Appendicitis
Conditions
Keywords
Appendectomy, Appendicitis, False Positive Reactions, Humans, Radiation Dosage, Tomography, X-Ray Computed, Young Adult
Brief summary
To determine whether low-dose (LD) CT is noninferior to standard-dose (SD) computed tomography (CT) as the first-line imaging test in adolescents and young adults in regard to negative appendectomy rate (NAR).
Detailed description
* Acute appendicitis is a very common disease. Many patients are adolescents or young adults. * CT is the current standard imaging test for the diagnosis of appendicitis. * In recent years, the awareness of carcinogenic risk associated with CT radiation has increased. * According to a recent single-institutional randomized controlled trial, LD CT (employing a quarter of standard radiation dose) was found to be noninferior to SD CT with respect to NARs in adolescents and young adults with suspected appendicitis. * However, LD CT is not yet widely accepted. * To establish LD CT as the first-line imaging test, a multi-institutional study is needed to confirm the generalizability of the prior single-institutional study.
Interventions
DIAGNOSTIC_TESTDiagnostic CT with low-dose radiation
Effective dose is aimed at approximately 2 millisievert (mSv) in an average patient.
DIAGNOSTIC_TESTDiagnostic CT with standard-dose radiation
Effective dose is aimed at approximately 8 millisievert (or less) in an average patient.
Sponsors
Ministry of Health & Welfare, Korea
Seoul National University Bundang Hospital
Radiology Imaging Network of Korea for Clinical Research
The LOCAT Group
Kyoung Ho Lee, MD
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
DIAGNOSTIC
Masking
DOUBLE (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
15 Years to 44 Years
Healthy volunteers
No
Inclusion criteria
* Emergency department visit with suspected symptoms and signs of acute appendicitis * Intravenous contrast-enhanced computed tomography examination requested due to suspicion of appendicitis * Willing to provide telephone or cell phone numbers for follow-up * Signed informed consent provided prior to study entry
Exclusion criteria
* Prior cross-sectional imaging tests to evaluate the presenting symptoms and signs * Prior history of surgical removal of the appendix
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Negative Appendectomy Rate | 1 week after surgery | Negative appendectomy rate was defined as the percentage of negative (unnecessary) appendectomies among all non-incidental appendectomies. As a secondary analysis, negative appendectomy rate in an alternative definition was calculated by excluding cases with appendiceal neoplasms without superimposed appendicitis, as appendectomy would be clinically necessary in such patients. Any surgery performed for the treatment of presumed appendicitis was counted as non-incidental appendectomy, even though the surgical procedures were more extensive than simple appendectomy (e.g., ileocectomy). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Number of Appendectomies | 3 months after CT | Appendectomy rate. The percentage of appendectomies among all randomized cases. |
| Number of Negative Appendectomies | 1 week after surgery | The percentage of negative appendectomies among all randomized cases. In January, 2016, when more than 2000 patients were enrolled, the data and safety monitoring board noted a between-group imbalance in the number of appendectomies. Because of the concern that such an imbalance might potentially jeopardize the comparability for the prespecified endpoints, the study protocol was amended to adopt the following additional secondary endpoints, which were assessed among all randomly assigned patients: the number of appendectomies, number of negative appendectomies, prevalence of perforated appendicitis, and prevalence of non-perforated appendicitis. |
| Prevalence of Perforated Appendicitis | 1 week after surgery | The percentage (i.e., prevalence) of perforated appendicitis among all randomized cases. In January, 2016, when more than 2000 patients were enrolled, the data and safety monitoring board noted a between-group imbalance in the number of appendectomies. Because of the concern that such an imbalance might potentially jeopardize the comparability for the prespecified endpoints, the study protocol was amended to adopt the following additional secondary endpoints, which were assessed among all randomly assigned patients: the number of appendectomies, number of negative appendectomies, prevalence of perforated appendicitis, and prevalence of non-perforated appendicitis. |
