Due to lack of epidemiological studies, rumination syndrome has been previously considered as a rare paediatric disorder. In this study, for the first time we have described the epidemiology of rumination syndrome in a cohort of children and adolescents with normal intelligence. In this study, 5.1% of 10-16 year old children fulfilled Rome III criteria for adolescent rumination syndrome. There was no significant gender difference in prevalence of this condition and it was not significantly associated with emotional stress. Approximately 12% of children suffering from rumination syndrome had disturbances of daily activities. In 18%, rumination syndrome overlapped with other functional gastrointestinal diseases.
The first study that has assessed the prevalence of rumination syndrome was published in 1993 by Drossman et al.
. This is the first US householder survey using a questionnaire. In this study the prevalence among adults was noted to be 10.4%. Epidemiology of rumination syndrome in children has not been studied in detail. Most of the previous studies on rumination syndrome have been carried out in subjects with learning disabilities. It has been reported in 6 -10% of infants with developmental delay
 and 8-10% of mentally handicapped adults
[6, 14]. These findings led to the belief that rumination is a condition predominantly seen in children and adults with learning difficulties. Subsequently this syndrome was increasingly recognized in children and adolescents with normal mental capabilities. A previous study assessing functional gastrointestinal disorders from our group has shown rumination syndrome in 4% of school aged children, using Rome III criteria
, but the number of children with rumination syndrome in that study was not sufficient to describe clinical characteristics. In the present study we found rumination syndrome to be present in 5.1% of Sri Lankan children aged 10-16 years. This highlights the significant prevalence of rumination in children of normal intelligence.
The gender difference in prevalence of rumination syndrome has not been studied earlier. Even though, rumination has been reported in males
[15, 16], the majority of patients in previous hospital based studies and case reports on this disorder were females
[3, 17–19]. In a previous review of 147 children with rumination syndrome, 68% were females
. However, in the current study we did not observe a significant gender difference in the prevalence of rumination syndrome. Hospital based studies on functional gastrointestinal diseases are subjected to potential biases such as differences in healthcare seeking patterns. In fact females tend to seek healthcare more than that of males for functional gastrointestinal diseases such as irritable bowel syndrome
 and that may be the possible reason for high percentage of females in previous hospital based studies and case reports.
Abdominal pain and weight loss are the commonest symptoms associated with rumination syndrome in children and adults
[4, 7, 20]. We found similar results. However, percentage of children with abdominal pain, nausea and weight loss observed in our study is less than that reported by Chial et al. in their hospital based study (38% and 42.2% respectively)
. Furthermore, only 2 (2%) of our children with rumination syndrome had constipation compared to 21.1% seen in the previous study
. Associated symptoms such as pain, weight loss and alteration in bowel habits are troublesome symptoms and hence important determinants of health care consultation. Therefore, children with these symptoms are more likely to seek health care. This may be the reason for the high percentage of these symptoms observed in the previous hospital based study
. In contrast to this, our patients with rumination had higher percentage of bloating than reported in the previous study (4.1%).
Extraintestinal somatic symptoms such as headache and limb pain are known to be associated with functional gastrointestinal diseases in children
[21, 22]. In agreement with this, symptoms commonly seen in our children with rumination syndrome were headache, limb pain and light headedness. Presence of extraintestinal somatic symptoms is more suggestive of the presence of a functional disorder than an organic disorder such as gastro-oesophageal reflux. In addition, somatic symptoms can exaggerate associated disabilities and contribute to poor quality of life. Therefore, direct inquiry of these symptoms is important during evaluation of a child suspected of the rumination syndrome.
Emotional stress is known to modulate foregut motility such as gastric emptying in children with functional gastrointestinal diseases
. Emotional stress and other psychiatric disorders such as depression and anxiety are commonly reported in adult patients with rumination syndrome
. Therefore, we hypothesized that rumination syndrome is more common among children who were exposed to stressful life events. However, we failed to demonstrate a significant association between rumination syndrome and exposure to stressful life events. Only stressful life event which was associated with rumination syndrome was a change in school.
In a previous hospital based study, 72.7% of children with rumination syndrome have missed school due to symptoms
. However, school absenteeism is much less in our school based survey (11.8%). It is possible that children included in the hospital based study had more severe symptoms which led to school absenteeism.
Both children and adults with one functional gastrointestinal disease sometimes tend to have overlapping other functional gastrointestinal diseases at the same point in time
[25, 26]. The reason for this phenomenon is not entirely clear and it is possible that some FGD tend to share similar patho-physiological mechanisms such as abnormal visceral sensitivity, abnormal intestinal motility and malfunctioning brain-gut communications. In agreement with this, several other functional gastrointestinal disorders overlapped with rumination syndrome in our study and 18% of affected children fulfilled Rome III criteria for at least one other FGDs. Abdominal pain predominant FGD and constipation were the FGD overlapping with rumination syndrome in this study. In agreement with our study, a previous study using Rome III criteria and conducted in a secondary referral centre, showed rumination syndrome overlapping with irritable bowel syndrome, functional abdominal pain and functional constipation
There are several strengths of our study. We have included a large number of children and adolescents in this study to get a valid cross-sectional cohort of paediatric population in Sri Lanka. We also had a significant number of children with rumination to describe their clinical profile in a meaningful way.
Rumination syndrome is an underappreciated condition in both adults and children
[28, 29]. This is due to misdiagnosis of rumination syndrome as having vomiting secondary to gastroparesis or gastro-esophageal reflux
. Lack of awareness among physicians may significantly contribute to under diagnosis
[28, 29]. Therefore it is not surprising that this has left a clinical impression that rumination syndrome is a rare disorder. However, our results show that a sizable proportion of children and adolescents have symptoms of rumination.
It has been stressed that eliciting key elements of the typical history is the most successful way to diagnose rumination syndrome
[30, 31]. Physiological studies such as 24 hour pH monitoring and impedance studies are helpful to identify the condition when clinical diagnosis is difficult
. It had been stated that gastroesophageal reflux, esophageal achalasia, gastroparesis, bulimia nervosa, and obstructive anatomical disorders must be excluded by appropriate diagnostic tests before making the final diagnosis of rumination syndrome
. Cardinal symptoms of reflux (painful regurgitation and burning epigastric pain) were not found in our sample of children with rumination. In addition organic conditions like achalasia and bulimia nervosa are rare diseases in children
The main drawback of this study is that we did not carry out clinical evaluation and diagnostic tests to rule out these organic causes. It was practically impossible for us to carry out these investigations in a large epidemiological study involving over 2000 participants. In this backdrop, our results may over-represent the true prevalence of rumination syndrome in adolescents and caution is need when interpreting our results. Nonetheless, results of this study may help clinicians to be aware that symptoms of rumination are reasonably common in children and adolescents.