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Irritable bowel syndrome - interpreting a diagnosis

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Public Lecture delivered on 20 November 2010 at Health Promotion Board Auditorium, SIngapore. Organized by CNETS.

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Irritable bowel syndrome - interpreting a diagnosis

  1. 1. Interpreting an Irritable Bowel Syndrome Diagnosis Yap Chin Kong Gastroenterology & LiverClinic Dr Yap Chin Kong Consultant Gastroenterologist Hepatologist & Clinic Director MBBS, MMed, MRCP, FRCP @ Mount Elizabeth Medical Centre, Singapore
  2. 2. Typical IBS sufferer
  3. 3. Irritable bowel syndrome Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Diagnostic criteria (Manning/Rome) 1 Abdomen pain relieved by defecation 2 Looser stools at onset of pain 3 Frequent stools at onset of pain 4 Abdomen distension 5 Passage of mucus in stools 6 Sensation of incomplete defecation
  4. 4. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Other symptoms Gas and bloating Visible abdomen swelling Abdomen pain or discomfort Heartburn Back and muscle ache (fibromyalgia) Irritable bowel syndrome
  5. 5. Pain, diarrhea, bloating etc Hmmm... IBS Address patient’s symptoms
  6. 6. Address patient’s concerns I’m concerned of cancer - my colleague had it A colonoscopy will rule that out
  7. 7. Is it irritable bowel syndrome ? Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Addressing patient’s concerns 1 Worried about serious disease 2 Wants to rule out colon cancer, inflammatory bowel disease, celiac disease 3 Wants relief of symptoms: pain, diarrhea etc 4 Up to 10% of population have IBS
  8. 8. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Diagnostic approach to abdomen symptoms Addressing patient’s concerns History is very important Examination: BMI (weight, height) Pale, jaundice Mass in abdomen Enlarged liver Tenderness Lumps (lymph nodes) Rectum examination
  9. 9. Investigations - tools Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Addressing patient’s concerns 1 Blood, stool tests: anemia, inflammation, celiac disease in Caucasian 2 Colonoscopy to exclude colon cancer, inflammatory bowel disease, others 3 Ultrasound scan: liver, pancreas, gallbladder, ovaries 4 Reserve list: Gastroscopy, video capsule, CT scans
  10. 10. White blood cell Red blood cell Features of colon inflammation Simple stool test
  11. 11. Warning signs: may not be IBS Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health 1 Moderately severe pain alone 2 No relationship with bowel movement 3 Severe diarrhea or diarrhea alone 4 Passage of blood 5 Weight loss 6 Fever 7 Anemia
  12. 12. Doctor’s role: a fine balance Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Not doing enough to exclude serious disease Doing too many tests Some may have risks Cost Balance patient’s concerns with realities
  13. 13. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health I Functional Motility disorder with visceral sensitivity No structural abnormality Irritable bowel syndrome IBS- Constipation IBS- Diarrhea IBS- Constipation/Diarrhea Some causes of abdomen pain
  14. 14. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health II Organic Acid related: GERD, ulcer Cancer ± diarrhea Inflammatory bowel disease (Crohn’s, ulcerative colitis) ± diarrhea Eosinophilic enteritis ± diarrhea Ischemic colitis ± diarrhea Diverticulitis ± diarrhea Infections (ameba, tuberculosis) ± diarrhea Celiac sprue ± diarrhea Tropical sprue ± diarrhea Stones in gallbladder or bile duct ± diarrhea Carcinoid (neuroendocrine tumor) with liver metastases ± diarrhea Carcinoid (neuroendocrine tumor) lung ± diarrhea (no pain) Some causes of abdomen pain
