Since publication of Rome III in 2006, there has been a marked and exciting expansion in the science of functional gastrointestinal disorders (FGIDs), which have led to improved understanding and better treatments. The Rome Foundation has sought to maintain a strong knowledge base in the field and that has occurred mainly with revisions every 6-10 years. Rome IV updates include a redefinition of FGIDs and diagnostic criteria, addition of newly recognized disorders, and major changes in criteria for existing disorders(1).
The definition of FGIDs changed with Rome III from the prior absence of structural disease to a more appropriate disorder of GI functioning. Now to reach a more meaningful approach to these disorders scientifically, Rome IV expanded upon this concept with an agreed-upon definition: Disorders of gut-brain interaction. These disorders are classified by GI symptoms related to any combination of:
- Motility disturbance
- Visceral hypersensitivity
- Altered mucosal and immune function
- Altered gut microbiota
- Altered central nervous system (CNS) processing
This definition is most consistent with our evolving understanding of multiple pathophysiological processes that, in part or together, determine the symptom features that characterize the Rome classification of disorders. We believe it to be readily understood and acceptable to clinicians, academicians, regulatory agencies, the pharmaceutical industry, and to patients.
The addition of new diagnoses with known aetiologies under Rome IV now include: reflux hypersensitivity syndrome (esophageal disorders chapter) where there is heartburn with normal physiological degrees of reflux, cannabinoid hyperemesis (gastroduodenal disorder chapter), episodes of vomiting like cyclic vomiting syndrome caused by cannabis narcotic bowel syndrome (Centrally Mediated Disorders of Gastrointestinal Pain chapter) which is centrally mediated hyperalgesia from opioids and opioid-induced constipation (Bowel disorders chapter) which relates to the peripheral effects of opioids on producing constipation
New chapters have been added to meet our growing understanding of these disorders: Intestinal Microenvironment and the Functional Gastrointestinal Disorders combines knowledge of the microbiome, food, and nutrition to improve understanding of the luminal aspects of GI function. Pharmacological and Pharmacokinetic Aspects of Functional GI Disorders has been changed to Pharmacological, Pharmacokinetic, and Pharmacogenomic Aspects of Functional Gastrointestinal Disorders to include the role of genetics in the clinical response to pharmaceutical treatments. Gender, Age, Society, Culture and the Patient’s Perspective has been split into two articles to reflect the rapid growth of knowledge in these areas: Age, Gender, Women’s Health, and the Patient, and Multicultural Aspects of Functional Gastrointestinal Disorders. Psychosocial Aspects of Functional Gastrointestinal Disorders has been changed to Biopsychosocial Aspects of Functional Gastrointestinal Disorders to reflect the multidetermined nature of biopsychosocial processes. The Rome III Chapter, Functional Abdominal Pain Syndrome is now called Centrally Mediated Disorders of Gastrointestinal Pain to reflect the predominant CNS contribution to the symptoms.
The Sphincter of Oddi disorder (SOD) criteria has been revised. Recommendations to perform biliary sphincterotomy based on clinical criteria (biliary dilatation and increased liver chemistries or increased pancreatic enzyme levels) for presumed sphincter of Oddi pain has not had convincing supportive evidence. Thus, balancing the benefits of symptomatic relief with the potential risks of pancreatitis, bleeding, and perforation has been challenging, and the Rome III criteria for them were not particularly helpful in providing proper guidelines. Now, driven by evidence that debunks the value of sphincterotomy for type III SOD, the chapter committee has reclassified these disorders, and they provide a more rational treatment algorithm. The previous type III SOD categorization of the Milwaukee classification has been removed.
The new diagnosis B3a Chronic Nausea Vomiting Syndrome combines the previous Rome III entities Chronic Idiopathic Nausea and Functional Vomiting. This owes to a lack of evidence delineating different diagnostic approaches and management of nausea compared with vomiting, and the clinical observation that these two symptoms commonly are associated. Although we recognize patients may present only with nausea, the clinical approach to diagnosis and management remains the same.
Other major changes likely to affect a large portion of patients include removal of the term “discomfort” from IBS criteria, and the existence of functional bowel disorders on a spectrum of symptom presentations. Figure 1 indicates that the relation of the functional bowel disorders exist on a continuum as related to the degree of pain or the consistency of stool. Thus as shown on the left, when there is little or no pain, patients may have functional diarrhea or constipation, but in patients with greater degrees of pain patients are classified as IBS, C or D respectively. This is based on evidence that patients often migrate across categories over time.
Finally, there is also a change in how to identify the IBS subtypes The Rome III classification for IBS subtypes required that the proportion of total stools using the Bristol Stool Form Scale be used to classify IBS with predominant diarrhea (>25% loose/watery, <25% hard/lumpy), IBS with predominant constipation (>25% hard/lumpy, <25% loose/watery), mixed-type IBS (>25% loose/watery, >25% hard/lumpy), and IBS unclassified (<25% loose/watery, <25% hard/lumpy). However, because patients can have large periods of time with normal stool consistency, a majority of them have unclassified IBS subtype relative to the other groups. Based on this observation and the results of a Rome Foundation Normative Symptom Study, the criteria have been changed and relate to the proportion of days with symptomatic stools (i.e., loose/watery and hard/lumpy) rather than all stools (including normal ones). As a result, the unclassified group is reduced markedly. One of the most exciting features for Rome IV involve the development of novel educational materials in addition to the Rome IV book. This includes 5 books: the Rome IV diagnostic algorithms, the Rome IV Multidimensional Clinical Profile (MDCP), Rome IV for primary care and non GI clinicians, Rome IV pediatric functional GI disorders and a book on validated adult and pediatric questionnaires. In addition we are releasing the Rome IV Interactive Clinical Decision Toolkit, an intelligent software program that incorporated the knowledge from the diagnostic algorithms and the MDCP.