Chronic constipation is a common problem in childhood with an estimated prevalence of 3% in the Western world 1. According to the ROME-III criteria, functional constipation is defined as a child experiencing two or more of the following symptoms: (1) two or fewer defecations in the toilet per week, (2) at least one episode of faecal incontinence per week, (3) stool retentive posturing, (4) painful or hard bowel movements, (5) presence of a large faecal mass in the rectum or (6) large diameter stools that may obstruct the toilet without objective evidence of a pathological condition. Infants up to four years of age have to fulfil two or more criteria for at least one month while children older than four years need at least two months of symptoms 2, 3. In the majority of patients, constipation is difficult to treat and often a long-lasting problem. Up to 50% of children followed up for six to 12 months continue to have symptoms and need ongoing laxative use 4.
Although functional constipation is one of the most prevalent, frustrating and long-lasting paediatric functional gastrointestinal disorders, treatment of functional constipation is often based on experience rather than evidence 5. An explanation could be that constipation is often seen as a minor problem which will either spontaneously resolve or respond to advice on diet. This attitude ignores the impact on well-being of the child and family life. In children, constipation and faecal incontinence can lead to social withdrawal, low self-esteem and even depression. Furthermore, the lack of understanding, delayed diagnosis and suboptimal treatment of functional constipation contribute to ongoing symptoms and multiple medical consultations and consequently unnecessary costs.
The lack of well-designed placebo-controlled studies is confirmed by the excellent Cochrane review by Gordon et al. 6. In their review, which included 18 randomized controlled trials (RCTs) with a total of 1643 children, the authors conclude that polyethylene glycol preparations may be superior to placebo, lactulose and milk of magnesia with respect to the defecation frequency. Furthermore, some evidence was found for the efficacy of liquid paraffin, whereas evidence was lacking demonstrating the superiority of lactulose compared with other agents. The very transparent GRADE analyses showed, however, that the overall quality for the primary outcome, defecation frequency per week, was low or very low because of sparse data, inconsistency (heterogeneity) and high risk of bias. So, the true effect may be substantially different or is even likely to be different from the estimate of effect. These results should therefore be interpreted with caution because of these methodological shortcomings. Another drawback of the included studies in this review was the short-term follow-up. It is, however, of great importance that studies concerning a chronic condition such as childhood constipation consider long-term outcomes (minimum of six months follow-up) with respect to both efficacy and safety outcomes.
Future studies executed in this common gastrointestinal paediatric problem, should use the same methods according to standardized protocols as suggested by international experts in the field of functional gastrointestinal diseases 7. To achieve this goal, homogeneous patient populations and outcome measures should be used, including the standard definition for functional constipation as described in the ROME-III criteria. To evaluate the efficacy of the different old and new laxatives available, a more valid outcome measure should be used in these children, such as ‘defecation frequency of three or more per week’, instead of the frequently used ‘defecation frequency per week’. Well-designed larger studies, especially placebo-controlled trials with long-term follow up, quality of life assessment and cost-effectiveness analysis, are needed with greater methodological rigour not only to be performed in tertiary centres but also more importantly to be executed in primary and secondary care.