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Salminen P, et al. "Antibiotic Therapy vs Appendectomy for Treatment of Uncomplicated Acute Appendicitis: The APPAC Randomized Clinical Trial". JAMA. 2015. 313(23):2340-2348.
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Clinical Question

Is antibiotic treatment for adult patients with acute appendicitis confirmed by computed tomography (CT) inferior compared to appendectomy?

Bottom Line

In adult patients with CT-proven, uncomplicated appendicitis initial non-surgical, antibiotic treatment did not meet the prespecified non-inferiority margin for success compared to surgery (medical management successful 75% of the time). However, the majority (72.7%) of patients who received antibiotic treatment did not require appendectomy 1 year following antibiotic treatment, and those who did have an appendectomy did not have significant complications.

Major Points

About 1 in 10 people undergo an appendectomy for acute appendicitis during their lifetime.[1] Despite the high incidence, the efficacy of an antibiotics-only approach is of unknown efficacy. There has been one Cochrane analysis [2] and several meta-analyses [3][4][5][6][7] comparing antibiotic treatment to appendectomy. In general, these trials were small and/or had eligibility criteria (e.g., no females) that limited generalizability. These trials showed that antibiotic therapy was inferior to appendectomy for acute appendicitis and the success rates of antibiotic treatment was 70-80% [8][9].

Published in 2015, the Appendicitis Acuta (APPAC) trial randomized 530 patients at 6 Finnish hospitals to surgical or medical initial management of acute appendicitis in open label fashion. Rather than the customary unified primary outcome, each arm had its own outcome. For surgical management the outcome was the successful completion of an appendectomy. For medical management, it was successful completion of antibiotics that didn't require an appendectomy in the following year. The success rate for surgery in this trial was 99.6%. The investigators prespecified that the non-inferiority margin for the medical management compared to surgical management to be 24% (i.e., participants in the antibiotic arm would not need surgery ~75% of the time). Ultimately, medically-managed patients did not require surgery 72.7% of of the time and the non-inferiority margin of antibiotics was not met.

While the authors concluded that while antibiotic treatment did not meet the specified non-inferiority margin, they do not discount antibiotic therapy as a treatment option for acute uncomplicated appendicitis. The 24% non-inferiority margin was based upon the anticipated success rate from prior literature and is not a clinically-meaningful threshold. The majority of patients who received antibiotic treatment did not require an interval appendectomy in the following year and had minimal or no complications. None of the 27.3% of patients who ultimately required a delayed appendectomy had significant complications such as intraabdominal abscesses or serious infection.

This trial was not blinded and the decision to pursue surgical intervention was largely driven by professional opinion of the surgical team. It is unclear if the non-inferiority margin would have been met in a blinded study or in an unblinded study with objective criteria to pursue surgical intervention.


As of July 2018, no guidelines have been published that reflect the results of this trial.


The full methodology for this trial was published elsewhere.[10]

  • Multicenter, non-inferiority, open label, randomized, controlled trial
  • N=530
    • Surgery (n=273)
    • Antibiotics (n=257)
  • Setting: 6 hospitals in Finland
  • Enrollment: November 2009-June 2012
  • Mean follow-up: 1 year
  • Analysis: Intention-to-treat
  • Primary outcome: Treatment efficacy, which was defined differently for each group.


Inclusion Criteria

  • 18-60 years old
  • CT diagnosis of uncomplicated acute appendicitis: Appendix wall greater than 6mm with one of the following:
    • Abnormal contrast enhancement
    • Inflammatory edema
    • Fluid collection around appendix

Exclusion Criteria

  • Pregnancy or lactating
  • Allergy to contrast media or iodine
  • CKD with serum creatinine >150 μmol/l (1.7 mg/dL)
  • Metformin medication
  • Peritonitis
  • Other serious illness
  • Complicated acute appendicitis in a CT scan, defined by presence of an appendicolith, perforating, periappendicular abscess or suspicion of a tumor

Baseline Characteristics

From the surgery group

  • Demographics: Male sex 64%, median age 35
  • Median VAS pain score: 6
  • Labs: CRP 36 mg/L, hgb 14.3 g/dL, leukocyte count 12.0 x109/L, creatinine 72.2 umol/L (0.82 mg/dL)
  • Hours of symptom duration:
    • 1-6: 16
    • 6-12: 31
    • 12-18: 64
    • >18: 160


  • Participants were randomized to group:
    • Surgery - Open appendectomy, though surgeons could opt for laparoscopic (5.5% in this trial). They received cefuroxime 1.5 and metronidazole 500 mg 30 minutes prior to incision and no further antibiotics unless there a wound infection.
    • Antibiotics - Ertapenem 1 g IV daily was administered for 3 days, first dose in the emergency department, then levofloxacin 500 mg po qday x7 days with metronidazole 500 mg PO TID. Patients were reevaluated 12-24 hours following admission the on-call surgeon. If there was evidence of progressive infection, perforated appendicitis or peritonitis the patient underwent appendectomy.


