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Walk the Even Hospital Database by book and chapter — the raw source passages that ground Ask, DDx, and the rest.
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©2013 UpToDate ® Print Email Avoiding bias in screening Bias Effect How to avoid Lead time Appears to improve survival time but actually increases "disease" time after disease detection Use mortality rather than survival rates. Length time Outcome appears better in screened group because more cancers with a good prognosis are detected Compare outcomes in RCT with control group and one offered screening. Count all outcomes regardless of method of detection. Compliance Outcome in screened group appears better due to compliance, not screening Compare outcomes in RCT with control group and one offered screening. Count all outcomes regardless of compliance. Reproduced with permission from: Fletcher RH, Fletcher SW. Prevention. In: Clinical Epidemiology - The Essentials, 4th ed. Lippincott Williams & Wilkins, Baltimore 2005. Copyright © 2005 Lippincott Williams and Wilkins. file://www.lww.com