Screening Flashcards
Testing (i.e. questions, physical exams, labs etc.) asymptomatic people
screening
Examples of screening?
“Annual physical”
Periodic:
- Colonoscopies
- Gynecological exams
- Mammograms
- PSA
What is the purpose and potential benefits of screening?
Detect diseases that are better treated before signs and symptoms show up and prevent people from suffering with or dying from them
Use knowledge of risk factors for disease to prevent or decrease the burden of the disease by modifying the risk factors
The disease that is being screened for should be?
A significant public health problem
- i.e. common and/or significant morbidity and/or mortality
Treatable with these stipulations:
- The potential for cure increases with early detection
- Treatment is easily available
The screening test should be?
- be sensitive to pre-clinical disease
- be safe
- be inexpensive
- be easily accessible/available
- lead to demonstrated improved health outcomes
A condition detected by screening that does not require treatment because it will not adversely affect the patient’s life
If treated, patient may be considered “cured” despite the fact that even ifuntreated, the condition would not have killed them before they died of something else
Pseudodisease
conditions that might not progress to symptomatic disease and may even regress.
Type I Pseudodisease (e.g., ductal carcinomain situ)
slowly progressive disease (conditions with a long detectable preclinical phase)
Type II Pseudodisease ( e.g., prostate cancer)
Unlike when a patient arrives with a concern, screening applies tests to ostensibly healthy people
Pretest probability is therefore usually very __
low
Screening mammography:
Pretest probability (screening clinic): _%
Sensitivity: _%
Specificity: _%
LR+: _
LR-: _
Post-test probability if positive: _%
Post-test probability if negative: _%
3
80
90
8
0.22
20
0.7
What are the harms of screening?
Harms of tests (e.g. radiation, perforation from colonoscopy, cost, time)
False positives:
- Psychological burden
- Further testing (over-testing)
- Over-treatment - even “safe” treatments impose burden, financial and otherwise
Substantial degree of overdiagnosis from mammography screening.
__% for women age 40–49
__% for women age 50–59
Nearly all in __ __ are overdiagnosed
Most __ cancers detected by mammography are overdiagnosed, especially in women aged 40–49
30
20
situ carcinomas
impalpable
Thyroid cancer screening in South Korea from 1999-2008
Thyroid cancer incidence increased 6.4X during this period
- __% of these cancers were small and detected mainly through the screening program
- Mortality from thyroid cancer remained unchanged
- Which criteria did this program fail to fulfill?
- The potential for cure apparently did not increase with early detection
- Testing did not lead to demonstrated improved health outcomes
95
Pap test in women < 25 yo
Detect cervical “pre-cancers” that in fact mostly resolve on their own
At least __% of women at this age have abnormal test results
Harms: increased anxiety, referral, colposcopy, biopsy, unwarranted treatment (some naturopathic practitioners offer escharotic treatment in this context)
10
PSA test
Intended to detect prostate cancer
In one trial, __-__% of the cancers detected by screening were considered overdiagnoses
Harms: Disease labeling and overtreatment, including unnecessary surgery and its complications
Australian study: __% of men who had PSA testing were not informed of the issue of overdiagnosis
21-50
82
