Serious events in older Ontario residents receiving bowel preparations for outpatient colonoscopy with various comorbidity profiles: a descriptive, population-based study

Background — Polyethylene glycol-based bowel preparations (PEGBPs) and sodium picosulfate (NaPS) are commonly used for bowel cleansing before colonoscopy. Little is known about adverse events associated with these preparations, particularly in older patients or patients with medical comorbidities.

Objective — To characterize the incidence of serious events following outpatient colonoscopy in patients using PEGBPs or NaPS.

Methods — The present population-based retrospective cohort study examined data from Ontario healthcare databases between April 1, 2005 and December 31, 2007, including patients >=66 years of age who received either PEGBP or NaPS for an outpatient colonoscopy. Patients with cardiac or renal disease, long-term care residents or patients receiving concurrent diuretic therapy were identified as high risk for adverse events. The primary outcome was a serious event (SE) defined as a composite of nonelective hospitalization, emergency department visit or death within seven days of the colonoscopy.

Results — Of the 50,660 outpatients >=66 years of age who underwent a colonoscopy, SEs were observed in 675 (2.4%) and 543 (2.4%) patients in the PEGBP and NaPS groups, respectively. Among high-risk patients (n=30,168), SEs occurred in 481 (2.8%) and 367 (2.8%) of patients receiving PEGBP and NaPS, respectively.

Conclusions — The SE rate within seven days of outpatient colonoscopy was 24 per 1000 procedures, and among high-risk patients was 28 per 1000 procedures. The rates were similar for PEGBP and NaPS. Clinicians should be aware of the risks associated with colonoscopy in older patients with comorbidities.