Inflammatory bowel disease (IBD) encompasses two types of idiopathic intestinal disease that are differentiated by their location and depth of involvement in the bowel wall. Ulcerative colitis (UC) involves diffuse inflammation of the colonic mucosa. Most often UC affects the rectum (proctitis), but it may extend into the sigmoid (proctosigmoiditis), beyond the sigmoid (distal ulcerative colitis), or include the entire colon into the cecum (pancolitis). Crohn disease (CD) results in transmural ulceration of any portion of the gastrointestinal tract (GI) most often affecting the terminal ileum and colon. Both diseases are classified by extent (mild, moderate, or severe) and location. CD also is classified by phenotype- inflammatory, structuring, or penetrating.
IBS occurs in genetically susceptible individuals after an inappropriate immune response to intestinal flora.
The North American incidence of IBD ranges from 2.2 to 19.2 cases per 100,000 person-years for ulcerative colitis and 3.1 to 20.2 cases per 200,000 person-years for CD. Prevalence in the United States of adult ulcerative colitis was 238 per 100,000 population and 201 per 100,000 population from data in a large study based on insurance claims. IBD is much more prevalent in North America and Europe than Asia or Africa. Although most IBD occurs in people age 15 to 30 years, up to 25% of patients will develop IBD by adolescence. There appears to be a bimodal distribution with a second peak of 10% to 15% developing IBD after age 60.
The intestinal immune system is key to the pathogenesis of IBD. The intestinal epithelium prevents bacteria or antigen entry into the circulation by sealed intracellular junctions. In IBD, these junctions are defective from either a primary barrier function failure or as a result of severe inflammation. Additional protective mechanisms include mucus production by Goblet cells and Paneth cells secretion of a-defensins with intrinsic antimicrobial activity. Excessive inflammatory reactions lead to continued deterioration of the epithelium and further exposure to intestinal microbes thereby furthering worsening the inflammation.
UC predisposes patients to the extraintestinal involvement of the skin, eyes, and bones. Most commonly these involved inflammatory arthropathies and primary sclerosing cholangitis. CD preferentially attacks the ileum and colon but can involve the esophagus, duodenum or stomach. Pediatric-onset cases have greater upper GI tract involvement. As in the case of UC, CD predisposes patients to extraintestinal manifestations including arthritis, aphthous stomatitis uveitis, erythema nodosum, and ankylosing spondyloarthropathy.
Microscopic evaluation in active IBD patients reveals pronounced infiltration of the lamina propria with a mix of neutrophils, macrophages, dendritic cells, and natural killer T cells. Increased numbers and activation of these cells increased the level of tumor necrosis factor-a (TNF-a), interleukin-1b, interferon-g, and cytokines of the interleukins-23-TH17 pathway.
UC most commonly presents as bloody diarrhea with or without mucus. Patients commonly describe tenesmus, a sensation of incomplete evacuation, and abdominal pain. The physical exam may reveal predominantly left lower or left upper quadrant abdominal pain. Signs of an acute abdomen including guarding, rebound tenderness or percussion tenderness warrant investigation for toxic megacolon.
Presentations of Crohn’s disease vary considerably depending on the region of gastrointestinal involvement. Manifestations vary based the underlying etiology of inflammation, fistula formation, or stricture formation. The symptom complex of right lower quadrant pain, weight loss, and non-bloody diarrhea are suggestive of a Crohn’s flare-up. Fistula formation may result in fecaluria, pneumaturia, and rectovaginal fistulas. Masses in the right lower quadrant suggest an abscess.
Diagnosing IBD requires a combination of clinical findings, inflammatory laboratory markers, imaging findings, and endoscopic biopsies. Hematologic findings include microcytic anemia, leukocytosis, and thrombocytosis, Inflammatory markers such as the erythrocyte sedimentation rate (ESR) and high-sensitivity C-reactive protein (hsCRP) are commonly elevated.
Ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) have all been used in the diagnosis of IBD or to assess for complications. US usage in trained individuals can evaluate the right lower quadrant for ileal disease. MRI can evaluate for rectal fistulas. Most commonly, CT is employed to evaluate for perforation or bowel obstruction. CT enterography can be helpful in assessing for strictures or in operative planning.
Endoscopy evaluation with either esophagogastroduodenoscopy, colonoscopy, or both is essential to obtaining biopsies to confirm a diagnosis of IBD.
The goal of treatment is to induce remission for either UC or CD. Treatment of IBD is divided into the management of the mild, moderate, and severe disease. Agents formerly reserved for the more severe disease are now employed sooner. UC treatment depends greatly on the extent of disease and presence of extraintestinal manifestations. For those with mild to moderate disease limited to the rectum, aminosalicylate agents like mesalamine are mainstays. Mesalamine is administered rectally but may be combined with oral therapy to induce or maintain remission. For those patients with the moderate disease who are refractory to mescaline, oral glucocorticoids or immunomodulators such as TNF-a monoclonal antibodies (infliximab) may be an option. Up to 25% of all UC patients will require total colectomy for the uncontrolled disease. Proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the procedure of choice for elective cases.
CD treatment depends on the portion of the GI tract involved, the degree of fistulizing or structuring, and any extraintestinal complications. Treatment of mild ileocecal disease is usually begun with mesalamine, which can be further augmented with the use of oral budesonide, a steroid with significant first-pass metabolization to limit systemic side effects. For more extensive disease, systemic steroid therapy with prednisone is necessary. The goal is to wean these steroids within six weeks. In those patients who cannot wean, an immunomodulating agent is added. 6-mercaptopurine (Purinethol), azathioprine (Imuran), or low-dose methotrexate. In those patients with moderate to severe disease, anti-tumor necrosis factor (anti-TNF) should be initiated. Before initiating biologic therapy, patients must complete purified protein derivative (PPD) to assess for latent tuberculosis. Surgical treatment may be necessary for those with severe fistulizing disease including diverting ostomy.
In patients presenting with new diarrhea, infectious etiologies of diarrhea including parasites Escherichia coli 0157:H7 and Clostridium difficile must be ruled out first. Other colitis etiologies should be considered including, but not limited to, microscopic, lymphocytic, and collagenous. Those presenting with abdominal pain must have other causes considered as well including, but not limited to, appendicitis, irritable bowel disease, celiac disease and functional abdominal pain.
Prognosis for both UC and CD depends on the extent of disease and treatment response. The stool markers lactoferrin and calprotectin are useful in determining postoperative recurrence of CD. Some evidence exists that these can also be used to predict future flares.
Continued surveillance for dysplasia is critical for long-standing UC patients. Cumulative risk of colorectal cancer is estimated to be as high as 30% for those with the disease of 30 years or more. The extraintestinal manifestation of primary sclerosing cholangitis leads to liver failure.
Patients with IBD need life long follow up for their disease. There is no particular diet or supplement that has been shown to delay or prevent the symptoms of the disease.
There are several gaps in our knowledge regarding the care of patients with IBD. Even though many advances have been made in treatment, a number of patients continue to miss out on these treatments. The best care for patients with IBD is from a multidisciplinary team that is dedicated to this pathology and is fully aware of the latest guidelines. Patients with IBD lead an unpredictable life with constant flare-ups and hence the interprofessional team should establish dedicated phone and support lines staffed by nurses and pharmacists. A network of healthcare providers should be easily accessible to deal with emergencies. Physician and allied healthcare collaboration are vital if one is to avoid delay in treatment. The goal is to halt the disease before widespread bowel damage and disability occurs. Furthermore, patient and healthcare communication should be improved and the patients should be supported during times of crises. Finally, evidence suggests that there is a great need to establish centers of excellence so that patients receive a consistent level of quality care across different healthcare settings. (Level V)
The mortality of patients with IBD is about 1.5 -5 times higher compared to the general population. Patients with Crohn disease suffer the highest morbidity and mortality. The major cause of death include infections, the progression of disease, surgical complications, and multiorgan involvement. More important, patients with IBD also have a high rate of colorectal cancer. Patients who develop pancolitis have the highest risk of colon cancer within two decades. Hence screening colonoscopy is recommended at 1-2 year intervals.
In addition to the disease, these patients are also managed with potent medications like steroids and biological agents, which have a host of adverse effects. Thus, the importance of the pharmacist who should be alert for any adverse reaction. Patients with IBD are also at risk for asthma or COPD.
Finally, IBD has enormous mental morbidity. Many patients develop depression, suicidal tendencies, and anxiety. thus, at every visit, the nurse should monitor the patient's mental status and make appropriate referrals.
The quality of life for most patients is poor to okay.