Raja Isteri Pengiran Anak Saleha Appendicitis Treatment Without Operation

Introduction:

Acute appendicitis is one of the most common surgical emergencies, with a lifetime prevalence approximately 1 in 7. The incidence is 1.5-1.9 per 1000 in a male and female population with approximately 1.4 times greater in men than in women.

Despite being a common problem, acute appendicitis remains a difficult diagnosis to establish, particularly in the young, elderly and female of reproductive age. Delay in surgery may risk appendicular perforation and sepsis. Reduced diagnostic accuracy and early surgery risk significantly high negative appendicectomy rate of about 20-40%. Diagnostic accuracy can be further improved by using ultrasonography or computed tomography scan. However, these modalities are costly and may not easily be available when needed.

Clinical prediction rule (CPR) such as Alvarado score, the modified Alvarado score, and the RIPASA score have been developed to improve the diagnostic accuracy of acute appendicitis. Alvarado and Modified Alvarado scores have been reported to have very low sensitivity and specificity when applied to an Asian population with a completely different ethnic origin and diet. Thus RIPASA score was developed specifically for an Asian population and have been reported to have a significantly better sensitivity (98%) and specificity (82%) over the former two scores. Since 2009, the RIPASA score has undergone broad validation in different population settings with a different prevalence of acute appendicitis across the world and reported similarly high sensitivity and specificity.

The standard management of acute appendicitis has remained largely been unchallenged since the late 19th century, largely because of the belief that if left untreated surgically, acute uncomplicated appendicitis will progress to perforation and peritonitis with increased morbidity and mortality. Furthermore current surgical management of acute appendicitis is associated with an unacceptably high negative appendicectomy rate of about 20-40% and significant post-operative complications.

Antibiotic non-operative therapy of intra-abdominal sepsis has been accepted as mainstay therapy for a condition such as diverticulitis. Since 2009, antibiotic non-operative therapy has been increasingly proposed as an alternative strategy for early uncomplicated acute appendicitis (EuAA) and has also been reported to be safe and effective in children with acute appendicitis complicated by perforation, abscess or phlegmon formation.

However, despite multiple randomized controlled trials (RCTs) and meta-analyses, the role of antibiotics in the management of EuAA in adults remains controversial. Early RCTs have reported treatment efficacy for antibiotic non-operative management strategy (AMS) of EuAA as high as 88-91% with a recurrence rate of acute appendicitis at 13-14% at 1-year follow-up. More recent RCTs comparing AMS versus surgical management strategy (SMS) have not been able to confirm non-inferiority of AMS over SMS. These later findings were also been supported by multiple recent meta-analyses. The discrepancies in reported studies are due to a lack of agreeable definition of EuAA, which was the common recommendation by all the recent meta-analyses. The NOTA study in 2014 reported using clinical prediction rules such as Acute Inflammatory Response (AIR) score (mean score of 4.9) and Alvarado score (mean score of 5.2) to define their group with EuAA, but this was only a prospective cohort study design and the mean score used were well below the threshold for diagnosing acute appendicitis.

RIPASA Score provides a range of score from 3.0-16.5 for diagnosing acute appendicitis. RIPASA score less than 7 are considered having a low probability of acute appendicitis and RIPASA score more than 7.5 are considered high probability of acute appendicitis. Thus it may be possible to identify a group of patients with EuAA based on their RIPASA score range who may benefit from AMS.

This study-working hypothesis is that RIPASA score as a CPR can determine a group of patients with a diagnosis of EuAA, who will benefit from AMS rather than SMS. The primary specific aim of this study is to confirm the non-inferiority status of AMS over SMS in EuAA. Secondary specific aims are to determine the range of RIPASA score which can be considered as providing a firm diagnosis of EuAA which can be management with AMS rather than SMS, step 3 impact analysis of RIPASA score as a CPR, and improve patient outcomes in terms of reducing unnecessary negative appendicectomy rate, hospital stay and complications arising from such surgery, and ultimately financial cost savings.

Methodology:

Trial Design:

This study also known as RIPASA-TWO trial is designed as a single center, open-label, non-inferiority, prospective RCT to compare 2 management strategies for suspected EuAA, AMS versus SMS, using RIPASA score to identify the group of patients with EuAA and to monitor the progression of the disease and guiding surgical decision based on the participants' RIPASA score.

Population and Study Setting:

The study setting will be based at Raja Isteri Pengiran Anak Saleha (RIPAS) Hospital, a tertiary referral center. All staffs of the Department of General Surgery (GS) and Accident \& Emergency (A\&E) Department at RIPAS Hospital will be brief of the trial design and purpose.

Recruitment:

Patients presenting to A\&E Department at RIPAS Hospital with right iliac fossa pain will be triaged and seen by the Casualty Officer. RIPASA score will be derived. Patients with RIPASA score between 7.5 to 11.5 and who satisfy the study inclusion and exclusion criteria will be referred to the on-call surgical medical officer (MO) for recruitment to RIPASA-TWO trial. Antibiotics will be withheld until patients have been seen by the surgical MO on duty and the RIPASA score is confirmed. The Surgical MO will inform and explain to the patient and family of the study and a study information sheet will be provided. Upon written signed consent to be recruited for the RIPASA-TWO trial, patients will be randomized to either arms - AMS or SMS.