  15. 15. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health IBS and NETs  IBS does not transform or increase the risk of NET  Patients with “IBS” and NET tumor may be due to (i) wrong IBS diagnosis (ii) correct IBS diagnosis + development of a new NET sequentially (iii) chance association simultaneously “guilt by association” vs “cause and effect”
  16. 16. Features of carcinoid (NET) Ito T, J Gastroenterol 2010 No symptoms 70% Carcinoid syndrome 3% Carcinoid syndrome Flushing Severe diarrhea Crampy pain Nausea, vomiting Wheezing
  17. 17. Ito T, J Gastroenterol 2010 Symptoms in carcinoid patients Diarrhea 4% Constipation 10% Abdomen pain 27% Flushing 1%
  18. 18. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Esophagus Stomach Duodenum Small intestine Large intestine Gallbladder Bile duct Pancreas Liver Long digestive tract
  19. 19. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Esophagus Stomach Duodenum Small intestine Large intestine Gallbladder Bile duct Pancreas Liver Long digestive tract We have the technology to examine the entire digestive system from mouth to anus
  20. 20. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Esophagus Stomach Duodenum Small intestine Large intestine Gallbladder Bile duct Pancreas Liver Gastroscopy
  21. 21. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Esophagus Stomach Duodenum Small intestine Large intestine Gallbladder Bile duct Pancreas Liver Colonoscopy
  22. 22. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Esophagus Stomach Duodenum Small intestine Large intestine Gallbladder Bile duct Pancreas Liver Video capsule “endoscopy”
  23. 23. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Esophagus Stomach Duodenum Small intestine Large intestine Gallbladder Bile duct Pancreas Liver Scans, endoscopic ultrasound
  24. 24. Video capsule “endoscopy”
  25. 25. PET scan
  26. 26. Endoscopic ultrasound scan revealed two 1 cm size tumors ? NET
  27. 27. Challenges in IBS Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health 1 Common condition 10% population affected 2 Not always an easy diagnosis to make with complete confidence 3 Because IBS is common, we get it right most of the time 4 Challenge is to identify the “IBS-like” case that is not really IBS 5 One consultation is not enough 6 Follow up is important to look for evolution and re-evaluate 7 “Difficult IBS” gets investigated the most 8 Correctly diagnosed “IBS” does not prevent the occurrence of another disease later on
  28. 28. Given a case study, willingness to diagnose IBS on history & physical examination alone Am J Gastroenterol 2010;105:848- Yes No Unsure IBS experts 70% 7% 23% Community gastroenterologists 52% 3% 45% General internal medicine physicians 34% 7% 59% Nurse practitioners 41% 9% 50%
  29. 29. Colon cancer (Singapore)
  30. 30. Colon cancer (Singapore) 1:20 life time risk
  31. 31. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Non-functioning NET does not produce hormone Asymptomatic carcinoid When NET grows bigger, can cause pain, bleeding, obstruction How does carcinoid(NET) cause diarrhea ?
  32. 32. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Functioning NET produces hormone (serotonin) Hormone in intestine goes to liver Hormone is destroyed by liver No hormone in blood, therefore no diarrhea Asymptomatic carcinoid How does carcinoid(NET) cause diarrhea ?
  33. 33. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Production of hormone by tumor metastases in the liver Hormone from the liver is released into the blood Hormone in blood causes diarrhea Gastrointestinal carcinoids (NETs) present late by the time diarrhea occurs OR NET in lung produces hormone that is released in the blood therefore causes diarrhea How does carcinoid(NET) cause diarrhea ?
