Irritable Bowel Syndrome Kian Keyashian, MD Assistant Professor of Medicine Oregon Health & Science University Talk Outline History Epidemiology/Associated Conditions Natural History Impact of Disease Pathophysiology Diagnosis Management
History Earliest reports from turn of the 19 th and 20 th century Diagnosis of exclusion extensive unsuccessful surgeries First formal definition by Manning in 1978 Clin Epidemiol. 2014 Feb 4;6:71-80 Epidemiology Most commonly diagnosed gastrointestinal condition Prevalence: North America 12% South America 21% Southeast Asia 7% Prevalence by type: US: IBS-D = IBS-C = IBS-M Europe: IBS-C/IBS-M > IBS-D Clin Epidemiol. 2014 Feb 4;6:71-80
Epidemiology Clin Epidemiol. 2014 Feb 4;6:71-80 Epidemiology: Prevalence in Primary Care Many do not seek medical attention 10-70% seek primary care for symptoms worldwide 30% will seek primary care in US 80% with IBS-D Clin Epidemiol. 2014 Feb 4;6:71-80
Epidemiology: Demographics Sex 1.5-3 fold higher in women than men Absolute difference in prevalence of only 5% Age 50% with first symptoms before 35 Prevalence 25% lower if over 50 Socioeconomic status Inconsistent evidence Family studies Twice risk if biological relative with IBS Clin Epidemiol. 2014 Feb 4;6:71-80 Associated Comorbidities Somatic pain syndromes (fibromyalgia, chronic fatigue syndrome, chronic pelvic pain) Seen in ½ of IBS patients Other GI disorders (GERD, dyspepsia) Psychiatric disorders (MDD, anxiety, somatization)
Natural History In long-term follow-up: 2-18% worsened 30-50% remained unchanged 12-38% improved Worse outcomes: Previous surgery Longer duration of disease Higher somatic scores Comorbid anxiety/depression Change in diagnosis: less than 5% Natural History IBS-C/IBS-D IBS-M Less common between IBS-C and IBS-D
Impact of Disease Reduced HRQoL and work productivity 13-88% seek care More distress, less social support In US annually: 3.1 million ambulatory care visits 5.9 million prescriptions Total direct and indirect expenditure > $20 billion Mortality: no increase compared to general population Clin Epidemiol. 2014 Feb 4;6:71-80 Pathophysiology
Postinfectious IBS Seen in 5% of those with travelers diarrhea Spontaneously resolve in roughly half of patients within 6-8 years of index infection Genetics Immune function Microbiome Psychological status Environmental factors Stress, severity of infection, treatment with antibiotics Neurogastroenterol Motil. 2014 Feb;26(2):156-67. Aliment Pharmacol Ther. 2015 Jun;41(11):1029-37. IBD and Food Patients: food is trigger Fact: Contribution of true food allergies small Food intolerances common Poorly absorbed carbohydrates Osmotic effects Increased fermentation in small bowel/colon
Rome III Criteria for Diagnosis Features of IBS
Diagnosis Abdominal pain/discomfort Altered bowel habits Diarrhea Constipation Both Stool consistency, not frequency, differentiates subtypes Better correlation with colonic transit IBS-M Diagnosis May actually have IBS-C Periods of progressive stool accumulation culminating in bowel purging Can assess with radiograph
Medications Exacerbating IBS Differential Diagnosis IBS-D Celiac disease 4-5 fold increased likelihood (esp in Europe) Microscopic colitis Small subset Over age 50, nocturnal stools, weight loss, shorter duration of diarrhea, recent new drugs, comorbid autoimmune diseases IBD diagnosis separated by 2-3 years Bile salt diarrhea (25%) Aliment Pharmacol Ther. 2015 Jul;42(1):3-11.
Differential Diagnosis IBS-C Colorectal cancer? Lower prevalence of CRC (OR 0.56) Unless at risk for colorectal cancer Dyssyngeric defecation Consider in refractory cases Diagnostic Testing
General Management Active listening Setting realistic expectations Not cure History and physical exam Exercise and Diet RCT of structured exercise with greater improvement in IBS symptoms 20-minute walk each day Diet Gluten-free: actually fructan and other protein free can cause IBS symptoms FODMAPs increase SB and colonic water secretion and fermentation Increase SCFA and gas RCT with evidence but gradually reintroduce
Management of IBS-D Antidiarrheals Serotonin Agents (5HT3 Antagonists) Antispasmodics Management of IBS-D Antidiarrheals Loperamide without chance in overall IBS Reduce stool frequency, increased consistency Less habituation than Lomotil Bile salt binders not RCTs
Management of IBS-D Serotonin Agents Alosetron 0.5-1mg daily or BID 15% therapeutic gain over placebo Dose dependent constipation Idiosyncratic ischemic colitis Ondansetron 4-8mg daily to TID Recent RCT with benefit improved consistency, global IBS, urgency, stool frequency, bloating Management of IBS-D Antispasmodics Poor quality trials Short-term relief Helpful in exaggerated gastrocolonic reflex Postprandial cramping/loose stools Constipation, dizziness, blurred vision Avoid in elderly Peppermint oil 187-225mg TID Helps some but reflux in others
Management of IBS-C Fiber Supplements Laxative Agents Prosecretory Agents Fiber Management of IBS-C Modest benefit in global IBS symptoms Soluble > insoluble fiber IBS-C > IBS-D Gradual titration to 20-30g/day Avoid wheat bran (fructans)
Laxatives Management of IBS-C Miralax improves stool frequency/consistency Bloating, gas, loose stools Stimulants without RCTs Management of IBS-C Prosecretory Agents Lubiprostone chloride-channel activators Improves global, bowel, abdominal symptoms 8 g BID Limited by nausea Linaclotide guanylate cyclase-c agonist NNT 7 based on meta-analysis 290 g daily Diarrhea helped by taking 30-60 minutes before breakfast
Other Agents Probiotics improve global symptoms, pain, bloating, flatulence Differences in preparations make recommendations difficult Rifaximin in non-ibs-c 550mg TID for 14 days Therapeutic gain of 9-10% Recurrence is the norm Other Agents Antidepressants affect pain perception, mood, motility NNT 4 (TCAs, SSRIs) AEs to benefit TCAs for IBS-D, anorexia, weight loss, insomnia SSRIs for IBS-C, anxiety
Other Therapies Psychological therapies NNT 4 CBT, hypnotherapy, dynamic psychotherapy Variable reimbursement, lack of clinicians, poor acceptance CAM Acupuncture meta-analysis with no benefit Chinese herbals with mixed results Summary of Therapies
Summary of Talk A large portion of the US population reports IBS symptoms to their primary provider. The natural history of IBS is one of stability, with very patients having a change in diagnosis. Diagnosis of IBS is based on clinical criteria, with a limited set of diagnostics to rule out other causes. Treatment should target the specific symptoms experienced by patients.