Allocation concealment:

A variable block randomization sequence of 4,6 and 8 will be used to allocate participants to either AMS or SMS. A web-based program will be used and accessed via secured username and password, to obtain randomization allocation for the recruited participants. Once the randomization allocation code has been given, the surgical MO will allocate the treatment according to the randomized arm. Recruitment will be stratified to two RIPASA score range, 7.5-9.5 and 10.0-11.5.

Study Protocol:

The surgical MO/SMO will login into the randomization allocation software to acquire the randomization allocation arm and code. The patient will then be admitted to GS inpatient wards. Patients randomized to AMS arm will receive the allocated antibiotic treatment. Those randomized to SMS arm will receive the usual Departmental antibiotic policy of preoperative antibiotics prior to appendicectomy.

For patients in the AMS arm, the RIPASA score will be repeated to monitor the progression of the patient's condition after 24 hours. If RIPASA score remains stable or decreasing, the patient will continue on the allocated intravenous (iv) antibiotic treatment. If RIPASA score is increasing but remain below 11.5, the team looking after the patient can consider ordering further investigations such as ultrasound or CT scan, but patients will continue at this point on the antibiotic. If the RIPASA score increases to above 12, the surgeon can consider appendicectomy.

For patients in the AMS arm who have not cross over to surgery, they will continue with iv antibiotics for 48 hours and if symptoms improved with decreasing RIPASA score to below 7.5, the antibiotic will be changed to oral route and the patient monitored regularly. If RIPASA score goes below 5, the patient can be considered for discharge and follow-up in 1 week in the clinic with an oral antibiotic for a total of 7 days.

For patient randomized to the SMS arm, patients will undergo appendicectomy, unless their repeated RIPASA score decreases to below 7.5 or if their symptoms improved. For these patients, they will remain on iv antibiotics and will be changed to oral route after 48 hours. If RIPASA score goes below 5, the patient can be considered for discharge and follow-up in 1 week in the clinic with an oral antibiotic for a total of 7 days.

Antibiotic:

Intravenous Amikacin 15mg/kg/day divided over 3 doses for 48 hours will be the antibiotic of choice for RIPASA-TWO trial and is based on the microbial antibiotic sensitivity from pus swab taken for all appendicectomy from the previous year (2016). After 48 hours, this will be converted to oral ciprofloxacin 500mg bd for 7 days. For patients allocated to SMS arm, the Department antibiotic policy is for a preoperative antibiotic combination of intravenous Cefuroxime 1.5g TDS and 500mg metronidazole TDS.

Statistical methods:

Sample size calculation:

According to Chong et al, the reported negative appendicectomy rate based on the RIPASA score was 14.7%. Hence this 14.7% can be considered as surgical treatment failure due to an unnecessary operation and the surgical treatment efficacy is about 85.3%.

The non-inferiority margin for RIPASA-TWO trial will be set based on this surgical treatment failure rate of 14.7%. Using the FDA-approved non-inferiority margin of 50% reduction in efficacy or 50% increase in failure rate will give AMS an acceptable failure rate of 22%. Thus a treatment failure for AMS between 14-22% will be considered as confirmation of non-inferiority. A treatment failure of less than 14% will be considered as superiority. Hence based on a difference in treatment efficacy rate of 7% (22% vs 14%), with a sample size powered at 80% at 5% significance, the sample size needed to show non-inferiority is 91 in each group. Assuming a dropout rate of 25%, the total number of patients needed to be recruited is 228 patients, based on a 1:1 recruitment.

All statistical analysis will be performed using SPSS statistical program. Categorical data will be presented using frequencies and percentages. Continuous data will be presented as mean ± SD. All analysis will be conducted based on intention-to-treat principle and per-protocol analysis. Statistical analysis for categorical data will be carried out using Chi Square exact test. Differences between groups with normally distributed variables will be tested using independent sample t-test. Variables with no normal distribution will be tested using Wann-Whitney test. Non-inferiority for AMS will be tested using one-sided Wald tests with an α level of 0.05.

Duration of Study:

Based on the previous study, the recruitment of 200 consecutive patients with acute appendicitis, took over 8 months. Half of this group had RIPASA score from 7.5 to 11.5. Thus for a sample size of 228 for the RIPASA-TWO trial, the expected recruitment time is about 19 months. Hence the study will be expected to complete within 2 years.

Interim Analysis:

An interim analysis will be conducted at 2-time points. For changes to antimicrobial sensitivity, the interim analysis will be conducted at every 6 months and any changes will be discussed with the Data Safety Monitoring Board for proposed changes to the antibiotic regime. The main study interim analysis will be conducted at 1-year post recruitment to assess safety efficacy of the trial to ensure that not too many patients are developing complicated acute appendicitis in the AMS arm.

Ethical Consideration:

Ethics approval for the study has been granted by the Medical and Health Research and Ethics Committee based in RIPAS Hospital.