Results of a first-of-its-kind clinical trial shed light on when antibiotics instead of surgery might be the better choice for treating appendicitis in some patients, according to a new study.

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The study was carried by researchers with The University of Texas Health Science Center at Houston (UTHealth), who led the Houston trial sites. The results from the national Comparing Outcomes of Antibiotic Drugs and Appendectomy (CODA) trial were published today in the New England Journal of Medicine. "This was the first multicenter U.S. trial to study appendicitis treatment, and it assessed a diverse population in addition to a wider variety of appendicitis than previous trials," said Mike Liang, MD, associate professor of surgery with McGovern Medical School at UTHealth, who was the principal investigator at Harris Health's Lyndon B. Johnson Hospital, which was one of the largest enrolling sites of the 25 across the country that participated in the trial.

"We found that antibiotics were not worse than surgery when measuring overall health status, allowing most people to avoid operation in the short term," said Lillian Kao, MD, division director of acute care surgery with McGovern Medical School and the principal investigator of the CODA trial site at Memorial Hermann-Texas Medical Center. "There were advantages and disadvantages to both treatments, and patients are likely to prioritize these in different ways based on their characteristics, concerns, and perspectives."

Across the U.S., 1,552 participants were randomized to receive either an appendectomy or treatment with antibiotics first for acute appendicitis. While nearly half of the antibiotics group avoided hospitalization for their initial treatment, overall, the time spent in the hospital was similar between groups. "People treated with antibiotics more often returned to the emergency department but missed less time from work and school," said Bonnie Bizzell, chair of the CODA Patient Advisory Board. "Information like this can be important for individuals as they consider the best treatment option for their unique circumstance. The CODA trial is really the first of its kind to capture these measures for appendicitis shared decision-making."

Other initial findings of the CODA trial include:

• Patients treated with either surgery or antibiotics experienced symptoms of appendicitis for about the same amount of time.
• Approximately 3 out of 10 patients in the antibiotic group underwent appendectomy within 90 days, but 7 in 10 participants avoided an operation.
• Patients with an appendicolith, a calcified deposit within the appendix, had twice the risk of complications than those without an appendicolith.
• Participants with an appendicolith had an increased chance of appendectomy within 90 days (4 in 10 with appendicolith versus 3 in 10 without).
• The CODA trial is the largest randomised clinical trial of appendicitis conducted to date and is funded by the Patient-Centered Outcomes Research Institute (PCORI).

"Many patients with appendicitis do well with and without surgery," Liang said. "Balancing these risks and benefits of each treatment should be personalized for each individual patient given their own situation and preferences. Using the data from this research, more information will be shared in the near future, including who might benefit most from surgery versus medical management as well as the long-term results of these two treatments."

"This is an important trial in many ways, primarily in that the question, the methods, and the outcomes were informed by patient stakeholders," Kao said. "Additionally, as a 'real-world' trial, CODA enrolled a broad spectrum of patients that truly represents the heterogeneous population that we serve. This is just the beginning of a national partnership that has the capacity to address unanswered questions regarding optimal patient-centred care in surgery." The CODA Collaborative, composed of clinicians at each of the 25 CODA trial sites, patient advisors, and other stakeholders, will continue to share results from the trial as ongoing follow-up with participants is completed.