Colonic preparation before colonoscopy in constipated and non-constipated patients: a randomized study.

AIM

To compare the efficacy of different doses of sodium phosphate (NaP) and polyethylenglicol (PEG) alone or with bisacodyl for colonic cleansing in constipated and non-constipated patients.

METHODS

Three hundred and forty-nine patients, older than 18 years old, with low risk for renal damage and who were scheduled for outpatient colonoscopy were randomized to receive one of the following preparations (prep): 90 mL of NaP (prep 1); 45 mL of NaP + 20 mg of bisacodyl (prep 2); 4 L of PEG (prep 3) or 2 L of PEG + 20 mg of bisacodyl (prep 4). Randomization was stratified by constipation. Patients, endoscopists, endoscopists' assistants and data analysts were blinded. A blinding challenge was performed to endoscopist in order to reassure blinding. The primary outcome was the efficacy of colonic cleansing using a previous reported scale. Secondary outcomes were tolerability, compliance, side effects, endoscopist perception about the necessity to repeat the study due to an inadequate colonic preparation and patient overall perceptions.

RESULTS

Information about the primary outcome was obtained from 324 patients (93%). There were no significant differences regarding the preparation quality among different groups in the overall analysis. Compliance was higher in the NaP preparations being even higher in half-dose with bisacodyl: 94% (prep 1), 100% (prep 2), 81% (prep 3) and 87% (prep 4) (2 vs 1, 3 and 4, P < 0.01; 1 vs 3, 4, P < 0.05). The combination of bisacodyl with NaP was associated with insomnia (P = 0.04). In non-constipated patients the preparation quality was also similar between different groups, but endoscopist appraisal about the need to repeat the study was more frequent in the half-dose PEG plus bisacodyl than in whole dose NaP preparation: 11% (prep 4) vs 2% (prep 1) (P < 0.05). Compliance in this group was also higher with the NaP preparations: 95% (prep 1), 100% (prep 2) vs 80% (prep 3) (P < 0.05). Bisacodyl was associated with abdominal pain: 13% (prep 1), 31% (prep 2), 21% (prep 3) and 29% (prep 4), (2, 4 vs 1, 2, P < 0.05). In constipated patients the combination of NaP plus bisacodyl presented higher rates of satisfactory colonic cleansing than whole those PEG: 95% (prep 2) vs 66% (prep 3) (P = 0.03). Preparations containing bisacodyl were not associated with adverse effects in constipated patients.

CONCLUSION

In non-constipated patients, compliance is higher with NaP preparations, and bisacodyl is related to adverse effects. In constipated patients NaP plus bisacodyl is the most effective preparation.