| Prevalence of Non-perforated Appendicitis | 1 week after surgery | The percentage (i.e., prevalence) of non-perforated appendicitis among all randomized cases. In January, 2016, when more than 2000 patients were enrolled, the data and safety monitoring board noted a between-group imbalance in the number of appendectomies. Because of the concern that such an imbalance might potentially jeopardize the comparability for the prespecified endpoints, the study protocol was amended to adopt the following additional secondary endpoints, which were assessed among all randomly assigned patients: the number of appendectomies, number of negative appendectomies, prevalence of perforated appendicitis, and prevalence of non-perforated appendicitis. |
| Need for Additional Imaging Test(s) | 1 week after CT | The proportion of patients requiring additional imaging test(s) in order to diagnose or rule out appendicitis. |
| Delay in Patient Disposition | 3 months after CT | * The interval from CT acquisition to appendectomy in patients undergoing appendectomy. Interval appendectomies following percutaneous abscess drainage and/or medical treatment were not included in this analysis. * The interval from CT acquisition to hospital discharge in patients not undergoing surgery. |
| Appendiceal Perforation Rate | 1 week after surgery | The percentage of perforated appendicitis among confirmed appendicitis cases. |
| Diagnostic Performance of CT Reports - AUC | 3 months after CT | \- Area under the receiver-operating-characteristic curve (AUC). |
| Diagnostic Performance of CT Reports - Sensitivity and Specificity | 3 months after CT | * Diagnostic sensitivity and specificity: the 5-grade likelihood scores for appendicitis were collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. * Sensitivity is a proportion of the positive test among the patient confirmed as having appendicitis. * Specificity is a proportion of the negative test among the patient confirmed as not having appendicitis. |
| Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | 3 months after CT | * Likelihood score for appendicitis in patients confirmed as having appendicitis. * Likelihood score for appendicitis in patients confirmed as not having appendicitis. Grade 1 denotes appendicitis definitely absent; grade 2, appendicitis probably absent; grade 3, indeterminate for the presence of appendicitis; grade 4, appendicitis probably present; and grade 5, appendicitis definitely present. |
| Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Indeterminate Interpretation (Grade 3) | 3 months after CT | The frequency of indeterminate CT interpretation (grade 3). Grade 1 denotes appendicitis definitely absent; grade 2, appendicitis probably absent; grade 3, indeterminate for the presence of appendicitis; grade 4, appendicitis probably present; and grade 5, appendicitis definitely present. |
| Diagnostic Confidence in Ruling Out Appendicitis: Normal Appendix Visualization | 3 months after CT | The frequency of normal appendix visualization at CT. Grade 0 denotes appendix not identified; grade 1, unsure or partly visualized; and grade 2, clearly and entirely visualized. |
| Diagnosis of Appendiceal Perforation at CT | 3 months after CT | * Diagnostic sensitivity: the number of correct detections of the perforation divided by the number of cases of perforated appendicitis. * Diagnostic specificity: the number of correct ruling out the perforation divided by the number of cases of appendicitis without perforation. |
| Length of Hospital Stay Associated With Appendectomy | 3 months after CT | The interval from CT acquisition to hospital discharge after appendectomy. |
Countries
South Korea
Participant flow
Recruitment details
From 20 Korean teaching hospitals with predominantly limited experience in low-dose CT
Participants by arm
| Arm | Count |
|---|---|
| Low-dose CT 2 millisievert | 1,535 |
| Standard-dose CT 8 millisievert or lower | 1,539 |
| Total | 3,074 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Inappropriate enrollment | 4 | 6 |
