Diagnosis of Acute Appendicitis: Low-dose Computed Tomography (CT) Versus Standard-dose CT

Study Overview
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Brief Summary
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The purpose of this study is to determine whether low-dose CT is not inferior to standard-dose CT in the rate of unnecessary appendectomy.

Detailed Description
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Acute appendicitis is a very common disease with the lifetime incidence of 7%. Abdomen CT is an established first-line diagnostic test in patients suspected of having acute appendicitis. Since many individuals suspected of having acute appendicitis are young, with a mean age of 30 years, CT radiation is of particular concern. The estimated lifetime attributable risk of death from cancer due to the radiation exposure of a single abdomen CT study is 2-7/10,000 for average adults ranging 20-40 years in age. The purpose of this study is to determine whether low-dose CT is not inferior to standard-dose CT in the negative appendectomy rate.

Official Title
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Negative Appendectomy Rate Following Low-dose CT vs. Standard-dose CT

Conditions
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Appendicitis

Intervention / Treatment
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* Radiation: Diagnostic CT
* Radiation: Diagnostic CT


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Suspected of having acute appendicitis Referred for abdomen CT from Emergency Department Exclusion Criteria: Body mass index < 18.5 kg/m2 (ultrasonography is favored) Intravenous contrast-enhancement is contraindicated

Ages Eligible for Study
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Minimum Age: 15 Years
Maximum Age: 44 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Low-dose CT<br> | Radiation: Diagnostic CT<br>* 2 mSv in an average patient (Low-dose (1/4 to 1/5 of standard-dose))<br>* Other names: low-dose CT;|
| Active Comparator: Standard-dose CT<br> | Radiation: Diagnostic CT<br>* 8 mSv in an average patient (Standard-dose CT)<br>* Other names: standard-dose CT;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Negative Appendectomy | Number of participants with unnecessary appendectomies (removal of un-inflamed appendix) | 1 week after surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Additional Imaging Test(s) | Number of participants who need additional imaging test(s) to diagnose or rule out appendicitis | 1 week after CT | 
| Appendiceal Perforation | Number of participants with appendiceal perforation | 1 week after surgery | 
| Interval Between CT and Appendectomy | Time interval between the CT acquisition and non-incidental appendectomy | 1 day after surgery | 
| Interval Between CT and Discharge Without Surgery | Time interval between the CT acquisition and discharge without surgery | 3 months after CT | 
| Interval From CT to Discharge After Appendectomy | Time interval between the CT acquisition and discharge after appendectomy | 3 months after CT | 
| Likelihood of Appendicitis in CT Report in Patients Confirmed as Having Appendicitis | Grade 1. Definitely absent. Clinical observation is recommended. Grade 2. Probably absent. Clinical observation is recommended. Grade 3. Indeterminate. Clinical observation or surgical exploration is recommended. Grade 4. Probably present. Surgical exploration is recommended. Grade 5. Definitely present. Surgical exploration is recommended. The data is used to calculate sensitivity, specificity, area under receiver-operating-curve and to measure diagnostic confidence. | 3 months after CT | 
| Likelihood of Appendicitis in CT Report in Patients Confirmed as Not Having Appendicitis | Grade 1. Definitely absent. Clinical observation is recommended. Grade 2. Probably absent. Clinical observation is recommended. Grade 3. Indeterminate. Clinical observation or surgical exploration is recommended. Grade 4. Probably present. Surgical exploration is recommended. Grade 5. Definitely present. Surgical exploration is recommended. The data are used to calculate sensitivity, specificity, area under receiver-operating-curve and to measure diagnostic confidence. | 3 months after CT | 
| Diagnosis of Appendiceal Perforation in CT in Patients With Confirmed Appendicitis. | True positive: Perforation was rated as present in CT report and confirmed as present. False positive: Perforation was rated as present in CT report and confirmed as absent. True negative: Perforation was rated as absent in CT report and confirmed as absent. False negative: Perforation was rated as absent in CT report and confirmed as present. The data are used to calculate sensitivity and specificity. | 3 months after CT | 
| Visualization of the Normal Appendix | Grade 0. Not identified Grade 1. Unsure or partly visualized Grade 2. Clearly and entirely visualized | 3 months after CT |