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Original Investigation
November 28, 2018

Risk of Appendiceal Neoplasm in Periappendicular Abscess in Patients Treated With Interval Appendectomy vs Follow-up With Magnetic Resonance Imaging: 1-year Outcomes of the Peri–Appendicitis Acuta Randomized Clinical Trial

Author Affiliations
  • 1Department of Surgery, Oulu University Hospital, Oulu, Finland
  • 2Division of Operative Care, Oulu University Hospital and Medical Research Center Oulu, University of Oulu, Oulu, Finland
  • 3Division of Digestive Surgery and Urology, Turku University Hospital, Turku, Finland
  • 4Department of Surgery, University of Turku, Turku, Finland
  • 5Department of Surgery, Kuopio University Hospital, Kuopio, Finland
  • 6Department of Surgery, Seinäjoki Central Hospital, Seinäjoki, Finland
  • 7Division of Surgery, Gastroenterology and Oncology, Tampere University Hospital, Tampere, Finland
  • 8Department of Biostatistics, University of Turku, Turku, Finland
JAMA Surg. Published online November 28, 2018. doi:10.1001/jamasurg.2018.4373
Key Points

Question  After successful initial nonoperative treatment of periappendicular abscess, is interval appendectomy necessary, or can patients be treated using follow-up examinations with magnetic resonance imaging?

Findings  This randomized clinical trial of 60 patients had to be prematurely terminated owing to ethical concerns after an interim analysis revealed a high incidence of neoplasms, resulting in an underpowered trial unable to draw firm conclusions on the primary end point of treatment success at 1 year after the intervention. The neoplasm rate of the whole study population was 20%; the rate in patients older than 40 years was 29%.

Meaning  The neoplasm rate after periappendicular abscess in this small study population was high; if this rate is validated by future studies, it would argue for routine interval appendectomy in this context.


Importance  The step after conservative treatment of periappendicular abscess arouses controversy, ranging from recommendations to abandon interval appendectomy based on low recurrence rates of the precipitating diagnosis to performing routine interval appendectomy owing to novel findings of increased neoplasm risk at interval appendectomy. To our knowledge, there are no randomized clinical trials with sufficient patient numbers comparing these treatments.

Objective  To compare interval appendectomy and follow-up with magnetic resonance imaging after initial successful nonoperative treatment of periappendicular abscess.

Design, Setting, and Participants  The Peri–Appendicitis Acuta randomized clinical trial was a multicenter, noninferiority trial conducted in 5 hospitals in Finland. All patients between age 18 and 60 years with periappendicular abscess diagnosed by computed tomography and successful initial nonoperative treatment from January 2013 to April 2016 were included. Data analysis occurred from April 2016 to September 2017.

Interventions  Patients were randomized either to interval appendectomy or follow-up with magnetic resonance imaging; all patients underwent colonoscopy.

Main Outcomes and Measures  The primary end point was treatment success, defined as an absence of postoperative morbidity in the appendectomy group and appendicitis recurrence in the follow-up group. Secondary predefined end points included neoplasm incidence, inflammatory bowel disease, length of hospital stay, and days of sick leave.

Results  A total of 60 patients were included (36 men [60%]; median [interquartile range] age: interval appendectomy group, 49 [18-60] years; follow-up group, 47 [22-61] years). An interim analysis in April 2016 showed a high rate of neoplasm (10 of 60 [17%]), with all neoplasms in patients older than 40 years. The trial was prematurely terminated owing to ethical concerns. Two more neoplasms were diagnosed after study termination, resulting in an overall neoplasm incidence of 20% (12 of 60). On study termination, the overall morbidity rate of interval appendectomy was 10% (3 of 30), and 10 of the patients in the follow-up group (33%) had undergone appendectomy.

Conclusions and Relevance  The neoplasm rate after periappendicular abscess in this small study population was high, especially in patients older than 40 years. If this considerable rate of neoplasms after periappendicular abscess is validated by future studies, it would argue for routine interval appendectomy in this setting.

Trial Registration  ClinicalTrials.gov identifier: NCT03013686.

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