The association between obesity and FAP according to the updated ROME IV criteria had not been investigated before. In the current study, our analysis of that association revealed a higher prevalence of overweight/obesity among children with FAP disorders compared to an age- and sex-matched control population of normal weight FAP children. Our results are in line with studies that had demonstrated a connection between body weight and FGID. Teitelbaum et al (8) showed a greater percentage of obese pediatric patients with constipation, gastroesophageal reflux disease, IBS, encopresis, and FAP compared with normal weight controls. In their study, functional disorders were assigned based on ROME II criteria without specification of subtypes of FAP. Bonilla et al (9) found a 20.2% prevalence of obesity in patients with FGID, but there was no healthy control group with which to compare their findings. This study showed that obesity is associated with poor outcome and disability at long term follow up. Other studies demonstrated higher percentages of recurrent abdominal pain (12) and FGID (7) in obese children. However, the first study, a non validated questionnaire was used and the latter was based on ROME III criteria for diagnosis of functional disorders.
Several factors may explain the association between obesity and FAP disorders. Dietary habits are a major factor in obesity development and previous studies showed the association between increased consumption of carbohydrates and high body weight (13, 14, 15). Carbohydrate malabsorption may cause gastrointestinal symptoms via the physiologic effects of both increased osmotic activity and increased gas production from bacterial fermentation (16). Moreover, there is some evidence that a low-FODMAP diet is effective in reducing IBS symptoms (17, 18). Recently, Schnabel et al showed an association between ultra-processed food (UPF) consumption and functional gastrointestinal disorders. In this large French cohort, an increase in UPF, which is characterized by high density of saturated fatty acids, sugar, sodium and low content of protective nutrients such as fibers, was associated with a higher risk of IBS. They also found that UPF consumption was associated with higher BMI. (19).
A potential association between obesity, FGID and gastrointestinal motility disorders has also been described. Delayed gastric emptying and impaired antral motility were found in children with RAP, FAP, IBS or functional dyspepsia (20, 21). Several studies have shown delayed gastric emptying and gastric and gallbladder dysmotility in obese individuals (22, 23). This may be attributed to increased gastric distention in obese causing poor fundal and antral tone (24), altered sensitivity of mechanoreceptors in the stomach musculature (25) and abnormal perception of satiety signals (26).
Another association between obesity and FGID is the gut microbiota. Increased risk of small intestinal bacterial overgrowth (27) and different gut microbiota composition (28) in obesity has been reported which might contribute to gastrointestinal dysmotility, excessive fermentation, altered visceral perception and gut permeability with their metabolites leading to pain-predominant FGID (29, 30).Finally, obesity and FGID share common psychological comorbidities, such as stress, depression, and anxiety, which can contribute to each other's development and aggravate each other (31,32,33).
Our study has demonstrated a few significant differences between overweight/obese FAP children and normal weight FAP children. We found that overweight/obese FAP children had more hospitalizations attributed to their abdominal pain compared with normal weight FAP children as described in other studies which suggested that pediatric obesity contributes significantly to increased health care utilization in children (34, 35).
We also found that obese FAP children are treated more frequently with PPI than normal weight FAP children. Overuse of PPI has been increasing in the last decade in hospitalized and ambulatory patients and their prescription continues to grow in all western countries (36).
The clinical implications of our current study findings relate to the management of overweight/obese children with FGID. They advocate that the treatment protocol of these children should be focused on guidance for nutritional assessment targeted towards weight loss together with other lifestyle changes (e.g., increase in physical activities) that may improve symptoms and prevent or at least minimize the need for medications and hospitalizations.
To the best of our knowledge, this is the first study to show an association between obesity and FAP diagnosed in children according to the updated ROME IV criteria for diagnosis of FAP which was made by a pediatric gastroenterologist in a clinic setting and not by collecting information from a self-administered questionnaire. This study is limited by its retrospective nature, missing more precise data on skinfold measurements, body composition, and other parameters. In addition, our control group might include children with FAP disorders, although we believe that due to the high number of children included, the percentage of children with FAP disorders would be similar to the general population.