Table 1.
Exposure and analytical sample size
| Sample size | |||
|---|---|---|---|
| Exposure period | Pre exposure | Exposure period | |
| Overall* | |||
| Exposure | 2476 | 9638 | |
| Control | 6033 | 36 765 | |
| Site 1: ENT endoscope exposure | January 2008–February 2009 | 561 | 675 |
| Control sites | 1345 | 1508 | |
| Site 2: ENT endoscope exposure | September 2002–January 2009 | 138 | 378 |
| Control sites | 637 | 1089 | |
| Site 3: colonoscope exposure | April 2003–December 2008 | NA | 6226 |
| Controls sites | NA | 12 739 | |
| Site 4: colonoscope exposure | May 2004–February 2009 | 2012 | 6189 |
| Control sites | 11 594 | 26 499 | |
| Site 5: dental exposure | February 2009–March 2010 | 1777 | 1794 |
| Control sites | 4051 | 5083 | |
| Site 6: dental exposure | January 1992–July 2010 | NA | 565 |
| Control sites | NA | 16 346 | |
*Total excludes site 4.
ENT, ear, nose and throat; NA, not available given exposure period and available data.