Colonoscopy screening for colorectal cancer: the outcomes of two recruitment methods

Mike Corbett, Sharon L Chambers, Bruce Shadbolt, Doug Taupin and Lybus C Hillman
Med J Aust 2004; 181 (8): 423-427.


Objectives: To determine the response to colorectal cancer (CRC) screening by colonoscopy, through direct invitation or through invitation by general practitioners.

Design and setting: Two-way comparison of randomised population sampling versus cluster sampling of a representative general practice population in the Australian Capital Territory, May 2002 to January 2004.

Intervention: Invitation to screen, assessment for eligibility, interview, and colonoscopy.

Subjects: 881 subjects aged 55–74 years were invited to screen: 520 from the electoral roll (ER) sample and 361 from the general practice (GP) cluster sample.

Main outcome measures: Response rate, participation rate, and rate of adenomatous polyps in the screened group.

Results: Participation was similar in the ER arm (35.1%; 95% CI, 30.2%–40.3%) and the GP arm (40.1%; 95% CI, 29.2%–51.0%) after correcting for ineligibility, which was higher in the ER arm. Superior eligibility in the GP arm was offset by the labour of manual record review. Response rates after two invitations were similar for the two groups (ER arm: 78.8%; 95% CI, 75.1%–82.1%; GP arm: 81.7%; 95% CI, 73.8%–89.6%). Overall, 53.4% ineligibility arose from having a colonoscopy in the past 10 years (ER arm, 98/178; GP arm, 42/84). Of 231 colonoscopies performed, 229 were complete, with 32% of subjects screened having adenomatous polyps.

Conclusions: Colonoscopy-based CRC screening yields similar response and participation rates with either random population sampling or general practice cluster sampling, with population sampling through the electoral roll providing greater ease of recruitment.

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  • Mike Corbett1
  • Sharon L Chambers2
  • Bruce Shadbolt3
  • Doug Taupin4
  • Lybus C Hillman5

  • 1 The Canberra Hospital, Woden, ACT.
  • 2 Brindabella Specialist Centre, Garran, ACT.



This study was made possible by a grant from the Canberra Hospital Private Practice Trust Fund and a donation from Medical Specialists Associated. No Medicare charges were incurred in the study. We wish to thank participating GPs, particularly Drs Glynn Kelly, Peter Gibson, Bob Hain, Paul Jones, Tuck Meng Soo and Phillip Verghese, for their assistance with recruitment. The encouragement of the ACT Division of General Practice is gratefully acknowledged. We thank Dr Joanna Holt, Dr Mark Bassett and Susan Duthie RN for essential logistical support, including costing of colonoscopies; Ms Barbara Stuart Harris for performing Cancer Registry checks; endoscopists, anaesthetists, nursing and clerical staff at the participating endoscopy centres; and Dr Paul Dugdale and Professor Anne Gardner for helpful comments.

Competing interests:

None identified.

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