Comparisons surgery vs. antibiotics except where specified.

Primary Outcomes

Treatment efficacy
Successful surgery, surgical group: 99.6% (95% CI, 98.0%-100.0%)
Did not require surgery in the following year, antibiotic group 72.7% (95% CI 66.8%-78.0%)
Intention-to-treat analysis yielded difference of -27.0% (95% CI −31.6% -∞; P=0.89) between groups
This did not meet the non-inferiority margin of 24%.

Secondary Outcomes

Overall complication rate
20.5% (95% CI 15.3-26.4; P<.001) vs. 2.8% (95% CI 1.0-6.0; P<.001)
Surgical site infections- Organ space, No.
1 vs. NA
Surgical site infections- Deep incisional, No.
4 vs. NA
Surgical site infections- Superficial, No.
19 vs. 1
Incisional hernias No.
2 vs. NA
Abdominal, incisional pain, or obstructive symptoms, No.
23 vs 4
Length of primary hospital stay, median (25th-75th percentile), days
3.0 (2-3) vs. 3.0 (3-3) (P<.001)
VAS score, median (25th-75th percentile)- At discharge from hospital
3.0 (2-4) vs. 2.0 (1-2) (P<.001)
VAS score, median (25th-75th percentile)- At 1 week post discharge
2.0 (1-3) vs. 1.0 (1-1) (P<.001)
VAS score, median (25th-75th percentile)- At 2 months post discharge
1.0 (1-1) vs. 1.0 (1-1) (P=.40)
Length of sick leave, median (25th-75th percentile), d
19.0 (14-21) vs. 7.0 (7-12) (P<.001)

Adverse Events

Appendicular tumor
4 (3 neuroendocrine, 1 adenoma) vs. 0


  • Difficulty recruiting patients since appendectomy is considered the standard treatment.
  • Most appendectomies were performed using the open approach. Surgical complications may have been lowered with a laparoscopic approach.
  • The outcome of the surgical group was not patient-centered. A more appropriate outcome may have been postoperative complications and disability, for which there was a 20% rate in this arm. This would have.[11]
  • Triple therapy with antibiotics may be excessive and may lead to more antibiotic resistance. Likewise, requiring CT scans to confirm the diagnoses was likely unnecessary in some cases and contributed to excess radiation exposure.[12]
  • Duration of antibiotic therapy may have been excessive.[13]


The authors declared that they have no competing interests.

Further Reading

  1. Flum DR & Clinical practice. Acute appendicitis--appendectomy or the "antibiotics first" strategy. N. Engl. J. Med. 2015. 372:1937-43.
  2. Wilms IM et al. Appendectomy versus antibiotic treatment for acute appendicitis. Cochrane Database Syst Rev 2011. :CD008359.
  3. Ansaloni L et al. Surgery versus conservative antibiotic treatment in acute appendicitis: a systematic review and meta-analysis of randomized controlled trials. Dig Surg 2011. 28:210-21.
  4. Liu K & Fogg L Use of antibiotics alone for treatment of uncomplicated acute appendicitis: a systematic review and meta-analysis. Surgery 2011. 150:673-83.
  5. Mason RJ et al. Meta-analysis of randomized trials comparing antibiotic therapy with appendectomy for acute uncomplicated (no abscess or phlegmon) appendicitis. Surg Infect (Larchmt) 2012. 13:74-84.
  6. Varadhan KK et al. Antibiotic therapy versus appendectomy for acute appendicitis: a meta-analysis. World J Surg 2010. 34:199-209.
  7. Varadhan KK et al. Safety and efficacy of antibiotics compared with appendicectomy for treatment of uncomplicated acute appendicitis: meta-analysis of randomised controlled trials. BMJ 2012. 344:e2156.
  8. Varadhan KK et al. Safety and efficacy of antibiotics compared with appendicectomy for treatment of uncomplicated acute appendicitis: meta-analysis of randomised controlled trials. BMJ 2012. 344:e2156.
  9. Styrud J et al. Appendectomy versus antibiotic treatment in acute appendicitis. a prospective multicenter randomized controlled trial. World J Surg 2006. 30:1033-7.
  10. Paajanen H et al. A prospective randomized controlled multicenter trial comparing antibiotic therapy with appendectomy in the treatment of uncomplicated acute appendicitis (APPAC trial). BMC Surg 2013. 13:3.
  11. Minneci PC & Deans KJ Treatment of Uncomplicated Acute Appendicitis. JAMA 2015. 314:1401-2.
  12. Alfa-Wali M et al. Treatment of Uncomplicated Acute Appendicitis. JAMA 2015. 314:1402-3.
  13. Pollara G & Marks M Treatment of Uncomplicated Acute Appendicitis. JAMA 2015. 314:1402.