| Overall Study | Withdrawal by Subject | 5 | 13 |
Baseline characteristics
| Characteristic | Standard-dose CT | Low-dose CT | Total |
|---|---|---|---|
| Abdominal tenderness Epigastric | 151 Participants | 147 Participants | 298 Participants |
| Abdominal tenderness Left lower quadrant | 97 Participants | 124 Participants | 221 Participants |
| Abdominal tenderness No tenderness | 139 Participants | 142 Participants | 281 Participants |
| Abdominal tenderness Other area(s) | 89 Participants | 106 Participants | 195 Participants |
| Abdominal tenderness Periumbilical | 129 Participants | 104 Participants | 233 Participants |
| Abdominal tenderness Right lower quadrant | 1303 Participants | 1305 Participants | 2608 Participants |
| Abdominal tenderness Suprapubic | 115 Participants | 112 Participants | 227 Participants |
| Age, Continuous | 28 years | 28 years | 28 years |
| Alvarado score High risk (9-10) | 88 Participants | 91 Participants | 179 Participants |
| Alvarado score Indeterminate risk (5-8) | 836 Participants | 864 Participants | 1700 Participants |
| Alvarado score Low risk (0-4) | 588 Participants | 564 Participants | 1152 Participants |
| Appendicitis inflammatory response score High risk (9-12) | 33 Participants | 20 Participants | 53 Participants |
| Appendicitis inflammatory response score Indeterminate risk (5-8) | 624 Participants | 643 Participants | 1267 Participants |
| Appendicitis inflammatory response score Low risk (0-4) | 846 Participants | 841 Participants | 1687 Participants |
| Body mass index (kg/m²) 18.5-24.9 (normal) | 1005 Participants | 1044 Participants | 2049 Participants |
| Body mass index (kg/m²) < 18.5 (underweight) | 147 Participants | 151 Participants | 298 Participants |
| Body mass index (kg/m²) 25.0-29.9 (overweight) | 292 Participants | 268 Participants | 560 Participants |
| Body mass index (kg/m²) ≥ 30.0 (obese) | 61 Participants | 50 Participants | 111 Participants |
| Body mass index (kg/m²) | 22.1 kg/m² | 21.9 kg/m² | 22.0 kg/m² |
| Body temperature | 36.8 ℃ | 36.8 ℃ | 36.8 ℃ |
| Chief complaint Abdominal pain | 1439 Participants | 1439 Participants | 2878 Participants |
| Chief complaint Fever | 24 Participants | 28 Participants | 52 Participants |
| Chief complaint Nausea/vomiting | 35 Participants | 37 Participants | 72 Participants |
| Chief complaint Others | 22 Participants | 22 Participants | 44 Participants |
| C-reactive protein (mg/dL) | 0.7 mg/dL | 0.8 mg/dL | 0.7 mg/dL |
| CT machine 128-channel | 567 Participants | 568 Participants | 1135 Participants |
| CT machine 16-channel | 300 Participants | 301 Participants | 601 Participants |
| CT machine 256-channel | 272 Participants | 272 Participants | 544 Participants |
| CT machine 64-channel | 381 Participants | 385 Participants | 766 Participants |
| Dose-length product (mGy·cm) | 486 mGy·cm | 132 mGy·cm | 274 mGy·cm |
| Duration of symptoms ≤ 12 hr | 621 Participants | 606 Participants | 1227 Participants |
| Duration of symptoms 13-24 hr | 430 Participants | 402 Participants | 832 Participants |
| Duration of symptoms 2-3 days | 354 Participants | 381 Participants | 735 Participants |
| Duration of symptoms ≥ 4 days | 115 Participants | 137 Participants | 252 Participants |
| Effective diameter (cm) < 20.0 | 242 Participants | 227 Participants | 469 Participants |
| Effective diameter (cm) 20.0-24.9 | 847 Participants | 891 Participants | 1738 Participants |
| Effective diameter (cm) 25.0-29.9 | 386 Participants | 362 Participants | 748 Participants |
| Effective diameter (cm) ≥ 30.0 | 45 Participants | 46 Participants | 91 Participants |
| Effective diameter (cm) | 22.8 cm | 22.8 cm | 22.8 cm |
| Iterative reconstruction Not used | 1362 Participants | 933 Participants | 2295 Participants |
| Iterative reconstruction Used | 158 Participants | 593 Participants | 751 Participants |
| Location of abdominal pain Epigastric | 118 Participants | 156 Participants | 274 Participants |
| Location of abdominal pain No pain | 32 Participants | 22 Participants | 54 Participants |
| Location of abdominal pain Other area(s) | 136 Participants | 177 Participants | 313 Participants |
| Location of abdominal pain Periumbilical | 173 Participants | 172 Participants | 345 Participants |
| Location of abdominal pain Right flank | 190 Participants | 209 Participants | 399 Participants |
