Table 1 Characteristics of included RCTs

Vons 2011 [23]

RCT,multicenter(6 centers)

n = 239 adult:>18 years;uncomplicated appendicitis

CT

n = 120 amoxicillin plus clavulanic acid 3 g ,iv 48 h,oral amoxicillin plus clavulanic for 8 days.

n = 119 a McBurney incision or laparoscopy

primary endpoint: occurrence of peritonitis within 30 days of initial treatment.

Secondary endpoints: 1.the number of days with a postintervention visual-analogue-scale pain score ≥ 4. 2. length of hospital stay. 3.absence from work. 4.incidence of complications other than peri tonitis within 1 year. 5.recurrence of appendicitis after antibiotic treatment

Salminen 2015 [8]

Salminen 2018 [24, Haijanen 2019 [50], Sippla 2017, Sippla 2020

RCT,multicenter(6 centers)

n = 530 adult:aged 18–60 years.uncomplicated appendicitis.

CT

n = 257 Ertapenem 1 g/d IV for 3 days, followed by 7 days of

oral levofloxacin (500 mg once daily) and metronidazole(500 mg 3 times per day).

n = 273 mostly Open appendectomy,laparoscopic appendectomy 5.5%.

primary endpoint: successful treatment.antibiotic group.

Secondary endpoints: 1.overall post intervention complications. 2.late recurrence (after 1 year) of acute appendicitis after conservative treatment 3.length of hospital stay 4.sick leave 5.postintervention pain scores 6.treatment costs

Otero 2022 [6]

RCT,multicenter(3 centers)

n = 39 children: aged 6–17 years. uncomplicated appendicitis.

ultrasound and/or computed tomography (CT)

n = 20 piperacillin/tazobactam iv for 24–48 h, followed by 10 days of oral ciprofloxacin and metronida-zole

n = 19 laparoscopic appendectomy

Primary endpoint: (1) one-year success rate of antibiotics-alone. (2) QOL measures assessed 1 month post discharge.

Secondary endpoints: length of stay and readmission rate.

Svensson 2015 [46]

Patkova 2020

Pilot RCT(2 centers).

n = 50 children: aged 5–15 years. acuteappendicitis,exclusing perforated appendicitis on the basis of generalized peritonitis、appendiceal mass.

ultrasound and/or computed tomography (CT)

n = 24 meropenem (10 mg/kg × 3 per 24 h) and metronidazole (20 mg/kg × 1 per 24 h) IV for at least 48 h,followed by 8 days of oral ciprofloxacin (20 mg/kg×2 per 24 h) andmetronidazole (20 mg/kg × 1 per 24 h).

n = 26 laparoscopic appendectomy

primary endpoint: resolution of symptoms without significant complications.

Secondary endpoints: 1.the time from randomization to discharge. 2.complications 3.recurrent appendicitis within 1 year 4.cost of treatment

Styrud 2006 [26]

RCT,multicenter(6 centers)

n = 252 adult, men:18–50 years. Excluded were patients with suspicion of perforation of the appendix.

laboratory results,the other diagnisis not clear.but The frequency of appendicitis was 97% in the surgery group.

n = 128 2 days of i.v. cefotaxime 2 g 12 hourly, and tinidazole 0.8 g daily,and received oral treatment with ofloxacin 200 mg twice daily, and tinidazole 500 mg twice daily for 10 days.

n = 124 open or laparoscopically

1.The cure rate of antibiotic group and operation group. 2.Recurrence rate of antibiotic group within one year 3.the time off work 4.Sick leave 5.Hospital stay

Peter O’Leary 2021 [35]

RCT

n = 186 adult:>16 years; uncomplicated appendicitis

< 45 years,US +/- MRI;>45 years,CT

n = 91 co-amoxiclav,1.2 g,IV 3 times daily until there was a clinical improvement followed by 5 days of oral co-amoxiclav(625 mg 3 times a day orally for 5 days).

n = 89 laparoscopic appendectomy

primary endpoint: evaluated the success rate for acute uncomplicated appendicitis at 1-year follow-up. Secondary endpoints: 1.quality of life 2.cost 3.length of stay 4.sickness days

Hall 2020

RCT

n = 54 children: aged 3–16 years. uncomplicated appendicitis.

