Prospective randomized crossover trial comparing fibre with lactulosein the treatment of idiopathic chronic constipation

Background Fibre is often recommended as the first-choice treatment but its effects can be uneven. The aim of the study was to compare the clinical efficacy and tolerability of fibre versus lactulose in outpatients with chronic constipation. Methods In a prospective randomized crossover trial, patients were randomized to receive fibre or lactulose for four weeks. Between treatments, patients had at least one week free of laxatives. Results 50 patients, of median age 50 years (range, 18–85) were recruited and 39 patients completed the trial. Compared to fibre, lactulose resulted in significantly higher mean bowel frequency (7.3, 95% CI 5.7 to 8.9 vs. 5.5, 95% CI 4.4 to 6.5; p=0.001) and stool consistency score (3.4, 95% CI 3.1 to 3.7 vs. 2.9, 95% CI 2.5 to 3.3; p=0.018). Scores for ease of evacuation were similar. The frequencies of adverse effects were not significantly different, but greater in the lactulose group. Mean patients’ recorded improvement score was significantly higher after taking lactulose than fibre (6.2, 95% CI 5.5 to 7.0 vs. 4.8, 95% CI 4.0 to 5.9; p=0.017). Of the 39 patients who completed the trial, 24 (61.5%) preferred lactulose and 14 (35.9%) preferred fibre. Conclusions Lactulose had better efficacy than fibre for chronic constipation in ambulant patients, although both treatments were equally well tolerated in terms of adverse effects.