| Location of abdominal pain Right lower quadrant | 1340 Participants | 1344 Participants | 2684 Participants |
| Location of abdominal pain Suprapubic | 204 Participants | 228 Participants | 432 Participants |
| Migration of pain No | 1068 Participants | 1060 Participants | 2128 Participants |
| Migration of pain Yes | 452 Participants | 466 Participants | 918 Participants |
| Race/Ethnicity, Customized Ethnicity Korean | 1504 Participants | 1520 Participants | 3024 Participants |
| Race/Ethnicity, Customized Ethnicity Non-Korean | 16 Participants | 6 Participants | 22 Participants |
| Radiologist who made initial CT report Attending radiologist | 863 Participants | 886 Participants | 1749 Participants |
| Radiologist who made initial CT report On-call radiologist or trainees | 657 Participants | 640 Participants | 1297 Participants |
| Rebound tenderness No | 950 Participants | 892 Participants | 1842 Participants |
| Rebound tenderness Yes | 570 Participants | 634 Participants | 1204 Participants |
| Segmented neutrophil (%) | 75 percentage of neutrophils | 75 percentage of neutrophils | 75 percentage of neutrophils |
| Sex: Female, Male Female | 834 Participants | 838 Participants | 1672 Participants |
| Sex: Female, Male Male | 686 Participants | 688 Participants | 1374 Participants |
| Site characteristics: annual number of appendectomies < 150 | 58 Participants | 59 Participants | 117 Participants |
| Site characteristics: annual number of appendectomies 150-299 | 323 Participants | 329 Participants | 652 Participants |
| Site characteristics: annual number of appendectomies 300-449 | 516 Participants | 518 Participants | 1034 Participants |
| Site characteristics: annual number of appendectomies ≥ 450 | 623 Participants | 620 Participants | 1243 Participants |
| Site characteristics: low-dose CT experience in the previous trial No | 1361 Participants | 1367 Participants | 2728 Participants |
| Site characteristics: low-dose CT experience in the previous trial Yes | 159 Participants | 159 Participants | 318 Participants |
| Site characteristics: number of beds < 650 | 360 Participants | 363 Participants | 723 Participants |
| Site characteristics: number of beds 650-949 | 535 Participants | 541 Participants | 1076 Participants |
| Site characteristics: number of beds ≥ 950 | 625 Participants | 622 Participants | 1247 Participants |
| Size-specific dose estimate (mGy) | 14.4 mGy | 4.1 mGy | 9.1 mGy |
| Target effective dose (low-dose CT vs. standard-dose CT) 2 mSv vs. 3 mSv | 23 Participants | 25 Participants | 48 Participants |
| Target effective dose (low-dose CT vs. standard-dose CT) 2 mSv vs. 5 mSv | 34 Participants | 34 Participants | 68 Participants |
| Target effective dose (low-dose CT vs. standard-dose CT) 2 mSv vs. 6 mSv | 396 Participants | 398 Participants | 794 Participants |
| Target effective dose (low-dose CT vs. standard-dose CT) 2 mSv vs. 7 mSv | 523 Participants | 527 Participants | 1050 Participants |
| Target effective dose (low-dose CT vs. standard-dose CT) 2 mSv vs. 8 mSv | 544 Participants | 542 Participants | 1086 Participants |
| Time of CT examination After hours | 869 Participants | 871 Participants | 1740 Participants |
| Time of CT examination Working hours | 651 Participants | 655 Participants | 1306 Participants |
| Volume CT dose index (mGy) | 9.4 mGy | 2.6 mGy | 5.2 mGy |
| White blood cell (10³/mm³) | 10.6 10³ cells/mm³ | 10.6 10³ cells/mm³ | 10.6 10³ cells/mm³ |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 1,535 | 0 / 1,539 |
| other Total, other adverse events | 0 / 1,535 | 0 / 1,539 |
| serious Total, serious adverse events | 43 / 1,535 | 40 / 1,539 |
Outcome results
Primary
Negative Appendectomy Rate
Negative appendectomy rate was defined as the percentage of negative (unnecessary) appendectomies among all non-incidental appendectomies. As a secondary analysis, negative appendectomy rate in an alternative definition was calculated by excluding cases with appendiceal neoplasms without superimposed appendicitis, as appendectomy would be clinically necessary in such patients. Any surgery performed for the treatment of presumed appendicitis was counted as non-incidental appendectomy, even though the surgical procedures were more extensive than simple appendectomy (e.g., ileocectomy).
