Table 1.
Proposed case–control designs and analyses
| 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 | |||
CRA: Colorectal Adenoma; CRC: Colorectal Cancer.
Duke A CRC: CRC diagnosed at stage Duke A; Duke B+ CRC: CRC diagnosed at stage Duke B, C or D.