Epi
Lead-Time Bias
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Lead-Time Bias
, Leadtime Bias
See Also
Screening Test
Contingency Grid
or
Cross Tab
(includes
Statistics Example
)
Bayes Theorem
(
Bayesian Statistics
)
Fagan Nomogram
Experimental Error
(
Experimental Bias
)
Length Bias
Selection Bias
Likelihood Ratio
(
Positive Likelihood Ratio
,
Negative Likelihood Ratio
)
Number Needed to Screen
(
Number Needed to Treat
,
Absolute Risk Reduction
,
Relative Risk Reduction
)
Negative Predictive Value
Positive Predictive Value
Pre-Test Odds
or
Post-Test Odds
Receiver Operating Characteristic
Test Sensitivity
(
False Negative Rate
)
Test Specificity
(
False Positive Rate
)
U.S. Preventive Services Task Force Recommendations
Definition
Early diagnosis falsely appears to prolong survival
Example
Disease 'A' is 100% fatal
Disease 'A' lasts 7 years from onset to death
Disease 'A' patients are asymptomatic for 4 years
Disease 'A' median survival 3 years after diagnosis
Screening Test
can identify Disease 'A' early
Detection occurs 2 years before clinical diagnosis
Disease 'A' still lasts 7 years before death
Disease 'A' is now asymptomatic for 2 years
Disease 'A' median survival 5 years after diagnosis
Screening Test
falsely appears to prolong survival
Screened and unscreened patients each survive 7 years
Screened patients know diagnosis 2 years earlier
References
Gates (2001) Am Fam Physician 63(3):513-22 [PubMed]
MacLean (1996) Med Clin North Am 80(1):1-14 [PubMed]
Nielsen (1999) Med Clin North Am 83(6):1323-37 [PubMed]
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