Table 1:

Description of the cohorts, administrative data definitions and reference standards for 5 colonoscopy data elements

ElementCohort description, sizeAdministrative data definitionReference standard
Colonoscopy caseAll successfully abstracted charts, n = 1845OHIP codes: Z555A alone or in combination with any of: E740A, E741A, E747A or E705A 14 of the most clinically plausible combinations were evaluated (see Figure 1 for the specific codes included in each definition)Colonoscopy was performed, or there was intent to perform colonoscopy according to endoscopist’s procedure note*
Nonhospital clinicCharts in which colonoscopy was intended or performed, n = 1282
  1. OHIP code E649A billed on date of colonoscopy

  2. No record in CIHI database overlapping with date of colonoscopy according to OHIP database (i.e., no record of procedure’s being done in hospital)

  3. OHIP code E649A and no overlapping record in CIHI database

Presence of endoscopist’s procedure note in nonhospital facility chart
Anesthesiologist assistanceCharts in which colonoscopy was intended or performed, n = 1282OHIP codes for anesthesia (003C or procedure code with “C” suffix [see supplementary tables, Appendix 1, available at]) billed on date as colonoscopy in same patient
  1. Presence of anesthesiologist record in chart regardless of type of sedating agent

  2. Use of propofol as sedating agent according to anesthesiologist’s record

Colonoscopy completenessCharts in which procedure billed with colonoscopy codes, and colonoscopy or flexible sigmoidoscopy was intended,§ n = 1477 (administrative data definition 1), n = 1016 (administrative data definition 2)
  1. OHIP code E747A (to cecum) or E705A (to terminal ileum) billed among colonoscopy procedures defined using most sensitive definition (Z555A ± other E codes)

  2. OHIP code E747A or E705A billed among colonoscopy procedures defined using most accurate definition (Z555A + E741 ± other E codes)

Colonoscopy “intended” and “complete” according to endoscopist’s procedure note
PolypectomyCharts in which colonoscopy was intended or performed,** n = 1256 (reference standard 1), n = 1252 (reference standard 2)
  1. OHIP code Z571A alone

  2. OHIP code Z571A, Z570A or E685A

  3. OHIP code Z571A, Z570A, E685A or E717A

  1. Polyp visualized or polypectomy described according to endoscopist’s procedure note

  2. Adenoma, advanced adenoma or sessile serrated polyp according to pathologist’s report††

  • Note: CIHI = Canadian Institute for Health Information, OHIP = Ontario Health Insurance Plan.

  • * Completed by the endoscopist; includes a description of the procedure, including findings.

  • Completed by the anesthesiologist; record of anesthetic administered during the procedure.

  • Procedures intended as flexible sigmoidoscopy for which E747A or E705A was billed were classified as false-positive. Procedures intended as flexible sigmoidoscopy for which E747A and E705A were not billed were classified as false-negative.

  • § Excluding those with prior total colectomy or right hemicolectomy.

  • Because the histologic findings of the polyp are not available in administrative databases, we could not define adenoma using these data.

  • ** Excluding those with missing data for reference standard.

  • †† Report on the histologic findings of specimens, such as polyps, obtained at colonoscopy.