Time frame: 1 week after surgery
Population: Patients who underwent appendectomy. Intention-to-treat.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Low-dose CT | Negative Appendectomy Rate | Negative appendectomy (NA) rate | 22 Participants |
| Low-dose CT | Negative Appendectomy Rate | Not counting appendiceal neoplasm(s) as NA | 21 Participants |
| Standard-dose CT | Negative Appendectomy Rate | Negative appendectomy (NA) rate | 16 Participants |
| Standard-dose CT | Negative Appendectomy Rate | Not counting appendiceal neoplasm(s) as NA | 16 Participants |
Comparison: Detailed in Ahn S, LOCAT Group. Trials 2014:15:28.95% CI: [-0.008, 0.033]
Secondary
Appendiceal Perforation Rate
The percentage of perforated appendicitis among confirmed appendicitis cases.
Time frame: 1 week after surgery
Population: Patients confirmed as having appendicitis. Intention-to-treat.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Low-dose CT | Appendiceal Perforation Rate | 182 Participants |
| Standard-dose CT | Appendiceal Perforation Rate | 176 Participants |
Comparison: Detailed in Ahn S, LOCAT Group. Trials 2014:15:28.95% CI: [-0.021, 0.091]
Secondary
Delay in Patient Disposition
* The interval from CT acquisition to appendectomy in patients undergoing appendectomy. Interval appendectomies following percutaneous abscess drainage and/or medical treatment were not included in this analysis. * The interval from CT acquisition to hospital discharge in patients not undergoing surgery.
Time frame: 3 months after CT
Population: Intention-to-treat.
| Arm | Measure | Group | Value (MEDIAN) |
|---|---|---|---|
| Low-dose CT | Delay in Patient Disposition | Interval between CT and appendectomy | 5.3 Hours |
| Low-dose CT | Delay in Patient Disposition | Interval between CT and discharge without surgery | 1.7 Hours |
| Standard-dose CT | Delay in Patient Disposition | Interval between CT and appendectomy | 5.4 Hours |
| Standard-dose CT | Delay in Patient Disposition | Interval between CT and discharge without surgery | 1.6 Hours |
Secondary
Diagnosis of Appendiceal Perforation at CT
* Diagnostic sensitivity: the number of correct detections of the perforation divided by the number of cases of perforated appendicitis. * Diagnostic specificity: the number of correct ruling out the perforation divided by the number of cases of appendicitis without perforation.
Time frame: 3 months after CT
Population: Patients confirmed to have appendicitis. Intention-to-treat.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Low-dose CT | Diagnosis of Appendiceal Perforation at CT | Sensitivity (%) | 43 Percentage |
| Low-dose CT | Diagnosis of Appendiceal Perforation at CT | Specificity (%) | 89 Percentage |
| Standard-dose CT | Diagnosis of Appendiceal Perforation at CT | Sensitivity (%) | 43 Percentage |
| Standard-dose CT | Diagnosis of Appendiceal Perforation at CT | Specificity (%) | 91 Percentage |
Secondary
Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Indeterminate Interpretation (Grade 3)
The frequency of indeterminate CT interpretation (grade 3). Grade 1 denotes appendicitis definitely absent; grade 2, appendicitis probably absent; grade 3, indeterminate for the presence of appendicitis; grade 4, appendicitis probably present; and grade 5, appendicitis definitely present.
