Predictive factors for colonoscopy complications.

Objective: To determine factors predicting complications caused by colonoscopy.

Design: Prospective cohort study.

Setting: A private hospital in Hong Kong.

Patients: All patients undergoing colonoscopy in the Endoscopy Centre of the Hong Kong Sanatorium & Hospital from 1 June 2011 to 31 May 2012 were included. Immediate complications were those that were recorded by nurses during and up to the day after the examination, while delayed complications were gathered 30 days after the procedure by way of consented telephone interview by trained student nurses. Data were presented as frequency and percentage for categorical variables. Logistic regression was used to fit models for immediate and systemic complications with related factors.

Results: A total of 6196 patients (mean age, 53.7 years; standard deviation, 12.7 years; 3143 women) were enrolled and 3657 telephone interviews were completed. The incidence of immediate complications was 15.3 per 1000 procedures (95% confidence interval, 12.3-18.4); 50.5% were colonoscopy-related, including one perforation and other minor presentations. Being female (odds ratioadjusted=1.6), use of monitored anaesthetic care (odds ratioadjusted=1.8), inadequate bowel preparation (odds ratioadjusted=3.5), and incomplete colonoscopy (odds ratioadjusted=4.5) were predictors of risk for all immediate complications (all predictors had P<0.05 by logistic regression). The incidence of delayed complications was 1.6 per 1000 procedures (95% confidence interval, 0.3-3.0), which comprised five post-polypectomy bleeds and one post-polypectomy inflammation. The overall incidence of complications was 17.8 per 1000 procedures (95% confidence interval, 13.5-22.1). The incidences of complications were among the lower ranges across studies worldwide.

Conclusion: Inadequate bowel preparation and incomplete colonoscopy were identified as factors that increased the risk for colonoscopy-related complications. Colonoscopy-related complications occurred as often as systemic complications, showing the importance of monitoring.