clinical and laboratory parameters、adiologicalassessment.In this trial, just 28% of participants received an ultrasound.

n = 27 a minimum of 24 h broad spectrum intravenous antibiotics, After the initial 12-hour period of NBM(nil by mouth), oral intake was advanced as tolerated, received a total of 10 days antibiotics following randomisation。

n = 27 open or laparoscopic appendicectomy

primary endpoint: the recruitment rate into the trial. Secondary endpoints: 1.Performance of study procedures. 2. Willingness of parents, children and surgeons to take part in a randomised study comparing operative versus non-operative treatment and identify anticipated recruitment rate. 3. Clinical outcomes of trial treatment pathways.

Ceresoli 2018

prospective RCT

adult:aged 18–65 years. uncomplicated appendicitis.

appendicitis inflammatory response (AIR) score with the adjunct of ultrasound.

n = 19 intravenous administration of 1 g of Ertapenem once a day for 3 days during hospitalization and further administration of amoxicillin/clavulanate 1 g every 8 h for 5 days.

n = 22 laparoscopic appendectomy

primary endpoint: the success rate of the treatment. Secondary endpoints: 1.complication rate 2.negative appendectomy rate 3. long-term negative outcomes within a year 4.Length of hospital stay 5. work absence

Talan 2016

Pilot RCT

n = 30 children(n = 1) + adult: aged > 5 years. uncomplicated appendicitis

CT and/or ultrasonography:CT with intravenous contrast in adults and ultrasonography in persons younger than 18 years, followed by CT if indicated.

n = 16 intravenous ertapenem for 2 day,followed 8-day supply of an oral antibiotic regimen of cefdinir and metronidazole.

n = 14 open or laparoscopic appendectomy

primary endpoint: the one-month major complication rate. Secondary endpoints: 1. appendectomy rate in the antibiotics-first group 2.quality of life 3. days unable to perform normal activities and work or school 4.days of analgesic use 5. pain scores 6. total hours in the ED and hospital at the initial visit from triage until ED or hospital discharge 7. total hours in the hospital (including the ED) through 1 month 8. Alvarado scores on day 1 for both groups and day 2 for antibiotics-first participants 9. hospital charges.

Sajjad 2021 [36]

RCT

n = 180 children: aged 5–15 years. uncomplicated appendicitis.

Ultrasound (USG) findings、PAS score、laboratory results

n = 90 intravenous meropenem (10 mg/kg/dose intravenous infusion 8 hourly) and metronidazole (20 mg/kg/day intravenous divided doses 8 hourly) for at least 48 h. Followed oral ciprofloxacin (10 mg/kg/dose twice daily) and metronidazole (20 mg/kg/day two divided doses) for another 8 days

n = 90 open appendectomy

1.successful cute rate 2.Total leukocyte count 3. C reactive protein

Eriksson 1995 [47]

RCT

n = 40 adult: aged 18–75 years, acute appendicitis.

ultrasonography and laboratory tests

n = 20 Cefotaxime 2 g 12 hourly and tinidazole 800 mg daily were given for 2 days, followed oral treatment with ofloxacin 200 mg twice daily and tinidazole 500 mg twice daily for 8 days.

n = 20 open appendectomy

1.Mean concentration of C-reactive protein during hospitalization and at 30 days of follow-up 2.Mean total white blood cell count during hospitalization and at 30 days of follow-up 3.Pain record during hospitalization and at 30 days of follow-up 4.cute rate

CODA collaborative 2020 [7]

RCT, multicenter(25 centers)

n = 1552 adult

computed tomography

(CT) alone or in combination with ultrasonography

or magnetic resonance imaging

n = 776 received an intravenous formulation for at least 24 h, followed by pills, for a 10-day total course. Clinical teams selected antibiotics from Surgical Infection Society and Infectious Diseases Society of America guidelines for intraabdominal infections.

n = 776 laparoscopic(96%) and open appendectomy

primary endpoint: 30-day health status

Secondary endpoints: 1.patient-reported resolution of symptoms 2.Visits to the emergency department or urgent care clinic for related symptoms 3. days in the emergency department or hospital related to appendicitis symptoms or treatment-related complications 4.days of missed work for the participant and the caregiver