The presence of mineralized stool, known as appendicolith, was associated with a nearly twofold increased risk of undergoing appendectomy within 30 days of initiating antibiotics, write David Flum, MD, of the University of Washington, Seattle, and coauthors in a paper published in JAMA Surgery on Jan. 12, 2021.
But the surprise was the lack of an association between appendectomy and factors often presumed to be consistent with more severe appendicitis.
Physicians have had their own ideas about what factors make a patient more likely to need an appendectomy after an initial round of treatment with antibiotics, such as a high white blood cell count or a perforation seen on CT scan, Dr. Flum said in an interview. But the research didn’t support some of these theories.
“This is why we do the studies,” Dr. Flum said. “Sometimes we find out that our hunches were wrong.”
Dr. Flum and coauthors measured the association between different patient factors and disease severity and the need for appendectomy following a course of antibiotics. They used adjusted odds ratios to describe these relationships while accounting for other differences.
An OR of 1.0 – or when the confidence interval around an OR crosses 1 – signals that there is no association between that factor and appendectomy. Positive ORs with confidence intervals that exclude 1.0 suggest the factor was associated with appendectomy.
The OR was 1.99 for the presence of appendicolith, a finding with a 95% confidence interval of 1.28-3.10. The OR was 1.53 (95% CI, 1.01-2.31) for female sex.
But the OR was 1.14 (95% CI, 0.66-1.98) for perforation, abscess, or fat stranding.
The OR was 1.09 (95% CI, 1.00-1.18) for radiographic finding of a larger appendix, as measured by diameter.
And the OR was 1.03 (95% CI, 0.98-1.09) for having a higher white blood cell count, as measured by a 1,000-cells/mcL increase.
Appy or not?
This paper draws from the Comparison of Outcomes of Antibiotic Drugs and Appendectomy (CODA) trial (NCT02800785), for which top-line results were published in 2020 in the New England Journal of Medicine. In that paper, Dr. Flum and colleagues reported on results for 1,552 adults (414 with an appendicolith) who were evenly randomized to either antibiotics treatment or appendectomy. After 30 days, antibiotics were found to be noninferior to appendectomy, as reported by this news organization.
The federal Patient-Centered Outcomes Research Institute funded the CODA research. Dr. Flum said the National Institutes of Health had not appeared interested in funding a look at the different options available to patients experiencing appendicitis. Congress created PCORI as part of the Affordable Care Act of 2010, seeking to encourage researchers to study which treatments best serve patients through direct comparisons. Its support was critical for Dr. Flum and colleagues in seeking to help people weigh their options for treating appendicitis.
The CODA study “models what the patient’s experience is like, and this has not been the focus of NIH as much,” Dr. Flum said.
The CODA team has sought to make it easy for patients to consider what its findings and other research on appendicitis mean for them. They created an online decision-making tool, available at the aptly named http://www.appyornot.org/ website, which has videos in English and Spanish explaining patients’ options in simple terms. The website also asks questions about personal preferences, priorities, and resources to help them choose a treatment based on their individual situation.