The quality of evidence is downgraded by study limitations (lack of blinding and selective outcome reporting) and by imprecise results (few patients).
A Cochrane review [Abstract] 1 included 25 studies with a total of 2 310 subjects. The age range varied from 6 months up to 16 years. The duration of the studies varied from 2 weeks to 12 months. 2 studies compared polyethylene glycol (PEG) with placebo, 5 compared PEG with lactulose, 3 compared PEG with milk of magnesia (magnesium oxide), 2 compared liquid paraffin with lactulose, 2 compared liquid paraffin with PEG, 1 compared PEG with enemas, 1 compared a dietary fibre mix with lactulose, 1 lactulose with senna and 1 lactitol with lactulose.
Polyethylene glycol (PEG) increased the number of stools per week compared with placebo (MD 2.61 stools per week, 95% CI 1.15 to 4.08; 2 studies, n=101; statistical heterogeneity, I2 =58%). Common adverse events included flatulence, abdominal pain, nausea, diarrhoea and headache. Participants receiving high dose PEG (0.7 g/kg) had significantly more stools per week than low dose PEG (0.3 g/kg) participants (MD 1.30, 95% 0.76 to 1.84; 1 study, n=90).
PEG showed significantly greater stools per week than lactulose (MD 0.70 stools per week, 95% CI 0.10 to 1.31; statistical heterogeneity, I2 =69%; 6 studies, n=465), although follow up was short. Patients who received PEG were significantly less likely to require additional laxative therapies (18% of PEG patients required additional therapies compared to 31% of lactulose patients; RR 0.55, 95% CI 0.36 to 0.83). No serious adverse events were reported with either agent. Common adverse events in these studies included diarrhoea, abdominal pain, nausea, vomiting and pruritis ani.
The stools/wk was significantly greater with PEG compared with milk of magnesia (MD 0.69 stools per week, 95% CI 0.48 to 0.89; 3 studies, n=211). However, the magnitude of this difference was quite small and may not be clinically significant. One child was noted to be allergic to PEG, but there were no other serious adverse events reported. One study found a significant difference in stools per week favouring milk of magnesia over lactulose (MD -1.51, 95% CI -2.63 to -0.39; 1 study, n=50).
Liquid paraffin (mineral oil) compared with lactulose revealed a relatively large statistically significant difference in the number of stools per week favouring liquid paraffin (MD 4.94 stools per week, 95% CI 4.28 to 5.61; 2 studies, n=287). No serious adverse events were reported. Adverse events included abdominal pain, distention and watery stools.
No statistically significant differences in the number of stools per week were found between PEG and enemas (MD 1.00, 95% CI -1.58 to 3.58; 1 study, n=90), dietary fibre mix and lactulose (P = 0.481; 1 study, n=125), senna and lactulose (P > 0.05: 1 study, n=21), lactitol and lactulose (MD -0.80, 95% CI -2.63 to 1.03; 1 study, n=51), hydrolyzed guar gum and lactulose (MD 1.00, 95% CI -1.80 to 3.80; 1 study, n=61), PEG and flixweed (MD 0.00, 95% CI -0.33 to 0.33; 1 study, n=109), PEG and dietary fibre (MD 0.20, 95% CI -0.64 to 1.04; 1 study, n=83), and PEG and liquid paraffin (MD 0.35, 95% CI -0.24 to 0.95; 2 studies, n=261).
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