Question

1. (a How do you define the term "Screening for Disease"? Please provide some examples.

(b) Why are positive results from screenings not always good enough before treatment is given?

(c) What is the importance of taking/using screenings and surveillance together?

2, What two reasons are given as to why a false alarm during screening may be controversial?

3. Distinguish between the following terms and provide some examples:

        - Primary prevention

      - Secondary prevention

      - Tertiary prevention

4. What do you understand by the following:

       - Reliability

      - Validity

5. How are reliability and validity inter-related?

Answer 1

(1) (a) - Screening for disease is defined as the presumptive identification of unrecognized disease in an apparently healthy , asymptomatic population by means of tests, examination or other procedures that can be applied rapidly and easily to the target population . for example ;- pap smear for cervical cancer , mammogram for breast cancer , clinical breast examination , blood pressure determination ,cholesterol level for heart disease , eye examnation or vision test and urinalysis .

(b) Without screening diagnosis of disease only occurs after symptoms develop .However the disease frequently begins long before symptoms occur and even in the absence of symptoms there may be a point at which the disease could be detected by a screening test . The time interval between possible detection by screening and later detection after symptoms is the detectable pre - clinical phase or DPCP ( detectable pre clinical phase ) . So, that detection of disease in the DPCP will lead to earlier treatment and that this , in turn will lead to a better outcome . The characterstics of a good screening test is ;- Inexpensive , easy to administer , minimal discomfort , Reliable ( consistent) and valid ( distinguish diseased and non- diseased people ) . where as if screening done just before the treatment then it give s false report . that means it does not fulfill the charcteristics of the good screening test .

(c) In managing the health of population , prevention measures may not be feasible or highly effective .Moreover the prevention strategies for many health conditions may not be well known , that why for this reason , screening and surveillance are important strategies in managing population health in communities and in populations receving health care services . The fundamental to the success of both screening and surveillance in terms of improving population health is knowledge of the natural history of the health problem and the ability to accurately detect the problem early .

(2) false alarm during screening is controversial by two reason either by the false psoitive or false negative .

A fasle positive is where we recieve a psoitive result for a test , or when we recieve a negative result , Its sometimes called a s false alarm or false positive error . some example of false postive are ;- A pregnancy test is positive when in fact we aren't pregnant or A cancer screening test comes back positive but we don't have the disease .

And in related concept is a false negative , where we recieve a negative result when we should have recieved a positive one for example ;- a pregnancy test may come back negative even though we are in fact pregnant .

(3) THE THREE LEVEL OF PREVENTION ;-

PRIMARY PREVENTION	SECONDARY PREVENTION	TERITARY PREVENTTION
primary prevention are those preventive measures that prevent the onset of illness or injury before the disease process begins .	Those prevention measures that lead to early diagnosis and prompt treatment of a disease , illness or injury to prevent more severe problems developing . The health educators such as health extensive practitioners can help individual acquire the skills of detecting disease in their early stages .	Those preventive measures that simed at rehabilitation following significant illness.At this level health services workers can work to retain , reeducate or rehabilitate people who have already developed an impairment or disability .
For example ;- immunization and taking regular excercise	For example ;- screening for high blood pressure and breast self - examination	For example ;- working towards rehabilitation from significant illnes or disability , regaining strength .

(4) The reliability and validity are concepts used to evaluate the quality of research .They indicate how well a method , technique or test measures something , Reliability is about consistency of a measure and validity is about the accuracy of a measure .

RELIABILITY refers to how consistently a method measures something .If thesame result can be consistently achieved by using the same method unde the same circumsatnces , the measurement is considerable relaible .

For example ;- we the temperature of a liquid sample several times under identical conditions .The thermometer displays the same thermometer every time ,So the result are reliable .

VALIDITY refers to how accurately a method measures what it i s intended to measures iF research has high validity .That means it produces results that corresponds to real properties , charcteristics and variations on the physical and social world .

For example ;- if the  thermometer shows different temperatures each time , even though we have carefully controlled conditions to ensure the sample's temperature stays the same , the thermometer is probably malfunctioning and therefore its measurement are not valid .

(5) the reliability and validity are interrelated as the relaibility is consistency across time ( test-retest reliability ) , across items ( internal consistency ) and across researchers ( internal reliability ) ,and the validity is the extent to which the    scores actually represent the variable they are intended to be . So, the assessment of reliability and validity is an ongoing process.