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Antibiotics for Diverticulitis: Pick Your Route of Delivery
Abstract & Commentary
Malcolm Robinson MD, FACP, FACG, AGAF, Emeritus Clinical Professor of Medicine, University of Oklahoma College of Medicine, Oklahoma City. Dr. Robinson reports no financial relationship to this field of study.
Synopsis: Oral antibiotics were not found to be inferior to intravenous antibiotics in the treatment of clinically diagnosed acute diverticulitis.
Source: Ridgway PF, et al. Randomized controlled trial of oral vs. intravenous therapy for the clinically diagnosed acute uncomplicated diverticulitis. Colorectal Disease 2008 Nov 7; Epub ahead of print.
Diverticular disease is extremely common in Western populations, ultimately affecting almost everyone. Most individuals with diverticulosis never have serious symptoms. However, acute diverticulitis requiring hospitalization is becoming increasingly common (undoubtedly now at a rate greater than 32/100,000 population each year). Less than 25% of clinical acute diverticulitis cases require surgery, but all patients who are hospitalized will be treated with bowel rest, intravenous fluids, and intravenous antibiotics. Antibiotics chosen for inpatients vary greatly, but metronidazole is commonly combined with a cephalosporin or a quinolone or a complex penicillin such as amoxicillin. However, a significant number of patients with symptoms that are clinically consistent with acute diverticulitis are treated in the community as outpatients with the administration of oral antibiotics.
This randomized controlled but unblinded study was performed in 2 busy District General Hospitals in southeast Ireland over 18 months beginning in January 2002. Diverticulitis was diagnosed by the presence of left iliac fossa pain and tenderness, often (but not always) accompanied by fever and leukocytosis. Patients with generalized tenderness or suspected perforation were excluded. Plain abdominal films and chest X-rays were used to support the suspected diagnosis. CT scanning was not routinely performed. Informed consent was obtained, and 79 consenting patients were randomized to receive either 24 hours of bowel rest with subsequent diet advancement as tolerated and intravenous antibiotics (ciprofloxacin 400 mg bid plus metronidazole 500 mg tid) or, in the oral arm, diet as tolerated along with oral antibiotic therapy with ciprofloxacin 500 mg bid plus metronidazole 400 mg tid. Daily abdominal tenderness was graded, and development of severe generalized tenderness would have led to exclusion from the study.
There were no particular requirements for specific follow-up laboratory or radiographic studies. There were no treatment failures or crossovers during the study. A majority of patients were female with a mean overall age of 67 years. There had been an average 3-day history of prodromal symptoms, and about 10% of patients had received outpatient antibiotics, but this prior treatment had no effect on outcome. White blood cell counts were 12,000-13,000 at admission, and erythrocyte sedimentation rates were in the 40 mm per hour range. Abdominal tenderness declined identically over 9 days in both groups. Total hospital stays were slightly longer in the intravenous group at 6.6 days vs the oral group at 5.5 days, although this was not statistically significant. Nearly 95% of patients ultimately had colonoscopy or barium enema.
Diverticulosis was confirmed in 80.5% of the oral therapy group and in 89.5% of the intravenous group (some in each group were lost to follow-up). The authors comment that hospitalization for diverticulitis and the use of intravenous antibiotics remains common, at least in Europe. Their study found no advantage for IV therapy over oral antibiotics.
As the authors themselves commented, the clinical diagnosis of acute diverticulitis is highly imperfect. This is, in my view, the major weakness of the study. The gradual resolution of abdominal tenderness over time did not closely correspond to falling white blood cell counts or sedimentation rates. A third study arm with placebo administration would have been exceptionally valuable since most clinicians appreciate that many similar episodes resolve spontaneously.
High hospitalization costs, and corresponding cost containment measures in the United States, have undoubtedly blocked the hospitalization of most patients with the "soft signs" of acute diverticulitis that were admission criteria in the present study. Nevertheless, we can all be more comfortable with the continued expansion of outpatient treatment for patients with similar presentations. An equally important issue is the rapidity with which patients who have left lower abdominal pain receive outpatient prescriptions for one or more antibiotics, often with no evaluation other than telephone contact. The rationality of this approach has never been properly evaluated to the best of my knowledge, and it is virtually certain that a large number of these patients are receiving powerful (and often expensive) pharmaceutical agents that they do not need. Even so, it would be hard to argue that oral antibiotic therapy isn't safer and cheaper than hospitalization for intravenous therapy. If consideration of the data from Ireland saves even a few patients from needless hospitalization, the study will have been worthwhile after all.