Rate of Early/missed Colorectal Cancers After Colonoscopy in Older Patients with or Without Inflammatory Bowel Disease in the United States

Objectives: Patients with inflammatory bowel disease (IBD) have an increased risk for colorectal cancer (CRC). Previous studies on early/missed CRCs after colonoscopy excluded IBD patients. The aim of this study was to compare the rate of early/missed CRCs after colonoscopy among IBD and non-IBD patients, and identify factors associated with early/missed CRCs.

Methods: All patients in the Surveillance, Epidemiology and End-Results Medicare-linked database who were 67 years or older at colonoscopy during 1998-2005 and those who were subsequently diagnosed with CRC within 36 months were identified. CRCs diagnosed within 6 months of colonoscopy were categorized as detected CRCs; CRCs diagnosed 6-36 months after colonoscopy were categorized as early/missed CRCs. The rate of early/missed CRCs was calculated as number of early/missed CRCs divided by number of detected and early/missed CRCs. The χ(2) test and multivariate logistic regression were used in statistical analysis.

Results: Of 55,008 CRC patients (304 Crohn's disease; 544 ulcerative colitis (UC)), the rate of early/missed CRCs was 5.8% for non-IBD patients, 15.1% for Crohn's, and 15.8% for UC (P<0.001). Compared with older non-IBD patients, early/missed CRCs among older IBD patients were less likely right-sided (both P<0.05). In multivariate logistic regression, the risk of early/missed CRCs was three times as high for IBD patients (Crohn's odds ratio (OR), 3.07; 95% confidence interval (CI) 2.23-4.21; UC OR, 3.05; 95% CI, 2.44-3.81). Sensitivity analyses confirmed the robustness of this finding.

Conclusions: Older IBD patients had a higher rate of early/missed CRCs after colonoscopy. Our finding supports intensive surveillance colonoscopy for older IBD patients as recommended by guidelines.