Comparison of Outcomes of Antibiotic Drugs and Appendectomy (CODA), United States, 2016-2020 (ICPSR 38541)

Version Date: Nov 14, 2022 View help for published

Principal Investigator(s): View help for Principal Investigator(s)
David R. Flum, University of Washington

Version V1

Slide tabs to view more

Antibiotics are considered a feasible treatment for appendicitis, yet appendectomy remains the treatment standard in the United States. Previous randomized trials comparing these treatments excluded important subgroups and recruited small sample sizes but questions remain about the applicability of these previous findings. This study conducted the Comparison of Outcomes of antibiotic Drugs and Appendectomy (CODA) randomized clinical trial to compare antibiotics with appendectomy among adults with appendicitis, including those with appendicolith. Those recruited comprised a diverse population, compared an overall measure of health status as the primary outcome, and included several secondary clinical and patient-reported outcomes, complications, and measures of healthcare utilization.

Flum, David R. Comparison of Outcomes of Antibiotic Drugs and Appendectomy (CODA), United States, 2016-2020. Inter-university Consortium for Political and Social Research [distributor], 2022-11-14.

Export Citation:

  • RIS (generic format for RefWorks, EndNote, etc.)
  • EndNote

Access to the data in this collection is restricted. Users interested in obtaining these data must complete a Restricted Data Use Agreement, specify the reason for the request, and obtain IRB approval or notice of exemption for their research.

Inter-university Consortium for Political and Social Research

2016-05-03 -- 2021-06-21
2016-05-03 -- 2021-06-21

The CODA randomized clinical trial aimed to compare antibiotics with appendectomy among adults with appendicitis, including those with appendicolith.

The specific aims of this study were as follows:

Aim 1: Compare patient reported outcomes (PROs) in patients randomized to the antibiotics or appendectomy strategy.

Sub Aim 1: Compare PROs in patients without appendicolith randomized to the antibiotics or appendectomy strategy.

Exploratory Aim 1: Assess the rate of eventual appendectomy after starting the antibiotics treatment regimens in the first week, early (1-4 weeks) and late (2-24 months) periods, and identify patient clinical characteristics (e.g., appendicolith) as well as clinician and practice site characteristics associated with eventual appendectomy in the antibiotic therapy group.

Aim 2: Compare clinical outcomes in patients randomized to antibiotics versus appendectomy.

Sub Aim 2: Compare clinical outcomes in patients without appendicolith randomized to the antibiotics or appendectomy strategy.

Exploratory Aim 2: Compare randomized patients to those in a concurrent observational cohort to identify selection characteristics and outcome differences between the two groups.

The CODA trial was a pragmatic, nonblinded, noninferiority, randomized trial comparing antibiotic therapy (10-day course) with appendectomy in patients with appendicitis at 25 U.S. centers. Patients, clinicians, professional societies, and others participated in trial design. Institutional review boards at each site approved the study, and participants gave written informed consent.

Participants were enrolled from 05/03/2016 through 02/05/2020. Consecutive English- and Spanish-speaking adults (age 18 years of age or older) with imaging-confirmed appendicitis in emergency departments (EDs) were approached, including patients with radiographic findings of appendicolith. The consent process included a standardized, informational video or pamphlet in English or Spanish. Consenting participants were randomized to treatment stratified by recruitment site and appendicolith status. Those declining randomization were offered participation in an observational study. Antibiotics consisted of intravenous formulations for at least 24 hours, followed by pills (10-day total).

For appendectomy, laparoscopic and conventional (open) surgical approaches were allowed; technique was not standardized. For both arms, protocol allowed crossover based on participant and clinician decision-making. The primary outcome (30-day health status) was assessed with the European Quality of Life - 5 Dimensions (EQ-5D), a 5-domain generic health status measure. Secondary outcomes included clinical and safety outcomes, and serious adverse events (e.g. death, life threatening event or inpatient hospitalization - excluding for treatment of appendicitis) were monitored, as were ED and urgent care (UC) visits for related symptoms, ED and hospitalization days related to appendicitis or treatment for appendicitis, and days of missed work (for patient and/or caregiver).

Enrollment of 1,552 participants was planned to ensure sufficient power overall (>82%). With an intention-to-treat framework, the 30-day EQ-5D using a linear regression model was assessed. To address potential selection bias, a secondary treatment per-protocol analysis of EQ-5D and severe adverse events was performed.

Randomization was stratified by site and appendicolith status.

Longitudinal, Cross-sectional

English- or Spanish-speaking adults (18 years of age or older) in emergency departments at 25 U.S. hospitals who had appendicitis that had been confirmed on imaging (CT, ultrasound, or MRI).


Variables in this collection may be grouped according to three general themes: (1) clinical intervention for appendicitis patients; (2) clinical outcomes for patients 30-days after intervention; and (3) clinical outcomes for patients 1-year after intervention.

A total of 8,168 patients underwent screening, of whom 1,589 (19%) were ineligible for enrollment in the trial for clinical or appendicitis-related reasons. A total of 1,552 participants (31% of the patients who were eligible) underwent randomization. An additional 510 consented to participate in the observational (also known as self-selection) cohort. 90% of participants in the randomized controlled trial completed the 30-day survey, and 79% completed the 1-year survey.

The EQ-5D questionnaire served as the primary endpoint for this trial. The PROMIS Global Health questionnaire and GI Quality of Life questionnaire were also used.




Weight variables for 30-days (SVY_WT_30D) and 1-year (SVY_WT_1YR) with two implied decimal places have been included. It is recommended to use these survey response weights when analyzing survey data collected at 30-days and 1-year.



  • The public-use data files in this collection are available for access by the general public. Access does not require affiliation with an ICPSR member institution.

  • One or more files in this data collection have special restrictions. Restricted data files are not available for direct download from the website; click on the Restricted Data button to learn more.