title: Factors associated with colorectal cancer occurrence after colonoscopy that did not diagnose colorectal cancer.
abstract: OBJECTIVE
  Up to 6% of colorectal cancers (CRCs) are diagnosed within 5 years of a colonoscopy that did not diagnose CRC (post-colonoscopy colorectal cancer, PCCRC). PCCRC and associated risk factors were examined within a national hospital episode database.
  
  
  METHODS
  A retrospective case-control study of all colonoscopies performed on adults recorded in Hospital Episode Statistics (HES) between 2003 and 2009 in England. PCCRC cases underwent colonoscopy 6 to 60 months before diagnosis; controls had not undergone colonoscopy 6 to 60 months before diagnosis. Multivariate logistic regression analysis examined associations with PCCRC.
  
  
  RESULTS
  A total of 1,439,684 colonoscopies were analyzed, including 67,202 cases of CRC and 8147 cases of PCCRC (12.1%). Multivariate analysis revealed that female sex (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.08-1.19; P < .001), older age (70-74 years) (OR, 1.09; 95% CI, 1.00-1.18; P = .039), increased comorbidity (Charlson index 5+) (OR, 1.16; 95% CI, 1.05-1.28; P < .003), and CRC of the right side of the colon (OR, 1.17; 95% CI, 1.11-1.23; P < .0001) were associated with PCCRC. Emergency colonoscopy (OR, 0.54; 95% CI, 0.59-0.69; P < .0001) was negatively associated with PCCRC. More individuals with PCCRC developed metastases within 12 months and fewer underwent surgery (OR, 0.33; 95% CI, 0.32-0.35; P < .0001) or chemotherapy (OR, 0.66; 95% CI, 0.62-0.69), P < .0001). PCCRC rates varied 2-fold between providers and PCCRC was associated with medium-volume providers compared with high-volume providers (OR, 1.13; 95% CI, 1.01-1.27; P = .035). The PCCRC rate fell from 13.8% in 2003 to 11.9% in 2009.
  
  
  CONCLUSIONS
  PCCRC occurred in 12.1% of patients with CRC between 2003 and 2009. PCCRC was associated with female sex, older age, increased comorbidity, CRC of the right side of the colon, elective procedures, and colonoscopy volume. PCCRC was associated with worse outcomes.
authors.affiliation: Department of Gastroenterology, Sandwell General Hospital, Lyndon, West Bromwich, UK.
authors.forename: Danny
authors.initials: D
authors.lastname: Cheung
authors.affiliation: Health Informatics Department, Queen Elizabeth Hospital, Birmingham, UK.
authors.forename: Felicity
authors.initials: F
authors.lastname: Evison
authors.affiliation: School of Cancer Sciences, University of Birmingham, Birmingham, UK.
authors.forename: Prashant
authors.initials: P
authors.lastname: Patel
authors.affiliation: Department of Gastroenterology, Sandwell General Hospital, Lyndon, West Bromwich, UK.
authors.forename: Nigel
authors.initials: N
authors.lastname: Trudgill
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D044682:Colon, Ascending / Q000473:pathology; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D015897:Comorbidity; D016208:Databases, Factual; D055088:Early Detection of Cancer; D017558:Elective Surgical Procedures; D004630:Emergencies; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors