Crohn's Disease: The Role of Nutrition Support

Donald R. Duerksen, MD, St. Boniface General Hospital and University of Manitoba, Winnipeg, Manitoba, Canada.

Disclosures
In This Article

Major Clinical Presentations of Crohn's Disease: The Role of Nutrition Support

Acute Exacerbation of Crohn's Disease

A flare of Crohn's disease may be defined by a Crohn's disease activity index (CDAI) >150, where factors such as diarrhea, abdominal pain, abdominal mass, sense of well being, extra-intestinal manifestations, weight loss, and laboratory features are considered.[16] Severe disease activity is defined by a CDAI > 300. Sulfasalazine and the 5-aminosalicylic acid (5-ASA) compounds may be useful for treating mild flares of disease; the value of corticosteroids in the management of these patients has also been proven.[17] For those patients not responding to oral steroids, intravenous corticosteroids may induce disease remission.[18]

Enteral nutrition may induce remission of Crohn's disease in 60%-80% of patients with an acute exacerbation.[19,20,21] While this is significantly greater than the 20% placebo remission rate reported in other clinical studies, no placebo controlled trial has yet been performed. The mechanism by which enteral nutrition induces clinical remission in Crohn's disease remains unclear.[1,2] Some hypotheses put forth include reduced antigenicity of the luminal contents due to absence of whole protein, exclusion of dietary components not found in enteral formula diets, alteration of host bacterial flora, reduction of total fat, and, in particular, linoleic acid (which may reduce inflammation by decreasing eicosanoid precursors), decreasing colonic fecal bile salt load (due to low-fat diets decreasing enterohepatic circulation of bile acids), and provision of specialized nutrients (such as glutamine in chemically defined diets). Bowel rest does not appear to be of major importance in effecting a remission.[22]

A recent meta-analysis of trials of enteral feeding in Crohn's disease concluded that enteral feeding was not as effective as corticosteroid therapy in this disease setting.[23] There is, however, a subset of patients who may benefit from enteral nutrition after failing steroid therapy.[24] The most effective type of enteral formula is currently a matter of contention, with most randomized controlled studies demonstrating no significant difference between elemental and polymeric formulas.[25,26,27] No definitive conclusions were drawn from the recent meta-analysis regarding type of formula because of the small number of patients that had been studied.[23] Polymeric formulae have the advantage of being less costly. Important clinical issues, such as the use of enteral nutrition in steroid refractory cases, the mechanism of enteral nutrition-induced clinical remissions, and the role of nutrition in maintaining remission, still need to be addressed. The East Anglian (UK) study demonstrated a prolonged remission compared with corticosteroids for patients fed an exclusion diet following induction of remission with enteral nutrition.[28] Thus, the exact role of nutritional therapy in the primary treatment of Crohn's disease in adults has yet to be defined.

In the absence of more data, the following approach to nutritional support of patients with an acute exacerbation of Crohn's disease should be considered: Severely malnourished patients should receive immediate attention to their nutritional status. If tolerated, enteral feeding is the method of choice; TPN should be reserved for those intolerant of the enteral route. In nonmalnourished or mildly malnourished patients with an acute flare of Crohn's disease, a trial of enteral nutrition should at least be considered as primary therapy, either as an adjunct to steroid therapy or as sole therapy. If after 5 days there is a poor clinical response to steroid therapy or enteral feeding is not tolerated, TPN should be instituted. Patients with severe disease activity should also receive immediate nutritional attention; it is justified to initiate TPN in many such instances because of the great likelihood of intolerance to enteral feeding.

Intestinal Obstruction

A frequent presentation of Crohn's disease is abdominal pain, nausea, and vomiting with radiologic evidence of obstruction. While the differential diagnosis is broad, principal considerations include exacerbation of Crohn's disease with transmural intestinal inflammation and edema causing luminal narrowing, fixed fibrotic stricturing from long-standing inflammation, and adhesions (particularly if there has been previous surgery).[29] If an acute exacerbation of disease is likely, a trial of intravenous corticosteroids should be initiated. If the patient is considered severely malnourished, TPN should also be started if there is no clinical improvement in 2-3 days (enteral nutrition is contraindicated in the setting of continued intestinal obstruction). If the patient is not severely malnourished, TPN is not indicated unless a fasting state persists longer than 5 days -- although fluid and electrolyte homeostasis should be provided.

Fistulizing Disease

Because of the transmural inflammation, fistula formation is a common complication of Crohn's disease. There is no indication to specifically treat asymptomatic fistulas between 2 portions of small bowel. Complicated, symptomatic fistulas between small bowel and portions of the urinary tract, female genital tract, and colon, and gastro-colic fistulas generally require surgical management.[29] In the setting of a severely malnourished patient, pre- and postoperative TPN would be indicated for reasons described above. Medical management with metronidazole,[30] azathioprine,[31] or cyclosporine[32] represent evolutions in the treatment of fistulas. Enteral feeding is indicated in low-output, distal enterocutaneous fistulas. In those cases where fistulas increase with enteral nutrition or are high output, enterocutaneous fistulas may respond to medical management, bowel rest and TPN, but the success rate of fistula closure in a spontaneously developing fistula in Crohn's disease is much lower than in fistulas that develop postoperatively. There are no controlled clinical trials comparing the success of this approach with surgery. However, to avoid unnecessary surgery, a trial of medical management with TPN is often warranted, particularly in refractory, low-output enterocutaneous fistulas.

Recently, a monoclonal, chimeric anti-tumor necrosis factor (TNF) antibody has demonstrated effectiveness in treating fistulas associated with Crohn's disease.[33] The interaction of nutrition support and in particular, TPN, with anti-TNF is unknown at present.

Perianal Disease

This complication affects 11%-28% of patients with Crohn's disease.[34] The natural history is variable, but is usually marked by frequent recurrences. A perianal disease activity index (PDAI) has recently been developed that may prove useful in the initial evaluation of this complication and in monitoring the response to therapy.[35] Surgical management is indicated for drainage of localized infection and for severe disease unresponsive to medical therapy.[36] Medical therapies that have been used in this setting include antibiotics (metronidazole, ciprofloxacin),[30] azathioprine,[31] and cyclosporine.[32] The most common immunosuppressive therapy used in this condition is azathioprine. It may take several months before a clinical benefit is achieved with this medication, and supporting patients with TPN while azathioprine takes effect is a reasonable option in patients with severe refractory perianal disease. Severely malnourished patients require early nutritional support. The optimum route of delivering nutrition has not been studied, and the role of bowel rest and TPN in this manifestation of Crohn's disease is not known. If disease is severe and difficult to control, bowel rest may be attempted. Patients with severe, refractory perianal disease who will be kept NPO for longer than 5 days should have TPN initiated in order to provide basic nutritional support.

Adolescents With Crohn's Disease

Of particular concern in adolescents with this disease is maintaining normal growth and development. Growth failure in patients with Crohn's disease may be due to decreased oral intake, increased stool losses, inhibitory effects of inflammatory cytokines on growth, or adverse effects of medications (eg, corticosteroids). Enteral nutrition using nasogastric or gastrostomy feeding may be particularly relevant to this population, because it results in induction of clinical remission in a significant number of patients,[23] has a beneficial effect on growth,[37,38] and may prevent the need for systemic corticosteroids.

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