Irritable bowel syndrome / functional bowel disorder
What is Irritable bowel syndrome?
Irritable bowel syndrome (IBS) is the commonest of the functional gastrointestinal disorders with an estimated prevalence of 10%. It accounts for up to 20 % of all GP visits and up to 50% of outpatient visits to a Gastroenterologist. It is a chronic, relapsing and often life-long disorder, characterized by the presence of abdominal pain/discomfort associated with defaecation, a change in bowel habit, the sensation of abdominal distension, and may include associated noncolonic symptoms. People with persistent symptoms of IBS have poor physical function, impaired quality of life and high healthcare costs.1
Incidence rates of IBS are seldom calculated, and prevalence estimates fluctuate both between and within countries. The pooled prevalence rate that one study cited for North America, Europe, Australia, and New Zealand was 8.1%.2 There appears to be a female predominance. IBS is common both in developed and developing countries.
The following physiologic and psychological variables have been proposed as potential factors in the aetiology and pathophysiology of IBS:
- GI dysmotility
- inflammation
- visceral hypersensitivity
- altered intestinal microbiota
- diet
- genetic predisposition
- stress exposure (including early life events)
Disturbances in the brain–gut axis, including disruption of central and autonomic functions, peripheral hormones, amines, and peptides, have been documented in patients with IBS.3
Diagnosing IBS: Based on the Rome IV criteria
Characteristic | Rome IV criteria |
Diagnostic time frame | - Symptom onset at least six months prior
- Symptom activity during the last three months
- Symptom frequency at least one day per week
|
Symptom description | |
Symptom association (2 or more) | - Related to defecation
- Associated with a change in the form of stool
- Associated with a change in the frequency of stool
|
The differential diagnosis of IBS should include coeliac disease, microscopic colitis, inflammatory bowel disease, bile acid malabsorption, colorectal cancer, and dyssynergic defecation. For the most part, patient diagnosis remains one of exclusion, with treatment being symptom driven.
Pharmacologic management of IBS focuses on the predominant bowel symptom (diarrhoea or constipation) and abdominal pain. Patient education, suggestions for lifestyle modifications, and reassurance should be provided with all IBS treatments.
Potential pharmacological interventions for IBS:
Abdominal pain/bloating | Constipation predominant IBS | Diarrhoea predominant IBS |
Antispasmodics | Psyllium | Opioid agonist |
Peppermint oil | Polyethylene Glycol | Antibiotics (Rifaximin) |
Mibeverine | Chloride channel activators | Probiotics |
SSRI or Tricyclic antidepressants | | Bile acid sequestrants |
While these pharmacological agents may transiently help symptoms, NONE alter the natural history of the condition apart from rifaximin (a nonabsorpable antibiotic). Rifaximin has been shown to improve symptoms and provide sustained relief.
References:
- Akehurst RL, et al: Health-related quality of life and cost impact of irritable bowel syndrome in a UK primary care setting. Pharmacoeconomics 2002, 20:455–462.
- Sperber AD, et al. The global prevalence of IBS in adults remains elusive due to the heterogeneity of studies: a Rome Foundation working team literature review. Gut 2016 Jan 27
- Camilleri M. Physiological underpinnings of irritable bowel syndrome: neurohormonal mechanisms. J Physiol 2014; 592(14):2967-80.
- Pimentel M, et al. Repeat Treatment With Rifaximin Is Safe and Effective in Patients With Diarrhea-Predominant Irritable Bowel Syndrome.
Gastroenterology. 2016 Dec;151(6):1113-1121.