITIIVE
w disease & +ve test = true positive
w/o disease & +ve test = false positive

NEGATIVE
w disease & -ve test = false negative
w/o disease & -ve test = true negative

TOTAL
true positive + false negative = total of unknown cases of disease
false positive + true negative = total person w/o disease

Question 33

draw ms danna’s table out and write out all the formulas

Answer 33

-

Question 34

sensitivity =
specificity =
PPV =
NPV =

Answer 34

sensitivity = have sick
specificity = no sick
PPV = positive predictive value
NPV = true negative value

Question 35

true or false:
PPV and NPV is sometimes inverse proportional

Answer 35

false - always

Question 36

what are the 2 simultaneous testing

Answer 36

Net Sensitivity Rate
Net Specificity Rate