  34. 34. USA GI + pancreatic NET is 2.85 per 100,000 Total NET is 5 per 100,000 Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Carcinoid
  35. 35. Colon cancer (Singapore) Carcinoid, NET (USA) 5 per 100,000 (male+female) 38 per 100,000 (male+female) Carcinoid, NET (Singapore)??? Incidence Statistics 1993-2002
  36. 36. Singapore Cancer Statistics 1993-2002 Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Sitenumber cases Adeno-cancer NET-cancer Rectum 3,893 115 Lung 3,416 80 Colon 5,676 70 Stomach 3,188 26 Small intestine 95 24 Pancreas 510 8 Total cases 16,778 323
  37. 37. Singapore Cancer Statistics 1993-2002 Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Sitenumber cases Adeno-cancer NET-cancer Rectum 3,893 115 Lung 3,416 80 Colon 5,676 70 Stomach 3,188 26 Small intestine 95 24 Pancreas 510 8 Total cases 16,778 323 300,000 cases IBS (10% of 3 million)
  38. 38. Why is there a difference ? • Singapore 300-400 cases NET-cancer over 10 years. • If we applied USA figures, we expect about 2,000 cases NETs over 10 years • Possible reasons (i) Real differences between East and West (ii) Under diagnosed (iii) Under reported: NET-cancer is notifiable, but NET is not. More study needed Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health
  39. 39. P-NET 0.32/100,000 1.01/100,000 GI-NET 2.53/100,000 2.10/100,000 Total 2.85/100,000 3.11/100,000 Yao JC, J Clin Onco 2008 Ito T, J Gastroenterol 2010 Incidence rates: West vs East
  40. 40. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health A test is available for NET: Chromogranin A
  41. 41. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health The Perfect World - A Perfect Test Sensitivity 100% Specificity 100% True Positive = disease present True Negative = disease absent
  42. 42. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health The Real World True Positive = disease present True Negative = disease absent False Positive = false alarm False Negative = disease missed
  43. 43. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health The Real World True Positive = disease present True Negative = disease absent False Positive = false alarm False Negative = disease missed
  44. 44. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Test A for disease X Test 1,000 people. Assume disease X is present in 1% = 10 people Sensitivity = 85% Specificity = 85%, false positive = 15% 85/100 x 10 = 8.5 have disease X (true positive) Number of false positive tests is 15/100 x 1,000 = 150 persons Total = 159 positive tests
  45. 45. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Test B for disease X Test 1,000 people. Assume disease X is present in 1% = 10 people Sensitivity =98% Specificity = 98%, false positive = 2% 98/100 x 10 = 9.8 have disease X (true positive) Number of false positive tests is 2/100 x 1,000 = 20 persons Total = 30 positive tests
  46. 46. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health What to do with a positive test? Further tests Scans, Bronchoscopy, Gastroscopy, Colonoscopy, Biopsy True Positive test Disease X False Positive test Normal people Test A = positive tests 1,000 tested Disease X = 10 Normal = 990
  47. 47. Sensitivity 85% Specificity 85% 1,000 persons True + (85%) False + (15%) 0 disease 0 150 10 disease (1%) 8.5 150 100 disease (10%) 85 150 500 disease (50%) 425 150 Test A for disease X
  48. 48. Sensitivity 98% Specificity 98% 1,000 persons True + (98%) False (2%) 0 disease 0 20 10 disease (1%) 9.8 20 100 disease (10%) 98 20 500 disease (50%) 490 20 Test B for disease X
  49. 49. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Principles of testing 1 High occurrence of disease - high pick up rate 2 Low occurrence of disease - low pick up rate 3 Low occurrence disease, most positive tests are false positive 4 High occurrence disease, most positive tests are true positive 4 More people tested - more disease found 5 More people tested - more false positive tests found 6 Positive test needs further tests to differentiate true disease from a false alarm
  50. 50. Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Principles of testing 1 Choosing a high risk group (with high occurrence of disease) will increase the yield and reduce false positive 2 High risk group for NET tumor is a family history of NET tumor 3 “IBS” is not recognized as a high risk group for screening
  51. 51. Rectum carcinoid confirmed CgA normal (false negative test)
  52. 52. Carcinoid (neuroendocrine) tumor • NET is out there • Not every type of pre-cancer or cancer can be detected early with screening • There are benefits and harm from screening a balance has to be achieved • Testing in patient with symptoms = diagnostic testing • Testing in healthy person with no symptoms = screening Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health
