Think carefully about when to withhold
For decades, it was standard practice to give antibiotics to all patients with acute uncomplicated diverticulitis (AUD). While most patients with a first diagnosis of AUD recover within a few weeks, a small proportion will develop a complication.1 Among generally healthy patients with an initial diagnosis of AUD, about 3% will progress to complicated diverticulitis, and about 1% will require emergency surgery within 6 months. Around another 6% of cases will develop chronic diverticulitis with ongoing diverticular inflammation that persists for weeks to months.
Because the complications are uncommon, we don’t know if antibiotics reduce the risk of progression to complicated diverticulitis, emergency surgery, or the development of chronic diverticulitis. Investigating these patient-centered and morbid outcomes would require trials enrolling thousands of patients and to following these patients for months. This trial hasn’t happened yet.
Dr. Anne Peery
To date, only small studies have compared the use of antibiotics with no antibiotics in patients with AUD. A review sponsored by the Agency for Healthcare Research and Quality published last year concluded that the current evidence was too sparse or too inconsistent to make strong conclusions about the use of antibiotics for patients with uncomplicated diverticulitis.2
With little evidence for or against antibiotics, recent guidelines have begun to recommend that antibiotics be used selectively, rather than routinely, in patients with diverticulitis.3 “Selectively” clearly means that there are some patients who should receive antibiotics, but the guidelines are vague about who those patients are. To this end, it is safest to refer to those small, underpowered trials to identify which patients are at the greatest risk of developing a complication.1,4 The authors of those trials considered a number of groups high risk and therefore excluded them from those trials. In the absence of further definitive research, it seems clear that those groups, listed below, should therefore be selected for antibiotic treatment:
- Patients with complicated diverticulitis including paracolic extraluminal air on CT scan.
- Patients who are immunocompromised.
- Patients with a high fever, affected general condition, or clinical suspicion of sepsis.
- Patients with inflammatory bowel disease.
- Patients who are pregnant or breast feeding.
As with most clinical trials, participants in these smaller trials were younger (median age, late 50s) and healthier (63% normal, healthy patient; 34% mild systemic disease; 4% severe systemic disease) than the general population. In secondary analyses, however, several factors were independently associated with a complicated disease course after an initial diagnosis of acute uncomplicated diverticulitis. As with the first list above, the following high-risk patients should also be treated with antibiotics at diagnosis:
- Patients with American Society of Anesthesiologists scores III or IV were 4.4 times more likely to have a poor outcome, compared with those with ASA score I.
- Patients with ASA score II were 2.0 times more likely to have a poor outcome, compared with ASA score I.
- Patients with symptoms for more than 5 days at diagnosis were 3.3 times more likely to have a poor outcome, compared with those with symptoms for 5 days or less.
- Patients with vomiting at diagnosis were 3.9 times more likely to have a poor outcome, compared with those who were not vomiting.
- Patients with C-reactive protein levels higher than 140 mg/L at diagnosis were 2.9 times more likely to have a poor outcome, compared with C-reactive protein level of 140 mg/L or less.
- Patients with white blood cell count greater than 15 x 109 cells/L at diagnosis were 3.7 times more likely to have a poor outcome, compared with those with 15 x 109 cells/L.
- Patients with a longer segment (>86mm) of inflamed colon on CT scan were more likely to have a poor outcome, compared those who had a shorter segment (<65mm).
To help clinicians think about antibiotic treatment in patients with AUD, a recent American Gastroenterological Association clinical practice update provided the following advice: First, antibiotic treatment is advised in patients with uncomplicated diverticulitis who have comorbidities or are frail, who present with refractory symptoms or vomiting, or who have a C-reactive protein level greater than 140 mg/L, or baseline white blood cell count greater than 15 x 109 cells/L.5 Also, antibiotic treatment is advised in patients with complicated diverticulitis or uncomplicated diverticulitis with a fluid collection or longer segment of inflammation on CT scan. Finally, patients with uncomplicated diverticulitis who are immunosuppressed are high risk for progression to complicated diverticulitis or sepsis and should be treated with antibiotics.
The lists above clearly leave some patients with AUD who may be managed without antibiotics. These patients are otherwise healthy, have good social support, access to health care, and are experiencing a mild, self-limited episode. Avoiding antibiotics requires shared decision-making with a well-informed patient. I have patients who have embraced this approach, while others found this unacceptable. Given the current level of uncertainty in the literature, I make it my practice to offer antibiotics to any patient who feels strongly about receiving them.
As with many issues in modern medicine, the use of antibiotics in AUD is an unsettled question. Given the known harms of progression of diverticulitis, it is clearly safest to treat patients who were excluded from the small studies we have or flagged by those same studies as being at increased risk of progression. Our uncertainty also demands a shared decision-making model, filling in our patients on what we can and cannot say with confidence. As is often the case, further research is desperately needed. Until that happens, antibiotics for AUD will remain a regular part of my practice.
Anne F. Peery, MD, MSCR, is with the center for gastrointestinal biology and disease at the University of North Carolina at Chapel Hill. She has no conflicts to disclose.
References
1. Daniels L et al. Br J Surg. 2017 Jan;104(1):52-61.
2. Balk EM et al. Management of Colonic Diverticulitis. Comparative Effectiveness Review No. 233. Agency for Healthcare Research and Quality. 2020 Oct. doi: 10.23970/AHRQEPCCER233.
3. Stollman N et al. Gastroenterology. 2015 Dec;149(7):1944-9.
4. Chabok A et al. Br J Surg. 2012 Jan 30;99(4):532-9.
5. Peery AF et al. Gastroenterology. 2021 Feb;160(3):906-11.e1.
