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home - IBD - Epidemiology - Crohns Epidemiology Written by Dr Sebastian Zeki

Knows the science underlying the pathogenesis of IBD in particular
relating to genetic and environmental factors involved and
differences between UC and Crohn’s disease

Understands the natural history of UC and Crohn’s disease including
its variability and the impact of therapy on the natural history

Understands the mechanism of action (as far as it is understood) and
rationale for using different treatment types in IBD including

aminosalicylates immune suppressants and biologic therapies
Able to use knowledge of modifiable and non-modifiable risk factors
to underly management decisions and to stratify risk for patients and
their relative

Able to explain to patients and their families the concepts underlying
the disease and the factors that they can alter and the risks of
complications and disease su ptibility in relatives

Crohns Epidemiology

Definitions Localised disease is intestinal CD affecting <30 cm in extent. Extensive Crohn’s disease is intestinal Crohn’s disease affecting >100 cm in extent whatever the location and applies to the sum of inflammation in discontinuous segments.While there is clearly a ‘‘grey area’’ of disease extent (between 30 and 100 cm) and the length is arbitrary, this definition of extensive disease recognises the greater inflammatory burden. Crohn’s Disease Presentation:Chronic diarrhoea-Most common.Abdominal pain and LOW- in 60%.Blood and/or mucus PR- in 40%.Extraintestinal manifestations - most common in colonic CD.Perianal fistulas- present in 10% at diagnosis. ClassificationCrohn’s can be classified by disease phenotype (Rome or Vienna classific-tion, modified in Montreal) Classification can be by Disease Activity (mostly according to the CDAI).Classification can be by genetic or other markers eg NOD2/CARD15 mutations assoc with ileal and stricturing CD but less important in non-whites.Classification can be by CRP or other indicators of inflammation.In 50%, those with a raised CRP correlate with increased CDAI.30% have raised CRP but no sx and 30% have normal CRP with high CDAI.There is a higher chance of relapse with a high CRP.If both CRP (>20 mg/l) and ESR (>15 mm 1st h)raised, relapse risk inc x10.If both negative, have a 97% chance of not relapsing in the next 6 weeks. Very high CRP levels are indicative of bacterial complication (such as an abscess).A variety of markers (orosomucoid, IL6, sIL2R, intestinal permeability) may also be predictive.Stool markers such as calprotectin, lactoferrin, or tumour necrosis factor are related to the extent of ulcerated intestinal surface and to the degree of inflammation.Stool markers may have a high predictive value for the presence of ileocolonic inflammation and for upcoming clinical relapse.(ASCA+/ANCA-) high sp for CDClinical permeability scores using inert macromolecules (such as lactulose, L-rhamnose, or mannitol) show abnormal values in a fraction of patients. -Relapse This is defined as a CDAI >150 with an increase of more than 70 points.or CDAI >150 with an increase of 100 points from baseline.-Early relapse is one occurring< 3 months of remission. Steroid-refractory colitis Active disease despite prednisolone up to 0.75 mg/kg/day over a period of 4 weeksSteroid-dependent colitis i) Unable to reduce steroids below the equivalent of prednisolone 10 mg/day within 3 months of starting steroids, without recurrent active disease, or ii) Relapse <3 months after stopping steroids -Remission This is defined as a CDAI <150 .Response = Decrease in CDAI >100 points Active disease Clinical disease activity is grouped into mild, moderate, and severe. Active disease= (CDAI) >220 with CRP >10 mg/l Refers to post surgical recurrence of lesions-Endoscopic recurrence Rutgeerts et al criteria: 0: no lesions; 1: < 5 aphthous lesions; 2: > 5 aphthous lesions with normal mucosa between the lesions, or skip areas of larger lesions, or lesions confined to the ileocolonic anastomotic lining; 3: diffuse aphthous ileitis with diffusely inflamed mucosa; 4: diffuse ileal inflammation with larger ulcers, nodules, or narrowingHyperaemia and oedema alone are not considered as signs of recurrence- Clinical recurrence The appearance of CD symptoms after complete resection of macroscopic disease. Crohn’s Overview EpidemiologyThe age of onset Peak is 15-30.Prevalence is equal in both sexes.It is more prevalent in whites than blacks.It is more common in Jewish people.Incidence, per 100,000 (North America) is 3-14.Prevalence, per 100,000 (North America) is 100 .70-80% need 1 operationA child with affected parents have 10% chance of getting it.There is a 44% monozygotic concordance.Nod2/CARD 15 accounts for 40% of small bowel Crohn's.There is a small decrease in fertility (normal in UC). -Recurrence -Pattern of relapseInfrequent (>1/year), Frequent (>2 relapses/ year)Continuous (no remission) Scored by age at diagnosis (A), disease location (L), and disease behaviour (B). Neither of predictive value in CD Diagnosis Change in diagnosis to UC in 1st year in about 10%–15% of casesIf cant classify then called colitis unclassified. Initial laboratory investigations -Anaemia and thrombocytosis. -The CRP broadly correlates with disease activity of CD ;ESR better correlated with colonic disease activity. Written by Dr Sebastian Zeki

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