CT Carcinogenic Risk in Patients With Appendicitis

Study Overview
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Brief Summary
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The purpose of this study is to compare the incidence rate of leukemia between CT-exposed and CT-unexposed group in patients who underwent appendectomy in South Korea.

Detailed Description
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South Korea has a single-payer healthcare system, administered by National Health Insurance Service (NHIS). As healthcare providers in South Korea need to claim reimbursement to NHIS for the vast majority of diagnostic and therapeutic procedures, the NHIS database enabled us to construct a large cohort who did or did not undergo CT for appendicitis. The purpose of this study is to compare the incidence rate of cancer between CT-exposed and CT-unexposed group in patients who underwent appendectomy in South Korea.

Official Title
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Carcinogenic Risk of CT in Patients With Appendicitis

Conditions
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Computed Tomography, Carcinogenesis, Radiation Exposure, Appendicitis

Intervention / Treatment
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* Radiation: Abdomen CT


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients will be entered in the cohort on the date of appendectomy under the diagnosis of appendicitis Exclusion Criteria: (a) patients who had a cancer diagnosis before the date of appendectomy, (b) those who had prior experience of CT examination more than 7 days before appendectomy, (c) those who had syndromes or diseases predisposing cancers, (d) those whose diagnosis was changed to appendiceal cancer and (e) those whose follow-up duration was shorter than a lag period.
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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| CT-exposed group<br> | Radiation: Abdomen CT<br>* Patients are divided into CT-exposed or unexposed group according to the presence of claims codes of abdominopelvic CT conducted within seven days before and after appendectomy. The seven-day threshold is arbitrarily determined considering the delay in the diagnosis of appendicitis and the postoperative examination for surgical complication.<br>|
| CT-unexposed group<br> | Radiation: Abdomen CT<br>* Patients are divided into CT-exposed or unexposed group according to the presence of claims codes of abdominopelvic CT conducted within seven days before and after appendectomy. The seven-day threshold is arbitrarily determined considering the delay in the diagnosis of appendicitis and the postoperative examination for surgical complication.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Age and sex-standardized incidence rate ratio (IRR) for malignancies of hematologic system | Hematologic malignancies are categorized into lymphomas, multiple myeloma, leukemias, myelodysplasia and others using ICD-10 codes. | Cancer occurrence after a lag period (2 years) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Age and sex-standardized incidence rate ratio (IRR) for malignancies of abdominal organs | age and sex-standardized IRRs for malignancies of abdominal organs for CT-exposed versus unexposed patients. | Cancer occurrence after a lag period (2 years) | 
| Age and sex-standardized incidence rate ratio (IRR) for all cancers | age and sex-standardized IRRs for all cancers for CT-exposed versus unexposed patients. | Cancer occurrence after a lag period (2 years) |