EBM

Question 1

what is screening

Answer 1

a process of identifying apparently healthy people who may be at increased risk of a disease or condition

Question 2

what makes a good screening

Answer 2

evidence that screening is effective and accurate, also clinically, socially and ethically acceptable. but also cost effective and quality assured

Question 3

how well the test detects having the disease when it is present. the true positives

Answer 3

sensitivity

Question 4

[number of results where disease is detected in people with the disease]/ [number of people with the disease] x100

Answer 4

sensitivity

Question 5

what is sensitivity also

Answer 5

false negatives

Question 6

how do u calc the percentage of false neg

Answer 6

100% - true positive %

Question 7

how well the test detects not having the disease - true negatives

Answer 7

specificity (ie false positives)

Question 8

[number of normal or negative results where disease is not detected in people without the disease] / [number of people without the disease] x 100

Answer 8

specificity

Question 9

is sensitivity and specificity affected by the prevalence of the condition?

Answer 9

no

Question 10

are positive/negative predicted values affected by the prevalence of the condition?

Answer 10

YES

Question 11

a highly sensitive test…

Answer 11

picked up most of the disease, very few false negatives

Question 12

a highly specific test…

Answer 12

correctly detects no disease, very few false positives

Question 13

what is PPV

Answer 13

positive predicted value is a measure of how reliable is the test result when it shows disease is present

Question 14

[number of people with a positive test result and have the disease] / [number of people with a positive test result] x100

Answer 14

PPV

Question 15

why does screening occur

Answer 15

reduce disease incidence
reduce disease mortality
earlier, less radical treatment
cost-effective, earlier treatment
overall population benefit

Question 16

what are the possible disadvantages of screening

Answer 16

false reassurance - -ve test doesnt mean no disease

over-investigation and treatment
anxiety increase in participants

longer period of morbidity with unaltered prognosis
potential harms from screening test