Identification of factors associated with sedation tolerance in 5000 patients undergoing outpatient colonoscopy: Canadian tertiary center experience

AIM: To develop a prediction model aimed at identifying patients that may require higher than usual sedation doses during colonoscopy. METHODS: A retrospective chart review on 5000 patients who underwent an outpatient colonoscopy at St. Paul’s Hospital from 2009 to 2010 was conducted in order to develop a model for identifying patients who will require increased doses of sedatives. Potential predictor variables including age, gender, endoscopy indication, high sedation requirements during previous endoscopies, difficulty of the procedure, bowel preparation quality, interventions, findings as well as current use of benzodiazepines, opioids and alcohol were analyzed. The outcome of study was the use of high dose of sedation agents for the procedure. In particular, the high dose of sedation was defined as fentanyl greater than 50 mcg and midazolam greater than 3 mg. RESULTS: Analysis of 5282 patients (mean age 57 ± 12, 49% female) was performed. Most common indication for the procedure was screening colonoscopy (57%). Almost half of our patients received doses exceeding Fentanyl 50 mcg and Midazolam 3 mg. Logistic regression models identified the following variables associated with high sedation: Younger age (OR = 0.95 95%CI: 0.94-0.95; P < 0.0001); abdominal pain (OR = 1.45, 95%CI: 1.08-1.96); P = 0.01) and Inflammatory Bowel Disease (OR = 1.45, 95%CI: 1.04-2.03; P = 0.02) as indications for the procedure; difficult procedure as defined by gastroenterologist (OR = 1.73, 95%CI: 1.48-2.03; P < 0.0001); past history of abdominal surgery (OR = 1.33, 95%CI: 1.17-1.52; P <0.0001) and previous colonoscopy (OR = 1.39, 95%CI: 1.21-1.60; P = 0.0001) and alcohol use (OR = 1.26, 95%CI: 1.03-1.54; P = 0.02). Age and gender adjusted analysis yielded inflammatory bowel disease as an indication (OR = 3.17, 95%CI: 1.58-6.37; P = 0.002); difficult procedure as defined by an endoscopist (OR = 5.13 95%CI: 2.97-8.85; P = 0.0001) and current use of opioids, benzodiazepines or antidepressants (OR = 2.88, 95%CI: 1.74-4.77; P = 0.001) having the highest predictive value of high sedation requirements. Our prediction model using the following pre-procedural variables including age, gender, indication for the procedure, medication/substance use, previous surgeries, previous high sedation requirements for colonoscopy yielded an area under the curve of 0.76 for Fentanyl ≥ 100 mcg and Midazolam ≥ 3 mg. CONCLUSION: Pre-procedural planning is the key in conducting successful, efficient colonoscopy. Logistic regression analysis of 5000 patients who underwent out-patient colonoscopy revealed the following factors associated with increased sedation requirement: Younger age, female gender, difficult endoscopy, specific indications as well as cardiopulmonary complications and current use of opioids/benzodiazepines. Age and gender adjusted analysis yielded similar results. These patients are more likely to need a longer recovery periods post-endoscopy, which could result in additional time and personnel requirements. The final predictive model has good predictive ability for Fentanyl ≥ 100 mcg and Midazolam ≥ 3 mg and fair predictive ability for Fentanyl ≥ 50 mcg and Midazolam ≥ 2 mg. The external validity of this model is planned to be tested in another center.