  53. 53. • Promote and ride on colon cancer screening which is on- going. Opportunistic screening for gastric, rectum and ileum NETs during gastroscopy and colonoscopy for other reasons • Small intestine NETs are nearly impossible to diagnose early • Consider the possibility of the condition in those with • prominent diarrhea (mimic IBS) • facial flush • wheezing (mimic asthma) • Unfortunately these symptoms indicate late metastatic disease for NET in the gut and are rare • May be early disease for NET in the lung What can we do now ? Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health
  54. 54. Singapore Cancer Statistics 1993-2002 Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Sitenumber cases Adeno-cancer NET-cancer Rectum 3,893 115 (36%) Lung 3,416 80 Colon 5,676 70 (22%) Stomach 3,188 26 (7%) Small intestine 95 24 Pancreas 510 8 Total cases 16,778 323 GI-NET cancer Rectum + colon + stomach account for 65% of all NET cancer
  55. 55. Singapore Cancer Statistics 1993-2002 Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health Sitenumber cases Adeno-cancer NET-cancer Rectum 3,893 115 (36%) Lung 3,416 80 Colon 5,676 70 (22%) Stomach 3,188 26 (7%) Small intestine 95 24 Pancreas 510 8 Total cases 16,778 323 Arising from the large numbers of gastroscopies and colonoscopies performed daily, there is opportunistic screening
  56. 56. Risks of medical tests
  57. 57. Managing your risks We see examples of risk every day
  58. 58. Risk and benefit go together
  59. 59. Managing your risks • Risk is part of medical tests and treatment • Weigh “risks” vs “benefits”: test vs non-test • Weigh “risks” vs “benefits”: treatment vs non- treatment Choose your doctor Experience with carcinoid Don’t hurry colonoscopy: tumors are small Track record
  60. 60. Risk of colonoscopy Sedation risk •For maximum safety, comfort, perform in a center with monitoring facilities •Get a doctor who is experienced, good track record: personal no sedation mishaps in 20 years, >10,000 procedures •Colonoscopy is possible without sedation •Awake colonoscopy - mild discomfort - case by case basis Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health
  61. 61. Risk of colonoscopy Procedure risk: •Perforation, bleeding. Get a doctor with experience, good track record: personal zero perforation rate in 20 years •Good colonoscopy technique Yap Chin Kong Gastroenterology & Liver Clinic For Digestive, Colorectal, Liver & Pancreatic Health
  62. 62. CT colonography
  63. 63. Arch Intern Med 2009;169(22):2078-2086 Radiation Dose Associated with Common Computed Tomography Examinations and the Associated Lifetime Attributable Risk of Cancer
  64. 64. Age 20 yr Age 40 yr Age 60 yr F M F M F M CT abdomen 250 330 460 498 700 660 CT coronary 150 390 270 595 420 790 CT brain 4,630 7,350 8,100 11,080 12,250 14,680 CT colon Not analysed Number of CT scans to give rise to 1 cancer Arch Intern Med 2009;169(22):2078-2086
  65. 65. Doctors try our best It’s not nice to be sick .... But there are risks & benefits In the diagnostic and therapeutic journey
  66. 66. First do no harm Given an existing problem, it may be better not to do something, or even do nothing, than to risk doing more harm than good Human acts with good intentions may have unwarranted consequences
  67. 67. Do I need a CgA test? No! High false positive results I attended a talk on carcinoid. I am worried. I have no symptoms
  68. 68. Do I need a CgA test? No! Unless symptoms are atypical on periodic review I have typical IBS symptoms
  69. 69. Do I need a CgA test? Maybe! Diagnose the cause of diarrhea: blood, stool tests, colonoscopy, biopsies, ± CT scan If suspect NET do CgA test I have persistent diarrhea for one month and lost weight
  70. 70. Do I need a CgA test? I have a family member with carcinoid Yes! Gastroscopy, colonoscopy Gallium PET scan baseline? How frequent? Annually? Q: CgA is negative, does it mean I am safe ?
  71. 71. Do I need a CgA test? Dr Yap performed a colonoscopy. He found and removed an incidental rectum carcinoid Yes! Up to 25% have another tumor Gastroscopy, colonoscopy Gallium PET scan baseline? How frequent? Annually? Q: CgA is negative, does it mean I am cured ?
  72. 72. Diarrhea & pain can be a challenging diagnosis NETs in Singapore: Unanswered questions More research and statistics needed Be mindful of the possibility but not over-react Maintain a balanced approach and perspective Maintain patient-centric focus
  73. 73. IBS NETColon cancer Other causes IBS symptoms
  74. 74. He who has health has hope, He who has hope has everything Yap Chin Kong Gastroenterology & LiverClinic
  75. 75. Wishing everyone good health Thank you! Yap Chin Kong Gastroenterology & LiverClinic www.gastroliver.com.sg

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