AIM: To compare the prevalence of Functional gastrointestinal disorders (FGIDs) using ROME III and ROME II and to describe predictors of FGIDs among eating disorder (ED) patients.

METHODS: Two similar cohorts of female ED inpatients, aged 17-50 years, with no organic gastrointestinal or systemic disorders, completed either the ROME III (n = 100) or the ROME II (n = 160) questionnaire on admission for ED treatment. The two ROME cohorts were compared on continuous demographic variables (e.g., age, BMI) using Student’s t-tests, and on categorical variables (e.g., ED diagnosis) using χ²-tests. The relationship between ED diagnostic subtypes and FGID categories was explored using χ²-tests. Age, BMI, and psychological and behavioural predictors of the common (prevalence greater than 20%) ROME III FGIDs were tested using logistic regression analyses.

RESULTS: The criteria for at least one FGID were fulfilled by 83% of the ROME III cohort, and 94% of the ROME II cohort. There were no significant differences in age, BMI, lowest ever BMI, ED diagnostic subtypes or ED-related quality of life (QOL) scores between ROME II and ROME III cohorts. The most prevalent FGIDs using ROME III were postprandial distress syndrome (PDS) (45%) and irritable bowel syndrome (IBS) (41%), followed by unspecified functional bowel disorders (U-FBD) (24%), and functional heartburn (FH) (22%). There was a 29% or 46% increase (depending on presence or absence of cyclic vomiting) in functional gastroduodenal disorders because of the introduction of PDS in ROME III compared to ROME II. There was a 35% decrease in functional bowel disorders (FBD) in Rome III (excluding U-FBD) compared to ROME II. The most significant predictor of PDS was starvation (P = 0.008). The predictor of FH (P = 0.021) and U-FBD (P = 0.007) was somatisation, and of IBS laxative use (P = 0.025). Age and BMI were not significant predictors. The addition of the 6-mo duration of symptoms requirement for a diagnosis in ROME III added precision to many FGIDs.

CONCLUSION: ROME III confers higher precision in diagnosing FGIDs but self-induced vomiting should be excluded from the diagnosis of cyclic vomiting. Psychological factors appear to be more influential in ROME II than ROME III.

Functional gastrointestinal disorders (FGIDs) are prevalent and affected individuals have poorer quality of life[1-5]. These disorders are different from other gastrointestinal (GI) disorders because structural abnormalities are subtle or cannot be demonstrated by formal investigation. Therefore the diagnosis of FGIDs has mainly relied on the use of self-report questionnaires[6,7]. With increasing interest and understanding in these disorders, various questionnaires have been designed and revised over the years to best reflect their true prevalence[6,7].

The main types of eating disorders include anorexia nervosa (restricting type AN-R or binge purge type AN-P), bulimia nervosa (BN) and eating disorders not otherwise specified (restricting type EDNOS-R or binge purge type EDNOS-P). Abnormal eating disorder related behaviours include restriction of food intake, binge eating, purging and excessive exercise[8]. Eating disorder (ED) patients frequently report GI symptoms including bloating, nausea, epigastric discomfort, and a sensation of fullness. These symptoms may not only lead to unnecessary diagnostic tests but more importantly the refusal of food intake and justification for continuing their disordered eating. We have previously studied the prevalence and characteristics of FGIDs using ROME II and found that patients with eating disorders exhibited a broad spectrum of different FGIDs[9]. Furthermore, we have observed a relationship between pelvic floor dysfunction and abdominal bloating and distension in ED patients[10].

ROME III adult diagnostic criteria for FGIDs were published in 2006 and preserved the majority of the diagnoses previously found in ROME II while significant changes were made in the gastroduodenal disorders group[6,7]. Functional dyspepsia has two new subdivisions in the ROME III diagnostic criteria: postprandial distress syndrome (PDS) and epigastric pain syndrome[6]. There is a more detailed classification of vomiting syndromes including exclusion of DSM-IV diagnosed ED patients from functional vomiting, but not cyclic vomiting syndrome. In addition, rumination syndrome is now categorised as a functional gastroduodenal disorder whereas previously it was classified as a functional esophageal disorder. There is also a more detailed classification of the functional biliary tract and sphincter disorders. The most significant change to the Rome III classification is an additional requirement of chronicity for a diagnosis, that is, the symptoms must be present for the last 3 mo, with symptom onset at least 6 mo prior to diagnosis. In contrast, using ROME II, symptoms present during 12 wk (3 mo, which may not necessarily be consecutive) in the previous year would fulfil the diagnostic criteria.

Since publication of the ROME III criteria, research has focused on one or a few FGIDs[11-14]. No study has described all of the FGIDs by ROME III in a single publication, especially in the context of eating disorders. Only few papers have described individual FGIDs using ROME III in patients with EDs[15].

The aims of the study were 1. to describe the prevalence and psychological and behavioural predictors of FGIDs among eating disorder patients using ROME III criteria and 2 to compare their prevalence with FGIDs in a similar group of ED patients using ROME II criteria. We were also interested in the prevalence of FGID categories and individual FGIDs with and without the 6-mo requirement of ROME III to determine if this was a factor in any altered prevalence of FGIDs.

