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Colorectal Cancer Screening Quality (Perforation) Methodology

Outpatient Perforation​
Short description of Indicator Number of outpatient colonoscopies followed by hospital admissions for perforation within 7 days of procedure, per 1,000​​
Rationale for measurement A colonoscopic perforation is a complication that will result in hospitalization. It is widely recognized as one of the most serious complications following lower gastrointestinal endoscopies.[1] This complication leads to higher costs and use of resources, is associated with a high rate of morbidity for the patient, and may even lead to death.[2] Colonic conditions that are known to affect the risk of perforation include pseudo- obstruction, ischemia, severe colitis, radiation-induced changes, stricture formation, bulky colorectal cancers, more severe forms of diverticular disease, and chronic corticosteroid therapy.[3] Certain procedure-related occurrences may increase the likelihood of perforations including polypectomy, colonic dilation and stent insertion. The elderly are also at higher risk of perforation.​
Evidence/references for rationale
  1. Lohsiriwat V. Colonoscopic perforation: Incidence, risk factors, management and outcome. World J Gastroenterol. 2010 Jan 28; 16(4):425–30.
  2. Rabeneck L, Paszat LF, Hilsden RJ, Saskin R, Leddin D, Grunfeld E et al. Bleeding and perforation after outpatient colonoscopy and their risk factors in usual clinical practice. Gastroenterol. 2008 Dec;135(6):1899–1906e1.
  3. Rex DK, Petrini JL, Baron TH, Chak A, Cohen J, Deal SE et al. Quality indicators for colonoscopy. Am J Gastroenterol. 2006 April;101(4):873–85.

Calculations for the indicator (Total number of outpatient colonoscopies followed by hospital admissions for perforation within 7 days of colonoscopy / Total number of outpatient colonoscopies performed among Ontario individuals, age 18 or older) X 100​0
Standardized Rate Calculation N/A​
Unit Rate per 1,000​​
Data sources
  • CIHI NACRS – Hospital admissions to define outpatient colonoscopies
  • CIHI DAD - Perforation related hospital admissions and colorectal cancer diagnoses
  • OHIP CHDB (Claims History Database) – Colonoscopy claims
  • RPDB (Registered Persons Database) – Demographics
  • PCCF+, version 6D - Residence
  • OCR (Ontario Cancer Registry) – Resolved invasive colorectal cancers

Time Frame 2014 - 2017​​
Geographic Scale Provincial (Ontario)​
Denominator description Total number of outpatient colonoscopies performed in the reporting period
  • Individuals ages 18 and older who had at least 1 colonoscopy in the reporting period
  • Colonoscopies were defined as a record in OHIP by fee codes: Z codes (Z555A, Z491A-Z499A)
  • Outpatient colonoscopies only, defined by linking OHIP claims to CIHI NACRS records


  • Individuals with a missing or invalid HIN, date of birth
  • Individuals with a total colectomy before the index date; total colectomy was identified using OHIP fee code S169A, S170A and S172A

Numerator description Total number of outpatient colonoscopies followed by hospital admissions for perforation within 7 days of colonoscopy
  • Colonoscopy perforation was defined when a patient was admitted to hospital with T812, K631, K650, K658, K659, S36510, S36511, S36991 as one of the diagnosis codes, and associated with diagnosis type 1, 6, W, X, Y, or M within 7 days following the colonoscopy, AND with any of the following conditions:
    • Patients with a diagnosis code Y604 (unintentional cut, puncture, perforation or haemorrhage during endoscopic examination)
    • Patients with no other procedures done
    • Patients with procedures performed during the hospitalization that would likely be done to support perforation (e.g., surgery). The definition excludes patients with colorectal cancer undergoing surgery that could be used to treat colorectal cancer


  • Patients with a second colonoscopy during admission
  • Patients with splenectomy, control of bleeding outside of the colon, cancer of GI tract
  • Patients with procedure codes suggesting hospital admission was for reasons other than to treat perforation

Considerations N/A​
Data availability & limitations Emergency department visits and same-day surgeries are included in the same NACRS file used to identify inpatient or outpatient colonoscopies​​​