Time frame: 3 months after CT
Population: Patients with incomplete reference standards were not included in these analyses. Intention-to-treat.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Indeterminate Interpretation (Grade 3) | 34 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Indeterminate Interpretation (Grade 3) | 53 Participants |
Secondary
Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis
* Likelihood score for appendicitis in patients confirmed as having appendicitis. * Likelihood score for appendicitis in patients confirmed as not having appendicitis. Grade 1 denotes appendicitis definitely absent; grade 2, appendicitis probably absent; grade 3, indeterminate for the presence of appendicitis; grade 4, appendicitis probably present; and grade 5, appendicitis definitely present.
Time frame: 3 months after CT
Population: Patients with incomplete reference standards were not included in these analyses. Intention-to-treat.
| Arm | Measure | Group | Category | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|---|
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 1 | 6 Participants |
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 2 | 9 Participants |
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 3 | 18 Participants |
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 4 | 91 Participants |
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 5 | 400 Participants |
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 1 | 742 Participants |
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 2 | 154 Participants |
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 3 | 16 Participants |
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 4 | 14 Participants |
| Low-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 5 | 9 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 3 | 34 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 1 | 6 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 1 | 710 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 2 | 5 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 5 | 8 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 3 | 19 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 2 | 103 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 4 | 68 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as not having appendicitis | Grade 4 | 10 Participants |
| Standard-dose CT | Diagnostic Confidence in Diagnosing and Ruling Out Appendicitis: Likelihood Score for Appendicitis | Patients confirmed as having appendicitis | Grade 5 | 466 Participants |
Secondary
Diagnostic Confidence in Ruling Out Appendicitis: Normal Appendix Visualization
The frequency of normal appendix visualization at CT. Grade 0 denotes appendix not identified; grade 1, unsure or partly visualized; and grade 2, clearly and entirely visualized.
Time frame: 3 months after CT
Population: Patients confirmed as not having appendicitis. Intention-to-treat.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Low-dose CT | Diagnostic Confidence in Ruling Out Appendicitis: Normal Appendix Visualization | Grade 0 | 36 Participants |
| Low-dose CT | Diagnostic Confidence in Ruling Out Appendicitis: Normal Appendix Visualization | Grade 1 | 137 Participants |
| Low-dose CT | Diagnostic Confidence in Ruling Out Appendicitis: Normal Appendix Visualization | Grade 2 | 762 Participants |
| Standard-dose CT | Diagnostic Confidence in Ruling Out Appendicitis: Normal Appendix Visualization | Grade 0 | 14 Participants |
| Standard-dose CT | Diagnostic Confidence in Ruling Out Appendicitis: Normal Appendix Visualization | Grade 1 | 64 Participants |
| Standard-dose CT | Diagnostic Confidence in Ruling Out Appendicitis: Normal Appendix Visualization | Grade 2 | 787 Participants |
Secondary
Diagnostic Performance of CT Reports - AUC
\- Area under the receiver-operating-characteristic curve (AUC).
Time frame: 3 months after CT
Population: Patients with incomplete reference standards were not included in these analyses. Intention-to-treat.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Low-dose CT | Diagnostic Performance of CT Reports - AUC | 0.983 AUC |
| Standard-dose CT | Diagnostic Performance of CT Reports - AUC | 0.986 AUC |
Secondary
Diagnostic Performance of CT Reports - Sensitivity and Specificity
* Diagnostic sensitivity and specificity: the 5-grade likelihood scores for appendicitis were collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. * Sensitivity is a proportion of the positive test among the patient confirmed as having appendicitis. * Specificity is a proportion of the negative test among the patient confirmed as not having appendicitis.