This is the first study of all categories of FGIDs using ROME III in ED patients and the first to compare prevalence based on ROME II and ROME III criteria[12,13]. The introduction with ROME III of the requirement of presence of symptoms for at least 6 mo is a key influence in the differences observed in prevalence of individual FGIDs in patients with ED.

PDS, a new FGID, was common in ED patients and the most significant predictor was starvation. This finding could be explained by the physiological repercussions of severe food restriction, such as delayed gastric emptying[26-28]. This is consistent with the recent finding of Santonicola et al[15], that there is a significant higher propensity for AN patients to have early satiety compared to BN patients. What occurred first cannot be determined; it could be starvation leading to impaired gastric emptying leading to PDS or it could be discomfort on eating for other reasons, including psychological, resulting in semistarvation because of fear of PDS symptoms of fullness and discomfort. Because these are eating disorder patients both could be true. PDS is also weakly predicted by depression, the greater the depressive symptoms the greater the likelihood of PDS. When starvation and depression are occurring together it is hard to ascertain, which came first, particularly among eating disorder patients as both are common.

Our data also suggests less exercise is associated with PDS. This is in keeping with our previous study that there was a worsening of oesophageal disorders in among patients undertaking excessive, intense exercise as a means of weight control[16]. The amount and intensity of exercise of eating disorder patients can be extreme[23] and could result in upper gastrointestinal problems which commonly occur in marathon runners[29]. This should not be interpreted to mean light to moderate exercise should not be undertaken, in fact the reverse is true, moderate exercise improves depression[30].

It is likely that the intermittent or long term negative energy balance in these patients results in an alteration of GI motility and that this leads to further food restriction in order to prevent resultant GI symptoms[31]. That is, the symptoms provoked by eating in the presence of dysmotility result in the reinforcement and continuation of the disordered eating.

Another key finding was that IBS was prevalent in both cohorts. IBS was only weakly predicted by laxative use (not abuse) in the ROME III cohort, whereas, in previous studies using ROME II criteria IBS was predicted by somatisation and anxiety[9]. This suggests the ROME III criteria, with the inclusion of the 6-mo criteria and the exclusion of unspecified bowel disorders (U-FBD), are more specific for the IBS symptom cluster. It is possible that laxative use may prime or condition the GI tract to IBS symptoms.

U-FBD was present in 24 percent of ROME III patients. We observed that somatisation was associated with decreased odds of U-FBD. Perhaps those who are lower on the somatisation spectrum will not report sufficient symptoms to qualify for a specific FGID, and thus become classified as U-FBD. In Boyd et al[9] more than three FGIDs present in ROME II was strongly predicted by neuroticism (indicative of psychopathology) whereas in the current study there were no predictors despite the presence of more than three ROME III FGIDs in 34 percent of patients. This finding again may relate to the improved precision of the criteria for FGIDs when the 6-mo time stipulation is used. Fluctuations in appearance and disappearance of FGIDs in ED patients have been reported for ROME II FGID[32]. The imprecision of ROME II diagnostic clusters and the capacity to diagnose based on acute or less temporally stable symptoms, could explain the relationship between presence of multiple FGIDs and neuroticism. The precision of ROME III diagnoses and requirement for more ‘chronic’ or temporally stable symptoms would explain the loss of association with multi-morbidity and neuroticism in the ROME III sample.

FH was predicted by somatisation in both ROME II and ROME III. In ROME III there was a substantial increase in functional gastroduodenal disorders of 46%. This was reduced to 29% if cyclic vomiting was not included in the diagnosis. There was a significant difference between the ED diagnostic subgroups for presence of gastroduodenal disorders with the patients who purge (self-induce vomiting) being more likely to report gastroduodenal disorders. This difference no longer remains after cyclic vomiting was excluded. This suggests that self-induced vomiting should not be included in cyclic vomiting as it is giving an inflated and misleading prevalence of this disorder. There was also decrease in functional bowel disorders of 11%; this decrease was 35% after unspecified bowel disease was removed.

The study would have benefited by a larger cohort of patients completing the ROME III and follow-up over 12 mo to investigate the stability of the FGIDs now with the introduction of requirement of the presence of symptoms for 6 mo or more. One potential weakness of the study is the reliance on self-report data. Although there were no differences between the two cohorts they were both inpatients at a specialised clinic and therefore not representative of all eating disorder patients.

Using the ROME III criteria in an ED patient sample, specific abnormal eating related behaviours such as starvation, exercise and laxative use are associated with the presence of certain FGIDs. These findings are consistent with the notion that FGIDs can arise from long term abnormal eating and the altered neuronal and hormonal physiology in the gastrointestinal tract[33,34]. Higher emotional states such as prolonged stress may predispose and then sensitise individuals to express their feelings as gut symptoms and in the long term abnormal eating reinforces the altered physiological states[35].

ROME III confers higher precision in diagnosing FGIDs particularly with the inclusion of the chronicity requirement of symptom onset at least 6 mo prior, compared to 3 mo with ROME II. It would be improved if self-induced vomiting was excluded from cyclic vomiting syndrome in addition to its exclusion from functional vomiting. Two of the new ROME III criteria, PDS and U-FBD, are prevalent among ED patients. Starvation, less exercise and depression predicted PDS, and somatisation U-FBD. As found previously for ROME II laxative use predicted IBS and somatisation FH[9,16]. ROME III appears to have less psychological input to the diagnosis of FGIDs than ROME II.