Table 1

Characteristics of randomised controlled trials of osmotic and stimulant laxatives versus placebo in chronic idiopathic constipation

Study	Country, and number of centres	Setting	Criteria used to define chronic idiopathic constipation	Criteria used to define response	Number of patients (% female)	Laxative used	Duration of therapy	Methodology
Wesselius-De Casparis 196824	Holland and Croatia, 3 sites	Secondary and tertiary care	Need for regular laxative use	No requirement for additional laxatives during treatment period	103 (not stated)	Lactulose 15 ml od (dose doubled if no response)	3 weeks	Randomisation and concealment of allocation unclear, double-blind
Baldonedo 199125	Venezuela, 1 site	Secondary care	Compatible symptoms and negative investigations	Mean number of stools per week	31 (93.5)	Polyethylene glycol 500 ml od	8 days	Randomisation and concealment of allocation unclear, double-blind
Corazziari 199626	Italy, 6 sites	Secondary and tertiary care	Rome I criteria and negative investigations	≥3 stools per week Mean number of stools per week	48 (77.1)	Polyethylene glycol 17.5 g bid	8 weeks	Randomisation and concealment of allocation stated, double-blind^*
Corazziari 200027	Italy, 5 sites	Secondary and tertiary care	Rome criteria (iteration unspecified) and negative investigations	≥3 stools per week without the use of rescue laxatives, and no straining, hard stools, or tenesmus Mean number of stools per week	70 (82.9)	Polyethylene glycol 17.5 g bid	20 weeks	Randomisation and concealment of allocation stated, double-blind^*
DiPalma 200028	USA, 4 sites	Secondary and tertiary care	Compatible symptoms and negative investigations within the last 2 years	>3 stools per week without the use of rescue laxatives Mean number of stools per week	151 (86.8)	Polyethylene glycol 17 g od	2 weeks	Randomisation and concealment of allocation stated, double-blind^*
DiPalma 200729	USA, 50 sites	Secondary and tertiary care	Rome I criteria and negative investigations	≥3 stools per week without the use of rescue laxatives, and ≤ 1 of straining, hard stools, or tenesmus Mean number of stools per week	304 (84.9)	Polyethylene glycol 17 g od	6 months	Randomisation and concealment of allocation stated, double-blind^*
Kamm 201031	UK, 27 sites	Primary care and commercial centres	Rome III	≥3 CSBMs per week Mean number of stools per week	368 (74.7)	Bisacodyl (Dulcolax) 10 mg od	4 weeks	Randomisation and concealment of allocation stated, double-blind^*
Mueller-Lissner 201030	Germany, 45 sites	Primary care	Rome III	≥3 CSBMs per week Mean number of stools per week	367 (77.7)	Sodium picosulfate (Dulcolax) 10 mg od	4 weeks	Randomisation and concealment of allocation stated, double-blind

↵* Full information not reported in published article, but obtained after correspondence with the authors.
bid, twice daily; CSBM, complete spontaneous bowel movement; od, once daily.