Sodium phosphate is superior to polyethylene glycol in constipated patients undergoing colonoscopy: a systematic review and meta-analysis

Background Constipation is an important and highly prevalent predictor of inadequate bowel preparation during colonoscopy. In North America, between 2 and 28% of the general population suffer from constipation. Despite the high prevalence of constipation, to our knowledge, no meta-analysis on the optimal bowel preparation for constipated patients has been performed. We aimed to systematically review the literature to determine the ideal bowel preparation regiment for patients with chronic constipation . Methods A comprehensive search of electronic databases (MEDLINE, EMBASE, SCOPUS, and Web of Science) was performed. We included studies that assessed the quality of bowel preparation in constipated patients receiving different agents prior to colonoscopy. The primary outcome was colon cleanliness. Secondary outcomes included tolerability of the bowel preparation and serious adverse events. Results Preliminary database search yielded 1581 articles after duplicates were removed. After screening of the titles and abstracts using the exclusion criteria, 358 full-text articles were retained. Full-text articles were reviewed and eight studies meeting the inclusion criteria were included for qualitative synthesis. Three randomized controlled trials identified a total of 1636 constipated patients, of whom 225 were eligible for meta-analysis. Of those, 107 (47.6%) received NaP and 118 (52.4%) received PEG. Patients receiving NaP before colonoscopy had a higher chance of a successful bowel preparation than patients receiving PEG (OR 1.87, CI 1.06 to 3.32, P = 0.003). In the studies comparing PEG to NaP, two found that NaP resulted in greater tolerability of the bowel preparation and one study found that PEG resulted in superior tolerability. Conclusions In chronically constipated patients undergoing colonoscopy, the use of NaP may result in superior colonic cleanliness when compared to PEG, however, quality of evidence was low. Further high-quality studies are required to delineate the optimal bowel preparation in patients with constipation.