Time frame: 3 months after CT
Population: Patients with incomplete reference standards were not included in these analyses. Intention-to-treat.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Low-dose CT | Diagnostic Performance of CT Reports - Sensitivity and Specificity | Sensitivity (%) | 97.1 percentage |
| Low-dose CT | Diagnostic Performance of CT Reports - Sensitivity and Specificity | Specificity (%) | 95.8 percentage |
| Standard-dose CT | Diagnostic Performance of CT Reports - Sensitivity and Specificity | Sensitivity (%) | 98.0 percentage |
| Standard-dose CT | Diagnostic Performance of CT Reports - Sensitivity and Specificity | Specificity (%) | 94.0 percentage |
Secondary
Length of Hospital Stay Associated With Appendectomy
The interval from CT acquisition to hospital discharge after appendectomy.
Time frame: 3 months after CT
Population: Patients who underwent appendectomy. Intention-to-treat. Interval appendectomies following percutaneous abscess drainage and/or medical treatment were not included in this analysis.
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Low-dose CT | Length of Hospital Stay Associated With Appendectomy | 3.0 Days |
| Standard-dose CT | Length of Hospital Stay Associated With Appendectomy | 2.9 Days |
Secondary
Need for Additional Imaging Test(s)
The proportion of patients requiring additional imaging test(s) in order to diagnose or rule out appendicitis.
Time frame: 1 week after CT
Population: Intention-to-treat.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Low-dose CT | Need for Additional Imaging Test(s) | 39 Participants |
| Standard-dose CT | Need for Additional Imaging Test(s) | 41 Participants |
Secondary
Number of Appendectomies
Appendectomy rate. The percentage of appendectomies among all randomized cases.
Time frame: 3 months after CT
Population: Intention-to-treat.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Low-dose CT | Number of Appendectomies | 559 Participants |
| Standard-dose CT | Number of Appendectomies | 601 Participants |
Secondary
Number of Negative Appendectomies
The percentage of negative appendectomies among all randomized cases. In January, 2016, when more than 2000 patients were enrolled, the data and safety monitoring board noted a between-group imbalance in the number of appendectomies. Because of the concern that such an imbalance might potentially jeopardize the comparability for the prespecified endpoints, the study protocol was amended to adopt the following additional secondary endpoints, which were assessed among all randomly assigned patients: the number of appendectomies, number of negative appendectomies, prevalence of perforated appendicitis, and prevalence of non-perforated appendicitis.
Time frame: 1 week after surgery
Population: Intention-to-treat.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Low-dose CT | Number of Negative Appendectomies | 22 Participants |
| Standard-dose CT | Number of Negative Appendectomies | 16 Participants |
Secondary
Prevalence of Non-perforated Appendicitis
The percentage (i.e., prevalence) of non-perforated appendicitis among all randomized cases. In January, 2016, when more than 2000 patients were enrolled, the data and safety monitoring board noted a between-group imbalance in the number of appendectomies. Because of the concern that such an imbalance might potentially jeopardize the comparability for the prespecified endpoints, the study protocol was amended to adopt the following additional secondary endpoints, which were assessed among all randomly assigned patients: the number of appendectomies, number of negative appendectomies, prevalence of perforated appendicitis, and prevalence of non-perforated appendicitis.
Time frame: 1 week after surgery
Population: Intention-to-treat.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Low-dose CT | Prevalence of Non-perforated Appendicitis | 342 Participants |
| Standard-dose CT | Prevalence of Non-perforated Appendicitis | 388 Participants |
Secondary
Prevalence of Perforated Appendicitis
The percentage (i.e., prevalence) of perforated appendicitis among all randomized cases. In January, 2016, when more than 2000 patients were enrolled, the data and safety monitoring board noted a between-group imbalance in the number of appendectomies. Because of the concern that such an imbalance might potentially jeopardize the comparability for the prespecified endpoints, the study protocol was amended to adopt the following additional secondary endpoints, which were assessed among all randomly assigned patients: the number of appendectomies, number of negative appendectomies, prevalence of perforated appendicitis, and prevalence of non-perforated appendicitis.
Time frame: 1 week after surgery
Population: Intention-to-treat.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Low-dose CT | Prevalence of Perforated Appendicitis | 182 Participants |
| Standard-dose CT | Prevalence of Perforated Appendicitis | 176 Participants |