A 1-L polyethylene glycol-ascorbate bowel preparation was associated with higher rates of high-quality colon cleansing but similar rates of adequate cleansing compared with 2-L PEG-ascorbate and 4-L PEG in hospitalized adults undergoing elective colonoscopy, according to a multicenter randomized trial.
In the INTERPRET trial, researchers randomly assigned 665 hospitalized adults across seven Italian hospitals to receive split-dose 1-L polyethylene glycol (PEG)-ascorbate, 2-L PEG-ascorbate, or 4-L PEG. Endoscopists assessing bowel preparation quality were blinded to treatment assignment.
The primary endpoint was adequate bowel cleansing, defined as a Boston Bowel Preparation Scale (BBPS) score of at least 6 with no segment score below 2. Adequate cleansing rates were similar across groups, occurring in 82% of patients receiving 1 L, 78% receiving 2 L, and 79% receiving 4 L. The between-group differences were small, and confidence intervals crossed zero, indicating no statistically significant differences.
The trial was designed to assess noninferiority of the 1-L regimen but did not reach its planned enrollment of 846 patients, enrolling 665. As a result, the study was underpowered to formally confirm noninferiority, and findings for the primary endpoint should be interpreted cautiously.
By contrast, high-quality cleansing (BBPS score 8–9), a secondary endpoint, occurred more often with the 1-L regimen: 47% vs 35% with 2 L and 37% with 4 L (secondary outcomes were analyzed without formal multiplicity correction). The absolute differences were 11.6 percentage points (95% CI, 2.5 to 20.5) vs 2 L and 9.5 points (95% CI, 0.3 to 18.5) vs 4 L.
High-quality cleansing in the right colon followed a similar pattern, occurring in 41% of patients receiving 1 L compared with 30% and 32% in the 2-L and 4-L groups.
Adherence exceeded 90% across all regimens. Willingness to repeat the preparation was highest in the 1-L group at 84%, compared with 82% for 2 L and 68% for 4 L.
Vomiting was more frequent with the 1-L regimen, occurring in 15% of patients vs 7% with 2 L and 11% with 4 L. Thirst was also more common with 1 L, while moderate to severe difficulty was reported more often with the 4-L regimen.
Polyp detection rates were 31% in both the 1-L and 4-L groups and 23% in the 2-L group. The trial was not designed or powered to evaluate detection outcomes, and this discrepancy should be considered hypothesis-generating.
Exploratory analyses suggested lower rates of adequate cleansing among patients with reduced mobility, constipation, obesity, or use of centrally acting medications.
The findings apply to clinically stable hospitalized patients, as the trial excluded those undergoing urgent colonoscopy or those with severe or unstable conditions. All study sites were located in Italy, which may limit generalizability.
“In hospitalized adults undergoing elective colonoscopy, 1-L PEG-ascorbate yielded higher rates of high-quality cleansing, including the right colon, than 2-L PEG-ascorbate and 4-L PEG, with similar rates of adequate cleansing and high willingness to repeat,” wrote Leonardo Frazzoni, MD, of the University of Bologna, and colleagues.
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Source: Annals of Internal Medicine
