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Table 1 Proposed case–control designs and analyses

From: An ongoing case–control study to evaluate the NHS Bowel Cancer Screening Programme

Study Criterion Cases Controls
Design 1    
  Previous diagnosis None None
CRA CRA
Duke A CRC Duke A CRC
  Index diagnosis Duke B+ CRC _
  Analysis Exposure to screening prior to first diagnosis of case
Controlling for previous history of CRA & CRC
Adjusting for screen-detection of CRC
Design 2   
  Previous diagnosis None None
CRA CRA
Duke A CRC Duke A CRC
  Index diagnosis Duke B+ CRC _
  Analysis Exposure to screening prior to index diagnosis of case
Controlling for previous history of CRA & CRC
Adjusting for screen-detection of CRC
Design 3   
  Previous diagnosis None None
CRA CRA
  Index diagnosis Duke B+ CRC _
  Analysis Exposure to screening prior to index diagnosis of case
Controlling for previous history of CRA
Design 4   
  Previous diagnosis None None
CRA CRA
  Index diagnosis Any CRC (Duke A-D) _
  Analysis Exposure to screening prior to index diagnosis of case
Controlling for previous history of CRA
Design 5   
  Previous diagnosis None None
CRA CRA
  Index diagnosis Any CRC (Duke A-D) _
Screen-detected Last screened in same year as case index screen
  Analysis Exposure to screening prior to index diagnosis of case
Controlling for previous history of CRA
  1. CRA: Colorectal Adenoma; CRC: Colorectal Cancer.
  2. Duke A CRC: CRC diagnosed at stage Duke A; Duke B+ CRC: CRC diagnosed at stage Duke B, C or D.